Iw|.. "V J, ‘ ‘ .f1. .15 In h: (7. . .1" ("I I ‘23 m r .< I I (I {a 1‘ l' 1.1anth u- w. r to. ..‘l..r1......§.r.;ttr£3l| ..1wl..1.~r..na .4... .m:..‘.|.r.....!‘.. ‘1: £11.. I .nlq. ,1 I ‘ u'.0l| \v?v. ‘ ...... AI LIBRARY Michigan State University This is to certify that the thesis entitled CALF HOUSING MOISTURE AND TEMPERATURE CONTROL presented by Truman Carl Surbrook has been accepted towards fulfillment of the requirements for PhD degree in Agricultural Engineering 77M £62m Major professor Date /O/7/77 // 0-7 639 CALF HOUSING MOISTURE AND TEMPERATURE CONTROL BY Truman Carl Surbrook A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Agricultural Engineering 1977 (g); .2 / \— ABSTRACT CALF HOUSING MOISTURE AND TEMPERATURE CONTROL BY Truman Carl Surbrook The purpose of this research was to investigate important environmental design parameters for confinement calf housing. Two identical housing units designed to house eleven calves in tie stalls and instruments were constructed. The building design was consistent with presently accepted recommendations for construction and insulation. The only deviation from typical farm housing and management was that the housing units were placed inside an insulated, unheated, research barn to eliminate the direct influence of solar radiation and wind upon the structure. Instrumentation was provided to determine and record dry and wet bulb temperatures at specific locations, and to measure electrical energy consumption for heating and ventilation. An orifice meter was designed, con- structed and installed in each calf housing inlet air duct to permit accurate determination of air flow through the calf chambers. Truman Carl Surbrook Heat and moisture production rates for Holstein bull calves one to eight weeks of age were determined by operating the calf chambers as open ventilation direct respiratory calorimeters. The inside environment was allowed to reach steady state conditions without supple- mental heat. Calf heat and moisture production was cal- culated directly from the inlet and exhaust air conditions at steady state. Inside environment computer simulation output was compared with calf heat and moisture production rates determined by calorimetry. Total stable heat and stable moisture production for the calf on a unit weight basis decreased with increasing calf weight. Moisture production increased with an increase in ambient tempera- ture above 100 Celsius. Studies were conducted of continuous minimum ventilation versus thermostat, time clock and humidistat control. Continuous minimum ventilation of 0.0625m3/min. per kilogram of body weight provided a good inside environment for the calves. Thermostat fan control was tested, however, relative humidity was maintained at a higher level than with continuous ventilation. Control set to operate fan above 60 percent relative humidity was effective at maintaining temperature and relative humidity at acceptable levels for winter conditions. A single four level fan ventilation system control was designed and tested. This system was capable of providing Truman Carl Surbrook an acceptable inside environment with automatic ventila- tion rate control under winter and spring conditions. Heated inlet air was compared to cold inlet air and was more acceptable.. Cold drafts on animals from the inlet were eliminated and the inside air temperature difference from ceiling to floor was less than with cold inlet air. Air flow patterns were evaluated. Cold inlet air directed down along the wall from the inlet caused severe cold drafts on calves. Major Professor Approved Wig/é fl EVVV‘fi/q/l Approved 0 Department ACKNOWLEDGMENTS I wish to express my appreciation to Dr. Merle L. Esmay, Dr. William G. Bickert, Dr. Russel Erickson and Dr. Galen K. Brown for their guidance and valuable assistance while conducting this research. I also wish to express appreciation to the tech— nical staff in the Agricultural Engineering and Dairy Science Departments for their many hours of faithful service in caring for the calves and assisting with the solutions to instrumentation and equipment problems, and to Mr. Erwin J. Raven of The Detroit Edison Company for providing valuable assistance in the construction of the calf chambers. My special thanks go to my parents, Mr. and Mrs. Floyd G. Surbrook and Mr. and Mrs. W. Earl Holman. Their advice, counsel, encouragement and help proved invaluable to the completion of this research, and to my family, my wife Mary and son David, for whom appreciation cannot be expressed in words. Their smile would have been enough, but with it they gave unboundless help, encourage- ment and understanding. ii LIST OF LIST OF LIST OF Chapter I. II. III. IV. VI. VII. TABLE OF CONTENTS TABLES O O O O O O O O O O O O O O O FIGUES O O O O O O O O O O O O O O O SYMBOLS O O O O O O O O O O O O O O 0 INTRODUCTION . . . . . . . . . . . . LITERATURE REVIEW. . . . . . . . . . Calf Temperature Comfort Zone. . . Calf Heat and Moisture Production. Calf Diseases and the Environment. Animal Calorimetry . . . . . . . . Ventilation Rates and Design Factors Animal Environment Simulation. . . RESEARCH OBJECTIVES. . . . . . . . . EXPERIMENTAL PROCEDURE . . . . . . . EQUIPMENT AND INSTRUMENTATION. . . . Construction of Calf Housing Chambers Electrical Energy Measurement. . . Temperature Measurement System . . Air Flow Measurement . . . . . . . CALF ENVIRONMENT COMPUTER SIMULATION RESULTS AND DISCUSSION . . . . . . . Calf Heat and Moisture Production. Ventilation Control Evaluation . . Heated Versus Cold Inlet Air . . . Winter Air Flow Patterns . . . . . iii Page . v . vii .xiii . 1 . 5 O 5 . 10 . 18 . 20 . 22 . 26 . 3O . 33 . 40 . 40 . 46 . 49 . 53 . 66 . 76 . 76 . 100 . 136 138 Chapter VIII. Conclusions IX. REFERENCES APPENDIX . SUMMARY 0 SUGGESTIONS FOR FURTHER RESEARCH. iv Page 150 151 154 156 163 LIST OF TABLES Table Page 1. Comfort Zone Temperatures for Calf Housing Reported in the Literature . . . . . . . . . . 9 2. Total Heat Production of Calves 6 to 11 Months of Age at Three Levels of Feeding and at High and Low Temperatures, Young (1974) . . . . . . l7 3. Summary of Winter and Summer Ventilation Rates from Calf Housing Literature . . . . . . . . . 23 4. Thermal Conductivity of the Calf Chamber Walls, Ceiling and Floor. ._. . . . . . . . . . . . . 45 5. Orifice Meter Data for Measurement of Air Flow Rate Through the Calf Calorimeters . . . . . . 57 6. Calibration Table for Orifice Meter Number Two, with a 0.2278 m Orifice and 0.3064 m Pipe at 15°Celsius . . . . . . . . . . . . . . 61 7. Orifice Air Flow Determination with Pitot Tube at an Air Density of l.l90 kg/m3 . . . . . . . 65 8. Steady State Experimental Data from Each of 15 Calorimeter Tests Used to Calculate Calf Heat and Moisture Production Rates . . . . . . 88 9. Stable Heat Production and Stable Moisture Production Results from Calorimeter Tests on Fifteen Groups of Eleven Holstein Bull Calves . . . . . . . . . . . . . . . . . . . . 89 10. Latent, Sensible and Total Heat Production Results from Calorimeter Tests on Fifteen Groups of Eleven Holstein Bull Calves. . . . . 91 11. Comparison of Three Sets of Values for Calf Basal Heat Production with Experimental Values of Stable Heat Production from This Research. The Age of Calves for the Experimental Group was a Weighted Average of the Calf Ages in - the Group. . . . . . . . . . . . . . . . . . . 99 V Table 12. 13. 14. Fasting Metabolism Standard Established for Calves by the Agricultural Research Council, London, 1965. O O O O O O O O O O O O O O O 0 Heating Energy Requirement Per Hour and Percent of Continuous Ventilation Heat Requirement for Calf Housing Ventilation Simulation with Four Types of Fan Controls . . . . . . . . . . . . Ventilation Rate for Each Outside Temperature Range of a Simulated Ventilation System with Four Thermostat Controlled Air Flow Rates. . . . . . . . . . . . . . . . . . vi Page 100 120 132 LIST OF FIGURES Figure 1. 7. 8. 10. ll. 12. Total Basal Heat Production of Calves from Birth to Three Weeks of Age as Reported by Brody, Roy and Settlemire . . . . . . . . . Total Heat and Latent Heat Production at Ambient Temperatures of 100 and 270C for Holstein Calves from 8 to 52 Weeks of Age as Reported by Yeck and Stewart (1960) . . . . Two Identical Chambers, Each Housing Eleven Calves, were Constructed for This Moisture Control Research . . . . . . . . . .‘. . . . . The Calves were Tied in 60 cm by 120 cm Stalls, and Bedded with Wood Shavings. . . . . Layout of Calf Chambers and Equipment Within the Research Barn . . . . . . . . . . . Wall Construction of the Calf Chamber. . . . . . Floor Construction of the Calf Chamber . . . . . The Calf Chambers were Fabricated at A Structures Laboratory and Transported in Sections for Assembly at the Research Barn . . Fresh Air Enters the Chamber from an Air Duct Through Two Adjustable Slots each 15 cm Wide and 130 cm Long. . . . . . . . . . . . . . . . All Controls were Grouped at One Location and Away from the Direct Influence of the Air Inlet, Exhaust Fan, and Inside Heater. . . . . 'Temperature Measurements at the Exhaust Fan and Elsewhere were Taken with a Wet and Dry Copper-Constantan Thermocouple . . . . . . . . Wet and Dry Bulb Temperatures were Taken in the Calf Stall with a Device Drawing Air Over a Wet and Dry Thermocouple . . . . . . . . . . . vii Page 12 14 42 42 43 44 44 47 48 48 51 51 Figure 13. 14. 15. 16. 17. 18. 19a. 19b. 20. 21. 22. Air Flow Rate Through the Calf Chamber was Measured with an Orifice Meter 4.8 Meters in Length . . . . . . . . . . . . . . . . . . Air Flow Rate is Determined from the Pressure Drop Across the Orifice and the Temperature of the Air. . . . . . . . . . . . . . . . . . Location of Thermocouples for Measurement of Conditions Inside the Chamber and for Orifice Air Flow Rate Determination . . . . . Schematic Diagram of the Orifice Meter and Manometer for Air Flow Rate Measurements. . . Four Connected Pressure Taps at Each Location on the Orifice Pipe Provide an Average Pressure to the Manometer . . . . . . Air Velocities Taken at Each of Five Locations in Equal Concentric Areas Provide Means of Determining Air Flow Rate of a Pipe with a Pitot Tube. . . . . . . . . . . . . . . . . Calf Barn Environment Computer Simulation Block Diagram . . . . . . . . . . . . . . . . Calf Barn Environment Computer Simulation Block Diagram . . . . . . . . . . . . . . . . Temperature and Absolute Humidity Curves from Real Calorimeter Test and Simulation for Calf Heat Production Rate of 2. 79 Kcal/hr-kg and Calf Moisture Production Rate of 2. 83 grams/ hr- -kg with Air Flow Rate of 5. 82 m 3/min . . . Temperature and Absolute Humidity Curves from Real Calorimeter Test and Simulation for Calf Heat Production Rate of 3. 96 Kcal/hr-kg and Calf Moisture Production Rate of 6. 21 grams/ hr-kg with Air Flow Rate of 12.49 m3.min. . . Temperature and Absolute Humidity Curves from Real Calorimeter Test and Simulation at Four Calf Heat Production Rates with 0.092 Grams Water per Hour per Kilogram of Body Weight. . viii Page 55 55 56 59 59 64 68 69 79 80 82 Figure 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. Calorimeter Tegt Temperature Data for May 24, 1977 with 22 C Inside Temperature . . . . . Calorimeter Test Temperature Data for May 11, 1977 with 13°C Inside Temperature . . . . . Psychrometric Data for Calf Heat and Moisture Production Rate Calculations, May 11, 1977 Calorimeter Test . . . . . . . . . . . Stable Heat Production Versus Body Weight for Holstein Bull Calves in Tie Stalls Bedded With Fresh Wood Shavings Every Two Days . . Stable Heat Production Versus Body Surface Area for Holstein Bull Calves in Tie Stalls Bedded with Fresh Wood Shavings Every Two Days I C O O O O O O O O O O O O O O O O O 0 Stable Moisture Production Versus Body Weight for Holstein Bull Calves in Tie Stalls Bedded with Fresh Wood Shavings Every Two Days 0 O O O O O C O O O O O O O O O O O O 0 Stable Moisture Production Versus Body Surface Area for Holstein Bull Calves in Tie Stalls Bedded With Fresh Wood Shavings Every Two Days 0 O O O O O O O I O O O I O O O O O O 0 Calorimeter 1 Heat and Moisture Production Page . . 85 . . 85 . . 87 . . 92 . . 93 . . 94 . . 95 Temperature Record Showing Change of Metabolic Rate at 6:00 a.m. with Increased Activity . Calorimeter 2 Heat and Moisture Production 0 O 97 Temperature Record Showing Change of Metabolic Rate at 6:15 a.m. with Increased Activity . Temperature and Relative Humidity Versus Time for Thermostat Fan Control Compared with Continuous Ventilation. . . . . . . . . . . Temperature and Relative Humidity Versus Time for Time Clock Fan Control Compared with Continuous Ventilation. . . . . . . . . . . Temperature and Relative Humidity Versus Time for Humidistat Fan Control Compared with Continuous Ventilation. . . . . . . . . . . ix 0 O 97 . 103 . . 104 Figure Page 35. Simulated Continuous Ventilation Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -20°C . . . . . . . . 108 36. Simulated Thermostat Fan Control (11.9°C) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -200c . . . . . . . . . . . . . . . . . . . . . 109 37. Simulated Humidistat Fan Control (70%) and Humidistat- Thermostat Fan Control Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -200 C. . . . . . . . . . 110 38. Simulated Continuous Ventilation Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -100 C. . . . . . . . . . 111 39. Simulated Thermostat Fan Control (11. 9°C) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -100 C. . . . 112 40. Simulated Humidistat Fan Control (70%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10°C. . . . 113 41. Simulated Humidistat- Thermostat Fan Control Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -100 C. . . . 114 42. Simulated Continuous Ventilation and Thermostat (11. 9 OC) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of 0 OC. . . . . . . . . . . . . . . . . . . . . 115 43. Simulated Humidistat Fan Control (70%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of 0°C . . . . . . . . . . . . . . . . . . . . . . 116 44. Simulated Humidistat- Thermostat Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of 0°C . . . . . . . . . 117 45. Simulated Humidistat Fan Control (60%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of —20°C . . . . . . . . . . . . . . . . . . . . . 121 Figure 46. 47. 48. 49. 50. 51. 52. 53. 54. 56. Simulated Humidistat Fan Control (60%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10 OC. . . Trial Fan Thermostat Settings for Simulations to Determine Proper Sequencing of Fan and Heater for Confinement Calf Housing Ventilation . . . . . . . . . . . . . . . . . Simulated Thermostat Fan Control (12.80C) Temperature and Relative Humidit Versus Time Plot for Outside Temperature -20 C. . . . . . Simulated Thermostat Fan Control (12.80C) Temperature and Relative Humidity Versis Time Plot for Outside Temperature -lO°C. . . . . . Simulated Thermostat Fan Control (13.3OC) Temperature and Relative Humidity Versus Time Plot for Outside Temperature -200C. . . . . . Air Flow Rate Required to Remove Heat and Moisture for a 54.5 Kg Calf in a Tie Stall Housing UnitO for Outside Temperatures of -20 0C to +100 C. . . . . . . . . . . . . . . . Inside Temperature and Relative Humidity for Simulated Continuous Ventilation 0.00617 m3/ min-kg for an Outside Temperature Starting at -110C and Increasing l0 C Per Hour . . . . . . Inside Temperature and Relative Humidity for3 Simulated Thermostat Fan Control 0.00617 m / min- Okg for an Outside Temperature Starting at -110 C and Increasing 10C Per Hour . . . . . . Inside Temperature and Relative Humidity for Simulated Four Level Ventilation System for an Outside Temperature Starting at -110C and Increasing 10C Per Hour . . . . . . . . . . . Control Diagram to Achieve Four Level Ventila- tion Rate Using One Inside Thermostat and Three Outside Thermostats . . . . . . . . . . Inside Conditions Resulting From A Four Level Ventilation Fan With One Inside Thermostat and Three Outside Thermostats With Outside Temperature Falling at a Rate of 0.50C Per Hour. . . . . . . . . . . . . . . . . . . xi Page 122 124 125 126 127 128 130 131 133 134 135 Figure Page 57. Temperature and Relative Humidity Versus Time Plots for Ventilation Inlet Air Cold and Heated O O O O O O O I O C O O O D O I O O O O 137 58. Calves Experience Warmer Temperatures in the Tie Stalls When Ventilation Inlet Air Was Heated Rather Than Cold. . . . . . . . . . 139 59. The Temperature Difference from Ceiling to Floor was Less with the Inlet Air Heated Than When the Inlet Air Entered Cold . . . . . 140 60. Top View of Air Flow Pattern with Cold Inlet Air Entering at an Angle . . . . . . . . . . . 141 61. Side View of Air Flow Pattern with Cold Inlet Air Entering at an Angle . . . . . . . . . . . 142 62. Side View of Air Flow Pattern with Cold Air Entering Straight Down Along the Wall. . . . . 142 63. Top View of Air Flow Pattern with Cold Air Entering Straight Down Along the Wall. . . . . 143 64. Top View of Air Flow Pattern with Cold Air Entering at an Angle and the Inside Heater Operating . . . . . . . . . . . . . . . 144 65. Side Views of Air Flow Patterns with Cold Air Entering at an Angle and the Inside Heater operating. 0 I O O O C O O O O O I I O C O O O 145 66. Top View of Air Flow Pattern with Heated Inlet Air Entering at an Angle . . . . . . . . . . . 146 67. Side View of Air Flow Pattern With Heated Inlet Air Entering Straight Down Along the Wall. . . 147 68. Side View of Air Flow Pattern with Heated Inlet Air Entering at an Angle . . . . . . . . . . . 147 69. Top View of Air Flow Pattern with Heated Inlet Air Entering Straight Down Along the Wall. . . 148 xii db EN Hm ELQ S O. L M LIST OF SYMBOLS area, m2 as subscript, basal ratio of orifice to pipe diameter as subscript, critical as subscript, ceiling and walls pipe diameter, cm and inches* orifice diameter, cm and inches* as subscript, dry bulb temperature enthalpy, Kcal./kg dry air thermal expansion factor as subscript, floor as subscript, ground total heat, Kcal. absolute humidity, grams of water/Kg. of dry air differential pressure, inches of water* as subscript, inside conditions flow coefficient limiting value of K as subscript, latent total moisture, grams * English Units are used for the orifice calcula- tions on pages 60 to 62 to maintain compatability with the original source. xiii m - moisture production, grams/hr.-kg u - viscosity of air, lbm/sec - ft.* 0 — as subscript, outside conditions Q - heat production, Kcal/hr.-kg q * - air flow rate, m3/min. and ft3/min. H l radius, m. p - air density, Kg/m3 and 1bm/ft3* Re - Reynolds number RH - relative humidity, percent S - as subscript, sensible T - temperature, °C T - as subscript, total t - time, sec., min., hr., days U - thermal conductivity, Kcal/mZ-hr-°C V - velocity, m/sec. and ft/sec.* v - volume, liters VS - specific volume, m3/Kg. dry air W - weight, kg. w - weight, grams wb - as subscript, wet bulb temperature Y - expansion factor for fluid Z - total heat production, Kcal/mz-day * English Units are used for the orifice calcula- tions on pages 60 to 62 to maintain compatability with the original source. xiv CHAPTER I INTRODUCTION Warm confinement calf housing was looked upon a few years ago as a means to reduce calf sickness and mor- tality. Building area per calf and labor input per calf were often reduced. Old and new buildings were fitted with fans and heaters, but sickness and mortality often were not reduced. The reasons for lack of success were complex, but often the precursor of mortality was inadequate design and construction of the facility and lack of understanding of ventilation system management. The cost of energy was often high because heat was required. There has been a revived interest in cold calf housing in individual hutches and in semi-open barns. A calf is likely to remain healthy if provided proper nutrition and housed in a dry area free from drafts. Meeting these basic requirements with cold housing is less complicated than with warm confinement housing, but area per calf and labor requirements increase and heat energy requirements go down. Personal experience working with farmers on calf housing, reviewing the published experiences of others, and studying reports of calf housing research, leave little doubt that warm confinement calf housing can work effectively and efficiently. Important design data is not available due to a lack of controlled research of warm calf housing. Calf rearing is a major problem for dairy farmers and beef producers, and the annual economic loss is great. Martin (1973) conservatively estimated the value of calf losses to the dairy industry in the United States at fifty million dollars annually. Studies showed the rate of calf mortality to be higher in larger dairy herds. Remmen (1973) of the Netherlands reported overall calf mortality in the first three months of life to be 9.8 percent on farms with less than ten calves and 13.99 percent on farms with 51 to 110 calves. Speicher (1973) reported, in the results of a questionnaire to Michigan dairy farmers, calf mortality to be 9.7 percent for herds less than 25 cows and 16.6 percent for herds greater than 85 cows. Large numbers of calves were reared in less space and with less care for the large herds than for the small herds. Speicher suggested that unsatisfactory environment seemed to be a factor where mortality was high. Bates (1974) claimed calf housing, and in par- ticular the environment, has received comparatively little attention from the standpoint of research. He further suggested that the design of a calf housing system presently must be based largely upon erperience, opinions of others and intuition, and he considered successful design largely an art. Speaking in terms of dairy housing as a whole, Bates urged more research and claimed that calf housing and environment was the area of greatest need for new knowledge. "The production of heat and moisture as affected by environment must be known as a requisite for design of ventilation and temperature control systems," Stewart (1970) stated. Data reported by Yeck and Stewart (1960) was for calves older than eight weeks of age. They found heat output of young calves to be highly variable. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (1974a) Handbook of Fundamentals stated in Chapter 8, Environmental Control for Animals and Plants, that basal heat production gathered for many farm animals is of little value from a design standpoint. "More useful to the engineer is the heat production under conditions of normal metabolic activity." Animal housing researchers have found the acquisition of environmental design information under controlled housing conditions to be tedious, time con- suming and expensive. According to Thompson (1974), a great deal of effort has been expended in the development and testing of various housing schemes. However, most reports of housing systems tended to be case reports rather than controlled experiments because of the expense of setting up a particular system. "The goal of animal shelter engineering is to integrate all known physical and biological knowledge to control the environment of the farm animal for optimum productivity and economic advantage," Jordan (1963). Calf housing must insure minimal sickness, mortality, energy and labor input, and investment, with maximum pro- ductivity to accomplish this goal. Esmay (1969) stated that maximum economy was gained during cold weather if moisture was removed without addition of supplemental heat. Total elimination of supplemental heat input cannot be achieved with calf housing, but with adequate design information supplemental heat input can be mini- mized. The measure of success of calf housing is too often the reduction of mortality. This is important, but McDowell and McDaniel (1968) reported that calves with a health disorder between 0 and 30 days of life were three times more likely to have serious health problems during first lactation than calves without illness. This dramatized the importance of calf housing designed to provide a healthy environment at minimal cost to ensure maximum productivity. CHAPTER II LITERATURE REVIEW Research covering the areas of nutrition, health and environment has been conducted on calves. Much of the environmental research has involved case studies rather than controlled experiments to investigate design parameters. For the most part, environmental research has been conducted on calves older than two months of age. Studies have often involved cold versus warm housing, and heat stress. Little research has been conducted on the heat and moisture output of calves. Brody (1930), Roy (1957) and Settlemire et a1. (1964) investigated basal heat production of calves from birth to three weeks of age. Yeck and Stewart (1960) reported stable heat and moisture output for calves two months to one year of age. Data are lacking in the literature on stable heat and stable moisture production of calves under eight weeks of age. Stable refers to heat and moisture produced by the calves and bedding. Calf Temperature Comfort Zone The calf is a homeothermal animal with a normal temperature between the upper and lower critical 5 environmental temperature limits. The core temperature (rectal temperature) remains essentially constant, Esmay (1969); the average adult core temperature is 38.50C, and the average calf temperature is 39.50C, Svendsen (1974). Roy (1957) reported that body tempera- ture of the newborn calf increased shortly after birth and reached a peak higher than the normal adult tempera- ture on the second day after birth. Body temperature declined slowly after the second day. The zone of thermoneutrality is within the region of homeothermy. This thermoneutral zone refers to the range of climatic conditions in which the calf exerts no physical or chemical means of regulation to maintain homeothermy, Hahn et al. (1974). Basal metabolism remains essentially constant and the animal regulates core temperature with normal body function. The upper limit of the thermoneutral zone is the critical tempera- ture above which the animal is no longer able to maintain homeothermy and the core temperature rises, Esmay (1969) and Svendsen (1974). Animals attempt to conserve heat by hair erection, and increase heat production by shivering at the lower end of the thermoneutral zone, Gonzalez and Blaxter (1962). Feed intake increases and raises the level of basal metabolism. Physical and chemical activity continue to increase until the lower critical temperature is reached. When heat loss exceeds heat production the core temperature declines, Svendsen (1974). Referring to the limits of the thermoneutral zone, Hahn (1974) pointed out that shifts in energy util- ization as the animal attempted to maintain homeothermy in an adversely warm or cool environment resulted in decreased efficiency. However, Gonzalez and Blaxter (1962) suggested that the economic optimal environmental temperature in a calf house was one which caused the calf minimal discomfort and considered piloerection of the hair as evidence of discomfort. He claimed that calves are kept for economic reasons and discomfort is of economic importance only if it leads to reduction in productivity. He further claimed that frequent piloerection and initial vasoconstriction do not lead to a decline in productivity. The optimum environmental temperature for rearing calves appears to be at the lower end of the thermoneutral zone provided control of the environment prevents stress and health problems. All researchers do not apply the same definition to the lower critical temperature. Gonzalez and Blaxter (1962) defined it as the temperature at which certain external body temperatures begin to decline. This is approximately the lower end of the thermoneutral zone. He reported that this lower comfort zone temperature is 12.80C for a three day old calf and 8.2°c for a 20 day old calf. Gonzalez and Blaxter found the following formula to hold true for lower comfort zone temperatures for a calf from birth to 30 days of age (t represents age in days, and TC represents temperature in degrees Celsius). 2 TC = 13.7 - 0.315t + 0.0024t (l) Bhosrekov et a1. (1966) also concluded from research on calves 4 days to 18 months of age that young calves were more affected by climatic stress than older animals. Gonzalez, in still air and 50 percent relative humidity, allowed the ambient temperature to slowly decline from 230C over a period of several hours. Piloerection com- menced at 190C and was complete at 150C. Basal metabolism increased below 15°C. The calf shivered at 110C. He concluded that the lower temperature limit for optimal economy in a calf house was 130C. Dowling (1974) reported that cattle can live at temperatures ranging from -400 to 400C. This may not hold true for young calves, but calves have been raised in cold shelters in cold climates without apparent adverse effects. Mitchell (1976) suggested a lower temperature limit of -l3OC for calves. Pajak and Jasiovowski (1955) observed no problems at —9OC, Davis et a1. (1954) reported good results at —l3OC, and Vasilets (1951) obtained normal growth at ~4OC. There are a wide variety of temperature and rela- tive humidity ranges which are considered acceptable for calves. These values are summarized in Table l. The values were obtained from research and field experience. The lower temperature is suggested as the design tempera- ture for winter ventilation in confinement calf housing. Table l.--Comfort Zone Temperatures for Calf Housing Reported in the Literature. Comfort Zone Relative Source Calf Age Temperature Humidity 00 % Gonzalez and 0 o Baxter (1962) — 13 25 Weller (1965) -— 15° -- Hallahan (1967) 60 25° -- Light (1968) 3 days 13: 16: <80 3 weeks 7 10 <80 Appleman and __ o o _ Owen (1970) 10 20 70 85 Boyd (1970) -- 10° 13° -- Bodman and o _ Bodman (1973) 1° 65 7° Hastings (1973) -- 10° <90 Hahn (1974) -- 10° 26° <75 Irish (1974) -- 10° 16° 65 - 80 McDowell and o o McDaniel (1974) 6 weeks 13 18 <75 Bickert (1976) —- 5° 10° -- 10 Little research has been conducted on calves at lower temperatures to determine the effects of relative humidity. Kibler and Brody (1954) conducted tests on the effect of temperature and humidity on cattle and were unable to draw conclusions concerning the effect of relative humidity. Sainsburg (1967) concluded that at cold temperatures high humidity caused hair coat dampness and increased heat loss. Hastings (1973) pointed out that humidity control is more important in winter than temperature control. He added that calves kept in tempera- tures of 00 to 70C and near 100 percent relative humidity suffered from exposure and died as a result of metabolic and caloric stresses imposed upon them. The symptoms observed were terminal diarrhea and pneumonia. Calf Heat and Moisture Production The rates of heat and moisture production of calves has been studied infrequently, and often no attempt was made to separate total heat into latent and sensible heat components. Latent heat is of greatest importance as a ventilation design parameter. The main purpose of a ventilation system is to remove animal moisture from the building. Heat, gases and dust must also remain within acceptable limits. Brody (1930), Roy (1957) and Settlemire (1969) reported total basal heat production (sensible and latent 11 heat) for calves during the first three weeks of life. Figure 1 summarizes the total basal heat production of calves per unit body weight reported by Brody, Roy and Settlemire. Roy (1957) concluded that heat production increased for the first 2 to 4 days of life, decreased rapidly until the eighth day, and then decreased more slowly. Settlemire (1969) concluded that basal heat pro- duction increased after birth to a peak around five days of age, then declined gradually to a rather constant level between 2 and 3 weeks of age. Basal metabolism refers to the heat production of an animal at complete rest 12 to 14 hours after eating. Roy and Settlemire claimed a higher level of metabolism for calves than adult animals, and therefore determination of heat production for calves was taken 24 hours after the last feeding. These basal heat production values for calves were determined by the method of indirect calorim- etry where oxygen consumption and carbon dioxide produc- tion were measured. Brody (1945) developed the following equation relating total basal heat production rate to body weight, which yields a value of 1.40 Kcal/hr. per kilogram of body weight for a 50 kilogram calf: 0b = 1.167e'°'°°45W + 0.475 (2) Kcal.! lun- kg. Total Heat 12 4.0 _ 3.0 ; 2.0 ' : \..’00’ ‘ E (.0” : -»----arody (I930) 3 E -------R0y (l957l 3 I -——-Settlemiro(l964) E o"~5 '.6"".'s"”26" ‘35 Calf Age days Figure l.--Tota1 Basal Heat Production of Calves from Birth to Three Weeks of Age as Reported by Brody, Roy and Settlemire. 13 Oh — total basal heat production, Kcal/hr - kg body we1ght W - body weight, kg e - 2.718 The value of basal metabolic heat production was often adjusted for body size by expressing it on the basis of body surface area or some fractional power of body weight. Brody (1945) developed the following formula for equating surface area to weight of calves: A = 0.15 w°'5° (3) A - calf surface area, M2 W - body weight, kg The Agricultural Research Council (1965) reviewed basal heat production research and established a standard for calves from 2.09 Kcal/hr-kg. at one month of age to 1.64 Kcal/hr-kg. at 12 months. They did not report values for young calves. Yeck and Stewart (1960) determined values for stable heat and stable moisture production for calves from eight weeks to one year of age. Figure 2 illustrates their results at 100 and 270C. Stable heat and stable moisture refer to the heat and moisture produced by the calf and bedding, but exclude heat from lights and equip- ment. Gonzalez and Blaxter (1962) determined the heat production of normal calves at rest by measuring oxygen 3.0 3 L 2.0 .C ‘. '5 O x (.0 'lUI1 14 : \ - : \ : ; 27° of \ TOTAL HEAT 3 t \ \ \ : n \ - 5 ‘\i T‘ ——e : loo C \ \ \ I . -.‘~ I : Dl\ — — -: E LATENT HEAT .3 8 l6 ' 2'4 ' 3'2 ' 40 ' 46 I Weeks Figure 2.--Total Heat and Latent Heat Production at Ambient Temperatures of 10° and 27°C for Holstein Calves from 8 to 52 Weeks of Age as Reported by Yeck and Stewart (1960). 15 consumption, carbon dioxide production, and urinary nitrogen excretion. The following formula was developed by Gonzalez and Blaxter to determine calf heat production. Z = 3.998v + 1.026 V - 1.602w (4) 02 co2 n Z - calf heat production, Kcal/day per square meter of body surface area v - volume of gas, liters per hour w - weight of nitrogen, grams per hour 02- oxygen co2 - carbon dioxide n - nitrogen Gonzalez concluded that the pre—ruminent calf metabolized 95 percent of the available digestible energy in milk, and lost 5 percent in feces and urine. Heat production was found to decrease with age. Z = 1963 - 8.8t (5) Z - calf heat production, Kcal/day per square meter of body surface area t - calf age, days The 1976 meeting of the NC-ll9 Regional Research Committee on Improving Large Dairy Herd Management Practices reported a formula for heat and moisture pro- duction for dairy calves, but the experimental procedure was not discussed. Separate formulas were reported for l6 latent and sensible heat production in the temperature range of 20 to 120C. A factor was added to convert from watts/calf to Kcal/hr.—calf. L S 10 ll (24.54 + 1.98T + 0.04T2) 0.862/W (6) QL (293.3 + 14.3T - 2.3T2) 0.862/W (7) heat production, Kcal/hr per kilogram of body weight temperature, 0C calf weight, kg latent heat sensible heat The sensible heat production for a 49 kilogram calf at 10°C would be 3.63 Kcal/hr-kg, latent heat 0.85 Kcal/hr-kg, and total heat 4.48 Kcal/hr-kg. The ASAE Yearbook (1977) reported values for calves 6 to 12 months of age with total heat estimated at 0.71 Kcal/hr-kg and latent heat at 0.11 Kcal/hr-kg at six months of age. Young (1974) reported values of total heat production at three levels of feeding and at temper- atures within and below the thermoneutral zone for calves 6 to 11 months of age (Table 2). Other reported values for heat production of calves were based upon Yeck and Stewart's (1960) heat production data. Hallahan (1967) used values of total heat production of 2.61 Kcal/hr-kg and latent heat 17 Table 2.--Total Heat Production of Calves 6 to 11 Months of Age at Three Levels of Feeding and at High and Low Temperatures, Young (1974). Temperature Total Heat Production Feeding Level °C Kcal/hr-kg. Fasting 18 0.77 -12 0.91 Maintenance 18 0.97 - 5 1.12 Ad Lib. 18 1.31 - 5 1.42 production of 1.22 Kcal/hr-kg. Light (1968) used values of 3.88 and 1.39 Kcal/hr-kg for total and latent heat. Irish (1974) used values of 4.33 and 1.06 Kcal/hr-kg for total and latent heat. Bodman and Bodman (1973) used values of 3.33 and 1.19 Kcal/hr-kg for total and latent heat. Yeck pointed out that for values obtained on calves less than 10 weeks of age the dissipation rates, when on a per unit body weight basis, were erratic. This variation of calf heat production values points out the need for further research. Appleman and Owen (1970) reported total heat production at 5.82 and latent heat production at 2.35 Kcal/hr-kg. Calf heat production as described by Roy (1970) consisted of: (l) basal metabolism or energy for vital 18 body processes; (2) energy for feeding and digestion; (3) energy for voluntary activity; and (4), for the ruminant calf, energy loss as a result of fermentation processes. McDowell (1974) reported that the basal com- ponent of heat production made up from 35 to 70 percent of the daily heat production of calves. Svendsen (1974) reported heat production 6 hours after feeding to be about 60 percent above the basal heat production level. When comparing calf heat production with that of adult cows, Blaxter and Wood (1951) reported the basal metabolism per kilogram weight for the calf was approxi- mately two to three times the value at maturity. Appleman and Owen (1970) claimed the heat production rate of calves to be twice as high as cows. Roy (1970) reported the values for calves to be considerably greater than for cows. Calf Diseases and the Environment Research in the area of calf environment is needed, Bates (1974). He listed the following priorities: (1) establish minimum air exchange rates to keep aerosal contaminants at acceptable levels, (2) determine the relationship of temperature and relative humidity to calf health, (3) examine the effect of environmental factors on lung tissue. McDowell and McDaniel (1968) tended to support the third point and urged more attention to calf health problems which they claimed affected the productiv- ity of the mature animal. 19 Roy (1970) reported the main cause of calf death during the first fortnight of life was Escherichia coli. E coli can cause a septicemia or a localized intestinal infection. The latter was more common and the former more frequently fatal. Some deaths occur as a result of the calf becoming infected by Salmonella EE' Calf pneumonia (Enzootic Bronchitis), reported Roy, was first seen with the development of intensive production systems. This viral pneumonia is a complex disease involving one or more viruses. Infection by viral agents is often followed by secondary bacterial invasion with Pasteurella hemolytica or Corynebacteria pyogenes. Although poor ventilation and high humidity of calf barns have been implicated as predisposing causes in outbreaks of pneumonia, the relative importance of various factors such as air temperature, air movement, relative humidity, ammonia concentration, and cubic area per calf has not been elucidated. Roy suggested that in confinement housing the warm temperature and high humidity tended to propagate the growth of E. 39;; in the facility. He stressed the importance of cleaning stalls prior to using for another calf. In cold environments, E. ggii, in his opinion, did not propagate as quickly. Anderson (1973) suggested that increasing virulence in an organism was achieved by subpassing the organism from animal to animal. Virulence 20 after several passes was increased to the point where it produced severe sickness in every animal innoculated. This was basically the chain of events Anderson observed in many large groups of calves housed in the same barn. Low humidity increased the dust problem and dust may serve as a carrier of pathogenic bacteria reported Yeck et a1. (1960). They recommended a relative humidity range of 55 to 75 percent and stressed that cold drafts should be avoided. Hastings (1973) reported evidence favoring a limited range of relative humidity in the calf barn. Bacteria in droplets remain viable in high relative humidities and low relative humidities longer than in average relative humidities. Bacteria probably stay sus— pended in the droplet in high humidities and become desic- cated in low humidities. He reported the relative humidity most bacteria lethal was 50 to 60 percent with fewer than one percent of the bacteria surviving over four hours. Animal Calorimetry Calorimetry must be used to determine the heat and moisture production of animals. Calorimetry is basically of two types, direct and indirect. Basal heat production rates reported earlier in this literature review were determined by indirect calorimetry. The animal was equipped with a face mask and respiratory gases were collected by a device called a spirometer. Heat liberated 21 by the animal was assumed to be the heat liberated in the respiratory chemical reactions. The rate of oxygen consumption, carbon dioxide production, and urinary nitrogen excretion were measured and from these quantities heat production was determined. Blaxter (1950) described a procedure for indirect calorimetry with calves. Direct calorimetry involves placing an animal or group of animals in a container and measuring heat pro- duction directly. Benzinger (1963) described his gradient layer calorimeter in which the inside walls of the calorimeter were lined with a thin layer of insulating solid matter through which thousands of thermoelectric junctions were interlaced in a uniform pattern. The gradient layer calorimeter was an integrating sphere for thermal energy and it intercepted the energetic flux at any distance or at any angle between the source of heat and the walls of the calorimeter. The device was fast and accurate, but expensive to build. Another form of direct calorimetry is the respir- ation type and can have a closed loop ventilation system equipped with gas adsorbers or can be of the open ventila- tion type. The major drawback of the open ventilation respiratory type direct calorimeter is the necessity to accurately measure air flow rate as well as inlet and outlet wet bulb and dry bulb temperature. If these measurements can be made accurately, total heat production 22 of the animal can be determined. It is then possible to partition total heat into sensible and latent heat components. Jordan (1963) explained that direct respira- tory calorimetry involved the measurement of sensible and latent heat, the animal heat loss being taken as the difference between the heat input and output within the chamber. Direct calorimetry was used in the animal psychroenergetic laboratory at the University of Missouri. Kelly et al. (1963) discussed instrumentation for direct calorimetry and pointed out that calibration of the calorimeter is a tedious requirement. They described the main sources of error as measurement of air flow rate, wet and dry bulb temperature and heat flow through walls. Ventilation Rates and Design Factors Moisture removal is of primary concern with con- finement calf housing; therefore, minimum winter ventila- tion rate is based upon the stable moisture production (latent heat). Table 3 summarizes recommended winter and summer ventilation rates from calf housing literature. There are a variety of opinions concerning con- finement calf housing ventilation system control. Mitchell (1976) preferred manual operation of the ventilation system. His reason was that humidity, not temperature, is the important environmental factor. Hastings (1973) 23 Table 3.--Summary of Winter and Summer Ventilation Rates from Calf Housing Literature. Ventilation Rate m3/min-kg Source Winter Summer Light (1968) 0.00617 0.03116 Boyd (1970) 0.00617 -- Bodman and Bodman (1973) 0.00683 0.04367 Irish (1974) 0.00350 to 0.00750 0.01000 to 0.03000 Mitchell (1976) 0.01000 0.06550 Bickert (1976) 0.00933 0.0625 to 0.08750 stated that the fan should be kept running continuously and not be subject to operator manual control. Boyd (1970) recommended a two speed fan with the low speed on a time clock for intermittent operation and the high speed on a thermostat. He suggested this as a means of obtaining relatively even minimum winter ventilation rates with a fan which delivers too much air. Boyd, others, discovered that available fans often have a rated ventilation capacity greater than required. The barn is cooled too rapidly with thermostatic control, resulting in rapidly fluctuating temperatures. Bates (1974) argued for con- tinuous minimum winter ventilation claiming that time clock control causes excessive temperature fluctuations. Bodman and Bodman (1973) recommended minimum continuous ventilation with thermostatic control of additional fans. 24 Some ventilation equipment manufacturers recommended variable speed fans with a temperature sensitive resistor sensing inside temperature rise. Two speed fans are also being installed with a two stage differential type inside thermostat. Low speed is controlled by the lower setting and high speed by the upper temperature setting. Bickert (1976) recommended an automatic multi- level ventilation system utilizing three fans. A con- tinuous ventilation rate is maintained at 0.00933 m3/min. per kilogram of body weight. A second fan raises the ventilation rate to 0.0250 m3/min. per kilogram of body weight when the outside temperature exceeds -40 to -1OC or if the inside temperature exceeds 10°C. A third fan raises the ventilation rate to 0.06250 to 0.08733 m3/min. per kilogram of body weight when the inside temperature exceeds 130C. When calf barn ventilation is increased to_control moisture and gases, the danger of a cold draft stresses the animals. This has led to heating inlet air. Bates (1974) suggested research concerning the method of adding heat to a calf barn. He recommended heat be added to the inlet air. Irish (1974) also recommended some means of tempering the inlet air. A potential problem exists which must be con- sidered when applying the heat to inlet air. The air movement over the heating element must be adequate to 25 prevent overheating. The heating element in the inlet duct will receive insufficient ventilation for an exhaust ventilated building if doors or windows are opened. The Jamesway Division of Butler Manufacturing suggests a continuously operating air recirculation system where recirculated air is mixed with the fresh inlet air required by the ventilation fan. Required supplemental heat is added to the air by the recircula— tion system. Recirculating air within the barn was also introduced to prevent stagnated air pockets in remote areas of barns and to reduce temperature variation within a building. Light (1968) reported a case of temperature stratification with a difference of 70C from floor to ceiling. Bates (1976) suggested removing ventilation air from the floor because this air is cooler and heat is conserved within the building. The problem with this procedure is that moisture is collecting in warm air in the upper portion of the building and escapes the ventila- tion system. There is some concern among animal scientists, veterinarians and engineers that air recirculation may be a contributing factor to the spread of disease organisms among aniamsl. This subject deserves investigation. Building size is another design factor of concern to some engineers. This also relates to the problem of variable animal loading. Hallahan (1967) reported loss 26 of ventilation system effectiveness in a large calf barn when it was only partially filled with calves. He concluded that the ventilation system would have operated more satisfactorily if the building had been filled to near capacity. Bates (1974) suggested the relationship between calf numbers housed in a single unit in relation to calf health is an appropriate subject for investigation. Anderson (1973) suggested a series of small buildings or separate rooms within one large building each with a separate ventilation and heating system. He recommended 10 to 12 calves and a maximum of 20 calves per room. Weaver et a1. (1949) reported that epidemics among dairy calves were more frequent and more severe among large herds than small herds. They reported that when calves were segregated into small properly constructed units and kept in separate pens pneumonia and mortality declined. Light (1968) also suggested reducing the number of calves housed in a single barn. Animal Environment Simulation Simulation of inside environment of commercial, residential and farm buildings has gained considerable popularity since 1970. Emphasis has been directed toward energy efficiency and prevention of animal stress. Mathematical models of various heat and mass transfer conditions range from simple to complex. 27 A common type of agriculture building ventilation model utilizes heat and moisture balance equations for determination of ventilation rates and supplemental heat recommendations. These are steady state fixed time models with constant inside and outside environmental conditions, Esmay (1969). Real time simulation attempts to model the actual conditions within a building. Phillips and Esmay (1973) demonstrated, with a systems model of summer environment in an egg production facility, that evaluation of design alternatives can be made with simulation, thus avoiding expensive prototype testing. An innovative feature of the Phillips-Esmay model was the use of logic for ventila- tion control operation. Albright and Scott (1974), utilizing the conventional heat balance equation, modeled the equation variables with Fourier series. They dis- agreed with the outside air conduction equation for heat transfer through building components, claiming that the solar effect was significant. The sol-air temperature concept, in their Opinion, yielded more accurate pre- dictions of inside air temperature. The simulation did not consider moisture balance for the building. Albright and Scott did assume that perfect mixing of the air occurs within the system. While the Albright and Scott simulation con- sidered the temperature to be a steady periodic function, 28 Buffington (1975) and Cooke and DeBaerdemaker (1975) considered conditions as transient. Buffington used conventional heat and moisture balance equations and developed mathematical models for the equation inputs. He calculated transient heat gains and losses by the trans- fer function method described in ASHRAE, Handbook of Fundamentals (1974). This method also used Fourier series. Christensen and Hellickson (1976) reviewed the previous methods applied to animal ventilation and con— cluded that all had the shortcoming that none based ven- tilation rate determination on livestock heat and moisture production. The ideal ventilation rate, in their opinion, was that required for moisture removal. They developed a generalized model predicting energy and mass transfer in confinement livestock structures to optimize insulation, heating and ventilation design. Wilson (1970) minimized the effort of complex modeling for accurate prediction of inside building sur- face temperature. He reported that ventilation would cause the inside air temperature to more closely track the outside temperature and make the system less sensitive to thermal conduction through the walls. This is true when the walls and ceiling are adequately insulated. Holtman (1976) suggested that a simulation be no more complex than is justified by the output desired. A simplified approach, utilizing conventional heat balance 29 and heat transfer functions, may yield results accurate enough to make appropriate judgments from the output. If the model is too complex, the result of a particular stimulus may be obscured in the output. CHAPTER III RESEARCH OBJECTIVES The successful design of an animal confinement environmental control system can only be achieved when there is a thorough understanding of the design parameters involved. Important design information is lacking in the literature. The problem of providing effective calf housing is complicated by an urgency for energy efficient designs. In recent years there has been a tendency to increase ventilation rates in confinement calf housing in comparison to past ventilation rate recommendations to ensure a healthy environment for the calves under adverse conditions. Published values for total and latent heat pro- duction used for calf housing ventilation design are not consistent. The highest values used are more than 100 percent larger than the lowest values. Only fragmented data are available on pre-ruminant calf stable heat and moisture production. An effective and efficient confine- ment calf housing ventilation system design can only be achieved if calf heat and moisture production are under- stood. The first objective of this research is: 30 31 1. Determine the total stable heat production and total stable moisture production of Holstein bull calves less than eightoweeks of age at ambient temperatures of 10 to 15 Celsius under typical farm housing conditions and management practices. The control of heating and ventilation for calf housing is another subject of controversy among animal scientists, veterinarians, and agricultural engineers. During recent years, however, there has been a tendency toward minimum continuous ventilation for winter condi- tions. Experts tend to agree that minimum continuous ventilation is effective, but it may not be energy efficient and necessary. In an attempt to provide con- trolled experiment comparative data on heating and ventil- ation controls, the second objective of this research is: 2. Evaluate the effectiveness of different ventilation controls to regulate temperature and relative humidity within a warm confine- ment calf barn, and compare energy require- ments for heating and ventilation with each control. The ventilation controls evaluated were: a. Fixed ventilation rate continuous operation. b. Fixed ventilation rate with thermostatic control. c. Fixed ventilation rate with humidistatic control. d. Fixed ventilation rate with time clock control. e. Four level ventilation rate with combin- ation of inside and outside thermostats. The ventilation rate increased in steps as the outside temperature increased. 32 Cold drafts directly upon calves will cause excessive cooling of the animal. Cold drafts are often considered the cause of calf sickness, although the chain of events linking drafts and sickness are not clear. There appears to be a relationship between cold drafts and calf sickness, and in recent years heating inlet air has been advocated. Heating inlet air in most cases requires major redesign of the ventilation air inlet system and causes a change in air inlet flow patterns. Research is needed to compare the effect of heated versus cold inlet air, and to study the resulting air flow patterns. Related research objectives are: 3. Evaluate the effect of heating inlet air prior to entering the barn compared to allowing the cold air to enter. 4. Determine winter air flow patterns within the calf barn with air entering cold and heated, with the inside heater on and off, and with different air inlet slot openings. The objectives of this research on confinement calf housing are a beginning. There are a number of additional questions deserving investigation if signifi- cant declines in calf mortality and disease are to be expected. CHAPTER IV EXPERIMENTAL PROCEDURE The type of confinement calf housing selected for this research was the tie stall with solid partitions 100 cm high. The stalls were 60 cm by 120 cm and the calves were tied by means of collars. The calves were bedded with wood shavings and the bedding was changed every second day. This type of housing is in common use where large numbers of calves are housed in minimum space. The building was constructed to conform to common insulating recommendations with conductance values of 0.322 Kcal/mZ-OC for the ceiling, 0.415 for the walls and 0.542 for the floor. The floor was insulated for this research because the chamber was to be used as a calorim- eter. It was necessary to eliminate the effect of a cold floor so that environmental stress would come from air in the chamber. The chamber was designed to house twelve calves; however, one stall in each chamber was used for equipment storage and instrumentation. Care was exercised to ensure tight construction and all joints between building sections were stuffed tightly with fiberglass insulation and sealed with 33 34 weather stripping to prevent air leakage. These joints were further sealed with duct tape to eliminate even the slightest air leak and then tested with ammonium chloride smoke with a differential pressure across the walls of 0.56 mm Hg. Two exhaust fans were installed in each chamber, one fixed rate and the other variable rate. When only one fan was in use the other was sealed to prevent air leakage. A 5 kilowatt electric heater was installed inside each unit and arranged to blow heat against the flow of ventilation air to achieve adequate mixing of the air and even distribution of the heat. A 7.5 kilowatt electric heater was installed in the air inlet duct 1.5 meters from the duct entrance to the chamber to provide adequate warm and cold air mixing. The elements in this heater were controllable in 2.5 kilowatt increments. A plywood duct was used between the heater and the entrance of the chamber to minimize heat loss. The air inlet to the chamber was two adjustable slots 15 cm wide and 130 cm long. A hinged door was used on the inlet slot to give desired direction to inlet air. The air entered a plenum duct from the outside in a tee arrangement with a vee divider at the tee to provide an even flow in two directions. The calf chambers were operated as open ventila- tion respiratory direct calorimeters. The procedure for 35 calculation of heat and moisture production of the calves was based upon achieving steady state inside environmental conditions based upon outside conditions and the rate of ventilation. Lights and supplemental heat were turned off to minimize perturbation of the steady state condi- tions. A ventilation rate was determined by experimenta— tion which would allow inside steady state conditions to be achieved with minimal deviation from the normal inside environment. Steady state was achieved within 15 to 30 minutes. The uncontrollable factor during the calorimeter tests was the inlet environmental air. The absolute humidity of the outside air will remain constant over a period of several hours even though the dry bulb tempera- ture changes. The exception is during times of changeable weather or when dew is forming or evaporating. An attempt was made to conduct calorimetry tests when there was little or no change in outside dry bulb temperature. This resulted in a number of tests being conducted at night, especially during more changeable spring weather. Calorimeter tests were not conducted within twelve hours of the time the chamber bedding was changed to allow the bedding to absorb liquid and to attain equilibrium with the inside environment. Tests were not conducted within an hour of the time chambers had been entered for calf care to allow the inside environment 36 sufficient time to return to normal closed operating conditions. Tests were not conducted until several hours after animal care was completed. A small amount of air leakage did occur around the door to the calorimeter, but this was eliminated during the test by sealing the door with duct tape. Wind outside the research barn would have some effect upon the air flow rate through the chamber so tests were not conducted when the wind velocity caused air flow measurement deviations greater than five percent. The determination of the absolute humidity of the outside air when the wet bulb temperature was below 00C was difficult to obtain accurately. An electronic device utilizing the change in resistivity of a material containing a salt solution was tried, but the results were unreliable. When the calorimeter was operated with the outside wet bulb temperature below 00C, one calorim— eter was operated for the heat and moisture production test, and the other was used to determine absolute humidity of outside air. Cold air was heated by the duct heater and wet and dry bulb temperatures of air in the inlet plenum were determined with a sling psychrometer at periodic intervals during the calorimeter test. The absolute humidity remained unchanged because heat only was being added to the inlet air. When the outside wet bulb temperature was above 00C, wet and dry bulb 37 temperatures were determined with the sling psychrometer near the entrance to the air inlet duct. Tests operated to compare the effectiveness and energy consumption of different ventilation system controls and the test to compare heated versus cold inlet air required a direct comparison against a control. Duplicate calf chambers were constructed for this purpose. Con- tinuous minimum winter ventilation was used as a common reference in ventilation control comparisons. A duplicate test was conducted with the Opposite chamber used as reference to eliminate the effect the calves may have had upon the results. Ventilation rates used were in the range of 0.00617 to 0.00750 m3/min. per kilogram of body weight. These ventilation rates conformed with present calf housing ventilation recommendations. The evaluation criteria for these ventilation control comparisons was the variability of inside temperature and relative humidity and the amount of energy consumed. The tests conducted using heated versus cold inlet air were evaluated on the basis of reduction of drafts on the animals, air flow pattern within the build- ing, ability to maintain a uniform inside temperature and energy efficiency. Because the inlet heater was located outside the chamber due to lack of space inside and to allow adequate straight duct following the heater for warm and cold air mixing, some loss of heat to the 38 outside did occur. An outside temperature of ~7OC surrounding the heater and duct resulted in a 10 percent loss. Studies of air flow patterns within a ventilated building is a time consuming and tedious process. Ammonium chloride smoke capsules were used for air pattern evaluations. This material was not toxic, but would cause respiratory irritation when inhaled. Therefore, smoke studies were conducted in an empty chamber with ventilation rates identical to the experimental chamber containing calves. Once the air flow patterns were deter- mined, limited smoke studies were conducted in the chamber with calves to verify results. The ventilation and heating controls to be tested were installed at a common location away from the direct influence of the inside heater, inlet air slot and fans. Wiring was provided to allow changes from one control to another. A mercury thermometer was provided at the con- trol location for calibration and control sequence setting. Ventilation and heating controls were test cycled for proper sequencing prior to each set of tests. A sling psychrometer was used to calibrate and set the humidistat. The wet and dry bulb temperature taken at the inlet to the fan was considered to be most representative of the conditions within the calf chamber. Dry bulb temperatures were recorded outside the research barn at 39 the entrance to the inlet duct and at the inlet plenum prior to the slot inlet to the calf chamber. Dry bulb temperature alone was considered an adequate measurement of outside conditions for the purpose of ventilation control and heated inlet air comparison tests. CHAPTER V EQUIPMENT AND INSTRUMENTATION Two identical calf chambers were designed to house 11 calves each in tie stalls and to have the capability of functioning as calorimeters for heat and moisture pro- duction determinations for calves to eight weeks of age. The chambers were of tight construction to eliminate air leakage. Instrumentation was required to meaSure dry and wet bulb temperature at specific locations, air flow rate through the chamber, and electrical energy consump- tion for lighting, heating and ventilation. Commercially available fans, heaters and controls suitable for agri- cultural applications were installed in each chamber. Construction of Calf Housing Chambers The calf chambers were erected inside an insulated research barn at the Dairy Science Teaching and Research Center on the campus of Michigan State University. The research barn was also used for other projects; therefore, some limitations were placed on the design and installa- tion of the chambers and equipment. The most serious limiting factor to be considered in the design and instal- lation was the 2.44 meter ceiling height. Duct work had 40 41 to be kept below the ceiling for accessibility and still allow head room for limited traffic to other areas. The outside and inside arrangement of the calf chambers is shown in Figures 3 and 4. The layout of the calf chambers and equipment within the research barn is illustrated in Figure 5. The orifice meters had to be placed on an angle because of the minimum length requirement of 4.75 meters. The chambers were designed with inside dimensions of 3.66 meters square and a height of 2.14 meters. This was considered to be the minimum Space requirement for housing twelve calves to eight weeks of age. The walls were constructed with 1.27 cm thickness exterior grade plywood, a polyethylene vapor barrier, and 7.6 cm of polystyrene insulation. Studs were placed into the walls for structural support with the insulation fitting tightly into the space between the studs. The outside surface was not covered. Figure 6 shows the type of wall construction. The ceiling construction was the same except the insulation thickness was 10.2 cm. The top surface of the floor was 1.90 cm thickness exterior grade plywood with a polyethylene vapor barrier beneath. Below the vapor barrier was a 5.1 cm layer of polystyrene insulation and a 0.64 thickness of exterior grade plywood. Minimum framing members were placed in the floor for strength. The floor construction is shown Figure 3. Two identical chambers, each housing eleven calves, were constructed for this moisture control research. \ Figure 4. The calves were tied in 60 cm by 120 cm stalls, and bedded with wood shavings. 43 Heater ontrols Temperature Recorder Healer ,kr-Orfikne Figure 5.-—Layout of Calf Chambers and Equipment Within the Research Barn. Exterior 1 Polystyrene Plywood /." Insulation 7.6 cm. l.27 cm. rStud Polyethylene Figure 6.—-Wall Construction of the Calf Chamber. ’/Ext. Plywood l.90crn. Polyethylene .’ Polystyrene Insulation \ ‘ / 5.l cm. Ext. Plywood 0.64 cm. Figure 7.-—Floor Construction of the Calf Chamber. 45 in Figure 7. The doors consisted of a wood frame and a 5.1 cm thickness of polystyrene insulation with a 1.27 cm layer of exterior grade plywood on each side. Table 4 is a summary of the thermal conductivity deter- minations for the calf chamber components. Table 4.—-Thermal Conductivity of the Calf Chamber Walls, Ceiling and Floor. Area (A) Conductivity(U) AU Component m2 Kcal/mz-hr-°C Kcal/hr-°C Ceiling Insulated Portion 10.82 0.322 3.48 Pine Joists 0.84 0.845 0.71 Walls Insulated Portion 26.76 0.415 11.11 Pine Studs 2.79 0.835 2.33 Door 1.67 0.581 0.97 Wall Plus Ceiling -- -- 18.60 Floor (including 13.38 0.542 7.25 2 cm wood shavings) The calf chamber was constructed in sections at the Agricultural Engineering Department Structures Labora- tory. The building sections were transported to the research barn for assembly. Higher quality construction was possible in the laboratory than could have been 46 achieved at the research site. The calf stalls, wiring, equipment and instrumentation were installed after the shell of the chamber was erected and the finish work com- pleted. Figure 8 shows the assembly of the separate chamber sections. Fresh air enters through two adjustable slots (see Figure 9). The location of the fan and heater controls are shown in Figure 10. Electrical Energy Measurement Energy consumption is a major concern in animal confinement housing, especially is supplemental heating is required. This is the case with calf housing and elec— trical energy consumed for lights, ventilation and heating was metered. Each calf chamber was equipped with a set of three kilowatt-hour meters. The arrangement of the kilowatt-hour meters, electrical panel and fan motor con- trollers is shown in Figure 3. The main kilowatt-hour meter measured the total electrical energy used in the chamber. A second meter measured the electrical consump— tion of the lights and a third meter measured the elec- trical consumption of the fans. The energy consumed by inside lighting actually contributed to heating; therefore, the heat consumed in the chamber was determined by subtracting the energy Consumed by the fans from the meter recording total energy consumption. All incandescent lighting energy can be assumed to be converted to heat. 47 Figure 8.--The Calf Chambers were Fabricated at A Structures Laboratory and Transported in Sections for Assembly at the Research Barn. Figure 9. Fresh air enters the chamber from an air duct through two adjustable slots each 15 cm wide and 130 cm long. Figure 10. A11 controls were grouped at one location and away from the direct influence of the air inlet, exhaust fan, and inside heater. 49 A separate electrical panel was provided for lights and auxiliary equipment not contained within the calf chambers. This panel received power ahead of the kilowatt-hour meter of calf chamber number two so that this energy consumption would not cause an error in the energy consumption figure for chamber number two. Temperature Measurement System Temperatures at the desired locations were deter— mined with copper—constantan thermocouples and recorded by a 24-point chart recorder. The sample time for all 24 points was 95 seconds. Temperature recordings were desired on a periodic basis so this sample time did not pose a problem. A 30 minute timer was used to trigger the recorder at desired sample intervals. The sample interval was dependent upon the type of test. The most common sample intervals were 5, 15 and 30 minutes. The locations of the thermocouples are shown in Figure 15, page 56. Two thermocouples were attached to the bottom surface of each chamber floor at the time the chamber was erected. One was used and the second served as a spare in the event one became damaged. A thermocouple was also attached to the outside wall surface and to the top of the ceiling of each chamber. These temperatures were necessary for the determination of heat flow through the 50 chamber walls, floor, and ceiling. These thermocouples were taped to the outside surface so the junction was in contact with the surface, but the tape did not cover the junction. Wet bulb temperature was required in the calf stall for one set of tests (see Figure 12) and at the inlet to the exhaust fan for all tests. Wet bulb tempera- ture of outside air was required for calorimeter tests, but an accurate determination was more conveniently taken manually with a sling psychrometer by the procedures described in Chapter IV. The wet bulb temperatures were measured by a fan-ventilated wet and dry thermocouple psychrometer. A thermocouple psychrometer modified, for wet and dry bulb temperature measurement, is shown at the inlet to the exhaust fan in Figure 11. One thermocouple was fitted with a wick which was kept moist by water in the reser— voir. The other thermocouple was kept dry. Water was held in the upper reservoir of the unit and withdrawn from the reservoir by siphon action due to evaporation from the wick. Once a reservoir had been made air tight, the water supply lasted approximately one week. The assembly containing the two thermocouples was inserted into the tube protruding down from the psychrom— eter. This tube was the inlet to a small squirrel cage fan. There was a separate passage for each thermocouple Figure 11. Temperature measurements at the exhaust fan and elsewhere were taken with a wet and dry c0pper-constantan thermocouple. ' Figure 12. Wet and dry bulb temperatures were taken in the calf stall with a device drawing air over a wet and dry thermocouple. 52 within the tube. An air velocity of 1.6 meters per second was required for adequate ventilation of the wet thermo- couple, Jensen et a1. (1971). The wicks were changed periodically and the psychrometer tubes cleaned to prevent dust accumulation from affecting the accuracy of the wet bulb measurements. These psychrometers were bulky and could only be operated in an upright position. A more representative wet and dry bulb measurement could be obtained by modifying the psychrometer because of the air entrance pattern to the exhaust fan (Figure 11). The wick had to be kept as small as possible in order to obtain an accurate determination of the wet bulb temperature. It was also necessary to tie the wick gently at the end near the junction to obtain a reliable reading. Air tightness of the water reservoir system was essential to prevent drops of water from forming on the exposed portion of the wick. Excessive water reaching the end of the wick would cause heating of the wet junction and result in an erroneously high reading. However, with daily inspection and maintenance, the thermocouple psychrometers provided an efficient and accurate means of automatically determining wet bulb temperatures at periodic intervals. Each thermocouple was calibrated to an accuracy of two tenths of a degree Fahrenheit with a mercury 53 thermometer graduated to a one one-hundredth of a degree Fahrenheit. The thermocouple was attached to the mercury bulb of the thermometer for several minutes. The 24 point temperature recorder was only available for the Fahrenheit temperature scale. The wet bulb thermocouples were calibrated again for accuracy with a sling psychrom- eter. The sling psychrometer could be manually ventilated in the space near the entrance to the inlet air tube of the thermocouple psychrometer to provide an accurate wet bulb measurement. It was only necessary to hold the sling psychrometer near the thermocouples to check the accuracy Of the wet and dry bulb thermocouples at the inlet to the exhaust fan. There was always sufficient air velocity for an accurate wet bulb measurement. The accuracy of the wet and dry bulb thermocouples at the inlet to the exhaust fan were verified prior to the start of each calorimeter test. Air Flow Measurement Accurate measurement of air flow rate was essen- tial for the Operation of the calf chambers as Open calorimeters. Air flow rates to be measured were in the range Of 2.0 to 20.0 m3/min. measured to within an accuracy of 5 percent at 8.5 m3/min. Calorimeter tests were operated in the range of air flow rates of 5 to 12 m3/min. Air flow rate had to be determined quickly 54 because both calorimeters were operated simultaneously. Three accurate measurement methods available were the venturi, nozzle and orifice meters. The orifice meter was chosen because it was relatively easy to construct. According to ASME (1971) and ASHRAE (1974b), orifice meters can be used for all types of fluids through pipes above a Reynolds number of 10,000 to a pre- cision Of one percent provided the meter is constructed to meet standard specifications. The Reynolds number for air to be measured during this research was in the range of 15,000 to 100,000. The pressure drop across the orifice was measured with a precision manometer to the nearest 0.001 inch of water (0.025 mm). A digital com- puter was used to generate calibration charts at a variety of temperatures which would enable orifice pressure drop to be converted directly to air flow rate (Figures l3, 14). The most critical factors for an orifice meter are the approach conditions. Ten pipe diameters of straight pipe are required upstream Of the orifice plate, and five pipe diameters of straight pipe downstream. The inside of the pipe must be smooth and pipe roundness four diameters upstream and two diameters downstream ‘should be to within 0.33 percent variation in pipe diameter. Round clamps were attached to the pipe 1.5 diameters either side Of the orifice to ensure pipe round- ness. Galvanized steel 1.6 mm thick was used for the 55 Figure 13. Air flow rate through the calf chamber was measured with an orifice meter 4.8 meters in length. Figure 14. Air flow rate is determined from the pressure drop across the orifice and the temperature of the air. 56 .coflumcHEnouoa oumm 30Hm Had OOHMHHO MOM Ono HOQEOQU onu OOHmcH mcofluHOcoo mo unofimusmmoz HON mOHQSOOOEHOnB mo cofiumooqll.ma ousmflm €216 /ss~_ no» oEmSO (la 7 . .lr (L 44> ~> . at m at 05:8 Boom no 05:3 \ (m 96% (.N o>ono 93¢) n39 aim nun) 3c. new.) ..\ as. \89 lime. fit too: too: so. _ leislll Cone: fl” EOMNIXFlllJouc: are 2.6. Q £00 53:. 1w. N lie“ T :2, eso. :2. 8%. 1.11 I 57 orifice plates. Guide holes were drilled through the pipe flanges and the orifice plate to keep the pipe and orifice centered to within 0.75 mm. A square edge was acceptable for the orifice rather than a 45 degree beveled edge by keeping the orifice plate thickness less than 3 mm. Two sizes of orifices were used to ensure adequate pressure drop for accuracy of manometer readings. A small orifice was used for low air flow studies during the cold winter months and a large orifice was used for higher air flow rates required during moderate weather. Orifice meter information is summarized in Table 5. The ratio Of the diameter Of the orifice, d, to the diameter of the pipe, D, was restricted to greater than 0.2 and less than 0.75. Table 5.--Orifice Meter Data for Measurement of Air Flow Rate Through the Calf Calorimeters. Chamber Pipe Small Orifice Large Orifice NO Diameter Diameter Air Flow Diameter Air Flow ' m m m3/min. m m3/min. 1 0.3072 0.1772 2 to 12 0.2278 4 to 20 2 0.3064 0.1773 2 to 12 0.2278 4 to 20 There are three choices of pressure taps which may be used with an orifice meter: (1) flange pressure taps, (2) vena contracta taps, and (3) one pipe diameter 58 upstream and 0.5 pipe diameter downstream. The last is the most convenient to use where a variety of flow rates are to be measured; therefore, the 1D and 0.5 D taps were used for the orifice meters in this research (Figure 16). According to the ASME research report on Fluid Meters (1971), The characteristics of fluid flow through the square-edge thin plate orifice has been studied extensively. From such extensive studies the discharge coefficients and expansion factors have been so well established that this meter can be used even for important measurements, without calibration. The extreme simplicity, reproducibility and adaptability Of the orifice are largely responsible for its being the most widely used differential pressure element. To eliminate error of measurement of pressure across the orifice, four taps were made in the orifice pipe at each pressure measurement location. The pressure taps were 90 degrees apart around the pipe and connected together, as shown in Figure 17 to provide an average pressure to the manometer. Calculating the air flow rate directly from dif— ferential pressure measured across the orifice is a trial and error process because an estimate of the flow rate is required to calculate the Reynolds number for the flow equation. It is more practical to calculate differential orifice pressure from air flow rate with the aid of a 59 l D l Pressure Tap/ Temperature Figure 16.--Schematic Diagram of the Orifice Meter and Manometer for Air Flow Rate Measurements. 1 To Manometer Figure l7.--Four Connected Pressure Taps at Each Location on the Orifice Pipe Provide an Average Pressure to the Manometer. 60 digital computer and generate a calibration chart for each orifice. The density of air changes significantly with changing temperature; therefore, charts were pre- pared to relate orifice differential pressure to air flow rate at five degree intervals. Table 6 is an example of an orifice meter calibration chart. The units in the equations relating differential orifice pressure and air flow rate are in the English System. It is important that these units remain in the English System to maintain compatability with the source of these equations, the ASME research report on Elgig Meters (1971). The calculation of orifice differential pressure is: 2 q/E w 5.982 K Y d2 F 3‘ ll (8) hw - pressure drop across orifice, inches of water q - air flow rate, ft3/min. p — air density, lbm/ft3 K - flow coefficient Y - expansion factor for air d - orifice diameter, inches F - thermal expansion factor of orifice plate For practical purposes, the expansion factor Y for air can be assumed to be 1.0. 61 Table 6.--Calibration Table for Orifice Meter Number Two, with a 0.2278 m Orifice and 0.3064 m Pipe at 15°Celsius. Air Flow Rate Differential Pressure ‘- Inches Of Water m3/min. cfm .0055 2.84 100. .0067 3.12 110. .0080 3.41 120. .0095 3.69 130. .0110 3.98 140. .0127 4.26 150. .0145 4.54 160. .0164 4.83 170. .0184 5.11 180. .0206 5.40 190. .0228 5.68 200. .0252 5.96 210. .0277 6.25 220. .0303 6.53 230. .0331 6.82 240. .0360 7.10 250. .0389 7.38 260. .0420 7.67 270. .0453 7.95 280. .0486 8.24 290. .0521 8.52 300. .0557 8.80 310. .0594 9.09 320. .0632 9.37 330. .0672 9.66 340. .0712 9.94 350. 62 The thermal expansion factor for the steel orifice plate F can be assumed to be 1.0 because the range in temperatures over which the orifice will be used will result in insignificant variation in orifice area. K- O b- Re = DVD (Reynolds number) (9) u 8 = d/D (10) _ 4 16 ' KO — 0.59415 + 0.41493 (8 + 1.58 ) (ll) _ 2 l6 — 0.00029 + 0.00383 (8 + 76.8878 ) (12) = KO + 1000. b/VRe (Flow coefficient) (13) pipe diameter, inches air velocity, ft/sec. viscosity of air, lbm/sec-ft ratio of orifice diameter to pipe diameter limiting value of flow coefficient, K intermediate flow equation variable A pitot tube was used as an alternate means to determine the air flow rate. The values determined by the orifice meter and the pitot tube were compared. The two values agreed within five percent. A standard pitot tube method for determining air flow rate for a round duct, ASHRAE (1974b), was used. The velocity of the air was determined in each Of five equal concentric areas, 63 (Figure 18). The following computation was used to determine the air flow rate: =/%-8 h. n.) p 60“ r2 5 q = (Vl + V + v + V + V5) (15) 2 3 4 V - velocity of air, m/sec. h - dynamic pressure - static pressure from pitot tube, inches of water. p - density of air, kg/m3 q - air flow rate, m3/min. r - radius of pipe, meters Table 7 is a summary of the pitot tube determina- tion of air flow rate for the large orifice plate in orifice meter number 2. The differential pressures were the average of three readings taken at each of the two locations shown in Figure 18. The dry bulb temperature was 18.9OC, the wet bulb temperature 15.00C, and the air density 1.190 kg/m3. 60W (.153)2 5 =9.43 m3/min. q = (10.69) The differential pressure across the orifice was 0.066 inches Of water, which from Table 6 gives an air flow rate of 9.62 m3/min. This is a deviation of 2.0 percent. 64 OOOO Equal Concentric 4’ ~ Areas 0000 Figure l8.--Air Velocities Taken at Each of Five Locations in Equal Concentric Areas Provide Means of Determining Air Flow Rate of a Pipe with a Pitot Tube. 65 Table 7.--Orifice Air Flow Determination with Pitot Tube at an Air Density Of 1.190 kg/m3. Differential Pressure Velocity Location Inches Of Water ~ m/sec. .95r .009 1.94 .84r .010 2.04 .71r .011 2.14 .55r .012 2.24 .32r .013 2.33 Total -- 10.69 CHAPTER VI CALF ENVIRONMENT COMPUTER SIMULATION The natural environment would not always produce desired atmospheric conditions at the appropriate time for experimentation. A computer model was developed to simulate the environment within the experimental calf housing units to aid in the extension of data over a range Of outside environmental conditions. The calf environment computer simulation was applied in two ways: 1. Simulation Of the inside environment during calorimeter tests to select heat and moisture production rates Of calves for comparison with experimental values. 2. Simulation of the effect upon the calf barn environment of different fan and heater controls for specific outside atmOSpheric conditions. These data supplemented experimental data for the evaluation of effectiveness and heating energy efficiency of different ventilation control systems. The calf housing units were inside an insulated, but cold, research barn away from the influence of solar radiation and wind. The temperature on the outside sur- face Of the calf housing units did not change enough 66 67 during a test to cause a noticeable change in heat flow through the ceiling and walls. Steady state heat flow was assumed at calf housing unit boundaries. A simple mathematical heat balance equation was considered appro- priate for this simulation. Outputs from the calorimeter simulation were inside and outside dry bulb temperature, relative humidity, absolute humidity and enthalpy of the air at five minute intervals. Outputs from the ventila- tion control simulation were inside dry bulb temperature, relative humidity, heating energy consumption, and a record of fan and heater operation at 30 second intervals. The assumptions for Operation of the simulation were: 1. The mass of air leaving the calf housing unit was equal to the mass of air entering. 2. Complete mixing of the air would occur during the time increment. 3. Calf heat and moisture production rates would remain constant. 4. Moisture flow through the walls would be insignificant. A flow diagram for the simulation is illustrated in Figure 19 a and b. The simulation determined the heat and moisture content of the air based upon the psychro- metric chart published by ASHRAE (1974) and determined the change in that heat and moisture content during a time interval Of one half minute. The new heat and moisture content of the air at time t + At was used to 68 INPUT EN- HAi EN; ' ___rl\.l\____f i_‘! H90" l+-l COED Hedges? H W L; PSYCHART subroutine ill 1,, I HA5 RHdeb ENi T ’- OUTPUT Figure l9a.-—Calf Barn Environment Computer Simulation Block Diagram. 69 Shh + .. z ENo INPUT X \ x INPUT A B At C D.\ x 2 130. To Z + _ Eqpt. Conductivity Heat of bldg. db Figure l9b.—-Calf Barn Environment Computer Simulation Block Diagram. 70 determine the enthalpy and absolute humidity at time t + At. Dry bulb temperature, relative humidity and air density for the successive iteration were determined from these two values by the Fortran Computer Psychrometric Package developed by Lerew and Bakker-Arkema (1975). The first step in the simulation was to determine mass of air within the chamber. Mass of air = Volume of chamber x density of air (16) The total heat and total moisture contained within the air were determined from the enthalpy of the air and absolute humidity inside the calf housing unit. Total heat in air = Mass of air x Enthalpy (17) Total moisture in air = Mass of air x Absolute (18) humidity Utilizing the heat and moisture balance equation, the heat and moisture of the air at the end of the time increment (At) was determined. This was essentially the procedure followed by real time simulations described in the literature review. However, those simulations did not assume the controlled conditions present in these calf housing unit tests. Therefore, more complex functions were necessary for realistic determination of the com- ponents in the heat and moisture balance equations. 71 Total heat in air (t + At) = Total heat in air (t) - ventilation rate x enthalpy difference x At - conductance of walls and ceiling x (Ti - To) x At - conductance of floor x (Ti - Tg) x At + calf heat production x At (+ heat input of recorder for calorimeter 2) (19) Total moisture in air (t + At) = Total moisture in air (t) - ventilation rate x absolute humidity difference x At + calf moisture production x At (20) The enthalpy difference in equation 19 and the absolute humidity difference in equation 20, were the average difference between inlet and outlet air which occurred during the time increment. The final step was the determination of enthalpy and absolute humidity of the inside air at the end Of the time increment. Enthalpy of air (t + At) = Total heat in air (21) (t + At)/Mass Of air Absolute humidity of air (t + At) = Total moisture in air (t + At)/Mass (22) of air The dry bulb temperature and relative humidity were determined from these values using the Fortran Psychrometric Package. The simulation continued with 72 these new values as inputs. Output variables were printed at the appropriate time interval for the particular simulation. The simulation time increment of one-half minute was chosen after studying calorimetry data. The time interval had to be short enough that change in inside environmental conditions was small. Heat input for the calorimeter tests and the calorimeter simulation were limited to calf heat produc- tion. The supplemental heater and lights were Off while the calf housing unit was Operated as a calorimeter. The temperature recorder was contained within the calorim- eter too, therefore, a constant heat input for the recorder was included in the simulation. An air flow rate was determined by experimentation which was approxi- mately at steady state conditions for heat and moisture balance. Inside environmental conditions changed only slightly during the test as inside steady state was achieved. Outside dry bulb temperature and absolute humidity taken from actual calorimeter tests were inputs to the calorimeter simulation. Values of calf heat and moisture production were input on a trial and error basis, with simulation output compared with actual calorimeter test data. The correct values for calf heat and moisture production were assumed when the curves for dry bulb 73 temperature and absolute humidity versus time from the simulation closely matched curves from calorimeter tests. Values for calf heat and moisture production from the simulation and from calorimeter tests were compared. The simulation of calf housing environment with different heater and fan controls used the basic model developed for the calorimeter simulation. A constant outside dry bulb temperature at 80 percent relative humidity was the input environmental condition. Calves weighing 54.5 kg were simulated with heat and moisture production rates selected from calorimeter test data assuming an inside temperature of 12.80C. Computer logic commands were added to control the operation Of the supplemental heater and the ventilation fan. At the beginning Of each half minute simulation interval the heater and fan logic commands would determine whether the heater and fan was to be operated. The ventilation fan controls simulated with con- stant outside conditions were: 1. continuous ventilation 2. thermostat controlled fan 3. humidistat controlled fan 4. humidistat and thermostat controlled fan. The outside temperature was increased at a rate of 10C per hour at 80 percent relative humidity with the following ventilation controls: 74 continuous ventilation thermostat fan control four ventilation rates controlled by inside and outside thermostats. The following example was taken from the simulation with thermostat control of the ventilation fan: C 80 81 85 86 90 91 HEATER LOGIC CONTROL IF (HX.LE.O) GO TO 80 IF (TDBI.LT.THOFF) GO TO 81 GO TO 85 IF(TDBI.GT.THON) GO TO 85 HX = 1. HTIME = HTIME + .5 GO TO 86 CONTINUE CONTINUE FAN LOGIC CONTROL IF(FX.LE.O) GO TO 90 IF(TDBI.GT.TFOFF) GO TO 91 GO TO 95 IF(TDBI.LT.TFON) GO TO 95 FX = 1. FTIME = FTIME + .5 GO TO 96 75 95 CONTINUE FX = O 96 CONTINUE HX 1 if heater is operating HX = 0 if not FX = 1 if fan is Operating ’if not ll 0 FX TDBI = inside dry bulb temperature THON = at or below this temperature heater Operates THOFF= at or above this temperature heater shuts Off THONTFOFF FTIME = accumulated fan operating time All heater and fan logic commands were similarly con- structed with Fortran IF statements. CHAPTER VII RESULTS AND DISCUSSION The data gathered in this research were considered important pieces heretofore missing in the perplexing puzzle of controlling moisture and temperature in con- finement calf housing. Though this research was sub- divided into four major objectives, all were interrelated. The ultimate Objective, however, was to provide some basic design parameters which would help agricultural engineers, animal scientists and veterinarians reduce calf sickness and mortality and increase calf housing energy efficiency. Calf Heat and Moisture Production The heat and moisture production calorimeter tests were conducted when the calf chamber contained 11 calves. The calves were Obtained from a large dairy farm 40 kilometers from theresearch site. Some stress did occur during shipment; therefore, tests were delayed a few days after the calves were delivered. The calves were not all the same age and the difference in age of the calves in a single unit was not greater than two weeks. 76 77 Both calf chambers contained calves from mid- January to mid-March, 1977, and periodic heat and moisture production tests were conducted. Calf group A was housed in chamber 1 and group B in chamber 2. Extreme difficulty was experienced in the accurate measurement of outside air absolute humidity during sub-freezing weather and, until an accurate procedure was developed, several sets of test data had to be discarded as inaccurate. Two sets of data taken on group B during March also were declared invalid due to an oversight in test check-out procedure. Weather conditions prevented tests spaced at regular intervals because the input air was not controlled. Another series Of heat and moisture production tests were conducted on calf group C in chamber number two from mid-April to the end of May, 1977. There were some periods when the temperature exceeded 25°C outside. Night temperatures generally ranged from below 0° to 10°C. Tests on this group of calves were generally con- ducted in the early hours of the morning. The principle of analysis Of heat and moisture production data from the calorimeter tests is that the inside dry bulb temperature and absolute humidity will eventually achieve a steady state in relation to the input conditions, provided animal heat and moisture pro- duction remain constant and other inputs are eliminated or controlled. If inlet air was of constant dry bulb 78 temperature and absolute humidity, inside air sought a fixed temperature and absolute humidity based upon the particular ventilation rate. The calf environment com- puter simulation described in Chapter VI illustrates this point in Figure 20 from simulation Of actual input data and previously calculated values for calf heat and moisture production. When inlet air finally became constant, actual and simulated conditions quickly achieved constant steady state values. The calf environment computer simulation did not always fit actual test data as well as data represented in Figure 20. Failure of the simulation occurred when high ventilation rates were used or when inlet air temperature changed rapidly. The problem with simula- tion under these conditions was the assumption of complete mixing of inlet air with air in the calf housing units and complete diffusion of calf heat and moisture produced in the time interval. This point is illustrated when Figure 21 is compared to Figure 20. The ventilation rate Of the test in Figure 21 was double that of the test in Figure 20. However, reasonably accurate inside steady state environmental conditions were eventually achieved in spite of this shortcoming. The real and simulated temperature and absolute humidity of Figure 21 agreed 45 minutes after the beginning of the test. 79 #- _ \ /le Inside l5°C " _ .. e L ~ - -~ ~- 2 - . E _ Simulation 0 s - --.., ’2 '00 . - ' ' o . . . " '"IOIAir/ ....°’0000000000 4=OOom 500 600 I I I I I I time 6, 8.0 .8 \ a S .. Real Inside 0 ,3: 7.0 ‘2: :2 “'7- 5 Simulation :2 .2 Inlet Air 3.2 61) 4/28/77 Figure 20.--Temperature and Absolute Humidity Curves from Real Calorimeter Test and Simulation for Calf Heat Production Rate of 2.79 Kcal/hr-kg and Calf Moisture Production Rate of 2.83 grams/hr-kg with Air Flow Rate of 5.82 m3/min. 80 o O . 2 20° /Reol lnsude a _ a r— B O. b x- -II"' . . g __ \ Simulation *- l5° \Outside Air 8=I300m 9=OO 980 I I , I2.0 _ . 3 Simulation \ g - '6 Real Inside 2: ll.O =6 . . g Outsnde Air 7.9 a _ ‘3 4/20/77 D ‘S ICLO Figure 21.--Temperature and Absolute Humidity Curves from Real Calorimeter Test and Simulation for Calf Health Production Rate of 3.96 Kcal/hr-kg and Calf Moisture Production Rate of 6.21 grams/hr-kg with Air Flow Rate of 12.49 m3/min. 81 Different values of calf heat and moisture pro— duction were put into the calorimeter simulation until an output was Obtained which closely matched the calorim- eter test data. Figure 22 is an example of this procedure for a single value of calf moisture production and four values of calf heat production. The calf heat production rate Of 1.40 Kcal/hr-kg for the simulation would produce the identical steady state inside temperature as the value Of 1.46 Kcal/hr-kg determined from the calorimeter test. The heat and moisture production calorimeter tests were of sufficient duration to ensure steady state inside environmental conditions. The standard heat and moisture balance equations were used to determine the heat and moisture output of the calves. The equation for total stable heat production in Kcal per hour is: Qt w = 60g 9 (EN1 - ENC) + AUcw (Ti - To) (23) + AUf (T. - T ) - Recorder Heat 1 9 Qt - calf heat production rate, Kcal/hr-kg W - calf weight, kilograms q - air flow rate, m3/min. p - air density, Kg/m3 Ti - inside temperature, °C TO - temperature of outside surface of wall and ceiling, °C °C Temperature Ab. Humidity grams/k9 82 Simulation (5° £166 Kcal/hr-qu _ __ __ __ __ __ __+ +-—+ t t t ‘ *"" L46 : . .K- -—.-—.———_ Real IIISIdO _ e e e 0 ° ° . J .27 '0. H I 5"— 5=|IO om 5'00 2/24/77 Group A Air Flow Rate 4.68 m3/min. 8.0 Simulation 7.0 _ Real Inside 6.0 /0uteide Air 5.0 I Figure 22.--Temperature and Absolute Humidity Curves from Real Calorimeter Test and Simulation at Four Calf Heat Production Rates with 0.092 Grams Water per Hour per Kilogram of Body Weight. 83 T - temperature Of the earth or ground, °C 2 ENi- enthalpy of inside air, Kcal/kg dry air ENO- enthalpy of outside air, Kcal/kg dry air AU -therma1 conductance of walls and ceiling, Kcal/hr-OC AUf- thermal conductance of floor, Kcal/hr—OC Lights and heat were Off during the test, but the tempera- ture recorder was in calorimeter number two and it had to be subtracted as a constant supplemental heat source. This term in the heat balance equation was not considered for calorimeter number one. Qt W = 60g 0 (ENi - ENO) + 18.60 (Ti - To) (24) + 7.25 (Ti - Tg) - 57.0 The equation for the stable moisture production in grams water is: m w = 60q p (HAi - HA0) (25) m - calf moisture production rate, grams/hr-kg W - calf weight, kg q - air flow rate, m3/min. p - air density, kg/m3 HA.-absolute humidity of inside air, grams/kg dry air HA -absolute humidity of outside air, grams/kg dry air 84 The average calf heat and moisture production, on a unit weight basis, was determined by dividing by the total Weight Of animals within the chamber at the time of the test. Some tests were conducted 12 hours after fresh bedding, while other tests were as long as 48 hours after fresh bedding was added. This accounted for some variability in calf moisture production rate, but had only a minor affect upon calf heat production results. Latent heat was determined by multiplying the moisture production by the heat Of vaporization of water at the inside environmental temperature. Sensible heat was the difference between total heat and latent heat. The heat and moisture production of the calves was determined by measuring the inlet dry bulb tempera- ture and absolute humidity, and the outlet dry and wet bulb temperatures, with a known air flow rate through the calorimeter. An air flow rate, which would result in nearly constant inside environmental conditions for the particular inlet air, was determined by prior experimen- tation. Steady state inside environmental conditions were achieved in 15 to 30 minutes. A portion of the temperature record representing steady state conditions for each calorimeter test was selected for the calf heat and moisture production determination. Figures 23 and 24 are typical temperature records for calorimeter tests. 85 25°C ' - 3:45am. I 445 4:45 .. .— T Inside .. 20° -;;;°°---.., ,... . .Té.°° _ 0.......;‘::z:‘:’...;.0:.....e:eeto:eeoeeoooe- ' ' II 'e.eeeeIt " K Tdb Outside ' ' Steady State ‘ ” Re ion " l5° 9 5/24 Figure 23.--Calorimeter Test Temperature Data for May 24, 1977 with 220C Inside Temperature. 5=OOa.m. 5=30 6:00 ISP 3 t s s i —+ : Inside TI /TI . H mm- db w - (0° T\\ _"t04((((. _ 5°__ .‘.‘:;!‘..’......,O‘.."”"i"rt.¢¢¢..: °°'°'°° Tdb Steady State — LIV Region 5/Il Figure 24.--Calorimeter Test Temperature Data for May 11, 1977 with 13°C Inside Temperature. 86 The data from Figure 24 were used for an example of calf heat and moisture production determination. The steady state conditions for the test were located on the psychrometric chart, Figure 25. The out- side absolute humidity was determined with a sling psychrometer as described in Chapter V. Stable heat production was determined from equation 24, and stable moisture production from equation 25.» Table 8 is a summary of the steady state psychrometric data for each of the 15 calorimeter tests. The following is a sample calculation of the stable heat and moisture production of eleven calves in calorimeter number two. The steady state environmental region is shown in Figure 24, with the environmental conditions for inside and outside air located on the psychrometric chart in Figure 25. 430.2 (10.38 - 6.88) + 18.60 (130 - 8O) QtW = + 7.25 (13° - 13°) - 57.0 QtW = 154.7 Kcal/hr. Qt = (1541.7 Kcal/hr)/623 kg. = 2.47 Kcal/hr-kg. mW = 430.2 (5.0 - 1.9) = 1333.6 gram/hr. m = (1333.6 gram/hr)/623 kg. = 2.14 grams/hr-kg. The results of the fifteen calf heat and moisture production calculations were summarized in Table 9. The 87 .ume kuaEHuoamu nbma .HH has .mGOflumasonv mumm coauospoum muspmfloz can umam mamu Haw mama oauuweouno>mmll :xm .5. .3 .0. Inr Ala a~n04 m noun mm SGNDOI "5: .mm musmflh 88 .ummu um mm>amo .4. 'IIIIII i‘t I’ll‘t‘. m¢.>a N.MH m.mH m.- em.ma ~.HH a.ma vmum U mm.oa o.m m.m a.ma mm.o m.H H.o Haum U mm.aa v.m H.aa m.ma mm.m v.m m.oH vim U ~m.aa m.m H.AH ¢.va H~.m N.m m.m mmtv U om.HH q.o m.oa o.mH mo.m m.~ m.HH mmiv U HN.NH m.h >.HH a.ma oa.m v.¢ m.m mmiv U Hw.ha m.HH m.ha ¢.ma mm.ma m.h w.ha omlw U ~m.aa m.h H.HH m.ma H~.m m.m m.h vmlm «m mm.~a m.h m.HH ~.va Hm.m m.m «.5 «min m nm.ma m.n m.aa a.ma wv.n m.m m.m HHIN m wm.aa 0.5 m.oa a.ma Hm.m m.m ~.h vmlm «d HN.~H 0.5 h.HH a.ma Hm.m m.m ~.n vmim m HN.~H ¢.h h.HH v.va vv.h m.m m.m HHIN d oo.m m.m m.m ~.n vv.m m.H n.m I mum « h>.m ~.m m.> o.oa vw.v h.H m.m I Hmua a .mx\amom .mx\mamum Do Do .mx\amox .mx\mEaHm oo mama macaw hmaanucm wquHESm.mn< n39 QUE hmamcucm wuflpfladm.mn< ape HH£ uaauso mQOfluflccou mumum mummum “Ha uchH .moumm cowuospoum muaumfloz can ummm «ado oumasoamo on com: mwmma ummeHuoamo ma mo comm Baum mumo Housmaauwmxm mumum hcmmumll.m manna 89 .Amvmav aboum mo coauazwm an pacwEhwuoa m .mm>aao Ha mo unmww3 mmauw>¢~ .umwu um mm>aauH m.m> ow.a a.mm mm.a mv mm.a m.vm «Nam o o.vm va.~ m.Hm nv.~ om vv.a m.mm Haum o 0.5aa mo.m m.aoa mm.m mm mm.a «.mm vim o a.moa mm.m n.¢oa mn.m 5H mm.a m.om mmlv o a.mma hm.m m.mm mm.~ ma vm.H o.om mmiw o m.moa mm.m a.moa mm.~ vH vm.H h.mv mmnv o h.h- H~.m m.mva om.m m mm.H «.mw omiv u a.mv mH.H m.¢m mm.a vm Nv.H m.mm vmlm Hm m.wm mv.a a.mh mm.a vm N¢.H m.mm «mum m «.mm an.a a.mm nm.~ Ha mm.a «.mm HHIN m o.nm mm.o b.mm m¢.H me ne.a a.mm wmrm ad m.hm mv.a m.m> ~m.a me >¢.H a.mm «Nam é h.vm ~v.a a.mm m~.~ mm mm.a m.mm HHIN a ~.Hm mm.H a.mma m¢.m wm om.a ~.Hm mum m ~.m> hm.a m.H~H hm.m Hm mm.a v.m¢ Hmla d .Hnums .Hnnmx .HSINE .uslmx mmmo E .mx mama maouu \mamum \maaum \Haox \Hmom mm<.m>< mwné uzmfio3 ammwusm N unmade wusumaoz usmuso and: L .mm>amo Hana cwmumao: cm>mam mo mmsouw downwam co mummy HmquaHono scum muasmmm coauoapoum musumwoz manmum 0cm cofiuoapoum puma magnumiu.m manna 90 total heat production was partitioned into latent and sensible heat in Table 10. The heat and moisture pro- duction data were plotted against body weight and body surface area (Figures 26 through 29). Curves were fitted to the experimental data of Figures 26 through 29 by second order regression. When the calf heat production per unit weight was plotted against body weight there was at first a rapid decline in calf heat output with increasing body weight (Figure 26). A similar effect was observed when heat production was plotted on the basis of surface area (Figure 27). A rapid decline in heat output occurred at first as body surface area increased. Calf group C was raised during the spring with an inside ambient temperature higher than groups A and B raised in winter. Inside temperatures for calorimeter tests conducted on groups A and B ranged from 7° to 14°C. Inside temperatures for group C ranged from 130 to 22°C. This difference of inside temperature did not produce a difference in stable heat production for these calorimeter tests (Figures 26 and 27). A difference in stable moisture production was observed, however, between groups A and B compared with group C (Figures 28 and 29). The increased moisture production at elevated ambient temperatures was expected because of the need to dissipate more heat. Mitchell (1976) reported water 91 Table 10.--Latent, Sensible and Total Heat Production Results from Calorimeter Tests on Fifteen Groups of Eleven Holstein Bull Calves. Heat Production Kcal/hr-kg Weight Date Group kg. Latent3 Sensible Total 1-31 A 49.4 1.17 2.10 3.27 2-5 A 51.2 0.80 2.63 3.43 2-11 A 53.5 0.84 1.45 2.29 2-24 A 59.1 0.84 0.98 1.82 2-24 A 59.1 0.54 0.92 1.46 2-11 B 53.2 1.01 1.26 2.27 2-24 B 55.5 0.88 1.08 1.96 2-24 B 55.5 0.70 0.96 1.66 4-20 C 48.4 3.67 0.29 3.96 4-25 C 49.7 1.73 1.12 2.85 4-26 C 50.0 1.93 0.65 2.58 4-28 C 50.5 1.67 1.12 2.79 5-4 C 52.4 1.82 0.86 2.68 5-11 C 56.5 1.27 1.20 2.47 5-24 C 64.8 1.04 0.62 1.66 lCalves were resting and quiet. 2Calves became excited and active at feeding time. 3Latent heat of vaporization taken as 0.59 Kcal per gram of water. Kca|./ hr:- kg. 92 4.0 . 3.0 : \ I ‘, q 3 2.0 f \,\\ 3 - ~". I - ‘1\' - . I .0 45 50 55 60 65 Calf Weight kg. Figure 26.--Stab1e Heat Production Versus Body Weight for Holstein Bull Calves in Tie Stalls Bedded With Fresh Wood Shavings Every Two Days. 93 If / \ Iso_ , N“ ; E . I. r. . E \ : \ .; H30 , O r 0 L. x: . 50 L3 Figure 27 L4 L5 l.6 Surface- Area m2. .--Stab1e Heat Production Versus Body Surface Area for Holstein Bull Calves in Tie Stalls Bedded with Fresh Wood Shavings Every Two Days. grams Water / hr: kg. 94 / / N (D /d /! é A.e\e>“‘" o 45 50 55 60 65 Calf Weight kg. Figure 28.--Stable Moisture Production Versus Body Weight for Holstein Bull Calves in Tie Stalls Bedded with Fresh Wood Shavings Every Two Days. 95 ISO _ - N' ' 1 F - fi E .1 he ‘ 5:, I00 _ ' o - I 3 ’ - a) . . \_.__.\. E E “~“~;L~u . ~“~1 E a. 50 , . )- - A a 8 L3 L4 L5 |.6 Surface Are 0 m2. Figure 29.--Stable Moisture Production Versus Body Surface Area for Holstein Bull Calves in Tie Stalls Bedded With Fresh Wood Shavings Every Two Days. 96 consumption at 320C double that for a 45 kg calf at 100C. Appleman and Owen (1970) reported that a 45 kg calf con- sumed twice as much water at 270C as at 100C. Yeck and Stewart (1960) observed fluctuating heat output for young calves. Analysis of temperature records for the heat and moisture production test revealed anomalies in the inside condition for no apparent reason. The anomalies were in the form of sudden increases in inside wet and dry bulb temperatures. Such an effect was observed in the wet and dry bulb temperatures of Figure 24 shortly after 5:30 a.m. Records of the events occur- ring during the heat and moisture production tests the morning of February 24, 1977 provided one explanation. Tests were being conducted simultaneously in both calorim- eters. The temperature records, Figure 30 for calorimeter l and Figure 31 for calorimeter 2, reveal similar anomalies between 6:00 and 6:15 a.m. The calves were resting quietly until about 6:00 a.m. when the milk for animal feeding was placed just out- side the calorimeter in preparation for feeding. The calves, hearing this preparation for feeding, became aroused and active. A few minutes later when feeding preparation commenced outside calorimeter 2, the second group of calves were aroused and became active. The increased rate of metabolism from resting to an active condition appeared in the temperature record. Comparative l5°C l0° 50 l5°C IO“ 50 97 5=300m 300 I I l l I b ....‘.°oo.. .po\ . *.oo...oo : -.'°o IHSid . ....°° '- '- ....0000 a TWb ... . - _ Outside Tdb _ *-o‘..............'...OOOOOOOOOOtOOttOOOQOOoboo - A2/24 Figure 30.—-Calorimeter 1 Heat and Moisture Production Temperature Record Showing Change of Metabolic Rate at 6:00 a.m. with Increased Activity. 530cm. 6=OO _...' I I l I :00. . ..........0000 .Tdbo .0 +0.....~.. '- .........°'o.o... ”ISide .0...'Hoe k\ ' '0 - - Tub Outside .. - totoootooottotoooo06990.0 {09cootoopopoooootoOokaot - Tdb _ B 2/24 Figure 31.-~Calorimeter 2 Heat and Moisture Production Temperature Record Showing Change of Metabolic Rate at 6:15 a.m. with Increased Activity. 98 heat and moisture production data for these two states of activity were listed in Tables 9 and 10. Total heat production increased 25 percent and the moisture produc- tion increased 55 percent over the resting condition level for calf group A. This increase occurred in less than five minutes. The increase in heat production was 18 percent and moisture production 25 percent for calf group B. Published research data is lacking on heat pro- duction of calves from birth to eight weeks of age. The data in Figure 1, on basal heat production, were listed in Table 11 for comparison with corresponding results from this research. McDowell (1974) reported that the basal component makes up 35 to 70 percent of the daily average heat production of calves. Applying these per- centages, the data from this research falls within this range when compared with the basal values in Table 11. Table 12 lists fasting metabolism for calves up to one year of age, Agricultural Research Council, 1965. The value of 2.09 Kcal/hr-kg at one month is in the range of values determined from these calorimeter tests (Figure 26). 99 Table 11.--Comparison of Three Sets of Values for Calf Basal Heat Production with Experimental Values of Stable Heat Production from This Research. The Age of Calves for the Experimental Group was a Weighted Average of the Calf Ages in the Group. Calf Heat Production Kcal/hr-kg Basal Stable Days Settlemire(l964) Roy(l957) Brody(l930) Experimental 0 1.79 1.58 1.83 1 -- 1.83 2.00 2 2.42 1.96 2.25 3 2.67 2.13 2.38 4 2.58 1.96 2.42 5 2.21 1.75 2.46 6 2.25 1.67 2.08 7 -- 1.58 -- 8 2.04 1.50 1.83 9 2.29 -- 1.83 3.96 10 1.96 -- 1.92 11 -- 1.50 1.75 2.27 12 1.83 -- 1.75 13 -- 1.46 1.83 14 1.96 -- 1.79 2.85 15 -- 1.38 1.92 2.58 16 -- -- 1.75 ’17 -- 1.33 1.71 2.79 18 -- -- -- 19 -- 1.29 -- 20 1.83 -- 1.85 21 -- 1.29 1.79 22 1.88 -- '- 23 -- -- -- 2.68 24 -- -- -- 1.96 100 Table 12.--Fasting Metabolism Standard Established for Calves by the Agricultural Research Council, London, 1965. Age Fasting Metabolism Months Kcal/hr-kg 1 2.09 3 2.01 6 1.86 12 1.64 Ventilation Control Evaluation Controlling the operation of ventilation fans and heaters within a warm confinement calf barn to remove moisture produced by the calves and maintain uniform inside temperature is a difficult task. Several types of controls have been used to operate warm confinement calf housing ventilation fans. Comparison of different ventilation controls used on farms is difficult because conditions vary from farm to farm. The two calf housing units constructed for this research were operated simultaneously to provide a com- parison between an experimental control system and a common reference ventilation system. Continuous ventila- tion was used as the reference for comparison and evalua- tion. Uniformity of inside temperature, level of relative 101 humidity, and amount of heating energy used were the con- trol evaluation criteria. A computer model of the environment within the calf housing units, with logic control to simulate the operation of the ventilation fan and heater, was develOped to aid in the evaluation of the experimental fan and heater controls. This was necessary because the weather was not always ideal for the experimental operation of the calf housing units. The continuous ventilation rate for the calf housing unit used as control was 0.00617 m3/min. per kilogram of body weight (10 cfm/cwt). The ventilation rates were higher for the housing units with thermostat, time clock, and humidistat controls to compensate for the fan not operating continuously. The calf barn tempera- ture for these tests was assumed to be the temperature at the inlet to the fan. A minimum of three tests were conducted with thermostat, humidistat and time clock control. However, because the results for each control were similar, only one temperature and relative humidity versus time plot was reported for each set of tests (Figures 32, 33 and 34). The thermostat, time clock, and humidistat tests reported were conducted with an average outside tempera- O ture of —3.90, -8.9 , and -4.00C respectively. Temp. Relative Humidity l5°C IO" 80% m 0 102 I I /'\ V/‘L ' . / \/ ._,/'\, _ : .-. a 0-0’ \ - C I\ 3 I- 0’ \‘ .‘ ’.‘ — \ :I s‘ - I ‘ ' 0 ~ ‘0-.. : \ I 0’ ‘0....‘ ’7 ‘ . .. _ \ I ‘0 \ I _ _ \ I \ ' - s; t ‘I '- _ . \ I _ . \l _ l I l 2:00 3100 4=OO time Thermostat, 4.54 m3/min. ------ Continuous, 3.4l m3/min. Avg. Inlet Air -3.9°C 2/l9 Figure 32.--Temperature and Relative Humidity Versus Time for Thermostat Fan Control Compared with Continuous Ventilation. l5°C a 5 g... 10° 80 7. z: 2 so 3 I ..">_’ 2.6 O a: 40 103 K on off an off an F0" 5 min. 5min. I 1 O . .’/ \‘ / . .\\ II Tl \L 7\ N.‘ ,‘. ‘b .x/ f \‘ 2 I l I | .1 \ 1 ‘ ’ \° ,’ A : I ‘ 1 1 a \ ’ \ - t- I. \\I ‘\ I, .~“’ ‘\ : .. . I ‘ - I 1’ 1 : ,I ' 1, : Z I Z I I 537 , 6=OO t Ime Time Clock, 5.96 m3/min. ----- Continuous, 4.83 m3/min. Avg. Inlet Air -8.9°C Figure 33.--Temperature and Relative Humidity Versus Time for Time Clock Fan Control Compared with Continuous Ventilation. Temp. Humidity Relative 104 i— _ l 5" C ,; .-" k .,. I I .\' >0’°\ / \ .— I" .- - IN; ‘(0\ / f 0-0 ‘. o . \ . I ‘ .‘o ’ \ I‘ - ’I\‘ 'I I‘ I g ’ ‘ - ‘ I \ r- I, \.~..‘ I, ‘.--a--o..! \ ’ .-.. _ I 0° ' I I I I 00 300 300 in me , IIIII III-IFOH off on off on I z'lw‘fi\\ //\\: - O-o_O-O-o-o _ ’. .- 8 0 °/. _ 1 \fi-\ / i '- .I. - F --.--. O-.. : b . ' \ I. I _ 60 4? ”A .L ‘L‘ IL ‘\ I, .- F- ‘ ’0 ...... ’ “ 'I 0‘ .’ ‘ - : ‘o” ‘ ' ‘ I ‘ l _ \ l t l I - l' I 1 1 L, ‘ l t ' \ I \f - i- I _ I" “ ’ ‘l : " ° I I - P 40 -\ I _ 1 ~. - Humidistat, 5.96 m3/min. ------- Continuous, 2.84 m3/min. Avg. Inlet Air ~4.0°C Figure 34.—-Temperature and Relative Humidity Versus Time for Humidistat Fan Control Compared with Continuous Ventilation. 105 The resulting inside temperatures for the controls tested were within the range of 100 to 150C. Relative humidity for continuous ventilation was lower in each case than the ventilation systems controlled by thermostat, time clock and humidistat (Figures 32, 33 and 34). A limitation involved with time clock ventilation control was its inability to adapt to changing outside environmental conditions. The inside temperature and relative humidity were maintained within satisfactory limits with an inlet air temperature of -8.9OC (Figure 33). At higher inlet air temperatures the ventilation would be insufficient to remove moisture. The time clock was set to operate the fan five minutes on and five minutes off. The humidistat ventilation control tests did not provide adequate air movement through the calf housing unit. The record of fan operation, Figure 34, revealed the fan was off about one hour between periods of opera- tion. Heat production within the calf housing unit was great enough to cause a slow increase in relative humidity, resulting in long off periods for the fan. Calibration of the humidistat in the field was difficult to accomplish. The humidistat was set to Operate the ventilation fan above 81 percent relative humidity. Calibration of the humidistat was attempted with a sling psychrometer. Actually, the target set point was 75 percent relative humidity. 106 Heating energy use was measured for the fan con- trol tests of Figures 32, 33 and 34. The heat requirement for continuous ventilation was five times as great as for thermostat fan control for a single test. However, the ventilation rate was too high for the continuous ven- tilation test resulting in excessive energy consumption. The trade off, however, was inside relative humidity averaging 20 percent higher for the ventilation system with thermostat control. In the case of the test with time clock control, the continuous ventilation system consumed only slightly more heating energy. The contin- uous ventilation consumed 2.3 times the heating energy as the humidistat fan control. The relative humidity averaged more than 20 percent higher for the humidistat control than for continuous ventilation. A computer model with logic controls to simulate fan and heater operation was used to provide additional information for ventilation control evaluation. Eleven calves of 54.5 kilograms average weight were assumed to be contained within the housing unit with an average inside temperature of 12.7OC. Heat production rate, 2.20 Kcal/hr-kg, was taken from the curve of Figure 26. Moisture production rate, 1.98 grams/hr-kg, was taken from Figure 28, assuming the upper curve to represent 150C and the lower curve 100C. The lights were on during the simulation contributing continuous heating of 0.4 107 kilowatts. The ventilation rate for all simulations was 0.00617 m3/min.-kg (10 cfm/cwt). This ventilation rate was chosen because at the time these control comparison tests were conducted, the heat and moisture production data were not available. The relative humidity of the outside air was assumed to be 80 percent. Simulation data were collected for outside temperatures of -200, -100, and 0°C. Inside temperature and relative humidity versus time were plotted for continuous ventilation, thermostat fan control, humidistat fan control and combination humidistat-thermostat fan control for outside temperatures of -2o°, -1o°, and 0°C (Figures 35 through 44). Inside temperature, relative humidity, fan and heater operation were plotted at half-minute intervals. The humidistat fan control and the combination humidistat-thermostat fan control produced identical results at -20°C. Temperature and relative humidity from the simulation were acceptable for all fan controls. The environment within the calf housing unit was considered acceptable when the temperature remained generally within the range of 100 to 150C and the relative humidity remained below 80 percent. The relative humidity fluc- tuated more than 30 percent for the humidistat fan con- trols. Relative humidity averaged 65 percent for Temperature °C °/o Humidity Relative 108 ml 80 - - - 1.1.": 70 .0 I), I . 50 v IIIy "V“h Figure 35.--Simulated Continuous Ventilation Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -20°C. Temperature °C °lo Relative Humidity 109 I ‘ ll IO°|_ Fan ,. II 1 1.. .. A , I I III III Figure 36.--Simulated Thermostat Fan Control (11.90C) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -20°C. Temperature °C % Relative Humidity 110 '50: A /\ '°°L. .... \_/\_/__ .22. .1 9 I 80 V ’° V / w / 60+ I/ 25 . Figure 37.--Simulated Humidistat Fan Control (70%) and Humidistat-Thermostat Fan Control Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -20°C. Te mperature °C Humidity % Relative 111 I5°r IO° #- Fan ‘ h - Hezter .- 80 L 25 InHL 4h- 70 fl 60 V V V Figure 38.—-Simu1ated Continuous Ventilation Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10°C. Temperature °C Hunfidfly 8% Relative l5° |O° 8C) 70 6C) 112 ‘ VVVV Ml Figure 39.--Simulated Thermostat Fan Control (11.9°C) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10°C. °C Temperature °/o Humidity Relative 113 I zoo 1" 15°" I. lO° — i _ Fan - - - - Heater ”)0 F‘—r 25 "fin. ep- 90 fl a) C) .. J / 60 Figure 40.--Simulated Humidistat Fan Control (70%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10°C. °C Temperature ‘7. Humidity Relative 114 20° :1/ [—- * Fna He'a'ter- '00 e 25 min. +- .. I m (3 N 7O / 60 Figure 41.--Simu1ated Humidistat-Thermostat Fan Control Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10°C. Temperature °C ‘7. Relative Humidity 115 I5° A A I \[\ r |O° Fan ' Heater ¢ 25 min. ;>- 80 / / 70 60 Figure 42.--Simulated Continuous Ventilation and Thermostat (11.9OC) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of 0°C. °C Temperature °/o Humidity Relative 116 30° 25° 20° l5° a: C) .4 C3 60 Cr 25 min. 4 \ l Heater Figure 43.--Simulated Humidistat Fan Control (70%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of 0°C. °C Temperature Relative Humidity 70 117 20° '5°\/ \ l0°h _ - _ —_ Fan— ' Heater 90 ‘7 25 min. —> SC) l//////////4av——a— 70 60 Figure 44.—-Simu1ated Humidistat-Thermostat Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of 00C. 118 thermostat control compared to an average of 50 percent for continuous ventilation (Figures 35, 36 and 37). Temperature and relative humidity were adequately maintained with thermostat fan control and continuous ventilation for an outside temperature of -100C (Figures 38 and 39). Temperature and relative humidity varied over a wider range for thermostat control than for con- tinuous ventilation. The fans with humidistat control (Figures 40 and 41) operated periodically in a manner similar to Figure 34 for an outside temperature of -10°C. The humidistat did not control the temperature in the calf housing units. The thermostat set at 18.3OC started the fan (Figure 41) before the humidity had risen to 70 percent. The simulation temperature and relative humidity results for continuous ventilation and thermostat fan control were identical for an outside temperature of 00C (Figure 42). The temperature and relative humidity were maintained within acceptable limits. The humidistat was incapable of controlling the inside environment (Figure 43). The thermostat set at 18.30C operated the fan to limit the temperature rise within the calf housing unit (Figure 44). These simulations indicate that thermostat con- trolled ventilation and continuous ventilation will main- tain an acceptable environment within the calf housing 119 unit. The humidistat, however, will not control tempera- ture and relative humidity adequately to ensure a healthy environment within the calf housing unit. The heating requirements of the four simulated O and 00C outside temperatures control systems at —200, -10 are shown in Table 13. The heating energy values are also shown in percent of the continuous ventilation heating requirement for comparison purposes. With thermostat fan control, only 79 percent as much heating energy was used to maintain an average relative humidity of 65 percent at an outside temperature of -200C, compared to an average relative humidity of 50 percent for continuous ventila- tion. The humidistat set to operate the ventilation fan above 70 percent relative humidity did not provide satis- factory control of temperature and moisture within the calf housing unit. When 60 percent was used in the humidistat simulation, inside temperature and relative humidity were maintained within tolerable limits (Figures 45 and 46). At 00C, the ventilation fan operated con- tinuously with results identical to Figure 42. The humidistat set at 50 percent resulted in less heating energy usage with an outside temperature of ~200C than did the thermostat for control (Table 13). Selection of proper temperature setting of thermostats for fan and heater operation is an important 120 .pcmecoufl>cm moflmcw manmumaoom cm nmpfl>oum * wooa ow.o wmm ow.H wah mm.a eawomv #mumflwwfism . o . o . AU m.mHv #mumOEHOSBI whm mm o amw No A new mm H o Amonv Hapmflwflfism wmm av.o wmm mm.o wow mm.H AwOFV umumwwfifidm wooa om.o wmm ov.H wmh mH.N *AUom.HHv unpmofium£8 wooa 00.0 wcoa mm.H wooa hh.m «mSODaHuCOU msoscflucoo 53M unoccfiucoo 33M msoscwpcou nsx M0 w #mmm MO w ummm NO w #003 HOHHCOU Gow»maflucm> Uocal UOONI .maouucou cam mo momma Hsom SDHB cowumasaflm cofiumaflucm> mcflmsom mamu How pcmamnflswmm “mom coflumHflpcm> mooscflucoo mo “amoumm was unom Ham ucaEwuflcqmm mmumcm mcflummmil.ma manna Temperature °C °/o Humidity Relative 121 I5°L A A l0 '- . V -H;a't-er .- “F* 25 WHO. .11 ——a- 80 .. I V/ 'V/ V Figure 45.—-Simulated Humidistat Fan Control (60%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of —20°C. Temperature °C Relative Humidity '7. I5° l 0° 122 fi Fan - _- _ 80 70 60 25 min. Figure 46.--Simu1ated Humidistat Fan Control (60%) Temperature and Relative Humidity Versus Time Plot for an Outside Temperature of -10°C. 123 and difficult task. The simulation provided useful information for selection of thermostat settings. The heating thermostat for all simulations was set to Operate at or below 11.4OC. Simulations were conducted with cooling thermostats set to operate the fan at or above 11.90, 12.80 and 13.30C (Figure 47). A fan thermostat setting at 11.9OC provided a satisfactory environment (Figures 36, 39 and 42). With the fan thermostat set at 12.80C, satisfactory results were obtained at -20°C outside temperature (Figure 48), but not when the outside temperature was -1OOC (Figure 49). A fan thermostat setting of 13.30C did not provide proper inside environ- mental control at any outside temperature simulated. Figure 50 shows how the relative humidity in all simula- tions eventually climbed to 100 percent. These simula- tions indicated the most desirable fan thermostat setting for temperature and humidity control was between the on and off temperature setting for the heating thermostat (Figure 47). A problem with animal confinement ventilation systems was achieving an increase in ventilation rate to maintain temperature and moisture control as outside temperature increased. Figure 51 shows the minimum air flow rate in m3/min. per kilogram of animal weight to remove moisture produced by the calves and to remove heat produced by the calves for a range of outside temperatures. °C Temperature 124 I4°~ I3.3° [1'12" I 3L l2.8° “522.9" Heater 0" Off A o. '2 l real}? —L on " On Figure 47.—-Tria1 Fan Thermostat Settings for Simulations to Determine Proper Sequencing of Fan and Heater for Confinement Calf Housing Ventilation. Temperature °C Humidity ‘7. Relative l5° |0°| 80 70 60 125 W " III Fan -—--‘--- ---‘----- +——25 min. a. Figure 48.--Simulated Thermostat Fan Control (12.80C) Temperature and Relative Humidity Versus Time Plot for Outside Temperature -200C. 126 9 1505 A A A A 2 - O 8 2 M O .2 I0 I Fan - - - fieater. IOO a: 25 min. 1"] e- :9 >~ 2:390 I s 3 I I :§ 8C) 0 m y 70 I y Figure 49.--Simulated Thermostat Fan Control (12.80C) Temperature and Relative Humidity Versus Time Plot for Outside Temperature -10°C. Temperature °C °/o Humidity Relative 127 : VVVIVV I I 9C) 147 I/’ ,. II V 60 Figure 50.--Simu1ated Thermostat Fan Control (13.30C) Temperature and Relative Humidity Versus Time Plot for Outside Temperature —20°C. m3/min-ka body weight Air Flow Rate .0l 5 .OIO .005 128 I Vent. Level 4 I .0312 m3/min-ltg ‘ I - Remove Calf Moisture _ Vent. Level 2 Vent. Level I / a ___ / "”4" moosqfiu Icou pwumaseflm How muwvwfidm o>flumem can ousumummfioa mpflmcHlt.~m musmwm OO O O O O o o o o a a a Auw oo 0 O O O a a o a o a a o a a 00 O dOOi $ OF 0 O O O O O O O O O O 00 o o o o a o oo o . . . . . . ¢ . . . . . . . . lTli. . Q o 5. 0m co 00 oo 08 O O 000 O _ _ O O O O O .0. O O O 0 0 0° C... . O . O. O C. C O . no... 0 no a a a e a a a e o O O O 0 one o 0 one. a a... o o o a a a a O P 0 5°”— 0,. KuptwnH “HOWE 9. unto: edurel 131 .HDMWHmmm 00H ocflmmmuocH can anat no mcwuumum musumummfioa . so am now mxuaasxms haooo.o Houoaoo can umumoeumae UmHMH58Hm wow huwpwesm o>fiumamm can muaumummsme opflmcHil.mm onsmah om C) p. lumwnu 9Ml°I93 C) a) °/o 00 0 0 0 0 0 m 0 0 co 0 o a O 0 O O 0 O O O 0 oo o o o o a 000 O O O 0 0 0 a o o 0 0 0 0 O O OO O 0 0 o . €000 . . . . . . . . . . 0° . . . I 000000 cc— 0 no... 0 a o a a e on o a a a no a a 1 0000 no. a a a e a 0.... o. o o o o o o o o u o e a one. a one. a a 1 O O O. O I on. a. OJNDJdeal 132 ventilation rates and outside temperature ranges for each are shown in Table 14. Table l4.--Ventilation Rate for Each Outside Temperature Range of a Simulated Ventilation System with Four Thermostat Controlled Air Flow Rates. Outside Temperature Range 3 Ventilation Rate C m /m1n. per kg body wt. T < -10 ‘ 0.0050 -100 i T < -10 0.0069 -1° 5 T < +5O 0.0112 +50 5 T 0.0312 The four level ventilation system maintained inside temperature and relative humidity within acceptable limits even though the relative humidity fluctuated between 55 to 75 percent (Figure 54). A four level ventilation system was tested during spring weather. The system consisted of a single four speed fan controlled by a two stage thermostat inside and three outside thermostats. The control wiring is shown in Figure 55. Tests were conducted over a wide range of outside temperatures resulting in similar inside conditions as Figure 56. Ventilation rates for the fan at each level are shown in Figure 56. The ventilation rate for the test of Figure 56 was too high, resulting 133 .Hsom mom 00H mowmmouocH can anat no mcfluumum musumummEmB mpfimuso so How Emumwm coaumaflusm> Ho>oq Hoom wovMHSEfim How wufiowesm m>Hu0Hom can musummmmfima oUHmGHII.¢m onsmfim on a o O O O O O 000 On 0 000 O O 0 00 JO 0 o ioP o 00 a a a o a a O O O O 00 a 00 000 ca 00000 a a 00 0000000 L. ON a a o o a o 3.3.. om w .264 .23) 3:04 m .26... .Eo> 50004 N .264 .Eo> \\ lotséms 080.. _ .25.. ..§> a.» a ‘00— 00. o a an o a o o a a an a q I. O O O. #0”— enumea KuplwnH % a. armoredwal 134 4 Level Fan Z -NOJ-b ] r " " “I I" “' “I r'— “I I I l I Outside Thermostats I l l : : : SPDT ' l l I ' L_ _. _l l... ._ _J L... _ _J l5°C 7° -5 Inside 2 level H; “J _ _ —"1| Thermostat l I 3° 0 Differential } I L__-___J lO°C Action on temperature rise Figure 55.--Control Diagram to Achieve Four Level Ventilation Rate Using One Inside Thermostat and Three Outside Thermostats. Temp. Humidity Relative l5°C IO" 50 70 °/o 50 135 .—.\ Inside . I}; A— \.\ ._..v._._.._.\/"' \/./ E ._ °\.~ __~. ‘a_m i__ _ \". ” ~ ..... ~\"’ Outside _ \ _ ” 3rd level. ’ < ‘ \._ w - \._.. : d \. - __ 2" level : L /'\ llll Tll' °" ./ \ \ ,-—~\ ’\ \._._. -—- .l, . .— °°°°° / / \lnsidt/ \V/ \\ L ‘TTT$illllll 7 time I l l 6pm Ime 60m Fan level I. 5.25 m3/min. 2. 6.39 " 3. 9.65 " 4. ”.78 " Figure 56.--Inside Conditions Resulting From A Four Level Ventilation Fan With One Inside Thermostat and Three Outside Thermostats With Outside Temperature Falling at a Rate of 0.5°C Per Hour. 136 in an average relative humidity of 60 percent. The temperature settings for each ventilation rate are shown in Figure 55. Heated Versus Cold Inlet Air A study was conducted to evaluate the effect of heating the inlet air prior to entering the barn compared to allowing the air to enter cold. Tests showed no energy consumption difference between heating the calf barn with a heater inside and heating the inlet air prior to entering. Figure 57 is a plot of temperature and relative humidity versus time for heated inlet air com- pared to cold inlet air. The outside temperature for this trial was 00C and the heater in the inlet duct cycled on and off as the heat requirement was satisfied. During colder weather, the temperature in the calf housing unit receiving the heated inlet air fluctuated less than the chamber with the inside heater. Experience from these tests showed that it was desirable to sub- divide the heating elements in the inlet air duct and control the elements with two thermostats inside the barn. The thermostat with the lower setting called for higher heat output only if conditions were not satisfied by the first thermostat. This reduced the temperature fluctua- tions within the calf housing unit during warm weather when less heat was required. l5°C lO° a s .2 50 00 z: E 80% :I I 0 .2 g 60 m 137 Inside Air >C\‘M A\ \ \ n .‘ r, ‘ /\/ 3‘5}. .; ‘ .\. /: \/ l - \/./:\ _ : AV- L \._._._._._.\.§.Alnlet—. Air he\at/e_£:—_ t I l l 7pm . llpm tlme [III .// A. A: 747 z/ 5". l‘/ \ / \ I, ‘ 'O ‘c I! “ \{ I ‘ . _ 1! l f -" 1 1 : t i , l _ _ .I X [X ‘ - ‘.' ‘ : ‘ol’ ‘0. : Heated Inlet ------- Cold Inlet 284 m3/mino Figure 57.--Temperature and Relative Humidity Versus Time Plots for Ventilation Inlet Air Cold and Heated. 138 The effect of the heated and cold inlet air on the calves in the stalls was determined by placing a thermocouple near the head of a calf. The calves experienced colder temperatures with cold inlet air (Figure 58). Heating the inlet air, Figure 59, resulted in less temperature stratification in the barn. The temperature difference from floor to ceiling was less with heated inlet air. When the inside heater blew warm air into the entering cold air some temporary mixing occurred. The temperature versus time plot (Figure 59) was determined with a vertical column of thermocouples spaced at 15 cm intervals from the floor to the ceiling. The location of those thermocouples is shown in Figure 60. Winter Air Flow Patterns A study of the air flow patterns in the calf barn was conducted with inlet air heated and cold and with the air dropping straight down along the wall from the inlet slot and entering at an angle. Also, with the inlet air entering cold, the air flow was studied with the inside heater operating. Air flow patterns are shown in Figures 60 through 69. When the cold air entered at an angle, Figure 61, the calves in the center stall were exposed to some drafts, but with the solid partitions the calf could get down in the stall for protection from drafts. These minor 139 l' Calf Stall |Ooc -/.X / .\' - .”,, , /r . \ ./ \ - L , - L ‘\\, - 50 '— ‘vok ’°~~¥ .- I’f \ Ir "\ + __- I \“ ” \‘. ’/ \‘\ - .. ‘--./ s - r - l l l l l I I l l l l 7pm 9pm llpm time I Fan Inlet - -- 0’. . . - a \ 1" \k / '0 C - .”"s\\‘. / \./”o\ .- __ ’1 \- I I \ I’.’ \\ _ I- \\ .l ‘ I ‘ .— I \ I s "’ \./’ \ I - 50 1 —— Inlet Air Heated --- -— - Inlet Air COId Figure 58.--Calves Experience Warmer Temperatures in the Tie Stalls When Ventilation Inlet Air Was Heated Rather Than Cold. 140 ceiling l5°C COLD INLET A '- [X E A A_i’/A\/ 1' _ g/Wzv v, _ '- flaar - — — - I- — off ..07 Heat 9 '9 2.0 3.0 4.0 time min. L _ - ll ll HEATED INLET _ I\ .. llll l5°C It . 0 I, \ “mm; H [A /\ _ , / ‘ \/\\ ‘ L \ 1 . \ "' I 0° , . / I \ V T ‘ I \ / \ my I ‘ / \ I III] 5" I] \l L :1 \\. - : / \ L V \ _‘_' : ll \\ \ I heated inlet air \I _ 0° 1 \ _. \unheated inlet air _ — — — Heat Off on Figure 59.--The Temperature Difference from Ceiling to Floor was Less with the Inlet Air Heated Than When the Inlet Air Entered Cold. 141 “E? ,4 j x \ \J k/ / / F‘—O' at——F \\ \K ‘A/ A/’ x F" *F #— F loar to Ceiling Thermocouples f i at’J: F'~a. f .A'F Fa; 1 I 1'“ F\ | _________ fl ,--------_ ‘1:— a* Figure 60.--Top View of Air Flow Pattern with Cold Inlet Air Entering at an Angle. * F designates air flow at the floor level. 142 in \ . F” l r? t t Figure 61.-—Side View of Air Flow Pattern with Cold Inlet Air Entering at an Angle. L [r l l l / /,/ / ,1 l ? __l/l, Figure 62.--Side View of Air Flow Pattern with Cold Air Entering Straight Down Along the Wall. 143 R n/ m\ i/ Figure 63.--Top View of Air Flow Pattern with Cold Air Entering Straight Down Along the Wall. 144 Figure 64.—-Top View of Air Flow Pattern with Cold Air Entering at an Angle and the Inside Heater Operating. 145 NE 1 1r l l CT: /l (Left Side of Figure 64) (Right Side of Figure 64) I ‘_ L.::' :j)\ 4— l3 -It ,—L- Ha l \ / Figure 65.--Side Views of Air Flow Patterns with Cold Air Entering at an Angle and the Inside Heater Operating. 146 Low $ Low Figure 66.—-Top View of Air Flow Pattern with Heated Inlet Air Entering at an Angle. 147 .— ‘_ Uf ,_L— 1 <— <— \L .:_.—_ ”it \—’-. t t /Hf Figure 67.--Side View of Air Flow Pattern With Heated Inlet Air Entering Straight Down Along the Wall. Figure 68.--Side View of Air Flow Pattern with Heated Inlet Air Entering at an Angle. 148 ——.. 3 L T G—- // \\ «F—F F-Jb _________ _.l r__—_.-___- f fig Figure 69.--T0p View of Air Flow Pattern with Heated Inlet Air Entering Straight Down Along the Wall. 149 drafts did not seem to bother the calves when the ambient temperature was above 100C, but when the temperature was below 10°C, the calves in the center stalls on occasion were observed shivering. Directing heated air down along the wall was not desirable because drafts were created. An up draft occurred in the stall beneath the inlet (Figure 67). When the air was directed down along the wall all calves in the building experienced undesirable cold drafts to some degree (Figures 62 and 63). Directing the inside heater toward the cold air inlet was desirable (Figures 64 and 65) with heated air becoming mixed with cold inlet air. This mixing avoided cold drafts on the calves and helped mix the air in the barn to reduce temperature stratification. CHAPTER VIII SUMMARY A need has existed for many years for environ- mental design information collected under controlled con- ditions for confinement calf housing. Two identical housing units were designed and constructed for eleven calves in tie stalls bedded with fresh wood shavings every two days. Calf body weight during these tests ranged from 45 to 65 kilograms. The research was con— ducted at the Michigan State University Dairy Science Teaching and Research Center. The building designs were consistent with presently accepted recommendations for construction and insulation. The only deviation from typical farm housing and management conditions was placement of the housing units inside an insulated research barn to eliminate the direct influence of solar radiation and wind. The air intake was on the south side of the research barn and the fan exhaust was on the north. Wind influence upon the ventilation system was typical of farm conditions. Instrumentation was provided to determine and record dry and wet bulb temperatures at specific locations 150 151 and to measure electrical energy consumption for heating and ventilation. An orifice meter was designed, con- structed and installed in each calf housing inlet air duct to permit accurate determination of air flow rates through the calf chambers. Heat and moisture production rates for Holstein bull calves were determined by operating the calf chambers as open ventilation direct respiratory calorimeters. Supplemental heat was turned off and the inside environ- ment was allowed to reach steady state conditions. Calf heat and moisture production was calculated directly from the inlet and exhaust air conditions at steady state. Studies of different ventilation controls, cold inlet air compared to heated inlet air, and air flow patterns within the housing units were conducted for winter ventilation conditions. A computer model of the inside environment was used to simulate inside tempera- ture, relative humidity and heating energy use with several different ventilation fan controls. Conclusions l. The total stable heat production of Holstein bull calves in tie stalls bedded with fresh wood shavings every two days decreased on a unit body weight basis with increasing weight. Heat production at 50 kilogram weight was 3.1 Kcal/hr-kg while at 65 kilograms heat production declined to 1.7 Kcal/hr-kg. 152 2. Total stable heat production did not change for tests conducted over a range of inside temperatures of 100 to lSOCelsius. 3. Stable moisture production of Holstein bull calves in tie stalls bedded with fresh wood shavings every two days decreased on a unit body weight basis with increasing weight. Moisture production with 100C ambient temperature was 1.8 grams/hr per kilogram of body weight for a 50 kilogram calf, and 1.3 grams/hr—kg for a 58 kilogram calf. Calf weight ranged from 45 to 65 kilograms. 4. Stable moisture production was about 70 per— cent higher at 150C ambient temperature on a unit weight basis than at 100C. 5. Continuous ventilation provided inside temperatures from 100 to 15°C and relative humidity averaging 55 to 60 percent for outside temperatures, less than -100Celsius. 6. Thermostat fan control provided inside temperatures from 100 to 150C and relative humidity averaging 65 to 70 percent for outside temperatures less than -100Celsius. 7. Computer simulation of humidistat fan control indicated that temperature could be maintained from 100 to 15°C and relative humidity less than 80 percent, if the heater thermostat was set at 11.4OC and the humidistat at 60 percent for outside temperatures less than -100 153 Celsius. Higher humidistat settings were not capable of controlling moisture in the calf housing unit. 8. Time clock ventilation fan control would not adjust to changing conditions to maintain a satis- factory environment within the calf housing unit. 9. A four air flow rate system providing con— tinuous ventilation with three successively higher air flow rates controlled by outside thermostats maintained inside temperature between 10 and 15 C and relative humidity less than 75 percent. 10. Heating the inlet air to a confinement calf barn reduced cold drafts on calves and reduced tempera- ture stratification from ceiling to floor. 11. Directing cold air down along the wall from the inlet was undesirable, causing drafts on the calves. 12. Cold inlet air was tempered by directing the supplemental heater toward the air inlet, causing mixing of the cold inlet and warm heater air. CHAPTER IX SUGGESTIONS FOR FURTHER RESEARCH This research was intended to gather information concerning a few basic design parameters for confinement dairy calf housing. As Bates and others point out, con- siderable new knowledge must be gained through controlled research if calf housing is to be considered more a science than an art. The following are additional areas of concern in the overall effort to increase productivity and efficiency through the improvement of calf heath. l. A more thorough investigation should be con- ducted to determine the affects of high relative humidity and low temperature on the calf's susceptibility to sick— ness and death. 2. Study the growth behavior, including air transport, of pathogenic organisms in the calf environment. 3. Conduct a controlled study with large numbers of calves to establish statistical significance to test of cold versus warm calf housing with each type of housing. 4. Using the Finite Element technique, develop a real time model of the interior environment of animal housing to be used to study structural design alternatives 154 155 of confinement environment. Perhaps with alternative designs, some buildings now ventilated mechanically could be ventilated naturally. 5. Investigate the relationship between air flow patterns and distribution and calf barn size. A number of experts advocate smaller barns for calves, however, their reasons are probably from a health standpoint--not better environmental control. Hallahan (1967) suggested that smaller barns could be managed better from the stand- point of environmental control. 6. Investigate the effects of calf body cooling by radiation to cold surfaces such as manure pit liquid, wet floor, and cold walls. Determine if radiation exposure has an adverse effect on calves in elevated stalls. REFERENCES 156 REFERENCES Agricultural Research Council, 1965. 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Transactions of the American Society of Agricultural Engineers, 3: 57. Young, B. A., and R. J. Christopherson, 1974. Effect of Prolonged Cold Exposure on Digestion and Metabolism in Ruminants. Livestock Environment. American Society of Agricultural Engineers Special Publi- cation, SP-0174: 75. APPENDIX 163 SI METRIC TO ENGLISH CONVERSIONS Absolute Humidity grams water/kg dry air x 10-3 = lbs. water/1b. dry air Air Flow Rate m3/min x 35.22 = cfm Area 2 2 m X 10.76 = ft Enthalpy Kcal/kg dry air x 1.80 = Btu/1b. dry air Heat Production Kcal/hr-kg x 180.4 = Btu/hr-cwt Length m x 3.28 = ft. cm x 0.0328 = ft. cm x 0.394 = in. Moisture Production grams/hr-kg x 0.1 = lbs/hr-cwt Temperature (0c + 40) 1.8 - 40 = OF Thermal Conductivity Kcal/hr-mZ—OC x 0.2048 = Btu/hr-ftz-OF Kcal/hr-OC x 2.20 = Btu/hr-OF Velocity m/sec. x 3.28 = ft/sec Weight kg x 2.20 = lbs. 164