I'll! THE S '1‘ Date MINI”!lilfllllllllllllillllllIlll“HIHUIIIIHW 31293 10675 4256 i.” tunafiy L Mmh‘. mm Stan: mety ~ This is to certify that the thesis entitled A COMPARISON OF LOW-TEMPERA TURE STIRRED IN- BIN DRYING WITH IN-BIN NATURAL AIR DRYING 0F SHELLED CORN presented by Eliud Ng'ang'a Mwaura has been accepted towards fulfillment of the requirements for M.S. degree in Agricultural Engineering Major professor January 9, 1981 0-7639 ovenous FINES: 25¢ per W W m“ { -*\\\\ i RETURNING LIBRARY MATERIALS: N i I - . Place in book return to remove 5‘13” change from circulation records A COMPARISON OF W'TEMPERA‘I‘URE STIRRED IN-BIN DRYING WITH IN-BIN NATURAL AIR DRYING OF SHELLED CORN BY Eliud Ng ' ang ' a Mwaura A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Agricultural Engineering Department 1981 ABSTRACT A (DMPARISON OF IOU-TEMPERATURE STIRRED IN-BIN DRYING WITH IN-BIN NATURAL AIR DRYING OF SHELLED CORN BY Eliud Ng ' ang 'a Mwaura Low-temperature in-bin grain drying with supplemental heat results in overdrying at the bottom and underdrying at the top of the bin. To reduce this effect, stirring devices have been introduced. The objective of this thesis is to compare the performance characteristics of a lowtanperature stir—drying and natural air drying systems. The field tests were conducted at Kalchik Farms, Bellaire, Michigan in the fall of 1979 and 1980. The corn was dried to 22-23% moisture in a high temperature dryer before drying to 15-16% in the low-temperature and natural air drying phases. The grain quality and the drying costs were analyzed and compared. The results indicate that low-temperature stir—drying requires slightly less energy than natural air drying, is a more reliable system, and results in better quality corn. The total drying cost for the stirred low-temperature drying was $1.45/ton per percentage point moisture reroval, compared with $1.88/ton—point for the natural air system. The author wishes to acknowledge the guidance and the encouragement of Dr. Fred‘w. BakkerbArkema, and his advice as the major professor. Appreciation is expressed to Juarez Silva and Juan Rodriguez for their assistance in data collection and companionship. The author is indebted to Steven Kalchik, his father, mother, brother and sister on.whose farmlthe research presented in this thesis was conduc- ted. Their help and hospitality is sincerely appreciated. Special thanks and appreciation is sincerely expressed to the Nether- lands Government and the University of Nairobi, Kenya for financial support. ii TABLE OF CONTENTS LIST OF TABLES ......................... LIST OF FIGURES ........................ LIST OF SYMBOLS ........................ Chapter 1. INTRODUCTION ...................... 2.3 Michigan Corn Production and Energy Use ,,,,,, Corn Drying in Michigan .............. Corn Production and Drying Problems in Kenya . . . Objectives .................... Importance of Grain Drying ............ Corn Quality as Affected by Drying Methods . . . . 1 Effect of Drying on Nutritional Feed Value , .2 Effect of Drying on Corn Milling Quality , , 3 Drying Corn for Seed ............ 4 The Effect of Drying on Corn Commercial Grade 2.2.4.1 Test Weight ' ----------- 2.2.4.2 Stress Cracks and Broken Corn - . . 2.2.4.3 Other Corn Quality Characteristics Affected by Artificial Drying - - Drying Systems . . . ............... 2.3.1 ColumnBatchDryers 2.3.2 High-Speed Continuous Cross-flow Dryers. . . 2. 3. 3 Ian-Temperature and Natural Air In-Bin Storage Drying ....... . . ..... 2.4 Stirred Bin Low-Temperature Corn Drying ...... 2.4.1 Effects of Stirring Management Techniques onCornDrying . . . . . . . ..... iii Page vi vii p... NUIWD 13 14 14 16 18 18 19 20 21 21 23 27 28 30 34 Chapter Page 2 . 5 W—Terperature and Natural-Air In-Bin Drying Theory and Simulation ............... 37 2 . 5. l Thin-Layer Drying Equations for Corn ..... 41 2.5.2 Corn Moisture Adsorption ........ . . . 44 2 . 5. 3 In-Bin Low-Temperature Drying ........ 45 2 . 6 low-Temperature , In-Bin Stir Drying Theory and Simulation .................... 50 3. EXPERIMENTAL ....................... 52 3.1 Instrumentation and Measurement ........... 56 3.2 Economic Analysis .................. 56 3. 3 Drying Computer Simulation ............. 57 4. RESULTS AND DISCUSSIONS .................. 58 4.1 Effect of Stirring on Drying Time and Moisture Content Distribution ............... 58 4.2 Effect of Stirring on Corn Quality ......... 63 4.2.1 Stress Cracks ................ 63 4 . 2 . 2 Breakage Susceptibility ........... 63 4.2.3 Broken Corn and Fine Materials ........ 65 4. 2. 4 Viability Change ............... 65 4. 3 Energy Consumption and Operating Costs ....... 66 4.4 Capital Budgeting Analysis ............. 7O 5. C(NCLUSIONS ........................ 74 6. SUGGESTIONS FOR FUTURE WORK ................ 75 7. REFERENCES ................... 4 ..... 76 8 APPENDICES ........................ 81 Appendix A ........................ 82 Appendix B ........................ 92 Appendix C ........................ 105 Appendix D ........................ 110 Appendix E ........................ 130 iv Table 10 11 12 LIST OF TABLES Page Drying of corn stored on farms by selected states . . 6 Percentage of corn stored on farms in Michigan by size group .......... . ............. 7 Percentage of shelled corn dried artificially on farms in Michigan in 1974, 1975 and 1977 ........... 8 Numerical grades and sample grade requirements for yellow, white and mixed corn ................ 15 Effect of stirring management on drying time and dry matter loss (airflow rate 5.7 m3/m2) ........ 51 Moisture content variation with depths, for different drying systems ............. 59 Computer simulation results of natural air (NA), low- temperature-nonstirring (LT—NS) , low-temperature stir— ring (LT-ST) and natural air stirring (NA-ST) . . . . 60 Quality parameters for low-temperature stir dried corn and natural air dried corn in 1979 and 1980 ..... 64 Actual energy consumption and operating costs (1980 prices) for low-temperature stir drying and natural air drying at the Kalchik Farms, Bellaire, MI . . . . 68 Standardized energy consumption and Operating costs (1980 prices) for low-temperature and natural air drying at Kalchik Farms, Bellaire, MI ........ 69 Estimates/assmptions for a 10 year budgeting analysis (1980 prices) ............ . ....... 72 Economic analysis results for three high temperature— low- teiperature combination drying/ storage systems for Michigan (1980 prices) ................ 73 LIST OF FIGURES Figure Page 1 Batch column dryer ................... 24 2 Crossflow dryer with forced air drying and reversed flow cooling ............... . ..... 25 3 Schematic of a crossflcw (continuous flow) grain dryer . . . . . . . . . . . . ............ 26 4 Schematic of grain stirring device ........... 32 5 T p view patterns formed by single auger grain stirrer . 33 6 Path of auger horizontal travel ............ 54 7 The effect of stirring on in-bin corn drying. . . . . . 62 vi DEL DELT DEPI‘H DFK IMISRA DMS DRUG LIST OF SYMBOLS constant area, m2 - constant mass concentration coefficient, kg/m3 specific heat, kJ/kg-°C air flow rate, m3/min diffusion coefficient, emZ/sec moisture content by delGuidice thin-layer equation , decimal d. b. time increment, hr total bed depth, m drying parameter, l/hr dry matter loss by Misra thin-layer equations, percent dry matter loss by Sabbah and delGuidice thin-layer equations , percent dry matter loss by Rugumeyo thin-layer equations , percent experimental corn moisture content, decimal d.b. mass transfer rate, kg/cxm2 sec acceleration due to gravity , m/ sec 2 dry weight, kg/m mass flow rate per unit area, kg/h-Im2 gravitational acceleration 9. 8 m/sec2 convective heat transfer coefficient, w/ (m2-°C) vii h latent heat of vaporazation of water in a product, kJ/kg hxy convective coefficient, w/(m?-°C) H absolute humidity of air, kg/kg HIN inlet air absolute humidity, kg/kg HR time, hr i internal energy, kJ/kg INDPR number of nodes between prints k parameter, l/hr k thermal conductivity, w/m-°C K coupling coefficient K phenomenological coefficient K thickness,1m K subscript or superscript K extinction coefficient, l/Hl L length, m ITHNS low temperature (electric heat) non-stir in-bin drying IHLST low temperature (electric heat) stir in-bin drying m1 constant M moisture content, dechmal, d.b. MISRA :moisture content by Misra thin-layer equations, decimal d.b. MPM meters per minute MR moisture ratio, decimal NA natural air in-bin drying NEQ equation type NLPF rmntem'of layers per meter p pressure, N/mfi PS saturated vapor pressure, Pa viii PSDB 0.050 H TA TAIR TBTPR TIN vapor press, Pa heat energy, W/Im2 heat flow rate kJ/h-m? heat flow rate kJ/hr radius, m air relative humidity, decimal radius,rm air relative humidity, decimal moisture content by Rugumayo thin-layer equations, decimal d.b. moisture content by Sabbah equation, decimal, d.b. moisture content by Sabbah and delGuidice equations, decimal d.b. time, hr thickness,1m temperature, °C ambient air temperature, °C bulk temperature, °C mixed mean fluid temperature, °C plate temperature, °C air temperature, °C ambient air temperature, °K drying or rewetting air temperature, °K time between output, hr equivalent reference storage time, hr grain temperature, °K inlet or initial grain temperature, °C inlet or initial air temperature, °C ix 2 2') C: X total time, hr heat loss coefficient, w/(m2—°C) fully developed fluid flow rate, m/hr weight, kg width, m distance, m x-coordinate equilibrium moisture content, decimal, d.b. inlet or initial moisture content, decimal d.b. y-coordinate distance, m LIST OF SYMBOLS USED AS SUBSCRIPTS air downward diameter equilibrium storage array for humidity ratios - kg-HZO/kg dry air heat inlet long loss initial outlet product surface time air temperature array total useful upward vapor water Greek Symbols a constant 3 finite difference 6 constant A difference 0 grain temperature, °C or °K (1 dynamic viscosity, kg/ (rm—hr) p density, kg/mfi o constant variance of observation errors 0 Stefaanoltzman constant, 5.67x10-8w/(m2 -°K“) T shear stress, N/zm2 v kinematic viscosity, m?/hr 9 diagonal matrix 1 . INI‘HJDIIII‘ ION The United States is the leading corn producer in the world. In 1978 the U.S. produced nearly 50% of the total world corn production (FAO, 1979) . In 1979 the U.S. produced 198 mega metric tons of corn for grain (USDA 1980) . The energy consumption on American farms is low compared to other sectors . According to Friedrich (1978) energy use in the United States is as follows: On farm food production 3—4% Entire food production 12-17% Industrial processes 37% Transportation 26% Others 20-25% Thus, compared with energy use in industrial processes and transporta- tion, energy consumption in agriculture is indeed small. However, consider- ing the annual total agricultural energy consurption of 2.65 x 109 mi! (2.5 quadrillion BI‘U' 5) energy conservation in agricultural production will result in considerable overal energy savings (Friedrich, 1978). In its 1976 annual report to the Congress, the U.S. Energy Research and Development Administration (ERDA) pointed to the following facts (Friedrich, 1978): 1. A barrel of oil saved can result in reduced oil imports. 2. It costs less to save a barrel of oil than to produce one through the development of new technology . 3. Energy conservation is beneficial to the environment in comparison to energy produced and used. -1- -2... 4 . Capital requirerents to increase the energy efficiency are generally lower than the capital needs to produce an equivalent amount of energy from new sources since most new supply technologies are highly capital intensity. 5 . Conservation technologies can generally be implerented at a faster rate and with less government involverent in the near ‘ term than can new supply technologies. 6. Energy efficiency actions can reduce the pressure of acceler- ated introduction of new supply technologies . Since the actions persist over time the benefits are continuing. With an abundant energy supply at reasonable costs , it is still pro- fitable for one U.S. farmer to produce enough food for more than 50 other individuals (CAST, 1977) . However, with the continuing fossil fuel supply limitations, rapidly increasing costs and lack of price projections, the profit margin in agricultural production is continuously decreasing. It is therefore , important to (misider ways and means of improving production techniques and increasing the energy efficiency on American fanms. The Council for Agricultural Science and Technology (CAST , 1977) suggested the following with regard to farm operations : . reduce energy use for fertilizer application and tillage; - substitute enterprises that consume less energy; - invest in alternate technologies that substitute energy inputs and reduce energy use; . invest in alternative energy sources such as solar , wind and biomass; - modify fanm enterprises to make them more efficient for the natural environmental conditions; and - cease farming if the adjustments are too difficult. -3- Artificial corn drying is an energy intensive system. About 60% of the emergy required to produce corn on the farm is used for artificial drying (Ag Engr. Dept. MSU, 1974) . Inspite of the high energy demand for drying. over 80% of the corn produced in the U.S.A. is artificially dried (ASAE 1978) . Artificial drying has the following advantages (Brooker et al. , 1974): - artificial drying allows early harvesting which in turn reduces storm and shattering field losses and permits early land prepar- ation for the next crop; - planning the harvest season to make better use of labor, be- cause harvesting is independent of grain moisture content f luc- tuations in the field; - long time storage without deterioration; - enables farmers to take advantage of higher price a few months after harvest; - maintenance of grain viability; - maintains grain quality; and - allows the use of full season hybrids (longer maturing varieties) that yield more grain per hectare- Considering the above advantages it is obvious that energy intensive corn drying cannot be avoided without undue loss of corn quantity and quality at the farm level. The current artificial grain dryers use convection type heaters that burn fossil fuel, usually liquefied petroleum (LP) gas or natural gas. According to Friedrich (1978) , high temperature dryers operate at about 50 percent efficiency in utilizing fuel to evaporate the moisture in grains. It takes about 4650 to 8140 M of heat to retove one kilogram of water from corn depending on the initial and final moisture content, the amount of -4- fines in the grain, and.weather conditions (Brooker,et a1.,l978). It is obvious that the current high temperature grain dryers use too much fuel. There is room for improvement and design of alternative grain drying systems is necessary to reduce energy used for grain drying. ASAE (1978) listed four possibilities of reducing fossil fuel require- ments for grain drying: 1. increased use of high moisture corn storage used to feed animals on or nearby farms where corn is grown; 2. combination systems using the advantage of high speed, high temperature dryers coupled with energy savings of in-stoarge, low temperature or natural air drying. 3. solar heated drying systems; and 4. incineration of crop residues used as a crop drying energy source. Energy savings of up to 50 percent using different combination drying systems have been reported by BakkereArkema et a1. (1978, 1979 and 1980), Kalchik et a1. (1979), and Silva (1980). 1.1 [Michigan Corn Production and Energy Use According to the USDA (1980), Michigan ranked ninth.in the United States in 1977 and 1978 and eighth in 1979 in the production of grain for corn. .Michigan corn accounted for 3.1% of the total united States produc- tion in 1977, 2.7% in 1978 and 3.1% in 1979. The shelled corn production in Michigan increased from 2.3 million tons in 1960 to 3.9 million tons in 1975 (Fedewa et al., 1979). During the same period, the energy used for drying increased from 75.2 x 1010 km to 329.5 x 1010 kJ (Brooker, 1977). According to the USDA (1980) the Michigan corn production in 1979 was just over 6.03 million tons. Infbrmation on corn drying energy for 1979 is not yet -5- available. If the same trend continues, the energy for drying corn in 1979 was likely to be over 400 x 1010 kJ. The increase in energy consump- tion is largely due to the shift from ear-corn to a shelled corn harvest- ing systems, and also due to the net increase in corn production. As previously stated, more than 60% of the energy required to produce corn on the farm is used for artificial drying in 1977, 74.9% of the Mich- igan corn was artificially dried in some kind of heated air drying system; over 88 percent of fuel was propane (Fedewa et al. , 1978) . l. 2 Corn Drying in Michigan Heated air drying of shelled corn is a cannon practice in Michigan due to the characteristic weather conditions. According to Fedewa et a1. (1975 and 1978) , corn drying practices are as shown in Tables 1, 2 and 3. It has been estimated that at least 60% of the 6.03 million ton Mich- igan corn crop was artificially dried in 1978 (Bakker-Arkema et a1. , 1979) , primarily in automatic batch dryers between 80° and 110°C, and in-bin batch type drying systems between 43° and 60°C. About 142 kg of water per ton is reroved from corn harvested at 26% moisture content and dried to 15.5%. Assuming an average energy efficiency of 7000 kJfl.mv 30am mdoooaucoo n.0H m.oa N.om CHQLCHInoumm o.oe N.bm H.mm nuumm whoa mhma vhma mama Hmsuo .hhma Em. mbmH .vhma ca cooEoE ca mend co seaoaodefin cone EB 83an no octagon .m Sane. -9- ha) under different ecological and socio-econcrmic, environmental and technological conditions . Thus , the production problems are many and varied. large scale farmers produce corn almost entirely as a cash crop and usually have the equipment and the know-how to handle the crop more effi- ciently than the small scale farmers. The latter depending on how "small" they are , produce corn for home consumption and for cash if they have a surplus. Sate maize is consumed fresh before it matures and the rest is stored for seed and future consumption. Small scale farmers face major problems in drying, cleaning and storage of corn and other grains . Handling practices vary from place to place within Kenya. Same farmers, especially the subsistent farmers, harvest unhusked corn and suspend it frcm trees, on poles, over fires in their hares or on special platfonms. Others have traditional granaries in which dehusked or unhusked corn is kept for natural drying. The granaries vary in size, accessability for inspection and reroval, and the degree of protection against insects, rodents and the weather. Some maize may be sun-dried (either as ear-corn or shelled grain) by spreading it on mats, ground or flat rocks. Solar-drying at the harestead is economical, but is risky due to un- certainties about the weather, and labor availability for handling. There- fore, most farmers leave the crop to dry naturally in the field, and harvest when it is sufficiently dry (16 to 18%) for solar drying. This leads to field infestation by insects , birds , and molds. Also, the land preparation for the next crop is delayed. To avoid this delay, sate famers cut the cornstalksandstackthemin2t04meterdiameterconical stacksinthe field. The stacks are left in the field for up to two months to dry. The long term storage of corn is undertaken by the Kenya Cereals -10- Board (a Government agency) . The board is charged with drying and storage of cereals for the purpose of price stabilization and for erergency needs (such as occur during a drought). The Board handles 20% of the total Kenyan corn production. The rerainder is handled by individual farmers or co- operatives. The Board buys maize from famers at a specified quality standard and government set price. Maize that is above 13% moisture content (wet basis), or insect damaged, or contains specified foreign materials, broken or colored kernels, is not acceptable to the Board. For long term strategic storage (up to 3 years) , the Board uses Cyprus bins. Maize is artificially dried to 12% moisture for long term storage. For short term storage maize at 13% moisture is stored in masonry sheds in 90 kg bags. The Board handles about 500 thousand metric tons annually. According to FAQ (1979) , the total Kenyan maize (corn) production was 2.6 million tons in 1976; 2.553 million in 1977 and 2.35 million tons in 1978. The annual loss due to insects alone has been estimated at between 5 and 7%. This amounts to a monetary loss of approximately $16 million annually (Anderson and Pfost, 1978) . Grain storage problems differ in various regions of Kenya. Insect damage is by far the most severe problem. Drying problems are more severe in the surplus producing areas with higher rainfall than in the drier grain-deficient areas . Long-term storage conditions are most favorable at higher altitudes due to lower terperatures and lower relative humidities than in the lower altitudes. Judging from the available literature on grain drying and storage in Kenya , it appears obvious that storage problems are more severe than dry- -11- ing problems . However , storage and drying are closely related . Since the most severe insect infestation, plus molding and rotting occurs in the field while natural drying takes place, it is reasonable to postulate that artificial drying can contribute substantially in minimizing the storage problem. It has been observed that insect infestation in the field does not start at high ear moisture contents. Although the exact moisture con- tent at which this occurs has not been documented. It largely depends on the insect species. If the corn can be harvested before infestation, dried quickly before molding and then stored in a well maintained struc- ture (with regular insecticide application), grain can be stored on the farms much longer than amars currently possible. As stated earlier, most Kenyan corn producers are small scale farmers. As in Michigan (see Table 2) most small farmers dry their crop naturally, either in the field or in some type of a crib. Kenya has no oil nor metalic minerals and has a foreign exchange shortage. It is therefore, necessary to design grain drying systems that are effective, cheap, least energy (fossil fuel) consumptive and made of locally available materials. In the past the erphasis on grain storage problems in Kenya has been largely entomological. There has been little research effort on grain drying and storage structures; due to a shortage of agricultural engineers in the country. After their study on smallholder grain storage problems in Kenya Anderson and Pfost (1978) recamended that a thorough study should be conducted on grain storage needs in Kenya . They also recommend- ed that personnel be trained in seed science and grain drying and handling technology to alleviate the severe shortage of local personnel qualified to solve the grain drying/ storage problems . The research discussed in this thesis is a part of an effort to study the feasibility of natural air and combination drying systems in Michigan. -12- The knowledge gained.will be used to:modify these systems (if necessary) to suit Kenyan conditions. 1.4 Objectives The overal objective of this study is tolcompare the performance char- acteristics of in-bin shelled corn stirhdrying'with that of in-bin natural air drying. As a part of the combination drying systems, a continuous high temperature crossflcw dryer (Kan-Sun model 8-15-10) is used to dry corn from about 33 to 22-23 percent (wet basis), to prepare the corn for in- bin low temperature stir-drying and natural air drying. The specific Objectives are: - to model stirbdrying - to study the effect of stir-drying on: a. the grain quality and its uniformity b. the moisture content uniformity of the grain in the bin c. the drying time, and _ d. the energy consumption and the drying cost - to demonstrate the technical and economic feasibility of inrbin stirbdrying in high temperature/lowetemperature combination dry- ing. 2. LITERATURE REVIEW In this study high terperature, high speed drying was combined with low-tetperature stir drying. These drying processes affect grain quality in different ways. It is well known that grain and seeds are exceedingly durable but highly perishable if poorly handled. If well harvested, and stored at low moisture content and low temperature grains will retain the original germinability and other desirable qualities for a long period of time. The following literature review was developed to study the need for grain drying, the effect of various drying methods on grain quality, and the developrent of stirring devices for in-bin deep bed drying . 2.1 Importance of Grain Drying The importance of grain dryinghas been discussedbyBrooker et al., (1974) . Drying facilitates early harvest, thus reducing field losses from storm, insect damage and natural shattering. Field conditions are often better for harvesting early in the season. Early harvest perrmits early and timely seedbed preparation for the next cr0p. (This is particularly importantinsoretropicalareaswheretwoormorecropscanberaisedin one year). Grain drying penmits farmers to plan the harvest season to make better use of labor and machinery since harvesting is not dependent on fluctua- tions of the moisture content of the grain in the field. Finally, the early harvest enables farmers to take advantage of higher prices early in the harvest season. The most important advantage of grain drying is that it permits long- -13- -14.. time storage without deterioration in quality . By renoving excess moisture from the grain the possibility of natural heating of the grain due to respiration is reduced. Thus grain viability is maintained during storage. Dried grain (at moisture content below 13%) is less prone to insect, mites and fungi damage than wet grain. 2.2 Corn Quality as Affected by Drying Methods The desirable corn properties are dependent upon the intended use of the corn. In the U.S.A. corn is mainly used as animal feed, with smaller useage as a human food source, seed and industrial starch manufacture . Corn quality is dependent upon several factors: (1) the variety character- istics, (2) the environmental conditions during growth, (3) the time and the harvesting procedure, (4) the drying method, and (5) the storage prac- tice (Brooker et a1. , 1974) . During the drying process corn quality is affected by the grain telperature and the drying rate. Corn in the U.S.A. is officially graded for quality under the Grain Standards Act. The grades and grade requirerents are listed in Table 4. As can be seen from the table, the standard for corn only considers test weight, moisture content , broken and damaged corn , and foreign materials. There are other properties which are of importance to specific corn users that are excluded from the standard: such as millability, viability and susceptibility to breakage . 2.2;; Effect of Drying on Nutritional Feed Value The most important quality factor of corn for animal feed is the nu- tritional value . The effect of drying telperature on the nutritional value of corn for animal feed has received considerable research attention. Hathaway et a1. (1952) found that drying corn at temperatures above 60°C -15- AvhmHV.Hm um meOOHm "condom Sufi-nob roe booed-nee wo mmasuocuo we nowg3.Ho “mono coaoHOM oHQMQOHuoohoo haemHoumaeuo woo mm: boaez no “onward: no .HSOm no .xumoe_me snags Ho “mmooam mcamuooo 30H33_Ho um>amsaoca .m .02 o» H .02 mwomno on» mo man now mucmewuaooou mew pone poo mwoo noan3 cuoo on Harem macho maoemm o.mH o.m 0.5 o.mm 0v m o.oa o.H o.m o.om me e o.h m.o o.v m.nH mm m o.m N.o o.m m.mH em N o.m H.o o.m o.vH mm H Hobo? w w w ha momma ommmEmo zoom ououmaoz_ Harmon woo now-.- 3ng anon wamcuox owomema -aa=uHuz muHEHA_EoEmez .cuoo ooxae new open3 .3OHwa MOM mucmewufiooon moose mHoEmm pom mmpmuo Hmoenmesz .v magma -16- significantly decreased its energy content and palatability. Sullivan et a1. (1975) reported that heat has a definite effect on the nutritional value of corn; also, that the decrease in comrercial quality due to drying at high terperatures may not result in a decreased value of corn as animal feed. Jensen et a1. (1960) reported that drying terperatures of 60°C, 82.2°C and 104°C have no deleterious effect on the nutritive value of corn for swine as measured by growth rate and feed use. Gansmann et a1. (1952) found only minor effects on nicotinic acid, pantothenic acid, pyridoxine, and riboflavin content of corn dried at 43.3°C, 48.8°C and 82.2°C. Recently, Jensen (1978) showed that roasting corn at 14% and 23% mois- ture at 27°C and 150°C reduced the availability of lysine. He found that niacin is unaffected by roasting temperature, but pyridoxine (vitamin B6) availability is significantly reduced in 14% moisture corn when it is dried at 160°C. From the above review it appears that corn drying at tetperatures above 60°C results in sore minor nutritional changes . However , nutrition- ists do not agree on the effects of drying terperature on the feed value of corn (Brooker et a1. , 1974) . It is generally recognized that physical and chemical properties such as consistency, energy content, palatability, hardness, color, moisture, vitamins, protein and amino acid profile are affected by drying terperature (Williamson, 1975) . 2.2.2 Effect of Drying on Corn Milling Quality Farmers and elevator operators who dry corn often consider only its feed value. Corn millers are concerned about the increasing volume of art- ificially dried corn coming into the market (Freeran, 1978; Rutledge, 1978) . High starch yield (millability) , maximum yield of selected fractions -17- and prime product mix, and low fat content are the most important desirable characteristics of corn for milling. Brekke et a1. (1973) compared corn dryemilling response to inrbin natural air drying with artificial drying in a small experimental fluidized dryer drying at air temperatures from 32 to 143°C (maximum.corn temperatures were 32 to 104°C respectively). They found that the yield of total grits recovered by sieving, aspiration and flotation decreased with increasing drying air terperatures . The fat content of the grits increased with increasing air temperatures. Prime products recovered by rolling and grading f01lowed.similar patterns; however, sometimes yields and fat contents were less satisfactory. The results also showed that the cold paste viscosity of selected products inr creased as corn was dried at elevated temperatures. The corn dried with natural air had the best drybmilling quality. Drying at 60°C yielded corn of acceptable dry-milling quality except for a high percentage of stress cracks. Freeman (1973) discussed the quality factors affecting the value of corn for wet milling. He indicated that drying at high temperatures causes "case hardening" of proteins. Case-hardened protein affects the millability by impairing separation and purification of starch. The result is starch with a high protein content and reduced viscosity. The drying temperature, drying rate and the initial corn moisture content determine the degree of case hardening. Freeman suggested that high moisture corn fOr wet milling should be mildly dried at low temperature (up to 5% mois- ture reduction) befbre drying in high temperature dryers. High drying terperatures may also destroy sore amino acids especially lysine. According to MacMasters (1959) the difficulties of processing arti- ficially dried corn are so great that sore corn wet-millers refuse to purchase corn known or suspected to have been dried at high temperatures. -18- Matson and Hirata (1962) concluded that since kernel viability is evi- dently more easily altered by drying conditions than the other properties examined, corn dried to preserve viability should invariability be suited for starch manufacture . The drying tetperature should not exceed 71°C . 2.2.3 Drying Corn for Seed Generally the techniques used to dry seeds do not differ greatly from those used to dry grain for other purposes. waever, extra dryer control and managerent must be taken in order to ensure a high degree of germina- tion (COpeland, 1976) . The drying air terperature, the drying rate and the initial moisture content are the most critical factors affecting the germ- inating quality. Copeland (1976) stated that the higher drying temperature limit varies with the type of seed, but should not exceed 38°C. The high- est safe terperature also depends on the initial moisture content. Ulile— man and Ullstrup (cited in Hukill, 1954) showed that seed corn can be dried safely at 49°C if the moisture content is less than 25%; for mois- ture above 25%, 38°C is the upper limit. An excessive drying rate may cause stress cracks. Over dried seeds are susceptible to mechanical damage, which is detrimental to seed quality (Copeland, 1976). 2.2.4 The Effect of Drying on Corn Comercial Grade The effects of artificial corn drying on its corposition, nutritional value, viability as seed, and industrial processing have been discussed in the previous sections of the literature review. The above factors are not included in the determination of comrercial grade . As shown in Table 4 the only factors considered in the grain standard code for corn are: (l) the test weight, (2) the moisture content, (3) the broken corn and damaged corn, and (4) the presence of foreign materials. Artificial drying has -19- a direct effect on the test weight, the moisture content and on the percent- age of heat damaged corn, and has an indirect effect on broken corn. These factors will be reviewed in the folloving section. 2.2.4.1 Test Weight The corn test weight is the true density and is influenced by grain shape, grain surface texture, moisture content, type and amount of impuri- ties, size and uniformity, tetperature, and other factors that affect the packing characteristics. According to Freeman (1973) , test weight may in- directly indicate the wet milling quality of corn. High terperature drying may cause case hardening of proteins and reduce the extent of kernel shrinkage resulting from moisture reroval and hence low test weight. Pro- tein damage affects millability by inhibiting separation and purification of the starch. Hall (1972) studied the effect of drying tetperature on test weight of shelled corn. According to his observations , the test weight increases significantly during drying. The increase is due to shrinkage with loss of moisture and decrease of the coefficient of friction on the surface, thus permitting closer packing of the kernels. The test weight increase is less at higher drying temperatures, possibly due to case hardening. Hall observed that the test weight reaches a maxitmlm and declines with further drying. The maximum test weight is reached at 14 to 16% moisture (Brooker et al. , 1974) . The amount of test weight increase with drying depends upon: (1) the degree of kernel damage, (2) the initial moisture content, (3) fire terper- ature reached by the grain during the drying process, (4) the final mois- ture content, and (5) the grain variety. Early harvested, high moisture grain is not exposed to much weathering and shows a higher test weight after -20- drying than the same grain harvested later at a lower moisture content (Brooker,et al. ,1974) . A higher test weight corn is a better quality grain and offers we saving in storage since less storage volule is required to store the same amount of dry matter. 2.2.4.2 Stress Cracks and Broken Corn Although drying per se does not directly affect the number of broken kernels, it is well knom that grain is physically and physiologically damaged when dried at excessively high terperatures . The drying and cool- ing processes directly affect the degree of stress cracking and thus deter- mine the susceptibility of corn to breakage during subsequent handling. Thorpson and Foster (1963) defined stress cracks as the fissures in the endosperm, or starch inside the kernel, in which the seed coat is not rup- tured. Their results which related the drying rate and the amount of expected breakage have been confirmed by various authors. Ross and White (1972) studied the effect of overdrying on stress cracking in white corn. Their results shov a general decrease in stress cracking as the white corn dried to lower moisture content, and as drying started at lower moisture contents. These phenomena are difficult to explain. However, there may be sore physical and chemical changes during over-drying which make the grain kernel more resistant to cracking during the cooling period. Gener- ally, stress cracking decreases with decreasing drying air tetperature. Slov cooling of both the white and yellow corn after drying results in a dramatic reduction in the number of checked kernels , particularly at dry- ing air tetperatm'es above 71°C (160°F). Gustafson et a1. (1978) concluded that the final moisture content for high-tenperature drying above 18% does not appear to cause any significant -21- increase in breakage susceptibility , but the product of heating time and change of moisture content (under 18%) appears to be the best predictor of change in breakage . Freeran (1973) indicated that broken kernels too large to be reroved by screening for wet milling may release starch granules during steeping. Free starch in the steeping water causes fouling of evaporator surfaces during steep water concentration. 2.2.4.3 Other Corn gialigg Characteristics Affected by Artificial Drying In addition to the factors discussed in previous section, artificial drying affects other grain characteristics such as color and taste. Ross and White (1972) concluded that darkening and yellowing of white corn was apparent when it was dried with air at 88°C and 104°C to lower moisture content . , and for those started at higher moisture content . Discoloration was only slight for samples dried at 71°C and those started at 25% mois- ture content dried at 104°C to 14% final moisture. High drying air tem- peratures and high drying rates are detrimental to grain quality, whatever the intended use of the grain. Lon-terperature and natural air drying, if properly managed, may result in better quality grain and reduced drying costs. 2 . 3 Drying Systems There are three basic methods of grain drying: high and low-tempera- ture methods , and combination drying. In the U. S.A. , high terperature drying has been the primary technique for more than 25 years. This method is fast, but has a very low energy efficiency, a high fossil-fuel consump- tion, and usually results in a low grain quality. Ion-temperature grain drying (energy for the lm heat may be obtained from electricity, liquid -22- propane, solar energy, or any other heat source) is an energy efficient process and usually results in high quality grain, if properly managed. Mold spoilage risk is the main problem encountered in warm and humid areas. Natural drying is a low terperature drying method and takes place when grain is either left standing (or stacked) in the field to dry, or harvested and kept in a crib to dry. The latter method is practiced in the third world tropics and is the most risky since it exposes grain to the weather, insects, rodents, birds, deseases and other destructive elements. Combination drying processes for drying shelled corn started in the late 1970's (Brooker et al. , 1978) . In these processes high speed batch or continuous flow drying is combined with low heat or natural air in- bin drying. The high speed, high terperature dryers dry the corn to a moisture range of 18-23%. The corn is then transferred to storage where it is slowly dried to a safe storage moisture content. Combination drying offers a number of advantages, including: 1. increased throughout 2. increased fuel efficiency, and 3. improved product quality (compared to corn dried by high speed, high tetperature processes. Brooker et a1. (1978) subdivided the on-the-farm high-and-low tetpera- ture drying methods into the following categories: 1 . high speed , high terperature batch and continuous dryers; 2 . continuous in-bin drying systems; 3 . batch-in-bin drying systems with and without stirring; 4 . low-heat and no-heat in-bin drying systems with and without stirring; and 5 . combination systems , in which high-speed batch or continuous -23- flow systems are combined with low heat in-bin drying systems. For the research reported in this thesis items (1) and (4) have been com— bined. These two grain drying techniques will now be reviewed in detail. 2.3.1 Column Batch Dryers Column batch dryers are stationary bed dryers, in which the air moves across a stationary grain column (see Figure l) . The dryer is often porta- ble so that it can be moved from location to location when not filled with grain. According to Brooker et al. (1974) column batch dryers have the folloving characteristics: 1. column thiCkness is usually from 30.5 om to 45.7 on; 2. column batch dryers Operate at high air flow rates (1.42 ma/min to 2.83 mB/min); 3. drying air terperatures vary from 82°C to 116°C; 4. due to the high air flow rate coupled with a narrow column, the moisture gradient across the column is less than with batch in- bin systers; and 5. dryingiscorpletedinaltoBhrperioddependingonthe initial grain moisture content , and the need for cooling. Column dryers are particularly popular because of their simple construc- tion and operation , and because their initial cost is generally lower than that of continuous flow types (Sutherland, 1975 ). They are suitable for moderate grain volumes (250 to 650 tons annually) with high initial mois- ture content. Because the dryer has no storage function, it requires well planned and coordinated handling and storage system (Brooker et al. , 1978) . The fuel consumption and tlnerefore, the operating costs depend on the moisture reroval range. The fuel efficiency decreases with decreasing /GRAIN HOPPER LEVELING AUGER GRAIN COLUMN PERFORATED SHEETS \ HEAT AND COOL PLENUM \ / DISCHARGE AUGER Figure 1. Batch Column Dryer. -25- GER FILLING AU A “~' #.. .. fi‘ ....... -Q. I 0.0 ......... O... cognac-0...... Q. ..... on o... .00.... ...... ooooooooooooooooooooo 000000000000000000 cccccccccc 000000000 oi. ...... OOOOOOOOOOOOOOOO .............. ............. ............. ...... 0.. O... ..... 00.0.0.0... ..... ....... .......... oooo 0. ........ ........ ...... n... 7 HEATED AIR pLEHU? -———--’r" nmR fl A I R oUT 6 ATIN :gAusER II‘IO 00L c AIR '“ ER AUG Lonome UH ,ersedflow re ° and - ing air dry . er with forced U 1974) rocker et Crossflow dry B a1 - (from 2. 0 e mgr cnflng -26.. I I II I II I IIIIIIIIIIIIIIII II IIIIIIIIIIIIII I I IIIIIII II II IIIIIIIIIIIIIIIII II'E’I IIIIIII ’t’ IIIPIPIPIDIPPDDPP PPDDPID IIII .. I. . III. 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UNLOADING AUGER Schetatic of a crossflcw (continuous flow) grain dry er (From Brooker et al., 1974) . Figure 3. -27- moisture reroval. It takes about 5800 kJ/kg of water removed when the final moisture content is 25% and 6970 to 8140 kJ/kg water when the final moisture content is 15%, at an initial moisture content of about 30%. These fuel efficiencies are important when considering combination drying such as dryeration and low temperature drying when moisture is reduced in a column dryer to 18-20%. The thicker the grain column is in a column dryer the higher is the fuel efficiency. However, thicker grain columns result in an increase in the moisture content gradient across the column. Kirk (1959) investigated column thicknesses of 10.2, 20.3, 30.5 and 40.6 am. He came to the following conclusions: 1. the 20.3, 30.5 and 40.6 cm columns are similar in their drying air requirements; 2 . the operating costs are not significantly increased with an in- crease of static pressure of up to 5.08 cm of water for grain column thicknesses of 20.3, 30.5 and 40.6 cm; 3. in the static pressure range of 0.63 to 5.1 cm of water column, the drying capacity increased linearly with static pressure , there were no significant differences in drying capacity for the drying columns of 20.3, 30.5 and 40.6 cm. The moisture and grain-temperature gradients across the dryer column and also the dryer operating costs, can be reduced either by decreasing the drying air flow rate at a constant air temperature , or decreasing the drying air temperature at a constant airflow rate (Morey et al. , 1976) . 2 . 3. 2 High-Speed Continuous Cross-flow Dryers There are two types of continuous crossflcw dryers as shown in Figures 2 and 3. Crossflow dryers have a wet grain holding bin at the top. Grain -23- flows by gravity from top to bottom through the drying and the cooling columns which are 20 to 45 cm wide. A column thickness of 30.5 on is most comon. Two fans for heated and cooling air, respectively, may be used (Figure 3). An alternative design is shown in Figure 2, where a single fan is used for heated and cooling air. The drying rate and the final moisture content are mainly dependent upon time, air temperature, airflow rate and the initial moisture content. Moisture is usually controlled by regulating the grain flow rate by a metering auger at the bottom of the dryer, while maintaining a constant air temperature and air f lowrate . The auger speed responds to a tempera- ture sensor located in the grain column near the lower edge of the drying section. The drying characteristics of crossflcw dryers are similar to those of column batch dryers. The grain on the plenum side is overdried while that on the air exhaust side is under—dried. The design shown in Figure 2 permits ambient air to be drawn through the grain in the cooling section; and is thus preheated as it cools the grain. This results in a 10-20% reduction of moisture gradient across the column (Bakker-Arkema et al. , 1980) . Sore designs incorporate a metering device that causes the grain on the plenum side to move faster than the grain on the outside. Thus, the moisture content gradient is reduced. 2 . 3 . 3 Low-Temperature and Natural Air In-Bin Storage Drying In-bin drying systems dry and cool the grain in a storage bin. In most instances the grain is left in the same bin for storage . Natural air and low temperature drying are similar processes (Bakker-Arkema et al. , 1978) . The difference is that no heat is added in case of the natural air system. low-temperature drying is accompanied by raising the drying air 3 to 5.5°C -29- above the ambient temperature by either electric heat, solar energy or other heat source (Zink et al. , 1978) . Liquid propane and electricity are the most comron heat sources for low temperature drying; both require low capital investment. Liquid propane gas is usually not used since it requires interval timers to limit the rate of heat application (Brooker et al., 1978). The air flow rate required for a drying system depends on the harvest date, harvest moisture, and the location. For natural air drying Brooker et al. (1978) suggested drying air flow rates of 4 ma/min-m3 for corn with moisture content (1%) 24-26%; 3.2 ma/m3-min for 22-24% MC and 2.4 m}m3-min for 20-22% no. Adding heat, even in small amounts increases the drying capacity in a low temperature drying system. The temperature increase also encourages faster mold development . To reduce mold growth the average temperature in the bin should be below 10°C. With addition of low heat, the air flow rate can be limited to 2.4 ma/min-ma for 24-26% m: grain, 1.6 ma/min-ma for 22-26% MC, and 0.8 m3/m'm-m3 for 20-22% MC corn. Although low-heat and natural air drying are slow, the quality of the finished grain is frequently high due to low application of heat. (Brooker et al. , 1978) . The main disadvantage of both the low~heat and natural air in-bin drying is that the grain at the bottom is overdried, while that at the top is underdried. Drying is stopped after the average moisture content in the bin reaches a desired value. Since unloading does not allow thorough mixing and blending to obtain a uniform moisture content, the underdried corn from the tOp of the bin may deteriorate in storage . Several improvements have been incorporated in in-bin drying to reduce -30- the vertical moisture gradient. They include, grain recirculating, rerov- ing the bottom layers when fully dried, stirring devices, and drying with alternating heated and unheated air (Browning et al., 1971), Brooker et al., 1974). According to Brooker et al. (1978) , the fuel efficiency of all deep bin in-storage drying is high (3500 k'J/kq of water, or lower in sore cases) . Therefore , these systems are usually used in combination with other energy saving systems. However, low-heat and natural air in-bin drying is limited to grain that is below 25% 1C. 2 . 4 Stirred Bin Low Temperature Corn Drying It is well known that when drying grain by forcing air (heated or natural) through a deep bed, all of the kernels do not dry at the same rate. As the drying air moves through the bed of grain an exchange of moisture from grain to air occurs in a finite depth of grain called the drying zone. The zone moves in the direction of airflow as drying continues. When the drying zone has corpletely passed through the grain , the en- tire mass has been dried to equilibrium with the drying air. When drying with low temperature or natural air, the time required to dry a deep bed of grain (of say over 4 m) may be more than eight weeks, depending on the initial moisture and drying conditions. The grain at the top of the bed may deteriorate by roting due to molds or due to moisture condensation. By the time the grain at the top is dried to the required moisture content, the grain at the bottom will have been overdried, especially if heated air is used for drying. Grain stirring during the drying process is one of thetedmiquesusedtorectifytreoverdryingoftrebottomlayersandtre undesirable vertical moisture gradient resulting from deep bed in-bin grain drying~ -31- Use of stirring devices was initiated in 1960; and became commercially available in 1962 (Frus, 1968; Toms, 1968, and Bern and Charity, 1978). Stirring device manufacturers claim the following advantages: (1) increased airflow, (2) loosened grain, (3) reduced vertical gradient moisture content, (4) reduced static pressure, (5) reduced drying time, (6) reduced operating costs, and ('7) better grain quality. Field research on the overall effect of grain stirrers has been limited and the manufacturers' claims have not been entirely substantiated (Williams et al. , 1978) . The disadvantages of using stirring devices include condensation in the unstirred grain near the bin wall (which results in spoilage), and the extra load placed on the bin wall by the stirring devices which may require strengthening (Brooker et a1. , 1978) . Stirring devices most comronly consist of one or more 51-mm (2 in.) diameter, right hand, standard-pitch angers suspended from tre bin-roof and side wall, and extending to near tl'e bin floor. The augers rotate clockwise (viewed from above) and simultaneously travel horizontally around the bin and radially from near the center to near the bin wall and back. The simultaneous radial and peripheral moverent of the stirring device results in a flower leaf pattern, concentric circles or spiral pattern, depending on the relative radial and peripheral velocities (see Figures 4 & 5). The stirring auger produces small ripples on top of the stirred grain bed. Frus (1968) observed that in previously unstirred corn, the kernels are moving up the front side of the auger and down towards the bottom along the backside of the auger. It appeared that the unstirred corn is pro- viding a "wall" against Much the auger moves the corn. The ripples pro- duced by the auger inidicate the width of the column of corn that has moved towards the bottom of the bin. Once the auger has stirred essentially all Figure 4. -32- D g-‘_.—. — I.’ ’..a _. —I—._ ‘— ' ..0.Y’I . TI\."I.’9.( . .I ‘ I—‘—.— . _.—-. —.-—._.—O _.—I —I-.—I_C-I-.~ 2’/'/4’ / /.r.r./ / z'r'llx'x'z / /'/ /./ /'/'/'/'/'/vg/ Sohematic of grain stirring device (After Brooker et al., 1974). -33- CONCENTRIC CIRCLES SPIRMS Figure 5. Top view patterns formed by single auger grain stirrer. -34- of the corn and has started moving through previously stirred corn , the amount of corn being moved up the front side and the amount of corn moving downwards along back side of the auger appeared to be considerably smaller. A small circular column of grain near the bin wall is never stirred. The thickness of the column depends on how close the auger comes to the wall. It is more difficult to move air through this unstirred corn once part of the bin has been stirred (Frus, 1968) . Bern and Charity (1978) studied the disturbance effects of auger-stir- ring dry corn (11.3% NC) . Their results indicate that the bomdaries of the cross-sectional area disturbed by a stirring auger are generally para- bolic in shape. The cross-sectional area decreases with increasing horizontal auger travel rate. 244.1 Effects of Stirring Managetent Techniques on Corn Drying The available literature on stir -drying shows that the following para- meters are affected by auger stirring devices: (a) grain bulk density, (b) airflow resistance and thus the airflow rate, (c) the drying time, (d) the degree of overdrying, (e) the M: gradient, (f) the drying efficien- CY: (9) the grain quality and thus,dry matter loss, and (i) the drying costs. The effect of stirring on the above factors depends o1 the stirring managetent, especially with respect to the frequency of stirring, the number of augers, and the auger design with respect to the rpm, the horizontal travel rate, and the auger diameter. The effects also depend on the grain coiditioi (moisture content, foreign material , etc.) and the drying air temperature. Bern et al. (1979) investigated the effects of auger stirring on air flcm resistance and bulk density of wet and dry shelled corn at 22.6% and 14.6% MS, respectively, and drew the following conclusions: (1) auger stirring -35- decreases .12 gig bulk density of wet corn by 7.9% and of dry corn by 6.9%, when placed in a bin with a mechanical spreader, (2) auger stirring increases in situ bulk density of dry gravity-placed corn by 2.4%, and 3 left unchanged that of wet gravity-placed corn . It is reasonable to expect an increase in airflow rate with stirring. Stirring loosens pockets of trash and fines , and decreases the bulk density of corn; thus a decrease in pressure drop with stirring. It is not pos- sible to specify the increase in airflow rate resulting from a decreased static pressure drop with stirring. The increase is a function of fan size and fan characteristic curve (Williams et a1. , 1978) . Baker et at. (1979) observed an increase in airflow rate of 3% with stirring. Bern (1973) (cited by Williams et al. (1978) developed the following empirical equation for pressure drop in stirred grain: AP: L = (0.0484pb- 0.1274) v2 + (4.033 010- 10.12) v + 1231-1310,)b [2.1] Bern observed a 10% increase in airflow rate after stirring. The best way to measure the change in airflow with stirring is to measure the pressure drop and use the fan curve to determine the airflow. Alternatively, especially for simulation purposes, the airflow may be determined by an iterative procedure balancing the air velocity and pres- sure drop, assuming that the fan output and efficiency remain the same before and after stirring. The effects of stir drying o1 drying time and drying efficiency has been studied by several researchers. All literature available indicates that intermittent stirring reduces drying time, but also reduces the drying efficiency. Drying efficiency is defined as the ratio of the amount of moisture reroved from the dried grain to the amount necessary to saturate -36- the drying air adiabatically. Continuous stirring reduces the drying rate during relatively poor weather, and reduces the drying efficiency in all conditions as compared with unstirred drying at the same conditions (Baker et a1. , 1979) . According to a simulation study on stir-drying by Colliver et al. (1979) , contimous stirring reduces drying time in all cases, but the reduction in drying time is less with relatively un- favorable weather. Their results indicate that stirring once a day re- quired the shortest drying time. They observed no significant differences for other methods (constant stirring and stirring once a week) except stirring once at the beginning of the drying process. They found that stirring once while drying in good weather was just as good as constant stirring, daily stirring and stirring once a week. Williams et a1. (1978) concluded that drying time was the same when stirring at 5, 10 and lS—hour intervals. The most important advantage of stirring is decreasing the overdrying at the bottom layers, thus resulting in a uniform moisture throughout the bin. Overdrying decreases and moisture uniformity increases with stirring frequency. The combined effect of shorter drying time, less overdrying and more uniform moisture content results in decreased mold damage, less dry matter loss and therefore, better corn quality (Baker et al., 1979; Colliver et al. , 1979; Frus, 1968; and Williams et al. , 1979) . Nbreover, the combined reduced drying time and decreased overdrying results in less energy consumption and therefore, reduced drying costs, (Baker et al. , 1979) . Williams et al. (1978) concluded the following about the stir drying of corn: (1) a stirring device allows drying at less than favorable drying conditions such as lower airflow rates , higher drying tempera- -37- ture and greater bed depths (compared to unstirred drying) with- out spoilage; (2) the additional costs for a stirring device cannot be justified based on the same equal fill depths or equal weight of grain in unstirred bin; and (3) the use of a stirring device allows a greater bed depth with per bushel costs equal to unstirred bin at a lower grain depth. The additional stirring device cost can be justified in this situa- tion. The above literature review shows that stirring devices are beneficial for in-bin grain drying. Intermittent stirring has been shown to perform better and costs less to operate than continuous stirring. According to Baker et a1. (1979) intermittent stirring (24 hours per week) results in a higher degree of mixing and higher drying efficiency than continuous stir- ring. Frus (1968) attempted to explain these phenomena by observing that once stirred, there was less upward and downward movetent of kernels dur— ing subsequent stirring. The optimum stirring frequency depends on the drying air and grain conditions and thus varies from bin to bin and from year to year . 2 . 5 lm-Temgrature and Natural-Air In-Bin Drying Theory and Simulation Much research has been done to study the processes by which water is reroved from biological materials . The drying process consists of simultan- ous heat and moisture transfer. Henderson and Perry (1966) and Brooker et. al. (1974) described the constant rate of drying during the initial drying period followed by a falling-rate drying period . The constant-rate period for extretely moist single kernel drying can be expressed by (Brooker et al., 1974): . 3 if: 11:31.15 (Pv wb - Pv 00= 151—}: (Too - lIwb) [2'2] Prediction of the drying rate during the falling-rate period is more complicated than during the constant-rate period. Semi-theoretical and enrurical relationships for predicting behavior of cereal grains during the falling-rate period have been proposed and used by several researchers and dryer designers. Brooker et al. (1974) indicated six possible modes of moisture re- moval frcmlcereal grains: (a) liquid movement due to surface forces (capillary flow); (b) liquid movement due to moisture concentration differ- ences (liquid diffusion); (c) liquid movement due to diffusion of moisture on the pore surfaces (surface diffusion); (d) vapor movement due to mois- ture concentration differences (vapor diffusion» (e) vapor movement due to temperature differences (thermal diffusion); and (f) water and vapor move- ment due to total pressure differences (hydrodynamic flow). The exact manner in.which water leaves the grain is dependent upon drying air temper- ature, air velocity, moisture concentration, and product type and condition (Stevens et al., 1978). Based on the above modes of:moisture removal, Luikov (1956) and his co— workers in the Soviet union developed the following systems of differential equations for describing the drying of capillary porous products: 3M_ 2 2 2 E-V K11M+V K126+V K13}? §9.= v2 K M.+ V2 K 0 + V2 K P St 21 22 23 BP — = 2 2 2 at V K31M + V K32 6 + V K33P [2.3] -39- where K11, K22, and K33 are phenomenological coefficients. The other K values are coupling coefficients. Luikov's equations can be simplified by neglecting the pressure and temperature gradients in a corn kernel during the drying and rewetting processes. This results in: ‘5? — 11 [2'4] The transfer coefficient Kll is called the diffusion coefficient, D. If D is constant, equation [2.4] reduces to: 81_ 2 ——E—D o) 3 + l HID [2.5] Q) fi’lE’ r2 where c is zero for planar symmetry, 1 for a cylindrical body, and 2 for a sphere. In solving equation [2 .5] , the following boundary conditions are often assumed: M = M [2.6] (r10) 0 Mk0, t) = Me [2.7] The analytical solution of equation [2 .5] for the average moisture content of various regularly shaped bodies can be obtained directly by integration (Crank, 1957) . For an infinite plane with boundary conditions [2.6] and [2.7] , the solution is: 8 0° 1 .____-_-.__ 2 2 MR = ‘“ 2 - 2 2.8 H2 1£1=o (2n+l) exp [ (2n+l) II x ] [ 1 9 for a sphere: ” 2 2 MR=L2 fife)? [- D911 x2] [2-9] H2 n=l -40- and for a finite cylinder: 4 MR = Z Xz—-exp "'Jl'3£‘ [2.10] where An are the roots of the Bessel function of zero order (Perry et al., 1963). In the above equations the average moisture content and the time are expressed as dimensionless quantities, MR and x, respectively: M - M MR = Mo _ M: [2.11] 1/2 x =$ (Dt) [2.12] where A represents the surface area and N the volume of the body. For a plane, A/V equals half-thickness; for a sphere A/V equals (radius)/3; for a cylinder A/V equals (radius)/2. Chu and Hustralid (1968) concluded that the equations [2.8] through [2.12] describe the drying rate of a solid satisfactorily in the moisture ratio, (MR) range of.: 0.4. Chu and Hustralid (1968) studied diffusion of moisture in corn kernels assuming that the kernel could be represented by a sphere of equivalent radius R. The specific conditions were as follows: (1) relative humidity 10-70% (2) air temperature 49°C - 71°C (3) corn moisture content 5 - 35% (dry basis» For a moisture content dependent diffusivity, the following equation was recommended: = ‘— exp [‘ ‘Z'D t.] [2.13] where -41- _ _ _ 2513 D — 1.513 exp (0.045 Tabs 5.485)M T [2.14] abs * M = 1.0655M - 0.0108 [2.15] o o 3L‘W'K R = . [2.16] 2(DW+WK+LK where Tabs is the absolute temperature °K, and L, W, K are the length, width, and thickness of the average kernel respectively. All the above equations work satisfactorily under the test conditions. However, for drying temperatures such as encountered in low temperature and natural air drying, several of coefficients of Chu and Hustrulid have been changed for use under low-temperature conditions (Rugumayo, 1979). 2.5.1 Thin-Layer Drying Equations for Corn Thompson et a1. (1968) developed an empirical thin layer drying equa- tion for corn in the range of 60 to 150°C: t=A1nMR+B (lnMR)2 [2.17] where: A = 0.004888 - 1.86178 [2.18] B = 427.3640 exp (-0.0330) [2.19] The most commonly used thin layer equations are modified versions of the Thompson equation (Brooker et al., 1974; Pfost et al., 1976). The equations have not proved to be totally satisfactory (Rugumayo, 1979). Flood et a1 (1969), Troeger and Hukill (1970), Muh (1974), and.Misra (1978), developed.empmical drying equations for corn in the temperature ranges of (a) 2.2°C to 21.l°C, (b) 32 to 71°C and 27 to 104°C, respective- ly. Flood et al. (1969): MR where 3" ll X ll L<1 ll Troeger Eflrr ENH- 0.664 exp (-kt > [2.20] exp (-xty) (6.0142 + 1.453 x 10-“(rh)2)0.5 (1.88 + 32)(3.352 x 10‘“+ 3 x 10‘8(rh)2)0-5 0.1245 - 2.197 x 10-3(rh) - (1.89 + 32) (2.3 x 10“5(rh) + 5.8 x 10-5) and Hukill (1970): P1(M-Me)q1 - P1(Mb—Mé)q1 for M6 3_M > MX QZ _ _ qz 1 P2(MrMe) P2(M.X Me) + tX1 for M.X1 > M > W 93 _ _ 93 PMW%) Pmkrg +ghflxmh>mi% DJU 0.40 (MO-Me) + ME 0.12 (Mb-Me) + ”8 [P1(M%1-Mé)ql- P1(Mb—Mé)q‘]/60 -43- : _ Q2 _ _ Q2 tx1 [P2(M:X2 ME) P2(Mk1 Mé) ]/60 + tx1 p1 = eXp(-2.4S-6.42 Mbl°25 - 3.15 (rh) + 9.62 Mb(rh)0°5 + 0.0548 - 0.036 va + 0.96 _ 0.67 p, — exp[2.82 + 7.49 (rh + 0.01) - 0.03228 - 0.5728 P3 = [0.12 (MO-Me) J “31"“) (quz/Q3) q1 = -3.468 + 2.87 MO - [0.019/(rh + 0.015)] + 0.02888 g2 = -exp(0.81 - 3.llrh) Q3 = ’1.0 Dhfll (1974): t = Aln MR + B (1nMR)2 [2.22] where A.= -3.287 - 0.10448 (37.7°c < 8 5_ 60°C) B = -3.34114 + 0.12868 (37.7°c < 8 5_60°c) A.= -8.2075 + 0.079838 (60°C < 8 5 82.2°C) B = 0.44881 — 0.004178 (60°C < 8 5_82.2°C) A = -4.69252 + 0.037068 (82.2°C < 8 5_104.0°C) B = -7.75868 + 0.023158 (82.2°C < 8 5_104.0°C) The following is the Misra (1978) M = (beMé) exp[-(exp(-7.l735 + 1.2793 ln(l.8T + 32) + 0.006lv)) t(0.0811 1n(rh) + 0.0078 Mb)] + Me [2.23] -44- T is drying air temperature, °C v is air flow rate in meters, per minute rh is air relative humidity, decimal t is time in hours. Only the Flood equation (also called Sabbah equation) and possibly the Muh equations, would appear of interest for use for low-temperature and natural air corn drying. These equations are empirical. Rugumayo (1979) developed an equation from mathematical diffusion theory similar to the model presented by Chu and Hustrulid (1968): Mt = (MO-Me) exp[(25.592-38.6298 Mt_1+ 26.6824 1n (M131) - 2 0.00448t (Mt_1) exp(rht) t] + Me [2.24] The moisture content predicted by equation [2. 24] was compared with the Flood equation [2.20] and the Misra (1978) equation. When compared with actual experimental data the Rugumayo equation gave better results than either Flood or Misra equations (Rugumayo, 1979) . 2. 5.2 Corn Moisture Adsorption Natural air grain drying is risky due to changing weather condi- tions. Grain may be rewetted by high humidity air at night or rainy days . Therefore it is necessary to account for grain moisture adsorption for proper evaluation of in-bin low temperature and natural air drying . Understanding of the adsorption kinetics provides useful information in grain quality and a guide for grain conditioning, storing, processing and fumigating. In grain rewetting studies, de1 Guidice (1959) developed the following empirical equation for rewetting of corn: “45.. .MR = exp[-4.309 (PS)0'466(rh)(rh)3At] [2.25] where M.—M MR'=.MF —e t-1 e The equation was tested at 15.6° C to 40.6° C dry bulb temperatures, 60% to 100% relative humidity, and air velocities of 3 mpm and 12.2 mpmt The del Guidice equation does not perform satisfactorily at air condi- tions outside these ranges (Rugumayo, 1979). The following equation for grain rewetting relationship was developed by Rugumayo: Mt = (Mb-Mé) exp[(l62.1l79-487.9552 Mt_1 + 118.6144 ln 2 2 (M 1) + 0.696588t (Mt_1) exp (rht )t] + Mé [2.26] t.- The equilibrium moisture content (Mg) in the above equation must be calculated from the DeBoer's equilibrium moisture content equations for shelled corn (Bakker-Arkema et al., 1974). 2.5.3 In-bin.Low~temperature Drying Lowetemperature and natural air drying simulation models have been proposed by several authors (Flood et al., 1969; del Guidice, 1959; Thompson, 1968; and Bakker-Arkema et al., 1977). Brooker et al. (1974) analyzed in-bin drying by making energy and mass balances on a differential volume (de) located at an arbitrary location in the stationary bed. The following set of three differential equations was obtained assuming the air and grain temperatures are equal: (a) for the enthalpy of air and product 8T 8T pp (cp + NEW) -3—t— + Ga[(Ca + HCV) a—t + Ga (Cw-CV) (100-T) + h ] 3” = 0 [2.27] fgé—x (b) for the humidity of the air flu; 31:0 [2.28] and (c) for the moisture content Op 3% = an appropriate kin layer equation. [2.29] Equations [2.26] through [2.29] are the basic equations for simulat- ing fixed bed grain drying. The equations can be solved with the help of a digital computer by writing the equations in a finite difference form. Four possible finite difference methods for computing the numerical derivatives in the model are discussed by Bakker-Arkema et al. (1977) . When equations [2.27] through [2.29] are written in implicit finite difference form the following equations are obtained: T -T [ Xrt xvt -At]+ G ppmp + Cw MX ,t - At) At alCaJ'CvHx-Axm] [ TX It-TX" AX,t] = [HXIt -HX- Axrt G ] [(Cw-CV) ('1‘x , €100) Ax a Ax 'hfg] [2.30] M ‘-M H -H xpt xpt-At xpt x- AXI’C _ CPI At ]+ Gal Ax ]— 0 [2.31] Mx t -Mth- At 0 J = T H M t p [ At ] m1[ x,t' X,t ' X,t - At' ] [2.32] Equations [2. 30] through [2. 32] can be rearranged to obtain three equations which are explicit functions of HX t: I GaAt(Ca+CvHx -AX,t)Tx —AX,t’AtGa(Hx t -HX -AX,t) I T = (Cw'cv)+ppr(Cwa,t -.At)Tx-Ax,t [2 33] - - __ + o x ,t GaAt(Hxlt Hx_m{'t)(cW CV] ppr(cp+cwa’t_AtT +GaAt(Ca+CVHx_AXIt) G At M =—a—-(H -H )+ [234] x,t [)pr x,t X-Ax,t ”5m; — At - * = M Xlt rm(TX’t I HX,t I MX,t’At' t) [2°35] The moisture content M*x t in equation [2.35] can be obtained using either a drying or rewetting thin—layer equation. The complexity of the pychrametric conditions in the drying or rewetting equation call for use of a search for the value of Hx' t which gives agreement in all the three equations simultaneously (Bakker-Arkena et al. , 1977) . The search algorithm developed by Bakker—Arkena et al. (1977) is outlined below: (1) Set initial Hx,t = Hx-Ax,t; (2) Calculate TX t from equation [2.33]; (3) If RHx t < 100% go to step (5); I (4) Simulate condensation to find TX ; set flag; ,t (5) Calculate Mx t from [2.34]; —48- (6) If condensation flag is set, exit; (7) Calculate M*x t from equation [2.35]. I The search terminates when H has reached a specified value of absolute humidity. The corresponding value of T and M are then computed from equations [2.33] and [2.34] respectively. The fixed bed equations are first evaluated at each node through the depth of the dryer and then are incremented one time step. At the end of each depth iteration, the average moisture content and dry matter decomposition are ccmputed. The equations for dry matter decomposition have been developed by Thompson (1972) and are based on the work by Steele et al. (1969) , who developed a quantative relation between the carbon dioxide production of shelled corn (dry matter loss due to grain respiration and mold growth) and time, temperature, moisture content and mechanical damage. The dry matter decomposition equation is: DM = 0.0883 (exp(0.006 mam-1) + 0.00102 TEQ [2.36] TEQ = At/AMm.AMI, [2.37] AM : 0.103 [exp(455/MDB.1.53)-0.0084 MDB + 1.558] for 13 _<_M _<_ 35 [2.38] MI“ = 32.3/exp(0.10448+1.856) AM = NH” for 8 _<_ 15.5° C or M < 19% [2.39] -49- AMT = M1" + [(M-l9)/100] exp(0.01838-0.2847) for 8 > 15.5° C and 19 < M _<_ 28% [2.40] AMT = MI" + 0.09 exp(0.01838—0.2847> for 8 > 15.5° c and M > 28% [2.41] According to Saul (1970) : AMT = 128.76 eXp(-0.l4040-2.496) [2.42] for 0 _<_ 15.5° C. AMT AMT are dimensionless multipliers for moisture content and I temperature respectively TBQ is the equivalent reference time, hr: At is the drying time interval, hr -50- 2.6 low Temperature, In—bin Stir DrLing Theory and Simulation A fixed bed grain drying model developed at Michigan State University (Bakker-Arkema et al., 1974; Rugumayo, 1979) was modified to simulate stir drying. The model uses equations [2.24], [2.26] and the DeBoer's equation (Bakker-Arkena et al., 1974) for drying rewetting and equili- brium moisture content. respectively. The model operates in accordance with the search algorithm developed by Bakker-Arkema et a1. (1977) and outlined in section 2.7.2. The following assumptions were made: 1. Stirring is instantaneous and there is no vertical moisture content gradient; all corn and air properties (within the grain) are equal to average conditions prior to stirring. 2. Due to the low drying air terperatures, the corn is assumed to be of the same temperature as the air. 3. The increase in air flow rate after stirring is negligible. To study the effect of stirring on drying time and dry matter loss, the actual East Lansing (at the Department of Agricultural Engineering, Michigan State University) hourly weather data for November 1976 was used for simulating different stirring methods for the following conditions: - bin diameter 1.6 m, height 2.13 m - £111 depth, 1.83 m (grain volume 1.13 m3) - air flow rate 2.85 m3/m2 and 5.7 m3 /m2 -51— - temperature range 5.6-24.5° C - relative humidity range 17 to 70% The results of this simulated study indicated that periodic stir- ring results in shorter drying time and higher grain quality (as indicated by less dry matter loss) than continuous stirring if poor drying weather conditions prevail;.in.favorable weather conditions continuous stirring does not perfonm any better than intermittent stirring (see Table 5). Similar results have been reported by other researchers (Baker et al., 1979; Colliver et al., 1979; Williams et al., 1978; and Bern et al., 1979). Frus (1968) observed little mixing of previously stirred corn. Baker et al. (1979) concluded that continuous stirring reduces drying effic- iencey and drying rate, and therefore the amount of water removed.per given time. The optimum frequency of stirring depended on drying conditions such as drying air temperature and relative humidity and corn moisture content and percentage of fine and foreign materials. Table 5. Effect of stirring management on drying time and dry matter loss (airflow rate 5.7 flffimz). No. of Stirring control Ave. NE Dry matter Drying stirs method WB loss % time hrs 3 Stir after 60, 120 and 15.47 0.034 232 216 hrs Stir every 48 hrs 15.49 0.032 232 Every 24 hrs if MC 15.49 0.031 232 at bottom is less than 16% WE 9 Every 24 hrs 15.48 0.025 221 w Continuous 18.49 0.038 313 3. EXPERIMENTAL The research reported in this thesis was carried out at the Kalchik Farms in Bellaire, Michigan, as a part of a continuing investigation on alternative on-farm grain drying methods in Michigan. The following five alternative drying systems have been tested by Michigan State personnel (Bakker-Arkema et al, 1979-1980; Silva et a1, 1979; Silva, 1980; and Kalchik et a1, 1979): 1. high terperature/natural air combination drying; 2. high temperature/ low terperature (electric heat) with and without stirring combination drying; 3. in-bin dryeration; 4 . in-bin counterf low drying; and 5. conventional batch drying. Kalchik Farms was chosen as the site for grain drying research because of the high harvest moisture content and unfavorable climatic conditions during harvest. It can be argued that any drying technique that operates successfully in Bellaire, Michigan, will work at any farm in the lower peninsula of Michigan. For the low-terperature in-bin combination drying research a single auger stirring device is used. The stirring device is a grain Stir-ator model 179 manufactured by the David Manufacturing Company, Mason City, Iowa. It has a single 51 mm (2 in) diameter right hand constant pitch auger with a 25mm (1 in) shaft. When stirring corn 3.67m (12 ft) deep, the 1.1 kW (1.5HP) motor drives the auger at about 500 rpm; the average tangential travel speed is -52- -53- 5.4 m/hr and the average radial travel speed is 1.7 m/hr. (In an etpty bin the average tangential travel speed is 25. 2 thr and the average radial travel speed is 6.8 thr). At a corn depth of 3.67m the auger travels horizontally in a spiral pattern as illustrated in Figure 6 . The auger remains at the inside bin wall during half of a revolution to improve the stirring of the grain next to the wall. The corn (variety DeKalb XL12) to be dried by the high/low-terperature stir drying process (LT-ST) was harvested at between 32 and 35% moisture content, wet basis (IVE-WE) . Before the test the corn was cleaned using a Farm Fans rotary cleaner and loaded into a wet holding bin (capacity 2. 54 tons) with a 12.5m New Idea Flight elevator. From the wet holding bin the corn was loaded into a Kan-Sun (model 8-15-10) continuous crossflcw dryer through a 0.15m diameter, 4.88m long screw auger. The corn was dried to 23-24% IVE-WE at 104.4°C at airflow rate of 80.68m per minute per m3 of grain. The corn was loaded into the low-temperature, stir drying bin through a 0.15m, 12.8m screw auger. A Farm Fans mechanical spreader was used to spread the corn evenly into the 5.5m (18 ft)-diameter, 3.7 high bin. The LT-ST bin was loaded first with about 1.8m of corn, after which a natural air (NA) bin (5.5m—diameter) was filled with the same amount of grain for cmparison. This meant that the upper 1.8m of grain was placed in each bin after the bottom portion had been partially dried for 1 1/2 days at about twice the (full bin) designed airflow rate. Both the LT-ST and the NA bins were filled to a total depth of 3.67m, equivalent to 86.5m3 (2444 bushels) of corn. After filling the LT-ST bin with the last 1.83m, the grain was immedi- ately leveled and stirred for 10 hours to equalize the moisture content -54- 180° North 90° 45° Grain Depth: 3.67m (12 ft) Bin Diameter: 5.5m (18 ft) Auger Horizontal Travel Rate: 5.66thr Figure 6. Path of auger horizontal travel. -55- throughout the bin. The average grain properties after the stirring were considered the initial conditions for the drying test. Drying air for the LT—ST bin was heated by a 20 kw.Aerovent electric heater to 4 to 6°C above ambient temperature, and pushed through the grain at the rate of 1.6m? per'mdn/mfi (2 cfm/bu of grain) using a 2.24 kW (3 HP) vane axial Aerovent fan. Ambient air was pushed through the grain in the NA bin at the rate of 2.0 m3 per min/m3 (2.5 cfm/bu) using a 3.73 (5 HP) kW centrifugal fan. The average ambient temperature was 4.5°C and the relative humidity varied from170 to 100% during the test (November 5th to 28th,1979). The stirring device was turned on for six hours every 48 hours. Dur- ing a six hour stirring interval the auger travels from the periphery of the bin to the center and back twice, and makes ten revolutions around the bin. This appears to be sufficient to completely stir and.mux.the grain in the bin. Previous computer simulations had demonstrated that stirring every 48 hours is to be preferred over continuous stirring (See Section 2.8). The following parameters were measured before and after stirring, at the top, muddle and the bottom of the bin: 1. grain moisture content, before and after drying; 2. grain test weight; 3. grain quality as determined by the proportion of broken kernels and foreign materials (BCFM), stress cracks, resistance to breakage, and viability; 4. air flow rate and inlet temperature; and 5. energy consumption (of the fan, heating and stirring device). _56- 3 . l Instrumentation and Measurement The grain moisture content was measured with a recently calibrated "Steinlite" moisture meter. The moisture content of all samples was checked with a GAC II Dickey-John moisture meter which has been calibrated against the standard oven method (Brooker et a1. , 1974) . The terperatures were measured with copper-constantan thermocouples and recorded with a Texas Instrument data logger. Sample quality evaluation was performed using standard methods for stress cracks (Thomson and Foster, 1963) . The 2, 3, 5-tripheny1tetrazolium chloride color test (TZ test) was used to determine the percentage of viable kernels. The TZ test distinguishes between viable and dead tissues of the embryo on the basis of respiration rate in the hydrate state. The T2 test is widely recognized as an accurate means of estimating seed via- bility (COpeland, 1976) . Breakage tests were conducted erploying a newly developed USDA method (Miller et a1. , 1979) . The airflow rate was determined from fan curves supplied by the fan manufacturer, after measuring the static pressure in the false floor of the bins. The electrical power usage was measured with a kWh-meter supplied by the electric power company. 3 . 2 Economic Analysis An economic analysis computer model, TELPLAN (Harsh et al., 1978) was used to calculate a ten year budgeting analysis for drying 381 tons (15000 bushels) per year using LT-ST, NA, and non-stirred 1cm-te1perature drying (LT-NS) . The break even drying costs for the three systere were cotpared. -57- 3.3 Drying Computer Simulation The computer simulation model described in Section 2.8 was used to simulate corn drying using weather data obtained on the experimental site. In addition to the assumptions outlined in Section 2.8, it was assumed that there was no increase in airflow rate after stirring during the 1979 test. This assumption is not generally valid since a stirring device loosens the grain and therefore, tends to increase the airflow rate. Some investigators have observed a 3 to 33% airflow rate increase after stirring (Williams et al., 1979; Bern et al., 1979; and Baker et al., 1979). The airflow increase is dependent upon the fan characteris- tic curve and the amount of fines and foreign materials in corn, and the corn depth. During the 1979 test, the corn.was high in foreign matter and there was no detectable static pressure difference before and after stirring. In 1980, a 25% increase in airflow rate was observed (124.6 mg before and 155.7 m3 after stirring). 4. RESULTS AND DISCUSSIONS 4.1 Effect of Stirring on Drying Time and Moisture Content Distribution The actual moisture content distribution in the LT-ST and NA systems as a factor of time and bin depth is given on Table 6. Similar simulated results are givei on Table 7. As can be seen on Table 6, drying from about 23.7% to 15% IVE-WE took three weeks (504 hrs fan operation ) in the LT-ST sys- tem in the fall of 1979. The fan on the NA bin was operated 600 hours in the fall before the low-terperature ambient conditions prevented further blowing . The mois— ture content at the top of the bin was 21. 2 perceit at that time. Drying was re-started for a few days in February when the ambient conditions in the Bellaire area reached an uncommonly high terperature (65°F or 18°C) . The warm weather caused slight molding of the corn at the top of the bin. About 2.4 tons (100 bushels) of the grain were reroved, mixed with dry corn and (without problems) used as cattle feed. Final drying of the NA bin comenced on April 13 and was completed within a week. The 5 m3 cen- trifugal fan had operated for 1525 tours. The average final moisture con- tent was 16.2 perceit with a M: in the top and bottom of the bin of 16.7% and 15.7%, respectively, after reroving the top 2.4 tons of wet moldy corn. In the fall of 1980 it took eleven days (264 hours) to dry corn from 21.76% to 15.52% in the low-temperature stir drying system. The shorter drying time (compared with three weeks in the fall of 1979) was partly due to the favorable drying weather, cleaner corn and therefore, higher airflow, -58... -59— Table 6. .Moisture content variation 'with depths, for different drying systems. Drying Drying Time Moisture Content % w.b. System Weeks Top Middle Bottom Average Max. Differ. LT—ST (1979)1 0 24.7 23.8 22.7 23.7 1.0* 1 19.8 20.8 20.7 20.4 1.0* 2 17.8 18.3 14.1 16.7 4.2 2 17.0 18.0 14.5 16.5 3.5 3 15.4 16.4 13.0 14.9 3.4 NA (1979) 3 21.6 19.8 14.7 18.7 6.9 NA (1979) 10 21.5 18.0 15.5 18.3 6.0 LJLST (1980) 0 22.30 19.25 19.73 20.43 3.05 18.52 19.13 18.08 18.58 1.05* 1 (6 days)18.39 19.02 15.29 17.57 3.73 1.5 (11 " 115.54 16.45 14.56 15.52 1.89 *Maximum moisture content difference immediately after stirring 1Stirring interval: 48 hrs for 6 hrs in 1979 and 48 hrs for 8 hrs in 1980 Drying conditions: average ambient temperature 4.5°C; Hr 70% in 1979 and 9.4°C, Rh 74% in 1980. temperature 10°C; Rh 58% (1979) temperature 14.5°C, Rh 53% (1980) LT-ST: -60- Table 7. Computer simulation results of natural air (NA), low. terperature-nonstirring (LT-NS) , low terperature stir- ring (LT-ST) and natural air stirring (NA—ST) . Item NA LT-NS L‘I‘S'I’ NA-ST Initial MC, 23% w.b. MC Top, % w.b. 16.5 16.5 15.5 15.8 MC Middle, % w.b. 15.5 13.4 15.5 15.8 MI Bottom, % w.b. 15.5 12.2 15.4 15.8 Max. M: Difference 1.5 4.3 0.1 0.0 Average IVE, % w.b. 15.7 13.9 15.5 15.8 Dry Matter loss, % 5.4 6.0 2.7 3.3 Drying Time, Hrs. 664 381 272 700 Drying Terperature, °C 4.5 10.0 10.0 4.5 Relative Humidity % 70 58 58 70 Airflow Rate m:"/m2 7.4 5.92 6.51 8.14 Grain Depth: 3. 66m. -61- and partly due to the fact that the corn was previously dried in a batch drier and loaded into the LT-ST at about 65°C. The latter procedure re- sulted in a considerable dryeration effect. Moreover, the corn was stirred eight hours (instead of six hours) every 48 hours. During stirring the wet corn at the top of the bin is mixed with drier corn at the bottom. It can be seen from Table 6 that corn in the middle of the bin is often wetter than the corn at the bottom and at the top after stirring. However, the maximum difference between the wettest and the driest corn was only about 1. 0% immediately after stirring. The grain along the bin wall was dried to the same moisture content as the corn in the rest of the bin. It was observed that the auger re- mained against the bin wall during one half of a revolution. The auger did not start rotating around the bin from the same position. The result was complete stirring of the corn at the bin wall and thus corplete drying of the corn at the bin wall. Frus (1968) had observed that the corn near the bin wall is not dried if the stirring auger does not travel close to the bin wall. In low—temperature in-bin drying the bottom layers dry faster than the top layers as the drying front progresses upwards through the bin. Thus , the bottom layer is overdried and the top layer is underdried. The stir- ring device reduces overdrying of the bottom layer and accelerates drying of the grain at the tOp of the bin. This can be seen from Figure 7. In natural air (NA) in-bin drying, overdrying of the bottom layers is not as severe as in low temperature in-bin drying. The relative humidity in NA drying varies with the ambient (no artificial heat is ap- plied). Thus, the equilibrium moisture content is higher, and the drying rate lower than with low electric heat application. Also , overdrying is minimal in natural air in-bin drying (See Tables 6 and 7). _62_ .ocfiGo 500 £315 co mfiunflm mo uomwmm we? .5 0.33m ES .m .3ng sun-mum mE\ mam . m scanned wow huge-5m gen-meme “UooH wHoumeo-zwe umcowufipooo mains mmDOI-m_->-: 02;”; omm ovN com 00H OH ow ow o _[._.___.w._.__ 3 c3 93 mo Eouuon 05 us wuoumeoz AT muoumfiu: momuoke no] :3 wfi mo sou up mush-woos [<1 (SISVG 13M) BHfllSIOW 1N3383d -63- Computer simulations have shown that introduction of a stirring device in a natural air in—bin drying may lower the drying rate, resulting in longer drying time. This is particulary so in poor drying weather con- ditions (low temperatures and/or high relative humidities). 4.2 Effect of Stirring on Corn Quality The average quality parameters for the low temperature stir dried and natural air dried corn are tablulated in Table 8. The stir-dried corn is of superior quality than the natural air non stir—dried corn. Stirring ensures uniform.corn quality throughout the bin. No hot spots are likely to occur in a stirred bin. 4.2.1 Stress Cracks The corn to be dried in 1979 in both the stirred and the non-stirred bins was harvested at 34.3% moisture and dried in a high speed, high temperature crossflcw continuous dryer to 23.7% for the stirred bin and 24.6% for the natural air bin. The high temperature drying resulted in 41% and 33% heat-stress cracks in the dried corn, respectively. There 'was a slight reduction (due to sampling error) of the percentage of cracked kernels after low-temperature and natural air drying. This indi- cates that no heat stresses occurred during the final drying processes. Similar results were observed in the fall of 1980. 4.2.2 Breakage Susceptibility The high temperature drying increased the breakage susceptibility from 15.7% to 24.9% and 21.6% for stir-dried corn and for natural air dried corn, respectively, in the fall of 1979, and from 16.1 to 33.2% in the fall of 1980. There was no increase in breakage susceptibility in the lowetemperature stir dried corn. There was a slight breakage -64- emm am Semi mush-68968 Soho .835 m2. om “Used 085mg Homage-m monomer-w I coma mam am uuse-.3 8838.896» .615 woe or 68.8 838893 8.838 8882 u 83 8838.8 ofibo e .m .m Stoops Essex-.58 .fieoefiooeo pose->98 so 8.8m H u: woo up 85mph: modes-U808...“ 0608mm .. 82 oz 1.3.2 so 8989.. beeefloooouou mos-88m . 83 H3338: Moo ox r mgr Te or mo.~ ~.mm 3 93 min .635 are are TS no; m.mm em mém mom coo: 8388809 roar New o «.8 So Hoe o 1 flow EB 835 gm. poo m.~m oom o.~ 5.8 mm Noe era 2 Too Tom Tom he; 5.3 mm rem mém 0.33 .889 so? 32 ofio o.o oAm om.m them mm or: 7mm $1.3 1 she hom Toe 24 omen o. 5mm mom 0.2: 8380809 rod- 1 The o mom Bo E: o u mém EB 8282 meme «853 0866 8394 m w 1. Hours HUGH p.883 poop-808m 2.8m beaefipooouom 2086 pg sou ohms 8.: 33> pope-8pm whohm 3389- 852 8mg .83 98 mama 5 500 omenp new Honda-mo com Eco Reno MUM phenomena-m... 33 How gong—muse 3380 .m 3me -65- susceptibility increase in natural air dried corn. The increase may have been caused by mold damage or may be due to sampling error. 4.2. 3 Broken Corn and Fine Materials During the fall of 1979 test the percentage of broken kernels and foreign materials (BCFM) of combine harvested corn was 0.9%. The corn was dried in a continuous flow dryer (Kan-Sun) , resulting in 1.8% BCFM. The BCFM increased to 3.3% and 2.8% after drying in the LT—ST and NA sys- tems, respectively. The increase in BCFM is partly caused by the stirring device and partly by the loading and unloading augers . In the fall of 1980 an increase of 1.05% in BCFM was caused by the stirring device. The BCFM was accumulated at the bottom of the LT-ST bin. However, after stir- ring continuously for 12 hours at the end of drying the BCFM was nearly unifonmly distributed throughout the bin. 4 . 2 . 4 Viability Change The viability count as determined by the triphenyltetrazolium chloride color test is given in Table 8. It can be seen that low-temperature stir-drying does not cause any change in the viability of corn. The via- bility change of 30.7% in the fall 1979 test was caused by drying from 34.3% to 23.7% in the high terperature (104°C) high speed continuous cross- flow dryer. A 56.2% total viability change was observed in 1980 after drying the corn at 116°C in a batch dryer (Farm Fans). The 7.3% change in the LT-ST phase may have been a result of holding the high terperature dried corn at about 70°C in the low-temperature bin for a six-hour tem- pering period. Natural air drying in the fall of 1979 resulted in a 22.3% change in viability. This was caused by molding due to the prolonged storage of the corn at a high moisture content, especially at the top of the bin. -66.. 4.3 Energngonsumption and Operating Costs The actual energy consumption and Operating costs for the different drying systems are given in Table 9. The standardized energy consumption and operating costs for the same systems are given on Table 10. The standardized parameters are based on combination drying 63.5 tons of corn iirm126% wb to 23% in a high temperature dryer and from 23% to 15.5% in the low-temperature and natural air systems;f0r estimating energy consump- tion per hectare a yield of 6.9 tons per hectare (100 bu/acre) is assumed. Tables 9 and 10 include the energy consumption and operating costs for high temperature drying of shelled corn from field.moisture content to a final moisture content of 15.5%. The energy costs are expressed in terms of cents per ton of dry corn (15.5% wb) per percentage point of:moisture removed. This unit is consid- ered the.most meaningful to farmers for the comparison of the different systems. The energy consumption for low-temperature and natural air systems is very dependent upon the ambient weather conditions. In the fall of 1979, 6061.kWhrs were required to dry 51.74 tons of corn from 23.7% to 14.9% wb in the lowetemperature stir-drying (LTBST) system. The weather conditions during the fall of 1979 were not favorable to drying (the average ambient temperature was 4.5°C and the average ambient relative humidity 70%). In the fall of 1980 the corn.matured early and the weather conditions (the average temperature was 9.4°C and the relative humidity 74%) were more favorable to drying. Thus, only 2748 kWhrs were required for drying 46.61 tons from 21.8 to 15.5% moisture content, wet basis. The standardi- zed energy consumption figures are 6340 kWhrs and 4457 kWhrs for 1979 and 1980, respectively. -67- It can be seen from Tables 9 and 10 that combination drying systems (LTBST and NA) are less energy consumptive than high temperature drying. The combination drying systems require the least energy input if the corn is harvested at sufficiently low initial moisture contents (e.g. below 23%) to allow direct drying in the low-temperature or natural air systems, without passing through the high temperature phase. Although the drying efficiency of the combination drying systems is better than that of high temperature systems, the combination systems may result in higher energy costs. This is due to the fact that electricity (which is more expensive per kilojoule than propane or natural gas) is the main energy source for these systems, whereas propane (or natural gas) is the principal energy source for the high temperature drying systems. The combination systems would undoubtedly be the least expensive if a cheaper energy source (such as biomass) had been used. When compared with loWbtemperature non-stir drying (LTBNS) and natural air (NA) combination drying systems, lowetemperature stir combination diying (LTBST) is less energy comsumptive resulting in lower operating costs. In the fall of 1979, the standardized energy drying efficiencies were 3921 and 3962 kJ/kgHzo for LT-ST and NA systems, respectively. The energy costs were 80.03 and 80.87 cents per ton per point for the ITLST and NA systems, respectively (See Table 9). Silva (1980) compared.natural air and low-temperature drying sys— tems at the Kalchik Farms in Bellaire, Michigan in 1978. His results indicate that the energy efficiency of the NA system was about 16% better than the LEBNS system. In terms of energy costs the NA was nearly 30% cheaper than the LTBNS. The fall 1979 test results indicate that the energy efficiency of the ITBST was about 1% higher and the energy costs about 1% lower, than that of NA drying at the same drying conditions. -68- emm or 6%.: $368.98» 65.36 SIS wow so “Uov.m muoumumoewu pomeoau monumee I ommH ram am 6.6.3 086896» amuse woe am “come 058% €038 088% I meme 8:68pm spanked-oh .fieoebooam Hep->98 so 88m 3 ”maceueoooo moezyo e .m .N e 8L m.mv v.ov mom meow me ma wv.H o.mH o.mm mmonu moooceucoo m.mn H.o> mma vmmw cam mm m.s m.mH o.mm boumm oeumeopoe «.mo N.Hm Hmm mwhm vmma evmm mo.om m.oH m.vm :oeumowoeou ~.wm m.>m moa mmom I omnm mm.om m.oa o.vm memH.ImcH .. 105 a? amen-mg m.hv «.mv Noe ommm vmma mam mo.om m.vm m.vm Ambmav ocemuo mooooeucoo muoumuooema been m.mo n.om mmm mvvv mmHH homm Hm.mv m.mH H.m~ cowumceoaou m.mo m.ov . hm mmom I mean Ho.mv m.mH m.Hm mommel BmJHH Tao Tom HS mmem mmd o3 See mam Tom 835 sou-mm ououonwoame been H.mm m.om mmm mamm meme mHmm wh.am m.vH m.¢m coeumceoaou m.mm w.bm maa mmom I Hooo vh.am m.va >.mm NmanJhmJuH m.hv o.mv omH nmmm meme mmm vh.Hm n.mm m.vm 30am moooceuooo monumnmoeme zoom Eumm gnawed Cum 5.3 comeboez maumm aqua ox\hx uz.wm.ma monum>e xeooamm Im>eoom moooeo humped muozx um moo» poquoo pooIcH uceomuoou\w( menace Iwmwm oomoouo mueoeuuooam mueucmoo momma umz w ouoo summon H38. mfig 838598 Spoon Eco scope-8 83.6.8: oofios one-Go poo ocemuo noun muspmuwoemuIsoa How -Ammoeuo ommav mumoo moeumumoo poo coeuoeomcoo mmuwom Hmovoe .E .8833 .u-fioo reopens mfi so 985 98 H332 .m manmfi ~69- mm.~o mmeo pom e.Hom ommm em mam om. eo.mm meme mmm m.mm~ mmom mm mom me. spoon oeumsopom om.~o meme ope «.moa mmoa mm mom mm. mmmuo_3oam mmOHU msgfifia mun-pong 20E em.om Nomm oma m.mm moo ooe «moo meme ooeposensoo msemuo hem Huuoomz 0.593096» poem mm.oo mmom mme ‘ o.mo mmo emo some or. mm.maummIo~ 83m. (season msemuo menu mo.om Hmmm mes e.em nee mmo emeo me. ououuumosmo poem 0.5.»ng 30H 82\ our mr\or mumueo useoo mosoeo homes on oa\szx arr (some (mum £55 8883 833 a: be oofimz msemuo umoo momma E05 mono mono IoHHu Icon» mfig momma-m mono-H. lone Iouo Iomdm Iomam .Hz .3333 55mm £03 an fig new Hone-um: poo unsung 30H MOM Eocene ommd mumoo mango pom cowugmcoo >988 mongoose-84m .OH 0.38. -70- Thus, introduction Of a stirring device resulted in energy savings in the low-temperature (electrical heat) combination drying system. The stirring device in the LT-ST bin was Operated intermittently every 48 hours for six hours in the fall Of 1979, and for 8 hours in 1980. The energy consumption for the stirring device was only 1% and 0. 7% Of the total energy consumed in 1979 and 1980, respectively. Thus, if periodically Operated, the stirring device consumes very little electric- ity, although resulting in a significant reduction Of drying time. The reduced drying time results in reduced energy consumption by the fan and the electric heater in low-temperature systems. Thus, the stirring device reduces Operating and energy costs Of a low—temperature drying system. 4.4 Capital Budgeting Analysis The Operating costs presented in Tables 9 and 10 do not include labor , maintenance , investment , interest on borrowed money, depreciation , and taxes. TO analyze these costs a 381-ton (15,000 bu) drying and storage capacity was designed for the low-temperature non-stir and natural air drying/storage systems. For the LT-ST system, it was assured that 762 ton Of corn can be handled since it is possible to dry two batches per year in this system. This results in reduced investment and other fixed costs per ton Of dried corn. With the LT-ST systan it is assumed that the farmer dries and sells the first 381 tons Of corn at the start Of the harvest season and dries the last 381 tons for long term storage on the farm. The cost estimates and assumptions are summarized in Table 11. The costs were estimated according to the procedure outlined in Appendix A and were used in a capital investment commuter model (TELPLAN) designed by Harsh (1978) . -71.. The economic analysis results (Table 12) indicate that for drying 381 tons Of corn annually, the total drying costs are nearly the same for the three systems analyzed (LT-NS, LTBST and NA). The total drying costs are $19.74, $21.00 and $21.32 per ton for the NA, LT—ST and DT—NS respec- tively. The drying and investment cost per ton can be reduced in the LT-ST system by drying two batches per year. The total cost for drying 762 tons per year in the LTBSt is $15.23 per ton, assuming that the first 381 tons is sold. (See Table 12). It.may be necessary to store all the corn dried on the farm. For 762 ton annual capacity six 381~ton extra bins are required for storage. Due to the extra investment, the total drying costs are $17.13 and $17.15 per ton for the LTBST and NA systems, respectively. Thus, for 762—ton annuall capacity the drying costs are nearly equal for the two systems. However, the total drying costs for the NA system increase faster (than for LTBST system) with increasing capacity because a drying fan is installed in each of the NA bins. In the LT—ST system stirrers, drying fans, and heaters are not required in all the bins. Thus, the LTBST system requires less investment costs than the NA system for capacities greater than 762 tons annually. However, the actual relative investment costs depend on the system.design. Thus, the LT-ST is the least expensive for drying capacities greater than 380 tons annually. Considering the superior grain quality after LTbST drying, the LTBST is a better drying system than either the NA or LT-NS system. -72- Table 11. Estimates/Assumptions for a 10 year budgeting analysis (1980 prices) 1 . Parameter Drying Combination Systems Estimated Low temp Low temp Natural with stir without stir air Annual quantity , ton 762 381 381 Total Invest- ment, $ 45032 38286 38274 Salvage value Of investnrent, % 10 10 10 Annual interest rate on loan,% 12 12 12 Energy costs3, $/ton point and 0 .72 0.80 0.73 ; S/ton 7.56 8.40 7.67 Labor costs, g $/ton 0.95 0.84 0.84 Maintenance, 5 for 10 yrs. 750 500 400 i 1See Appendix A 2It is assumed that corn will be harvested at 26% w.b., dried to 23% in a high temperature drier and dried to 15.5% in the final phase. 3Based on $0.07/kWhr electricity, $0.177/liter propane. Table 12. -73- Economic analysis results for three high temperature-low temperature combination drying/storage systems for Michi- gan (1980 prices)‘. System. 2Annual Cost in $ per ton Initial Capi- (381 tons annually) per percentage point removal tal Investment from 26-23-15.5% fixed variable Total. per ton, $ w;b. Cost,$ Cost, $ Cost,$ Low-temperature 1.19 .81 2.00 118.19 stir drying (12.50)3 (8.51) (21.00) ILMhtemperature stir 0.64 0.81 1.45 59.10 drying (762 tons)“ ( 6.72) (8.51 (15.23) Lowetemperature 1.15 0.88 2.03 100.49 without stirring (12.08) (9.24) (21.32) Natural air (without 1.07 0.81 1.88 100.46 stirring) (11.24) (8.51) (19.74) 1 See Appendix B and C for input and detailed analyses respectively. 2 Net present value for a 10-year planning horizon. 3 Figures in brackets are the equivalent cost, $/ton. “ Low-temperature stir-drying system.can dry twice as much as other systems per year. 5 . CONCLUSIONS The LT-ST drying reduces the total drying time from over 10 weeks in a NA system.to less than 3 weeks, depending on the weather conditions. When compared with high temperature dryers, the LTBST is a ‘more energy efficient systenland results in about 30% energy savings. HOwever, like most other combination systems, it is :more expensive to run than the high temperature dryers since electricity, which is more expensive per kilojoule than propane, is its main source Of energy. The combination systems studied require nearly the same Opera- ting Oosts per unit, if 380 tons Of corn are dried per year. However, the LTBST system would be about 40% cheaper if twice as much corn is dried per year without on-the-farm storage. If on-the-farm storage is required, the total drying costs in— creases faster with increasing capacity for the NA than for the IELST since a greater investment is required for the NA system. LTbST drying results in high, uniformlquality corn. "Hot spots" and overdried corn are reduced. Thus, the LTBST is a more re- liable drying system than either the NA or LTBNS systems. -74.. 6. SUGGESTIONS FOR FUTURE WORK As a result Of this study, the following suggestions are made for further investigation: 1. To study the effect Of stirring on energy costs if biomass or solar energy rather than electric heat is used as fuel for low-temperature drying . TO compare, side by side, continuous stirring with intermit- tent stirring. Per form an Optimi zation study to determine the Optimum rela- tive energy input for the fan, heater and the stirrer for corn drying from different initial moisture contents to 15. 5% M3, wb. Research should be done in tropical Africa, particularly in Kenya to study the technical and economic feasibility Of low-temperature stir-drying Of cereal grains using solar energy or biomass as source of heat. -75- 7 . REFERENCES Agricultural Engineering Department. M.S.U. Energy in Michigan Agriculture. American Society Of Agricultural Engineers. 1978. Energy--a Vital Resource for the U.S. Food Systems: Cost and Policy Impacts on Agriculture and the Consumer. ASAE. St. Joseph, MI. Anderson, D. G. and Pfost, D. 1978. Small Holder Grain Storage Problems in Kenya: Problems and Proposed Solutions. U.S.A.I.D. Nairobi, Kenya. Baker, K. D., Abbouda, E. K. and Foster, G. H. 1979. Stirring as an aid tO in-bin solar drying Of corn. ASAE Paper NO. 79-3522. Bakker-Arkema, F. W., Ierew, L. E., Deboer, S. F. and Roth, M. G. 1974. Grain dryer simulation. Research Report NO. 224. Agricultural Exp. Sta. Mich. State Univ. E. Lansing, MI. Bakker-Arkema, F. W., Brooker, D. B. and Roth, M. G. 1977. Feasibility study Of in-bin drying in Missouri using solar energy. In Solar Grain Drying Conference, ed. by G. C. Shove, Univ. IL, Urbana, IL. Bakker-Arkema, F. W., Hsieh, R. C. and Silva, J. S. 1979. Alternative methods Of on-farm grain drying in Michigan. MSU. Unpublished report. Bern, C. J., Anderson, M. E., Wilcke, W. F. and Hurburgh, C. R. 1979. Auger stirring Of wet and dry corn. ASAE Paper NO. 79-3523. Bern, C. J. and Charity, L. F. 1978. Disturbance effects Of auger stirring corn. Trans. ASAE 21(3) :371—374. Brekker, O. L., Griffin, E. L. and Shove, G. C. 1973. Dry milling Of corn artificially dried at various te'rperatures. Trans. ASAE 16(4): 761-765. Brooker, D. B., Bakker-Arkema, F. W. and Hall, C. W. 1974. Drying Cereal Grains. The AVI Publishing Company, Westport, CT. Brooker, D. B., Mackenzie, B. A. and Johnson, H. K. 1978. The present status Of on-farm grain drying. ASAE Paper NO. 78-3007. Browning, C. W. Brooker, D. B., George, R. M., and Browning, C. E. 1971. Batch in-bin drying by alternating heated and unheated air. Trans . ASAE 14(1) :193-194. -76— -77- CAST, 1977. Energy Use in Agriculture. Council Of Agricultural Science and Technology. Report NO. 68. washington, DC. Chu, S. T. and Hustrulid, Am 1968. NUmerical solution of diffusion equations. Trans. ASAE 11:705-710, 715. Colliver, D. G., Barret, J. R. and Peart, R..M. 1979. Usage Of stirring devices in low temperature corn drying. ASAE Paper NO. 79-3013. Copeland, L. O. 1976. Principles Of Seed Science and Technology. Burgen Publishing CO., Minneapolis, MN. Crank, J. 1957. The Mathematics Of Diffusion. Claredon Press, Oxford, England. del Guidice, P. M. 1959. Exposed layer wetting rates Of shelled corn. Uhpublished.M.S. thesis. Purdue Univ;,‘West Lafayette, IN. FAO, 1979. The 1978 Production Year Book. FAO, Rome. Fedewa, D. J., Pasconda, S. J. and Molenda, E. 1978 and 1979. Michigan Corn Harvesting and Marketing Statistics, Mich. Dept. Of Agric. Mich. Crop Reporting Service, Lansing, MI. Fedewa, D. J., Pasconda, S. J. and HOlkO,.M. 1979. Michigan Agricultural Statistics. Mich. Dept. Of Agric. Mich. Agric. Reporting Service, Lansing, MI. Flood, C. A., Sabbah, M. A., Meeker, D. and Peart, R. M. 1972. Simula- tion Of natural air drying system. Trans. ASAE 15(1):156-159. Freeman, J. E. 1978. Quality factors affecting value Of corn for wet mulling. In Proceedings 1977 Corn Quality Conference. University Of Illinois, urbana-Champaign, IN. Friedrich, R..A., 1978. Energy Conservation for American Agriculture. Ballinger Publishing Company, Cambridge, MA. Frus, J. D. 1968. Stirring device research.ASAE Paper NO. M.C. 68-402. Gustafson, R. J., Morey, R. V., Christensen, C. M., and Meromick, R. A. 1978. Quality changes during high-low temperature drying. Trans. ASAE 21(1):162-169. Hall, G. E. 1979. Test weight changes of shelled corn during drying. Trans. ASAE 15(2):320-323. Hathaway, I.L., F.D. Yung and T.T. Kresselbach. 1952. The effect of drying temperature on the nutritive value and commercial grade Of corn. JOurnal Of Animal Science, 11: 430-440. -78— Henderson, S.M. and R.L. Perry. 1966. Agricultural Process Engineer- ing. 2nd Edition. Edwards Bros. , Ann Arbor, MI. Hukill, W. V. 1954. Drying Of grain. In Storage Of Cereal Grain and Their Products. ed. by J. A. Anderson and A. W. Alcock. American Association Of Cereal Chemists, University Farm, St. Paul, Minnesota, MN. Jensen, A. H. 1978. The effect Of processing (rousting) on the nutri- tional value Of corn for swine. In Proceedings 1977 Corn Quality Conference. University Of Illinois, Urbana-C‘hampaign, I Kirk, D. E. 1959. Column thickness for shelled corn driers. Trans. ASAE 2(1) :42-43. Luikov, A. V. 1966. Heat and Mass Transfer in Capillary-Porous Bodies. Pergamon Press, Iondon, England. MacMasters et a1. 1959. A study Of the effect Of drying conditions on the suitability for starch production Of corn artificially dried after shelling. Cereal Chem. 36:247-260. Miller, B. S., Hughes, J. W., Rousser, R. and Pomeranz, Y. 1979. Standard method for measuring breakage susceptibility of shelled corn. Con- tribution NO. 79-338-J. Dept. Of Grain Science and Industry, Kansas Agricultural Experiment Station, Manhattan, Ks. Misra, M. K. 1978. Thin layer drying and rewetting equations for shelled yellow corn. Unpublished Ph.D. thesis, Univ. Of Missouri, Columbiamn, Morey, R. V., Cloud, H. A., and Lueschen, W. E. 1976. Practices for the efficient utilization Of energy for drying corn. Trans. ASAE 19(14): 151-155. Muh, K. K. 1974. Determination Of the coefficients Of a thin layer equation for corn. Unpublished M.S. thesis. MSU. East Iansing, MI. Paulsen, M. R. and Thomson, T. L. 1973. Effects Of reversing airflow in a cross-flow grain dryer. Trans. ASAE. 16(3) :541-543, 545. Perry, R. H. and Chilton, C. H. 1963. Chemical Engineers Handbook. McGraw—Hill Book CO. , New York, NY. Pfost, H. B., Maurer, S., Chung, D. S. and Milliken, G. 1976. Summarizing and reporting equilibrium moisture data for grains. ASAE Paper NO. 76-3520. Ross, I. J ., and White, G. M. 1972. Discoloration and stress cracking Of white corn as affected by overdrying. Transaction Of the ASAE 15(2) :327-329. -70- .1 Rugumayo, E. W. 1979. Corn drying with solar heated air. Unpublished Ph.D. thesis. Ag. Engin. Dept., MSU, East Lansing, MI. Rutledge, J. H. 1978. The value Of corn quality tO the dry miller. In Proceedings 1977 Corn Quality Conference. University Of Illinois, Urbana-Champaign, IL. Schmidt, S. C. 1978. Foreign market prospect for corn. _I_r_1_ Proceedings 1977 Corn Quality Conference. University Of Illinois, Urbana-Cham— paign, IL. Shove, G. C. 1978. Corn quality as affected by drying procedures. In Pro- ceedings 1977 Corn Quality Conference. University Of Illinois, Urbana-Champaign, IL. Shove, G. C. 1978. Corn drying with low temperature, high terperature combination system. ASAE Paper No. 78-305. Silva, J. S. 1980. An engineering-economic corparison of five drying techniques for shelled corn on Michigan farms. Unpublished Ph.D. thesis, Ag. Engin. Dept., MSU, East Iansing, MI. Stevens, J. B., Barrett, J. R., and Okos, M. R. 1978. Mathematical simulation Of low-terperature wheat drying. ASAE Paper NO. 78-3004. Sullivan, J. E. et a1. 1975. The effect Of heat on nutritional value Of corn. I_r_; Corn Quality in World Markets. ed. by L. D. Hill. Interstate Printers and Publishers, Danville, IL. Sutherland, J. W. 1975. Batch grain dryer design and performance prediction. Journal Of Agric. Engr. Res. 20:423-432. Thompson, R. A., and Foster, G. H. 1963. Stress cracks and breakage in artificially dried corn. USDA Marketing Research Report 631. USDA Washington, D.C. Thompson, T. L., Peart, R. M., and Foster, G. H. 1968. Mathematical simulation Of corn drying--A new model. Transaction Of the ASAE 11(4) :582-586. Troeger, J. M. and Hukill, W. V. 1970. Mathematical description Of the drying rate Of fully exposed corn. ASAE Paper NO. 70-324. USDA. 1980. Crop Production, 1979 Annual Summary. Statistical Reporting Service, USDA Washington, D.C. Watson, S. A., and Mirata, Y. 1962. Some wet-milling properties Of artificially dried corn. Cereal Chem. 39:35-44. Williams, E. E., Fortes, M., Colliver, D. G., and Okos, M. R. 1978. Simulation Of stirred bin low temperature corn drying. Paper NO. 78-3012. ' »-80- Williamson, J. L. 1975. Nutritional requirements Of livestock as related to corn quality. In Corn Quality in.Wbr1d Markets, ed. by L. D. Hill. Interstate Printers and Publishers, Danville, IL. Wbods, D. R. 1975. Financial Decision Making in the Process Industry. Prentice-Hall, Englewood Cliffs, NU} Zin, H., Brook, R. C., and Peart, R..M. 1978. Engineering analysis Of energy source for low temperature drying. ASAE Paper NO. 78-3517. 8 . APPENDICES -81- APPENDIX A INVESTT-m COST ESTIMATES -82— -83- Al. Batch-Low Temperature Stir Combination Drying (762 tons) l . System Operation From field > Moisture tester 1 Grain cleaner V Flight auger ‘9 Wet holding tank 1 Batch dryer > Nbisture tester 127 tons 127 tons 127 tons first 381 tons sold Initial moisture content 26% (from field) Intermediate moisture content 23% (from dryer) Final moisture content 15.5% (from bin) -34- 2. Estimated 1980 investment.cost Quantity 1 3 Item Batch dryer (120 bu/hr) Stirring devices Extra rings 24 ft. diameter bin Perforated floor wet holding tank Concrete (24 ft. bin) Grain spreader Grain cleaner Unloading auger + motor Sweep auger + motor 42 ft. auger + motor (6") 17 ft. auger + motor (6") Flight auger + motor Cost (S) $ 8,170.00 4,860.00 1,800.00 9,552.00 4,655.00 2,235.00 2,520.00 400.00 600.00 457.00 298.00 2,050.00 750.00 3,500.00 Tube axial fan (1.5" SP & 7500 cfm)2,640.00 Electrical heater (20 kWh) Electrical (wiring) Moisture tester Total investment at list prices Less 10% discount Installation .Miscellaneous (2% total invest- ment) TOTAL COST OF THE SYSTEM 1,560.00 1,000.00 220.00 47,277.00 42,549.00 1,600.00 883.00 $45,032.00 -85- 3. Estimated salvage value at the end Of 10 years Bins $ 5,893.00 Stirrers 3,000.00 Perforated floor 2,332.00 Electrical 500.00 Concrete 1,260.00 Miscellaneous 365.00 Installation 500.00 TOTAL $13,850.00 at 35% salvage cost = $4,847.00 % salvage value total investment = $5,425.00 +-$45,032.001¢:10%. 4. Estimated annual rate Of interest on loan: 12% per year 5. Estimated direct energy cost: $0.72 per ton per point 6. Estimated labor cost: $0.09/ton 7. Estimated maintenance cost: $750.00 -86- A2. Batch-Low Temperature Combination Drying (381 tons) 1. System Operation From field ;> Moisture tester L Grain cleaner 1 Flight auger 1 wet holding tank 1 Batch dryer >, Moisture tester 127 ton bin 127 ton bin 127 ton bin Initial moisture content 26% (from field) Intermediate moisture content 23% (from dryer) Final moisture content 15.5% (from bin) Quantity -87- Estimated 1980 investment cost m Batch dryer (120 bu/hr) 24 ft. diameter bin Perforated floor wet holding tank Concrete (24 ft. bin) Grain spreader Grain cleaner unloading auger + motor Sweep auger + motor 42 ft. auger + motor (6") 17 ft. auger + motor (6") Flight auger + motor Tube axial fan (1.5" SP & 7500 cfm) Electrical heater (20 kWh) Electrical (Wiring) Moisture tester Total investment at list prices Less 10% discount Installation Miscellaneous (2% total investment) TOTAL COST OF THE SYSTEM Cost (5) 8,170.00 9,552.00 4,655.00 2,235.00 2,520.00 400.00 600.00 457.00 298.00 2,050.00 750.00 3,500.00 2,640.00 1,560.00 1,000.00 220.00 40,617.00 36,555.00 1,000.00 731.00 $38,286.00 -88— Estimated salvage value at the end of 10 years Bins $ 5,893.00 Perforated floor 2,332.00 Electrical 500.00 Concrete 1,260.00 .Miscellaneous 365.00 Installation 500.00 Total $10,850.00 at 50% salvage cost = $3,797.00 % salvage value total investment = $3,797.00 % $38.286.00§710%. Estimated annual rate Of interest on loan 12% per year Estimated direct energy cost $0.80 per point per ton Estimated labor cost $0.08 per point per ton Estimated maintenance cost $500 in 10 years -83.. A1. Batch-Low Temperature Stir Combination Drying (762 tons) 1. System Operation From field 4;; Moisture tester 1 Grain cleaner Flight auger 1 wet holding tank ) Batch dryer 4;: Moisture tester 127 tons 127 tons 127 tons first 381 tons sold Initial moisture content 26% (from field) Intermediate moisture content 23% (from dryer) Final moisture content 15.5% (from bin) -34- 2. Estimated 1980 investment cost Quantity 1 3 Egg Batch dryer (120 bu/hr) Stirring devices Extra rings 24 ft. diameter bin Perforated floor wet holding tank Concrete (24 ft. bin) Grain spreader Grain cleaner Unloading auger + motor Sweep auger + motor 42 ft. auger + motor (6") 17 ft. auger + motor (6") Flight auger + motor Tube axial fan (1.5" SP & 7500 cfm)2,640. Electrical heater (20 kWh) Electrical (wiring) Moisture tester Total investment at list prices Less 10% discount Installation Miscellaneous (2% total invest— ment) TOTAL COST OF THE SYSTEM Cost (S) $ 8,170. 4,860. 1,800. 9,552 4,655. 2,235. 2,520. 400. 600. 457. 298. 2,050. 750. 3,500. 1,560. 1,000. 220. 00 00 00 .00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 47,277. 42,549. 1,600. 883. 00 00 00 00 $45,032. 00 _85_ 3. Estimated salvage value at the end Of 10 years Bins $ 5,893.00 Stirrers 3,000.00 Perforated floor 2,332.00 Electrical 500.00 Concrete 1,260.00 Miscellaneous 365.00 Installation .__ 500.00 TKHTJ. $13,850.00 at 35% salvage cost = $4,847.00 % salvage value total investment = $5,425.00 +-$45,032.00‘¢=10%. 4. Estimated annual rate Of interest on loan: 12% per year 5. Estimated direct energy cost: $0.72 per ton per point 6. Estimated labor cost: $0.09/ton 7. Estimated maintenance cost: $750.00 -86- A2. Batch-Low Temperature Combination Drying (381 tons) 1. System Operation From field ;> Moisture tester 1 Grain cleaner 1 Flight auger 1 wet holding tank 1 Batch dryer ‘> Moisture tester 127 ton bin 127 ton bin 127 ton bin Initial moisture content 26% (from field) Intermediate moisture content 23% (fromldryer) Final moisture content 15.5% (from bin) -87- 2. Estimated 1980 investment cost Quantity 1 3 111911 Batch dryer (120 bu/hr) 24 ft. diameter bin Perforated floor wet holding tank Concrete (24 ft. bin) Grain spreader Grain cleaner Unloading auger + motor Sweep auger + motor 42 ft. auger + motor (6") 17 ft. auger + motor (6") Flight auger + motor Tube axial fan (1.5" SP & 7500 cfm) Electrical heater (20 kWh) Electrical (wiring) Moisture tester Total investment at list prices Less 10% discount Installation Miscellaneous (2% total investment) TOTAL COST OF THE SYSTEM Cost ($) 8,170.00 9,552.00 4,655.00 2,235.00 2,520.00 400.00 600.00 457.00 298.00 2,050.00 750.00 3,500.00 2,640.00 1,560.00 1,000.00 220.00 40,617.00 36,555.00 1,000.00 731.00 $38,286.00 -88.. Estimated salvage value at the end Of 10 years Bins $ 5,893.00 Perforated floor 2,332.00 Electrical 500.00 Concrete 1,260.00 Miscellaneous 365.00 Installation 500.00 Total $10,850.00 at 50% salvage cost = $3,797.00 % salvage value total investment = $3,797.00 % $38.286.00‘310%. Estimated annual rate Of interest on loan 12% per year Estimated direct energy cost $0.80 per point per ton Estimated labor cost $0.08 per point per ton Estimated.maintenance cost $500 in 10 years APPENDIX B RESULTS OF CAPITAL MS‘IMEN'I‘ ANALYSIS USING A TELPLAN PROGRAM _92- -99- .AP Frogram No:_» Qi.. __ PENDIX B3 Form No ; 3 System: TOUCQ:TONE____ PHONE CAPITAL INVESTMENT MODEL -- INCLUDING BUY OR CFSTOM HIRE NAME “film-TEMPERATURE: ADDRESS P‘ ‘23.: ' ' e the in"“tmvnt of NON-STIR DRYING (381 tonsflpoa.) ioerm Tocnaluat LL: t . '“ - capital to reduce or elimunate costs including custom hire 8 leasing, ADJUSTED LINE NO. ANALYSIS Section I. Costs Reducing (Custom Hire or Leasing) Or Income Producing Information. la. Cost savings (or income produced) 01. '9 9 -2. Q .3: per unit'' for a certain class of ‘ expenses (or income). For example, custom rate per unit (5) 2a. Cost savings (or income produced) 02. lo 0 -0 - 0 Cl per unit’ for a second class of expenses (or income). For example, additional per unit annual losses associated with custom hire (5) 3a. .‘Jorml number of units’ per year 03, i0 D —4—0—0-0l _ — —| on which costs will be reduced (or income generated). b. Percent of units‘ indicated in Line 3a that will be absorbed by investment in the year of purchase. Section II. Investment Information. 4a. Total dollar cost including un- 04. IO .3 .82 8 6|0. Oi depreciated balance of trade-in — items. I b. Percentage undepreciated value of trade-in items is of total cost. 5a. If a used item enter estimated 05. IO 3 328 6| l 0| new cost of item. If new item enter same value entered in Line 4a. b. Years plan to use the investment. * It is very important to be consistent in your units. (For example, if the custom rate is stated on acres all the other units are also to be stated in acres). This computer program was designed by Stephen B. Harsh, Michigan State University. 6a. b. c. 10a. lla. _94_ Liyr no. Depreciation years 05, '1; _Q—‘i. Q] Q 8 l4 lll Salvage percent Month of purchase (0l=Jan,...., J/ “j/ 12=Dec.). Depreciation type (0=Have model choose best depreciation method to use; l=Straight line; 2=Straight line with additional 20%; 3:Double decline balance; 4=Ebuble decline balance with additional 20%; 5:1.5 decline balance; 6:1.5 decline bal- nce with additional 20%; 7=Sum—of- digits; 3:5um-of-digits with addi- tional 202). Does.investncnt qualify for in- -~ vestment credit (O=no; l=yes). Percent of total cost (input line 07. '1 0- Q I 0 8|]- 2 ° OI 4a) borrowed. Repayment period of lean-years _L_/ Annual rate of interest on loan(i) _’ _*w__ __#J/ Per hourx fuel cost of operating ()8. )9 9 ° 7- 2- '0 '0 ' 0 0| investment" (5) Per hourx fuel cost of operating _ r. _ _/ associated equipment" (3) Per hourx labor cost of operating (ML IQ 0 .(l 9 '0 D -0.0l investment & associated equipment. Per hourx cost of supplies of _ J/ operating investment 8 associated - equipment. W3 ICD .\J |U'| ICD Repairs costs of inVUstnpnt: Enter 10, estimated repairs costs over period or use in today's dollars (amount must exceed $25) 95 enter type”' of machine to have model estimate re— pairs costs. Types of machines are: l=Tractors; 2=Self-P. Combine, Self- P. Forage Harvester, Rotary Cutter; 3=Pull Type Combine. Pull Type For- age Harvester, Flail Harvester; 4= Self-P. Swather, Self-U.L. Wagon, Side D. Rake; 5=Fertilizer Equip; 6=Potato Harvester, Sugar Beet Har- vester, PTO Bailer; 7=Tillage Tools, Mower; 8=Seeding Equip; Boom Spray- ers; 9=Truck; 10=Air Blast Sprayer. Number of units‘ handled per hourx 11. * Refer to Page 1 " See instructions for Program 03, Form 3 for suggested guidelines. ’*‘ If you cannot find your machine in the list, similar or enter estimate of repairs costs. a conversion factor in line 11. are consistent in these lines. .7. D. ’13:; TFD .‘ . . . . ran/31.3.“157 ——- _. --_‘-—- —-——. . - .-.-- _-.__ try to match to a machine that is Hours are used as a measure for expressing costs in lines 8a, 8b, 9a, 9b and as You can use a different measure as long as you Section III. -95- 12a. b. 13a. Section IV. Tax bracket in year of purchase. Tax bracket for first 1/2 years of investment. Tax bracket for last l/2 years of investment. 251.5. Mb. 12. ADJUSTED Federal JFK! Rate of Return and Cash_Flow Information. l39|?9|3-0-| Desired percentage rate of re- turn on investment for first l/2 years of investment. Desired percentage rate of re- turn on investment for last l/2 years of investment. Additional debt load (annual ,3, [is [1.5'0410 .o_, / J principal & interest payment in thousands of dollars) that business can with- the current stand. Hndification of Assumptionsxx Lnter "O” on line following last modification to be 14a. b. 15a. 16a. b. 17a. b. 18a. b. 19a. b. 20a. b. made. If none, enter "0" on line 14) Assumption value desired 14. p l ' 0 l 0 ll __ -_ __ Assumption code 4’ Assumption value lesired 15- p 6‘ ' O I 0 2' _-,__ __ Assumption code ’/ Assumption value desired 15. 8" ' Q I Q 51' __ Assumption code a 4~4-/ Assumption value desired 17. 6- ' 9‘ Q 8+ _ Assumption code 4—/ Assumption value desired 18. Pl ° 0 I Q- 9-‘l __ Assumption code / 01. 6 1.0 Assemption value desired 19. - ° -‘ - __ Assumption code Assumption value desired 20. § 0 - 0_ 3| - _ Assumption code 4/ xx See instructions for Proyram 03, Form 3 en ' ~-_o to use this section. -96- Program No: 03 APPENDIX BZ Form NO: _ ___3_-:__._ S 95 t 91" -' 732' 293'? 72-53 _____ ”-5- __ CAPITAL INVESTH‘NT MODEL -- INCLFDING BUY OR CUSTOM HIRE A TELPLAN FROTRAM -_———_-_.._.——_ -_-_.._______‘_.‘-... -,.... Problem: To evaluate the investment of “‘“ capital to reduce or eliminate costs including custom hire 5 leasing, _DBXDIG (3_81 11011532231.) ADJUSTED L I 3’ NC . x“. .Vf‘i L Y5 I 5 In’ermation. Section I. Costs Reducing (Custom Hire or Leasing) Or Incore-firojucingr la. Cost savings (or income produced) 01, IO. 0 2 . 0. 0.’ per unit‘ for a certain class of ‘ "~"‘_'"-' expenses (or income). For example, custom rate per unit (5) 2a. Cost savings (or income produced) 02, '0— Q Q - 1. 1' per unit’ for a second class of —-.‘—‘—_--—- expenses (or income). For example, additional per unit annual losses associated with custom hire (5) 3a. Normal number of units" per year 03, P. O 4 .0 0 0']. 00' on which costs will be reduced (or income generated). b. Percent of units‘ indicated in Line 3a that will be absorbed by investnent in the year of purchase. Section II. InVestment Information. 4a. Total dollar cost including un- 04, depreciated balance of trade—in items. / b. Percentage undepreciated value of trade-in itens is of total cost. *4 5a. If a used item enter estimated 05. '94- 5 Q 32' 0" new cost of item. If new item enter same value entered in Line 4a. / b. Years plan to use the investment. ’ It is very important to be consistent in your units. (For example, if the custom rate is stated on acres all the other units are also to be stated in acres). This computer program was designed by Stephen B. Harsh, Michigan State tniversity. 6a. b. c. d. 10a. lla. -97- gig 5's: Depreciation years Salvage percent Month of purchase (OlzJan,...., 12=Dec.). Depreciation type (OrHave model .‘ choose best depreciation method to use; l=Straight line; 2=Straight line with additional 20%; 3=Double decline balance; 4=Double decline balance with additional 20%; 5=l.5 decline balance; 6:1.5 decline bal- ance with additional 20%; 7=Sunrof¥ digits; 8=Sunrof~digits with addi- tional 20%). Does investment qualify for in- a vestment credit (O=no; l=yes). IF4 '0 IC) ICD '00 .l--‘ IN IO Percent of total cost (input line 07. . 4a) borrowed. Repayment period of loan-years Annual rate of interest on loan(i) L Per hourx fuel cost of operating 05, investment" (5) Per hourx fuel cost of operating associated equipment" (5) k Per hourx labor cost of operating investment 5 associated equipment. Fer hourx cost of supplies of operating investment 5 associated equiprwnt. ,0, 002 sq Repairs costs of investment: Enter estimated repairs costs over period or use in today's dollars (amount must exceed $25) 95 enter type"' of machine to have model estimate re— pairs costs. Types of machines are: l=Tractors; 2=Self-P. Combine, Self- P. Forage Harvester, Rotary Cutter; 3=Pull Type Combine. Pull Type For- age Harvester, Flail Harvester; 4: Self-P. Swather, Self-U.L. Wagon, Side D. Rake; 5=Fertilizer Equip; 6=Potato Harvester, Sugar Beet Har- vester, PTO Bailer; 7=Tillage Tools, Mower; 8=Seeding Equip; Boom Spray- ers; 9=Truck; l0=Air Blast Sprayer. Number of units’ handled per hourx }1_ I0.Q Oil . 0 0| ' Refer to Page 1 ‘* See instructions fer Program 03, Form 3 for suggested guidelines. "’ If you cannot find your machine in the list, try to match to a machine that is similar or enter estimate of repairs costs. Hours are used as a measure for expressing costs in lines Pa, 8b, a conversion factor in line 11. 1'31? '3 II.‘ T (T You can use a different are consistent in these lines. (3d, [a 1). His“ ’I‘ITD 11.‘.'.);7.‘.“ .15 9b and as as Song as you ._98_ Section III. Federal Tax, Ratemgf¥fiefurn and Cash Flow Information. #/ 12a. Tax bracket in year of purchase. b. Tax bracket for first l/2 years ADJUSTED f :01} 3,5 I S C. 13a. Section IV. of investment. Tax bracket for last l/2 years of investment. Desired percentage rate of re- turn on investment for first l/2 years of invastment. Desired percentage rate of re- investment for last turn on 1/2 years of investment. Additional debt load (annual principal & interest payment in thousands of dollars) that the current business can with- stand. Modification of Assumptionsxx tnter "O" on line following last rmdification to be made. If none, enter "0" on line 14) 14a. Assumption value desired 14. “)1’ ' 0 IQ 1‘ .____ b. Assumption code ‘—/ 15a. Assumption value desired 15- "0‘6 ’ Q I Q a 7 b. Assumption code ’ 16a. Assumption value desired 16. '9 _8 0 Q Q q ---- b. Assumption code a AA—e/ 17a. Assumption value desired 17. '05 ° Q - q _ ____'__ b. Assumption code ,/ O 1 18a. Assumption value desired 18. l- - ° Q1(l 9‘ _ _ b. Assumption code / 19a. Assumption value desired 19. I-0 -l ' 6" l q _ ----_-- b. Assumption code ’ 20a. Assumption value desired 20. Ip-6 ' Qlo— 3| - A“ __ b. Assumption code se/ xx See instructions for Program 03, Form 3 on how to use this section. '-99- Program No: Q3 System: TOUQHlTON§____ PHONE CAPITAL INVESTMENT MODEL -- INCLUDING BUY OR CFSTOM HIRE A TELPLAN PROGRAH mart-v25 ___I.m-TEMPERATURE ADDRESS NON-STIR DWING (381 tonsg.a.) Problem: To evaluate the investment of, capital to reduce or elinunate costs including custom hire & leaSing, -------------------------------------------- 9{-E9-S‘3’l€{‘3E€_’_7‘3‘:'-{’l€9’1’€;_-_-__--_____- ADJUSTED _L_I.-;E no. musrs INPUT: Section I. Costs Reducing (Custom Hire or Leasing) Or Income Producing Information. la. Cost savings (or income produced) 0}. lg .0 -2. Q .3' per unit’ for a certain class of ' expenses (or income). For example, custom rate per unit (5) 2a. Cost savings (or income produced) 02, no 0 -0 - 0 0! per unit’ for a second class of expenses (or income). For example, additional per unit annual losses associated with custom hire (5) 3a. Normal number of units' per year 03. lo .0 .4_0_0.0| .. _ -l on which costs will be reduced ’"_"~'—*'_._ (or income generated). / b. Percent of units’ indicated in Line 3a that will be absorbed by investment in the year of purchase. Section II. Investment Information. 4a. Total dollar cost including un- 04. '0 3 .82 8 6|Q 0i depreciated balance of trade-in — items. ;_J/ b. Percentage undepreciated value of trade-in itens is of total cost. 5a. If a used item enter estimated 05. new cost of item. If new item enter same value entered in Line 4a. b. Years plan to use the investment. 503.8286IILOI ’ It is very important to be consistent in your units. (For example, if the custom rate is stated on acres all the other units are also to be stated in acres). This computer program was designed by Stephen B. Harsh, Michigan State University. ~100- 131). ’k' 'H'ipfl) 5 IKE; 1ij -. .'.':.;1.)'.-~1s 6a. Depreciation years 06. I; 9| 1- pl 0. g ‘5‘ 1:4 b. Salvage percent —4/ ""“"""" c. Month of purchase (01=Jan,...., ________._u___J/ 12=Dec.). // d. Depreciation type (OrHave model choose best depreciation method to use; l=Straight line; 2=Straight line with additional 20%; 3=Double decline balance; 4=Double dec ine balance with additional 20%; 5=l.5 decline balance; 6=l.5 decline bal- ance with additional 20%; 7=Surrof- digits; 8=Sunrof—digits with addi- tional 20%). e. Does investment qualify for in- ___“_____-_M"___rt__ vestment credit (O=no; l=yes). 7a. Percent of total cost (input line 07. '10 DIQB-|L2 '0‘ 4a) borrowed. -___ b. Repayment period of loan-years ./ C. Annual rate of interest on loan(fi) AJ/ 03. '9.0. 80. IQQ .0_0_| 8a. Per hourx fuel cost of operating investment" (5) b. Per hourx fuel cost of Operating __/ associated equipmentH (3) 9a. Per hourx labor cost of Operating 09. IO 0 . 0 8 l0 0 -()01 investnent & associated equipment. b. Per hourx cost of supplies of J/ operating investment 8 associated equipment. 10a. Repairs costs of investmnt: Enter 10, lo 05 0 0| estimated repairs costs over period or use in today's dollars (amount must exceed $25) 95 enter type"‘ of machine to have model estimate re- pairs costs. Types of machines are: l=Tractors; 2=Self-P. Combine, Self- P. Forage Harvester, Rotary Cutter; 3=Pull Type Combine. Pull Type For- age Harvester, Flail Harvester: 4= Self-P. Swather, Self-U.L. Wagon, Side D. Rake; 5=Fertilizer Equip; 6=Potato Harvester, Sugar Beet Har- vester, PTO Bailer; 7=Tillage Tools, Mower; 8=Seeding Equip; Boom Spray- ers; 9=Truck; 10=Air Blast Sprayer. lla. Number of units’ handled per hour" 11. Fl 00. l . 0 0| * Refer to Page 1 ‘* See instructions for Program 03, Form 3 for suggested guidelines. *“ If you cannot find your machine in the list, try to match to a machine that is similar or enter estimate of repairs costs. x Hours are used as a measure for expressing costs in lines 8a, 8b, 9a, 9b and as a conversion factor in line 11. You can use a different measure as long as you are consistent in these lines. Section III. ~101- LINE_£9; Federal Tax1_fate of Return and Cash Flow Information. 12a. b. 13a. Section IV. Tax bracket in year of purchase. Tax bracket for first 1/2 years of investment. Tax bracket for last 1/2 years // of investment. 12. IB 013043 0, _/ Desired percentage rate of re- l3. '15-'1- 5| 0 0 O'OI turn on investment for first l/2 years of investment. Desired percentage rate of re- turn on investment for last l/2 years of investment. Additional debt load (annual principal & interest payment in thousands of dollars) that the current business can with— stand. -_____--___-_/ Modification of Assumptionsxx Enter ”0" on line following last modification to be made. 14a. b. 15a. 16a. 17a. b. 18a. 19a. b. 20a. b. If none, enter "0" on line l4) Assumption value desired 14. p]; 0 9 0- ll Assumption code _4/ - ()6 O O 2 Assumption value desired la. l- - . - /- 1 Assumption code ’ O 8 O O 5 Assumption value desired 16. l- - . -| - 4 Assumption code 4a 4-/ . . O 6 O 0 8 Assumption value deSired 17. l- - . ‘ 4 Assumption code . . 0 1 0‘0 9 Assumption value deSired 18. l- - . - - 4 Assumption code / . . O l 6 l 0 Assumption value dCSlIed l9. l- — o -‘ - Assumption code / ()6 0 O 3 Assumption value desired 20. l- - . -‘ — 4 Assumption code / xx See instructions for Program 03, Form 3 on how to use this section. ADJUSTED W LEE —....——————.—.-— -_ *fi— _ .. --.— Section III. ~104- LINE NU. Afederal-Tax!_fiate of Return and Cash Flow Information. I . 12a. Tax bracket in year of purchase. 12. l-3 9| 3 Q l3- Ql b. Tax bracket {or first 1/2 years / of investnent. C. Tax bracket for last l/2 years _ 7- - - ,/ of investment. 13a. Desired percentage rate of re- 13. '- —| - -| - -(l ' Q‘ turn on investnent for first 1/2 years of investment. b. Desired percentage rate of re- / turn on investment for last l/2 years of investment. c. Additional debt load (annual _____ principal & interest payment in tbousands of dollars) that the current business can with- stand. Section IV. Hodification of Assumptionsxx Enter "0" on line following last modification to be made. If none, enter "0" on line 14) 14a. Assumption value desired 14- P ' ’ ‘l - ll b. Assumption code ‘—/ lSa. Assumption value desired 15. p ' ’ "I ' a b. Assumption code ’ 16a. Assumption value desired 16. p - - -l - a b. Assumption code a 444/ 17a. Assumption value desired 17. E - ' - - a b. Assumption code se/ 18a. Assumption value desired 183 8" ' -l - 4 b. Assumption code / 19a. Assumption value desired 19. f2 - ° -‘ - g b. Assumption code ’ 20a. Assumption value desired 20. F1 5 - Q! 0 3i b. Assumption code / xx See instructions for Program 03, Form 3 on how to use this section. A D. “ L75 TED ’ 1.1L": LE'SIS f 6a. b. c. 10a. lla. -lO3- _z._r_:.'_r_: no. Depreciation years 05_ '1. 9L]; 9' Q .8 ‘4. ‘11! Salvage percent Month of purchase (Ol=Jan,...., c.1/ 12=Dec.). Depreciation type (0=Have model choose best depreciation method to use; l=Straight line; 2=Straight line with additional 20%; 3=Double decline balance; 4rDouble decline alance with additional 20%; 5:1.5 decline balance; 6=l.5 decline bal- ance with additional 20%; 7=Susrof- digits; 3=Susrof-digits with addi- tional 202). Does investment qualify for in- -——- vestment credit (O=no; l=yes). Percent of total cost (input line 07. - 43) borrowed. Repayment period of loan—years _/ I Annual rate of interest on loan(‘) 99.23IQQ.0.Q' Per hourx fuel cost of operating 03. I investment" (5) Per hourx fuel cost of operating _/ associated equipmentH (5) Per heurx labor cost of operating 09_ I0. 0 .0. 8 '0 .0 . 0 q investment & associated equipment. Fer hourx cost of supplies of / Operating investment & associated equ:.1')iwl0nt . Repairs costs of investment: Enter 10, P 0 4 00' estimated repairs costs over period or use in today's dollars (amount must exceed $25) 95 enter type"‘ of nuchine to have model estimate re- pairs costs. Types of machines are: l=Tractors; 2=Self-P. Combine, Self- P. Forage Harvester, Rotary Cutter; 3=Pull Type Combine. Pull Type For- age Harvester, Flail Harvester; 4: Self-P. Swather, Self-U.L. Wagon, Side D. Rake; S=Fertilizer Equip; 6=Potato Harvester, Sugar Beet Har- vester, PTO Bailer; 7=Tillage Tools, Mower; 8=Seeding Equip; Boom Spray- ers; 9=Truck; 10=Air Blast Sprayer. Number of uni ts’ handled per hour” 11, 'Q Q 01- . Q 0| * Refer to Page 1 *' See instructions for Program 03, Form 3 for suggested guidelines. “‘ If you cannot find your machine in the list, similar or enter estimate of repairs costs. a conversion factor in line 11. are consistent in these lines. I: 1'". ’I '5 TED ..., . . . n .814.“ — _— -W~-___ try to match to a machine that is Hours are used as a measure for expressing costs in lines 8a, 8b, 9a, 9b and as You can use a different measure as long as you Section III. ~104- A 1'). ’ L75 TED iINE Np. anagrsrs Federal_l§x,_fip£e of Return and Cash flow Iniormation. 12a. Tax bracket in year of purchase. 12. l-39' 3 QIB- Q, ----, _____ b. Tax bracket for first l/2 years / of investnent. c. Tax bracket for last l/2 years - ._~..a/ of investment. 1.55 1.5 0 0 13a. Desired percentage rate of re- 13. I- -| - -' - -(l ' Q, -7‘_ -___ turn on investment for first 1/2 years of investment. b. Desired percentage rate of re- / turn on investment for last l/2 years of investnent. c. Additional debt load (annual principal & interest payment in thousands of dollars) that the current business can with- stand. Section IV. fiodification of Assumptionsxx Enter "0" on line following last modification to be made. If none, enter "0" on line 14) . . . l 0 14a. Assumption value deSired la. - ° ' ‘ ‘ _ b. Assumption ende ‘d/ 6 O 0 15a. Assumption value desired 15. ‘ ' 'l ' - __g b. Assumption code ’ . . . 8 0 0 16a. Assumption value aeSJred 16 - “ ° -l - _M b. Assumption code a eee/ _ g 6 O 0 17a. Assumption value deSired l7. - - ° -( - _E_* - b. Assumption code .i_/ l 0 O 9 18a. Assumption value desired 18. P'- - —' - -l _r ”H b. Assumption code / . . P J. 6 1 19a. Assumption value dCSlred l9. - - ° -‘ - _a u_ > b. Assumption code ’ 20a. Assumption value desired 20. F1 6 ° 0’ 03' i--- - b. Assumption code / xx See instructions for Program 03, Form 3 on how to use this section. 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How mammamcm OaEOCOOG am-agwo :8 g APPENDIX D CCMPUTER LISTING OF THE PROGRAM "FIXED" USED TO SIMUIATE CORN DINING IN A FIXED BED -110- APPENDIX D 10: 20=Ct so=cx 4o=c1 scat: ao=cx 7o=cx eo=cx 9o=cx 100=Ct 110=Ct 120=Ct 130=cx 140=Ct 150=cx 160=Ct 17o=c: xeo=c: 19o=cx 200=cx 210=cx 220=cx 230=cx 240=C¥ 250: 260= 270: 280: 290: 300: 310: 320: 330: 340=Ct 350: 360= 37o= 380: 390: 420=cx 430: 440: 450: 460: 470: 490: 490: soo=cx 510: 520= 530: 540: 550=Ct 560: 570: 580: 59o= 600: -111- PROGRAM FIXED (INPUTvOUTPUTvTAPE60=INPUTsTAPE61=OUTPUTvTAPE1) M I C H I G A N S T A T E U N I U E R S I T Y A G R I C U L T U R A L E N G I N E E R I N G D E P A R T M E N T F I X E D B E D G R A I N D R Y E R M O D E L F.U. DAKKER-ARKEMA: PROJECT LEADER M. G. ROTH: PROGRAMMER E.U.RUGUMAYO v MODIFIER ELIUD N. MUAURAvMODIFIER TO SIMULATE STIR DRYING DESCRIPTION MAIN PROGRAM FOR THE SIMULATION OF A FIXED BED DRYER SUDROUTINES USED BLOCKDATA LAYEQ READYTH ZEROIN FUNCTION SUDPROGRAMS USED SYCHART PACKAGE EMC SOLUE COMMON COMMON COMMON COMMON COMMON COMMON COMMON DIMENS EXTERN DEFINE EQUILIBRIUM RH FUNCTION (THOMPSON, ERH(T9XM) = 1. /MAIN/ XMT!THTDRHTIDELTvCMMvXMOIIABITIME /PRPRTY/SA9CA!CP7CVrCUvRHOPrHFG IPRESS/PATM /NAME/INAME!IPRODINEGVNEGI /ARRAYS/ T(5112)vH‘5192)9XM(51)9RH(51) /CONS/ CONIvC0N27C0N3vCON4vC0N5rCON61C0N71C0N12'CON13 /FLAGS/ JXIJMIICUN ION XMEFR(51)IDM(51)9TE0(51)!DEEP(21)IUB(SI)vINAME(3) AL SOLVE 1972) - EXP(- .382t(1.8tT + 82.)!XM**2) DATA RHCvaPRTvTIMEvITERCTrIEXITvJKoKCONvKAD/.999999999923*.0v5#0/ DATA IAB/O/ F(T) = T + 273.16 PRTT = 0.0 INPUT CONDITIONS OF DRYER TO BE SIMULATED READ lSOvXMOvTHINvCMMvDEPTH:INDPRvNLPFvTTvTBTPRrDELTvNEG CFM = 3.2807XCMM DEPTHF = 3.2807‘DEPTH HP=DEPTHF¥(CFM¥‘1.944)*3.0792E-6 HPHOUR=HP¥TT DTUAIR=HPHOUR/3.929E-4 ENJAIR = 1055.1tBTUAIR COMPUTE STEP SIZE! 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Pressure 1 standard atmosphere 1.013x102‘J/mg 1 bar 2 1.000x10 N/mz 1 lbf/in 6.895x103N/mz 1 in water 2.491x102N/m) 1 m Hg 1.333x102N/m“ . . 2 3 2 3 Surface per Unit Volume 1 ft /ft 3.280 m /m Specific Heat 1 BTU/1b F 4-.187x103J/kgK Temperature Difference 'Ihemial Conductivity 1 deg F (deg R) 1 B'IU/h ftz (°F/ft) 5/9 deg 0 (deg K) 1.731 W/mz (“C/m) —l32- APPENDIX E, continued: unit Cbnversions English or Metric SI Velocity 1 ft/h 8.467x10’5m/s Viscosity, absolute l lb/ft h 4.134xlo'4kg/m s (or dynamic) Viscosity, kinematic 1 ftzlh 2.58bt10" mzls Volume 1 bu (volume) 3.523x10-gmg 1 ft3 2.832x10_3m3 l U.S. g'al 3.785x10 m Airflow 1 cfm 2.832xlojm3/nun 1 cfm 2 4.719x10_1m /sec 1 cfm/ft2 3.048x10_3m/min 1 cfm/ft 5.080x10 m/sec HICHIGRN STQTE UNIV. LIBRGRIES llHI"WINIIIMIHWIHIIIIIIIHIIIHHIHVIIIIHHIIIHI 31293106754256