AN EQUAHON AND mMENSIonLE-s’s ’7; T271 PARAMETERS DESCRIBING) mango ‘ ‘ vmmnou DRYING ’ , Thais Iw the 059m of DI! D g 'j,_ MICHIGM STATE EEWEESETY I VerI E. Headfiey ‘ ' I 1964 at“: . _ - '_ i. 1.18 R A R T\/'ié::31igan 9*“6 1 Universi L IKEBI’ fix 5 0* mm?) {.2 -J This is to certify that the thesis entitled An Equation and Dimensionless Parameters Describing Infrared Vibration Drying presented by Verl E. Headiey has been accepted towards fulfillment of the requirements for __Eb.._D_deg1-ee in_Admj_n_Ls_Lration 6, Higher Education CZJW Major professor Date JUlY 30. 1961+ 0-169 ABSTRACT AN EQUATION AND DIMENSIONLESS PARAMETERS DESCRIBING INFRARED VIBRATION DRYING by Verl E. Headley An investigation was conducted to evaluate the variables involved in infrared vibration drying of high moisture shelled corn. These variables were evaluated and arranged in the dimensionless ratios. These dimensionless ratios were used for defining the drying constant, k. Frequency variation from 600 to 1450 cycles per minute had essentially no effect on drying rate. Tests were then run at 1000 cycles per minute. The optimum value of amplitude was 3/32 of an inch. Increasing the intensity from 1500 to 4600 Btu/hr.ft2, increased the value of the drying constant, k. As the wavelength was increased from 1 to 2.5 microns at a constant intensity, there was a linear increase in the drying rate. The drying constant decreased linearly as the velocity was increased at 100 ft/min and greater, The most rapid drying occurred with no forced air while vibrating the product. Depths of one to four inches were dried in the vibrating bed. Another approach for relating mathematically the variables involved was to derive a prediction equation for Verl E. Headley relating the drying constant ratio as a function of the var— iables involved with infrared vibration drying. The equa— tions were verified using an analysis of variance approach. The results indicated the prediction equation ’12": 2.22‘x 105[(F:—)(:t137‘$::)] + 6.42 p k' - 4.35 < k' < 4.35 + '1? as being valid for all grain depths up to and including four inch grain layers, when vibration only (no forced air flow) was used, with an overall correlation coefficient of 0.93 resulting. With forced air flow through the vibrating grain layer this equation was not valid. The equation for predicting the drying constant can be used to predict the drying rates for shelled corn with initial moisture contents in the range of 35 to 50 per cent dry basis. Approved filfi/v W 934 ’4’? AN EQUATION AND DIMENSIONLESS PARAMETERS DESCRIBING INFRARED VIBRATION DRYING By a” Verl E. Headley A THESIS . Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Agricultural Engineering 1964 ACKNOWLEDGEMENTS The author wishes to express his sincere apprecia- tion to Dr. Carl W. Hall, Chairman of the Department of Agricultural Engineering, for his guidance and encourage- ment throughout this entire study. Appreciation is also extended to the other members of the committee: Dr. A. M. Dhanak, Mechanical Engineering Department; Dr. F. H. Buelow, Agricultural Engineering Department; and Dr. I. J. Pflug, Food Science Department, for their cooperation and assistance in the preparation of this thesis. Sincere thanks is extended to James Cawood for his help in the research laboratory. ii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . ii LIST OF FIGURES . . . . . . . . . . . . . . . . . . v LISTOFTABLES..............,....viii ABBREVIATIONS AND SYMBOLS . . . . . . . . . . . . . ix 1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1 REVIEW OF LITERATURE . . . . . . . . . . . . . . . . 3 History of Infrared Radiant Energy Applications . . . . . . . ' 3 Agricultural Applications of Infrared Energy . . . . . . 6 Vibration or Fluidization of the Product and Its Effect on Infrared Drying . . . . . . 11 Effects of Rapid Drying and Cooling on Product Structure . . . . . . . . 14 Theory of Infrared Radiant Energy Transfer . . . . . . . . . . . . . 15 EXPERIMENTAL APPARATUS AND CALIBRATION PROCEDURES . 32 Vibration Apparatus . . . . . . . . . . . . . . 32 Frequency Calibration . . . . . . . . . . . . . 32 Amplitude Calibration . . . . . . . . . . . . . 34 Drying Chamber . . . . . . . 34 Forced Air Flow System and Calibration . . . . . 36 Grain Movement Calibration . . . . . . . . . 38 Calibration for Equivalent Effect Between Vibration and Forced Air Flow in Relation to Moisture Removal . . . . . . . 39 Infrared Radiant Energy Source and Calibration . . . . . . . 41 Calibration for Varying Wavelength at. Peak Infrared Intensity . . . . . . . . . 45 Method of Determining Total Heat Transfer Coefficient . . . . . . . . . . . . . 47 iii APPLICATION OF DIMENSIONAL ANALYSIS FOR DESCRIBING INFRARED VIBRATION DRYING . Selection of Variables Combining Infrared Vibration Drying Variables DRYING PROCEDURE RESULTS OF INFRARED VARIABLE STUDY Calculation of k Values Frequency Variation Effect Amplitude Variation Effect Infrared Intensity Variation Effect Wavelength Variation Effect Initial Grain Temperature Effect Forced Air Flow Effect . Grain Depth Variation Effect . . Effect of Total Heat Transfer Coefficient Variation Efficiency of Infrared Energy Utilization COMBINING INFRARED VARIABLES AS THE RESULT OF VARIATIONSTUDY............ RESULTS OF DATA ANALYSIS FOR ESTIMATING DRYING CONSTANT AS A FUNCTION OF DIMENSIONLESS RATIOS BY USE OF REGRESSION EQUATION VERIFICATION OF PREDICTION EQUATIONS SUMMARY Conclusions SUGGESTIONS FOR FURTHER STUDY REFERENCES iv Page 49 49 51 55 57 57 57 67 67 72 72 77 80 80 84 86 91 96 104 109 113 114 Figure 10. 11. LIST OF FIGURES Wavelength of Various Electromagnetic Waves . . . . . . . . . . . . . . . . . . Energy Distribution for Black Body Emitters as a Function of Wavelength for Different Temperatures (Eckert and Drake, 1959) . . Absorption Bands of Water Vapor and Carbon Dioxide (Eckert and Drake, 1959) . . . Absorption Characteristics of a Film of Water Three Millimeters Thick (Shuman and Staley, 1950) . . . . . . . . . . . . Effect of Air Velocity on Surface Temperature of Product in Relation to Convection and Radiation Heating (Hall, 1960) . . . . . . Effect of Air Flow Direction on the Rate of Infrared Radiation Drying of a Single Stationary Layer of Shelled Corn (Headley and Hall, 1960) . . . . . . . . Overall Infrared Drying Apparatus Plot of Power Consumed Versus Frequency of Vibration at Optimum Amplitude for Various Depths of Grain Layers, 641167-4 . . , . Percent Voids in Two Inch Vibrating Grain Layer Versus Frequency of Vibration, 641167-1 Temperature Distribution in Two Inch Stationary and Vibrating Grain Layers of Shelled Corn Versus Time, 641167-17 . . . . Forced Air Velocity Versus Moisture Removal From Two Inch Layer of Shelled Corn and Equivalent Velocity of Vibration Only, 641167- 9 . . . . . . . . Page 17 19 27 28 29 30 33 35 37 4o 42 Figure 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. Page Energy Received at Surface of Grain Layer Versus Number of Infrared Lamps Centered One Foot Above Drying Tray . . . . . . . . 44 Comparative Performance of Various Infrared Sources as Percent Volts Versus Percent Input, Output, and Temperature (Fostoria Pressed Steel Corporation, Fostoria, Ohio) . . . . . . . . . . . . . . . . . . . 46 Effect of Frequency of Vibration on the Drying Constant for Shelled Corn, 641167-13 . . . . . . . . . . . . . . . . . 65 Moisture Content of Shelled Corn Versus Time in Relation to Vibration Frequency Variation . . . . . . . . . . . . . . . . . 66 Effect of Amplitude Variation on the Drying Constant for Shelled Corn, 641167—11 . . . 68 Moisture Content of Shelled Corn Versus Time in Relation to Amplitude Variation . . . . 69 Effect of Infrared Intensity Variation on the Drying Constant for Shelled Corn, 641167- 8 . . . . . . . . . . . . . . . 70 Moisture Content of Shelled Corn Versus Time in Relation to Infrared Intensity Variation . . . . . . . . . . . . . . . . . 71 Effect of Wavelength at Peak Intensity Variation on the Drying Constant for Shelled Corn, 641167-10 . . . . . . . . . . 73 Moisture Content of Shelled Corn Versus Time in Relation to Wavelength of Infrared Energy at Peak Intensity . . . . . . . . . 74 Effect of Initial Grain Temperature on the Drying Constant for Shelled Corn, 641167- 2 . . . . . . . . . . . . . . 75 Moisture Content of Shelled Corn Versus Time in Relation to the Initial Grain Temperature . . . . . . . . . . . . . . . . 76 vi Figure 24. 25. 26. 27. 28. 29.’ 30. Page Effect of Forced Air Velocity (Vibration Effect Plus Forced Air) on the Drying Constant for Shelled Corn, 641167—7 . . . . 78 Moisture Content of Shelled Corn in Relation to Rate of Forced Air Flow Through Grain Layer, 641167—6 . . . . . . . . . . . . . . 79 Effect of Grain Depth on the Drying Constant for Shelled Corn, 641167—3 . . . . . . . . 81 Moisture Content of Shelled Corn Versus Time in Relation to Variation of Grain Depth . . . . . . . . . . . . . . . . . . . 82 A Plot of Total Heat Transfer Coefficient and Convection Heat Transfer Coefficient Versus Air Velocity Through Grain Layer, 641167-18 . . . . . . . . . . . . . . . . . 83 A Plot of Drying Constant Ratio for Shelled Corn Versus Dimensionless Ratios Describing Infrared Vibration Drying and Regression Equation for Estimating Drying Constant From Known Value of the Dimensionless Ratios, 641167-4 . . . . . . . . . . . . . 94 Verification of Equation RV = 2.22 x 105 PC I [(—vd) (fig + 6.42 Predicting the Infrared Vibration Drying Constant for Shelled Corn with an Initial Moisture Content in the Range of 35 to 50 Per Cent (Dry Basis) as Compared to the Experimental k Value When Applied to the Exponential Drying Equation, 641167—5 . . . . . . . . . 103 vii Table LIST OF TABLES Drying Constants for Shelled Corn Determined by Varying Infrared Vibration Drying Parameters One at a Time Comparison of Efficiencies of Radiant Energy Utilization in Vibration Drying of Shelled Corn Receiving Infrared Radiant Engrgy at the Rate of 3,250 Btu/hr.ft. . . . . . . . . . . Drying Constants for Shelled Corn Determined by Varying Infrared Drying Parameters Simultaneously to Establish Validity of Prediction Equations for Drying Constant . . . . . . . . Analysis of Variance Results in Relation to the Experimental Drying Constant Ratios for Shelled Corn and Those Calculated by Prediction Equation viii Page 58 85 90 102 A ABBREVIATIONS AND SYMBOLS amplitude of vibration bN(1T81T9) slope of regression equation Cd C ratio vertical cycle distance, Cd = 4A Speed of light in a medium heat capacity of grain Speed of light in vacuum diameter diameter of kernel of corn on basis of sphere depth of grain layer base of natural logarithm monochromatic emissive power of a black body emissive power of black body frequency of light wave oscillation frequency of vibration F-test for significant difference air mass flow rate ix 1' (‘N8 T0k TOR convective heat transfer coefficient total heat transfer coefficient, (hC + hr) intensity of infrared radiation received at the surface of grain grain thermal conductivity drying Constant for shelled corn drying constant for shelled corn at reference con— ditions using vibration without infrared energy estimated or predicted value of drying constant using dimensionless ratios experimental drying constant ratio, ka/kO drying constant ratio by prediction equation, ka/kO mean value of drying constantratios moisture content of shelled corn initial moisture content of shelled corn total number of observations -"9)k,coefficient of linear correlation absolute temperature in Kelvin degrees absolute temperature in Rankine degrees 17' initial grain temperature in Rankine degrees initial grain temperature in Fahrenheit degrees surface temperature of grain, oF OF temperature of surroundings, air velocity moisture content ratio pi, signifies a dimensionless ratio (7T87T9) product of dimensionless ratios 7781Té. (TTSTTQ) mean value of products of dimensionless ratios 6 drying time wavelength wavelength at peak intensity of emitter Stefan Boltzman constant reflectivity air density absorptivity monochromatic absorptivity xi emissivity emissivity of shelled corn monochromatic emissivity transmissivity refraction index ) standard deviation of sample points from 9 regression line statistical t distribution level of significance xii INTRODUCTION Artificial drying of agricultural products has ex- panded rapidly in recent years. Application of better farm— ing principles resulting in increased yields, and improved harvesting methods have created problems in the field to storage operations, primarily in drying. Corn harvesting machines (picker-shellers) harvest high moisture shelled corn more rapidly than conventional heated air grain dryers can reduce the moisture content to facilitate safe storage. Heated-air drying (convection heating) is a relatively in— efficient method of energy transfer. Likewise shelled corn is temperature sensitive as far as germination, milling properties, and nutrient value are concerned. These char- acteristics, along with high initial moisture contents of shelled corn, in some cases require that more than one pass be made through the heated air drying system to reduce the grain to a moisture content low enough to facilitatesafe storage, which in the same manner reduces the capacity of the grain dryer. Infrared radiant energy is a high intensity energy source. The application of infrared energy for the drying of agricultural products received considerable attention in the early 1940's. A misunderstanding of the characteristics of infrared energy transfer resulted in many failures in its early applications to the drying of hygroscopic food products. The absorption of infrared radiant energy by a prod- uct is primarily a surface phenomenon. Infrared rays im— pinge upon the surface of the product producing a skin heat- ing effect. Thus previous applications of infrared radiant energy for drying agricultural products have been limited to thin layers usually of one inch or less. -Recent satisfactory applications of infrared radiant energy have been reported by vibrating shelled corn layers up to two inches in depth. Proper manipulation of the prod- uct sufficient to produce thorough mixing allowed larger grain depths to be satisfactorily dried at increased infra- red energy intensities, thus increasing the capacity of an infrared drying unit. The objective of this investigation was to study infrared vibration drying particularly for drying high mois- ture shelled corn. This study was made to establish the- best combination of the variables involved in infrared vibra— tion drying of high moisture shelled corn, to combine these variables into their proper dimensionless ratios, and to establish a drying equation containing the proper combina— tion of dimensionless ratios incorporated into a drying con- stant which would best describe infrared vibration drying. REVIEW OF LITERATURE History of Infrared Radiant Energy Applications Excluding the solar source of infrared radiant en— ergy, man first produced this type of energy artificially when he discovered fire in prehistoric times. This he used to warm his body, and thus discovered that infrared does not heat the surrounding air, but only'that portion of his body directly exposed to the infrared rays or relatively Speaking that portion of his body seeing the infrared radiant energy source. Infrared radiant energy though generally not recog- nized has been used in domestic applications for years. The ever popular charcoal grilling of steak relies almost entire— ly on the radiant energy emitted from the glowing coals for cooking the meat. Food placed in an oven under flames is cooked largely from the absorption of infrared rays. .An electric toaster browns bread primarily by the action of infrared radiation as well as naturally convected heat. Thomas Edison in 1880 perfected the carbon filament lamp which he designed primarily for lighting purposes. This lamp was soon recognized as a means of supplying local heat for therapeutic treatments, thus the carbon filament "infrared" lamp originated. Industrial applications of infrared radiant energy were first made during the 1930's, with the Ford Motor Com— pany being given the credit as the first to apply this type of heat energy on a large scale. The Ford engineers adopted infrared radiant energy to replace steam heated ovens for baking enamel at 2500F on the finished automobile bodies. Out of this conversion grew the widely publicized Ford in- frared ”tunnels" now used for the complete automobile body baking operation. The carbon-filament infrared lamp was rused.wide1y in the early industrial applications, and it still is used in some industrial applications. Although artificially produced infrared radiant ' energy was used prior to World War II, it was not until the increased demand of war time production necessitated it that infrared radiant heating was really applied on a large scale industrially. Greatly accelerated experience was gained in this field during these years, and infrared heating-was applied with almost miraculous drying Speeds. Different types of industrial heating requirements, and previous rapid and satisfactory applications of artifi- cially produced infrared energy to numerous heating and dry— ing industrial processes brought about different designs in infrared elements. Some of these were the ceramic gas—fired infrared generators, quartz tube infrared lamps, tungsten filament infrared lamps, and calrod units. These infrared producing elements differ essentially only in design and Spectral energy distribution with each producing its own characteristic peak energy emission at a Specific wave— length depending primarily on the temperature and emission properties of the emitter. Industrial applications of infrared radiant energy have been numerous though problems did and still exist. Its applications are primarily where quick Spot heating and dry— ing are necessary. Some of the applications are drying in paper manufacturing, skin drying of foundry molds, softening of plastic sheets for cutting, Stamping and molding, injec- tion mold drying, paint drying, drying of freshly molded porcelain bathtubs prior to being placed into high tempera- ture kilns, baking enamel on traffic signs, preheating of metal products prior to high temperature welding operations, fusing Special labels on glass bottles, curing bakelite var— nish on small coils of wire, drying dye-printed pattern cloth, and numerous others (Hall, 1947). Application of infrared energy in the food process- ing industry has been applied with limited success. Such large scale applications as the baking of cookies, drying cookie icing, dehydrating noodles for packaging, cooking meat balls for Spaghetti, drying dog biscuits, and so forth have been reported (Food Engineering, 1958). Research for applying infrared radiant energy in other areas of food processing have also been reported, such as peeling of apples (Food Technology, 1956), controlling bacteria and fungi in grain, blanching of celery and apples, curing of onions, drying rough rice, and other cereal grains. In any event applications of infrared radiant energy have been successful primarily when heating or drying of only a single or thin layer of product. Attempts to use product layers of one inch depth and larger particularly in the area of agricultural products have resulted in failure denoted by uneven drying and surface scorching of the product, thus a basis for further research in the field of infrared drying agricultural products. Agricultural Applications of_InfraredEnergy Schroeder and Rosberg (1959) indicated favorable results with gas-fired infrared drying of stationary layers of rough rice. The most efficient moisture removal was achieved by intermittently eXposing the rice to increased infrared intensities until a surface temperature of 1220F was reached followed by cooling in atmospheric air. Bilowicka (1960) Showed the rate of temperature in- crease of rapeseed during heating and drying as being great— er for the larger infrared intensities. .A seed temperature increase of 81°F in ten minutes at a lamp height of 170 mm was obtained as compared to an increase of 680E at a lamp height of 340 mm. Person and Sorenson (1961) increased the capacity of infrared drying of hay by increasing the depth of the layer. Increasing the depth of the hay layer exposed to the infra- red radiant energy resulted in wide variations of moisture distribution in the hay. The 1.15 micron (wavelength at peak intensity) infrared energy source produced the lowest drying capacity, while the 3 micron infrared source at same intensity gave the highest. Energy utilization showed the 1.15 micron source as yielding an efficiency of only 13 per cent as compared to 38.1 per cent for the 5 micron infrared source. Hall (1960) presented the theory of infrared radiant energy in relation to the drying of agricultural and food products. It was illustrated that infrared radiant energy has only superficial penetration at the surface of hay or grain. White and whole wheat flour, exposed to an infrared radiant energy source emitting in the wavelength range of 0.7 micron to 3.5 microns showed only 0.14 per cent of the energy as being transmitted to a depth of 1/32 inch and beyond thus leaving 99.86 per cent of the absorbed energy concentrated in the thin surface layer of 1/32 inch or less. Aselburgs g£_gl. (1960) studied the effectiveness of infrared sources such as quartz lamps, quartz tubes, and calrod units in the blanching of apple tissue. The results indicated the depth of heat penetration as being influenced by wavelength characteristics, voltage input, and energy output. A quartz lamp with a maximum peak wavelength of 1.16 microns resulted in a 4.1 millimeter heat penetration into the apple tissue after a five minute exposure. Calrod units operating at the same voltage with a wavelength at peak intensity of 2.65 microns yielded a penetration of 5.9 millimeters in the same length of time. Vorobev (1961) studied the application of infrared radiant energy for grain drying. A laboratory model was constructed which consisted of an insulated steel cylinder with a weighing mechanism and infrared lamps at the t0p and an electric heater at the bottom. The grain descended over a series of revolving transverse cylinders to a convection dryer. The infrared radiation was applied to the grain when on the top of the cylinders, thus allowing intervals for evaporation of moisture. Three experiments were carried out with supplementary convectional drying temperatures of 20°C and 140°C, and without infrared heating, using 709, 1,114 and 1,320 calories per kilogram of moisture reduction. Picket and co—workers (1962) studied high energy intensities (heated air temperatures up to 900°F) for drying shelled corn. .Heated air and high moisture shelled corn were passed countercurrently through a small rotary drum dryer. The results indicated a definite effect of tempera— ture level upon moisture removal. Using air temperatures of SOOOF reduced 18 per cent moisture shelled corn to 16 per cent; at 700°F air temperatures, 18 per cent moisture shelled was reduced to 12.5 per cent; and at 900°F air temperatures 18 per cent moisture shelled corn was reduced to 8 per cent in two and two-tenths minutes. Some visible damage to the grain was observed at these exposure times and temperatures. Headley and Hall (1963) reported the drying rates of shelled corn using high temperature convection heating with air temperatures up to 800°F. High moisture shelled corn was exposed to elevated air temperatures and curves were established denoting time, temperature and percentage of moisture removal at the point of maximum allowable expo— sure time to visible kernel damage. Grain movement during drying when exposed to elevated heated air temperatures at 700°F increased the allowable exposure time to visible grain damage (surface scorching) from approximately ten seconds to eighteen seconds while in the same manner at 500°F air tem- peratures the allowable exposure time was increased from thirty seconds to approximately fifty-two seconds through grain movement. Works (1963) used infrared irradiation as an effec- tive treatment to increase the percentage of germination of seeds such as clover, alfalfa and white pine. 'The structure surrounding the seed embryo of some seeds blocks germination, and one of the most complete blocks is the impermeable seed’ 10 coat. Seeds possessing these characteristics fail to or are slow in germinating. Exposing seeds of this nature to infrared radiation for short periods of time improved the percentage of germination. Red clover seed samples un~ treated, exposed for 1.41 seconds to infrared radiant energy with wavelength at peak intensity of 1.2 H (quartz tubes), and exposed for 1.01 seconds to infrared radiant energy with wavelength at peak intensity of 1.14 A , showed germination percentages of 82.7, 98.7 and 97.9 respectively. Nelson and co-workers (1963) compared the effect of infrared radiant energy, radiofrequency and gas-plasma treatments on alfalfa seed for hard seed reduction. All three types of energy sources were about equally effective in increasing the germination of alfalfa seed by reducing the so-called hard seed percentages in seedlots. For infra- red radiant energy treatments the best germination results occurred when using a 1.36 second exposure time in an infra~ red field emitting its peak energy intensity at 1.18 microns. For radiofrequency treatments, a frequency of 39 megacycles for 14 seconds, produced the best germination, and using gas plasma, an exposure time of 3 minutes gave the best germina- tion for alfalfa seeds, thus lowering the amounts of hard seed. Food Engineering (1963) reported satisfactory re- sults in drying a heat-sensitive cheese with infrared radi- ant energy. Gas-fired infrared was used in conjunction with 11 a continuous belt system in drying heat-sensitive cheese at a one inch depth. Moving a one inch layer of cheese pellets, at a Speed of six feet per minute on a continuous belt sixteen feet long through a gas-fired infrared field with the source maintained five inches above the product, resulted in satisfactory drying of 1,500 lbs/hr of the cheese pellets with an absorption of 68 per cent of the heat energy input. Vibration or Fluidization of the Product and Its Effect on Inffared Drying'fi Reed and Fenske (1955) studied the effects of agita- tion on gas fluidization and the convection heat transfer coefficient. The convection heat transfer coefficient be- tween the vibrating plate and bed of carbon particles, as- sisted in fluidization by an air flow of 0.2 ft/sec, in- creased from 40 Btu/hr.ft2F to 72 Btu/hr.ft2F when the vibra— tion stroke was increased from 0.0625 inches to 0.313 inches at a vibration frequency of 1,000 cycles per minute. In the same manner holding the vibration stroke constant at 0.313 inches, while varying the frequency from 1,000 cycles per minute to 2,000 cycles per minute increased the convection heat transfer coefficient between the vibration plate and carbon particles from 72 Btu/hr.ft2F to approximately 100 Btu/hr.ft2F reSpectively. It was further illustrated that as the product of 12 the frequency (cycles per minute) times stroke (inches) was increased a point was reached in which the forced air flow, aiding in fluidization of the particles, could be eliminated as a factor in attaining a higher convection heat transfer coefficient. For aerated nickel powder when comparing air flows of 12 ft/min and 60 ft/min while using a vibration stroke of 0.313 inches (amplitude of 5/32 inch), a maximum convection heat transfer coefficient of 135 Btu/hr.ft2F was obtained at‘a frequency of 1,200 cycles per minute or a frequency-times-stroke product of 375 in/min. At this point the convection heat transfer coefficients for both forced air velocities of 12 and 60 ft/min were essentially identi— .cal, indicating that forced air could be eliminated as a factor for attaining higher heat transfer rates. Leva (1959) has presented the theory of fluidized beds pertaining primarily to air-solid relationships in relation to heat and mass transfer. Also it has been illus- trated that with increasing air flow and particle diameter the heat transfer coefficient also increases. Equations have been given indicating the relationship between heat transfer, air flow and mass transfer in fixed, expanded, and fluidized beds. Baader (1961) studied the behavior of loose material on oscillating sieves. It was shown that the separation of the lowest layer of material during oscillation takes place 13 only when the sum of all forces, operating between the mate- rial and the sieve and normal to the sieve surface, have reached zero. It was also concluded that the movement of the material in so far as the sieve was concerned was deter— mined by the frequency, amplitude, and angle of inclination of the sieve. For optimum sieve performance the duration of the material projection must coincide with the oscillation period of the sieve. _ Schertz and Hazen (1963) made a study preggcting the movement of shelled corn on an oscillating conveyere Mass rate and flow measurements were made to determine the rate of material movement. it was shown that the mean velocity of the conveyed material was not always constant with re— Spect to the depth of the layer. Predicted results were within 10 per cent of the observed values. Stephenson and McKee (1963) showed favorable drying results and capacities when using a small multistage infra- red dryer with three vibrating trays oscillating at inter- vals. Solenoids were used to produce vibration range of from 20 to 60 cycles per minute. The absorptivities of corn, oats, and wheat, part of which were blackened, were compared to those of natural surface color. It was assumed that most grains for all practical purposes could be treated as gray bodies. Shelled corn at 28 per cent initial moisture con- tent, exposed for two minutes in an infrared field generated by a 250 watt industrial drying lamp and located one foot 14 above the source, indicated corn kernals coated with black ink and natural surface as having temperatures of 85°F and 80°F respectively. This gave a temperature ratio, (éfi), of 0.93. Since a corn kernel covered with the dull black ink could be considered essentially as a black body, thus the temperature ratio could also be considered as a measure of the degree of absorptivity. Headleyand Hall (1963) illustrated that vibration of shelled corn in an infrared field provided a means of satisfactorily utilizing increased infrared intensities for drying without visible damage (surface scorching) occurring in the grain. A two inch layer of high moisture shelled corn, vibrated at a frequency of 1,200 cycles per minute at an amplitude of 1/4 inch, was satisfactorily dried from 35 per cent moisture (dry basis) to 15 per cent in forty-four minutes when exposed to an effective intensity of 1,620 Btu/hr.ft2. A constant rate of change in moisture content with reSpect to time was observed as seen from the linear- ity of the drying curve in the range of drying from 35 per cent moisture (dry basis) to 15 per cent moisture. Effects of Rapid Drying and Cooling TY ’ on Product Structure Thompson and Foster (1963) found that shelled corn dried in heated air with temperatures ranging from 140°F to 240°F was two to three times more susceptible to breakage 15 than when dried with unheated air. Most of the stress cracks (endosperm fissures) occurred during the drying peri- od in passing through the moisture content range of 19 to 14 per cent. Rapid cooling of the grain also increased the number of stress cracks, a damage undesirable for corn mill- ing. Reduction in the number of stress cracks appearing in the corn kernal were obtained by lowering the drying Speeds, especially through the moisture range of 19 to 14 per cent, and delaying the cooling of shelled corn immediately follow— ing the drying period, thus allowing time for grain temper- ing prior to rapid cooling. Theory of Infrared Radiant gnergy Transtr The largest radiant energy source available is the sun. The sun emits radiant energy nearly as a black body at a temperature of 10,8000R. 0f the radiation received by earth from the sun about 50 per cent lies in the infrared range. Almost all of the remaining 50 per cent received. lies in the visible range, except for a minute portion as ultraviolet. 0f the solar radiation directed toward earth from the sun, a portion is absorbed by the gaseous media surround- ing earth. The remainder is transmitted to earth, where again part is absorbed (e = 0.83) and the remainder earth reflected back to outer Space. Theoretically the earth 16 receives infrared radiant energy from the sun at the outer fringes of its atmosphere at the rate of 442 Btu/hr.ft2, a value commonly referred to as the "solar constant.” Infrared radiant energy rays are electromagnetic waves similar in nature to x-rays, radio, gamma, and visible rays varying only in frequency and wave length and traveling at a constant Speed of 3 x 1010 cm/sec in a vacuum. .In other media the velocity of infrared rays may be somewhat less and C can be calculated by equation, 71 =._X , more commonly called C the refraction index. The letter Cv denotes the velocity of the rays in a vacuum where maximum transfer occurs, and C is the velocity of the rays in any media under observation. However, for most practical purposes the velocity of all infrared rays are considered constant or that Cv equals C for air. Thus the Speed of radiant energy is described by equation, f ),= C, where f denotes frequency of wave oscil— lation, A_the wavelength, and C the constant Speed for light travel, 3.0 x 1010 cm/sec. All electromagnetic waves travel at this speed. As seen from Figure 1, thermal radiation occupies only a small portion of the electromagnetic Spectrum as far as wavelength is concerned, but in terms of quantity of energy infrared energy contributes practically one-half of all energy received on earth from the sun. 17 )\ in microns |09________._.__ __________ 10'3- COSNHC [OJ ________________ '0’6- GAMMA ULTRA VIOLET IO”| r- l0 — INFRA RED ‘04 .— R'ADIO WAVES m m L____.__.__._ __.______.__.__.____4 Figure 1 1:.7avelength of various electromagnetic waves 18 The sun emits radiant energy at a temperature esti- mated to be 10,8000R, and is considered to be an ideal emit— ter or more commonly referred to a ”black body” emitter. An energy source emitting radiant energy as a black body repre- sents the limit of performance, and no material can emit greater amounts than this. Thus a perfect or nearly perfect emitter of this type is said to have an emissivity equal to one (6 = 1). In 1900, a German physicist Max Planck developed an equation which describes the energy distribution as‘a func- tion of wavelength for a black body emitting at any tempera— ture. Planck's radiation formula has thus far stood up under all tests satisfactorily, including many refined sys— tematic measurements. Planck‘s law can be expressed as E - C1" b. _. ‘5' C. T ’ A 1(632/A -1) where Eb is the monochromatic emissive power of a black body; A., wavelength of radiation; T, absolute temperature of the emitter; C1 and C2, constants, the values of which depend upon the units used to describe the wavelength and Itemperature of emitter. Planck‘s equation illustrates how at various temperatures, a black body emits infrared radi- ant energy over a wide range of wave lengths. Each Planckian curve indicates infrared radiation intensity as a function of the wavelength for a black body emitting at a Specific tem— perature as shown in Figure 2. I75 -'_ 7 — ”T —_ _ * T ' —__ _‘T‘-""-'—— _-”’r #A‘A‘ * a j — Planck's Law «.71 o K) 01 IOO N U"! 0‘ O __—— Wien's Displacement Law N 111 Nanochromatic Thermal Radiation Intensity (Btu/in.3 sec.) Figure 2 Wave Length (microns) Energy distribution for black bcdy emitters as a function of wavelength for different temperaturestEckert and Drake,l"-‘;‘S§) 20 By differentiating Planck's equation and setting the first derivative equal to zero, the wavelength at which the slape of the tangent to each energy distribution curve is equal to zero is obtained. This also indicates the wave- 1ength,(Amax), at which the peak energy emittance for a black body radiating at a Specific temperature occurs, Dif- ferentiation of Planck's equation with reSpect to the wave- length yields a -clts 14(6 Ca/AT-1)+ 15(303/lT-1X'C2T2H dK d3 _ E. b 10 C A l (e 2/AT-1)?‘ dB . Setting the first derivative equal to zero, '33}. = 0, thus the equation becomes C 4 C2 KT 5 02 1T 2 '5C1 A ( e / -1)+ AC1CG / -l)(-i—2:r-) = 0. Further simplification is obtained by dividing through by C SCIA (e 1). The equation reduces to AmaxT 5 C3, where Amax is the wavelength at peak intensity, T the‘abso— lute temperature of the emitter, and C3 a constant, the value of which depends upon the units in which Amax and T are ex— pressed. When the wavelength of radiant energy at peak in- tensity is expressed in microns and the temperature of the black body radiator in Kelvin degrees, then the value of constant C2 is 14,387 1(OK. Thus the first derivative 21 reduces to Xmax TOK = 2,877.4 At OK and is usually expressed as Amax T0K = 2,900 “OK. This equation is a form of Wien's displacement law. From this relation it is seen that as the infrared emissive power of a black body increases with inw creasing black body temperature the wavelength at peak emis— sion shifts to shorter wavelengths. An equation describing the total emissive power of a black body radiator may be obtained by multiplying both sides of Planck's equation by d). and integrating from zero to infinity. This quantitative relationship is read as 00 E sJ/f.E dA. , or the total relationship reads 0 b b A. 0° 5 E = j/" C1 AT,dA~ b (592/111) 0 The integration yields an equation which represents the total infrared energy radiated by a black body emitter at any Spe- cific temperature. This equation is Eb = VtT4 and is known as the Stefan—Boltzmann equation or law, where E represents b the total emissive power (Btu/hr.ft2), 'd'the Stefan—Boltz- 9 Btu/hr.ft2R4), and T the abso— mann constant (1.714 x 10- lute temperature of the emitter (OR). Of the electromagnetic waves (infrared rays) imping— ing on the surface of an object, all must be absorbed, trans- mitted, or reflected. From the law of conservation of energy it follows that [)+ CX-t T'==1 (Kirchoff's Law). 22 ‘3 indicates the ratio of the reflected energy to the inci- dent energy and is called the reflectivity,“ theeratio of the absorbed radiant energy to the incident energy and is called the absorptivity, and. 7'the ratio the radiant energy transmitted to the incident energy, and iS called the trans- missivity. Solid and liquid bodies absorb practically all the infrared radiation penetrating through their Surfaces within a very thin layer. For most agricultural products it has been reported that the depth of penetration of infra- red radiant energy rays is no greater than from one to two millimeters below the surface.‘ Since the thickness of most solids is greater than these values, then Kirchoff‘s law can be written as p+0C= 1, thus transmissivity is essentially zero. Likewise the re- flectivity for most gaseous media between the infrared energy source and the product can usually be neglected, thus Kirchoff's law reduces to OC+T = 1. In the same manner where the gaseous media between source and product is kept relatively free of water vapor and carbon dioxide by proper air movement then the absorptivity of the gaseous media can be neglected, thus Kirchoff‘s law for air can essentially be written as 7': 1. The total emissivity of an infrared radiating surface at some specific temperature is defined as the ratio of the emissive power, E, of the surface to that of the emissive power, Eb’ of a black body radiating at the same temperature, 23 The total emissivity of a black body emitter is equal to one (€’==1). Thus for a black body the absorptivity and emis- sivity are equal, thusCXi = €A.= 1. The monochromatic emissivity of a radiating non— black body is defined as 6' = _£&_ . Integrating over the A. Box entire wavelength range, the total emissivity of a non—black 'oo . = E = l “/P emitter can be expressed as€ _E: jig-T ) eel (TS)Eb(Ts) dA . Arcrsmb (1*de In the same manner the absorptivityCXl= - EbCTiy O These relations Show that the emissivity (E ) and absorp- tivity (CK ) are a function of the wavelength at a Specific temperature of the emitter. For a surface which is considered to exist as a gray body, both the absorptivity and emissivity are independ- ent of the wavelength. Thus one can write for gray bodies (X=QA(TS) = fl (T5) = 5 (T5). The monochromatic absorptivity values and emissivity values are rarely avail— able for many products for all wavelengths. Unfortunately not too many surfaces exist in nature which can be considered as truly gray bodies either. -However, agricultural products, grain for example, are assumed to act as gray bodies and designate a relatively high absorption of infrared radiant energy. Shelled corn at about 20 per cent moisture (wet basis) was estimated to have an absorptivity of approximately 0.93, determined by Stephenson and McKee (1963). 24 During the drying period for agricultural products, initially relatively high in moisture, the absorption prop- erties undoubtedly change. Thus, the wavelength at peak infrared absorption by the product also changes. Ideally, for efficient absorption of infrared radiant energy during drying of agricultural products, it would be desirable to have an energy source whose maximum intensity could be varied to wavelengths correSponding to the wavelengths of maximum absorption by the product throughout the entire dry- ing period. The production of infrared radiant energy artifi- cially by electrical resistance elements or gas-fired infrared sources provide a relatively efficient production of infrared radiant energy in relation to the energy input. From 75 to 85 per cent of the wattage input to the tungsten filament lamp is dissipated as heat energy through infrared radiation. The greater portion of the radiant energy emit- ted by this source is primarily in the near infrared range of 0.76” to 5“ , with the wavelength at peak intensity lying usually between 1“ and' 2 M . Any energy waves emitted at wavelengths longer than 5[( are absorbed by the glass bulb of the infrared lamp. This energy may be trans— ferred away from the glass by conduction, convection, or reradiation at the temperature of the glass (Weitz, 1956). Gas—fired infrared is generally produced by the com— bustion of natural or propane gases. However, only 10 to 20 25 per cent of the flame energy is in the form of infrared energy, therefore the hot flame energy is usually used to heat some radiating refractory material. Such surfaces offer the advantage of controlling the wavelength range over which radiation is distributed by controlling the tempera— ture of the radiating refractory material. With small Schwank gas—fired infrared heaters (10,000 to 11,000 Btu/hr. range) about 55 per cent of the energy liberated from com- bustion is converted to infrared radiation and the remainder is primarily in the combustion gases and transferred essen— tially by convection (Heidlkamp, 1957). The manner in which energy is transferred from the source to the product differs considerably between convec- tion heating and infrared heating. In convection heating the air is at a higher temperature than the product, thus energy is transferred from the air to the product. In— creasing the velocity of heated air (within limits) over the product in convection heating increases the rate of energy transfer from the air to the product thus increasing the temperature of the product. Infrared radiant energy, on the other hand, is transferred directly from the source to the product. The transfer is essentially independent of the media through which the electromagnetic waves pass, with exception of water vapor or carbon dioxide which when present between the source absorb infrared energy at Specific wavelengths 26 as shown in Figure 3 (Eckert, 1959). Otherwise the infrared rays are transferred directly from source to product without loss in intensity to the gaseous surroundings and are ab— sorbed by the product depending upon its absorption char— acteristics (Figure 4). The transfer of infrared radiant energy to the prod- uct is primarily surface phenomenon. Radiant energy im- pinges upon the surface of the product with only superficial penetration. This results in a high concentration of energy at the surface resulting in increased product surface tem— peratures greater than that of the surrounding media. ,Thus increasing air velocities over a product receiving infrared radiant energy will result in energy being transferred from the product to the air and surface cooling will occur, a factor undesirable as Shown in Figure 5. Using low air velocities (20 ft/min) countercurrent to the direction of radiant energy transfer to a product being dried decreases its effectiveness, while air movement concurrent to the direction of infrared radiant energy trans- fer to the product increases the effectiveness of energy utilization when drying high moisture shelled corn with gas— fired infrared as seen in Figure 6. Application of the principles of infrared radiant energy transfer, along with a product movement sufficient to produce thorough mixing have permitted increased product depths to be dried satisfactorily. Increased infrared 27 mmwfl.oxwhn can whoxomqopflROAc cognac mum Loam> Loam; mo meson cowsanowna m wcduwa . I 385:5 £33 86; .v o. @o mo It _ . . _ _ o _ m///(\\\ _ u h _ _ . ‘ a _ . o . . ON _ l 1 , . .. ow D . - V\ n W. _ . . om m. l H I m _ __ . ._ . I _m __ m H U A ow fi . «6:65 c850 __ __ __ on; pg 58> as; no 5?. sum? n o oo. ts flemafi.amfiwsw can cgcmuxuflnp "luggage $55 use: Ho 53 u .«o momwnflawuomnwno consonants. 4 84..er 7:82;: 59:3 262, .N E f 3 fl M l l _ l _ .t -t tit ,t ON . l l _ p l v\ 1 mm _tllt om m _. , l t om _ l . l l _ , _t . t t -- .1.--tlr 8. mozqm omquE “39m; Temperature (°F.) 29 4oo———-- --- - -— - - — — - - ---..--, Equiiibrium Surface Temperature (no forced air flow) 300 Radiant Heating 200 *- Air Temperature T IOO Convection Air Velocrty ——> ; icn Figure ‘, Effect of air velocity an Surface ter-iperz‘aire cf prc-ciuci. 1:: reiat to convection and radiation heatzng Fall, 1960} .38 _,....m2..8§m Em naesgmuxuanp uaonoaaafiae wanes saga: Ho hand a co mompam:wuuwnulu nonnmcomna 4 museum NN hmcocu:=v clocmm m>oz. m... 3 o._ v.0 _ _ _ . o Illl. II ..I|II. I? I . Yn iUSDde om il-oo_ moz TemperatUre PF) 400 r—‘—'—- i * 300 200 ..___ —« ——---— IOOt“ Equilibrium Surface Temperature (no forced air flow) Radiant Heating 4. Air Temperature Convection Heating Figure S Air Velocity -—-> Effect of air velocity on surface temperature cf prcduct in relaticn to convection and radiation heating (Hall, 1960) 30 40— ——-—— -r — -——— ()4 O MT ,.Healer i \ /Producl 942’ (Shelled Corn) 20 Moisture Content (Percent dry basis) PrOdUCTTTTTTTTT‘~.“‘-~..__ E Lib/(Shelled Corn) Time (min) Figure 6 Effect of air flow direction on the rate of infrared radiation drying of a single stationary layer of shelled corn (Headley and Hall, 1963). 31 energy intensities have also been permitted, which reduced drying time along with increased drying capacities. :‘Infrared vibration drying involves both heat and mass transfer. When an electron is deflected from an atom it suffers a decrease in energy. The quantum of energy lost is emitted as radiation, and is called a photon. In the infrared range the photon energy is low, thus the primary effect on a biological product is heating. Infrared radiant energy is transferred directly from the source to the prod— uct and is essentially independent of the medium (air) through which it passes. The heating effect is a superfi~ cial phenomenon with a high concentration of energy on the surface of the product. Drying of biological products in relation to the in- ternal variables involves primarily thermal and moisture dif- fusion. These values are not known for most biological prod- ucts. With infrared drying the rate of vapor diffusion from the surface may effect the drying rate, but at increased forced air velocities over the product convection controls and vapor diffusion effects are negligible. With infrared vibration drying of biological prod- ucts, transient conditions exist throughout the products in relation to temperature, moisture diffusion, and other phys- ical characteristics both internal and external. In this study the drying constant, k, of the exponential drying equa- tion was related to the external variables involved in infra- red vibration drying. “EXPERIMENTALTAPPARFTUS'AND CALIBRATION PROCEDURES Vibration Apparatus Since the absorption of infrared radiant energy by a product is primarily a surface phenomenon, increased product depths in infrared dryingrequired some sort of grain movement Sufficient to produce thorough mixing or cycling product surface exposure. (Grain vibration was pro- duced by remodeling a small orbital sander with circular type motions. The vibrator was altered to hold the mounts for a circular six inch diameter drying tray, and was mounted to a reinforced steel framework. Construction of the vibrator was such that the drying tray could be clamped into place and vibrated while being exposed to an overhead radiating infrared field. The drying tray was circular, metal, six inches in diameter, four and one—half inches in height, and constructed with a wire mesh base containing eight openings per inch. This allowed the fine particles to be excluded and collected below during vibration (Fig— ure 7). Frequency Calibration The frequency of vibration was varied by placing a 32 33 Figure 7. Overall infrared vibration drying apparatus. A. Hemispherical installation of seven 375 watt infrared heat lamps; B. Grain vibrator with variable amplitude attachments; C. Detachable circular grain tray with wire mesh base; D. Apparatus for vibration frequency variation and input voltage-current measurement; E. Forced air flow apparatus with flexible tube attached to vibrating grain tray for drawing air through grain layer concurrent to the direction of infrared energy transfer; F. Apparatus for forced air flow variation and input voltage—current measure- ment; G. Variacs used to alter wavelength of infrared radi- ation at peak intensity by limiting input voltage to infra- red lamps. 34 calibrated Variac in series with the series wound vibrator motor, thus limiting the voltage applied to the motor. An ammeter was also placed in a circuit to measure the current. Calibration frequencies were determined by using a strobo— scope aimed at a spot on the vibrating drying tray. The frequency of vibration was determined in relation to various power inputs to vibrate grain depths as shown in Figure 8. Amplitude Calibration The amplitude of vibration was varied by construct— ing a cam which could be attached directly over the existing drive cam, but carrying a different eccentricity. Amplitude variations, determined with a dial indicator, were estab- lished as 1/16 inch, 3/32 inch, and 1/8 inch. Drying Chamber The infrared drying chamber was a cubical box with dimensions two feet on a side. The chamber was lined with heavy weight aluminum foil to reflect infrared rays. On the top of the drying chamber was mounted the hemispherical metal frame to which were mounted seven 375 watt infrared lamps directed downward at a distance of one foot from the center of the drying tray. Power Consumed (watts) 35 + 4 inch grain layer /{ I 75———i + 3 " " " r ' / D/ T I _O_ 2 II II II I I + l II II n I 70 i """°"‘ 0 " " " I ' // / I A: 3/32 inch ’/ I . i j / 65 7 ( ‘1 I '/ ' . - I I / r i i ! ," so 3 i ' E / i . I / I I I I I i__i_____-___ . I 900 I000 H00 I200 Frequency (cycles/mini 35 1 I 400 500 600 700 800 I300 I400 |500 I600 I700 Figure 8 Plot of power consumed versus frequency of vibration at Optimum amplitude for various depths of gran layers. 36 Forced AirFlow System and Calibration The forced air flow apparatus consisted of.a blower mounted outside the drying chamber to which was attached several feet of five inch aluminum pipe. A flexible, fab— ricated, sealed connection was attached from the end of the five inch air duct to the bottom of the vibrating grain tray. Air was drawn through a stationary two inch grain layer and the air velocities measured in the five inch tube by use of' a hot wire anemometer. An average velocity for each forced air flow setting was determined by averaging measurements taken both vertically and horizontally across the cross sec— tion of the five inch circular duct. To correct the air velocity to that of the velocity through the vibrating grain layer, it was necessary first to correct the measured aver— age air velocity in the five inch diameter duct to that pass— ing through the six inch diameter empty drying tray. The next step was to determine the percentage voids in a two inch grain layer when vibrating at various frequencies. This was accomplished by attaching a graduated probe in the center of the drying tray. A two inch layer of Shelled corn was vibrated at various frequencies, and the increase in height of the grain layer determined with the stroboscope. Using these grain heights the percentage of voidage of the vibrating or mechanically-fluidized bed was determined as shown in Figure 9. With the percentage voids as the basis com: 009 soswhnfr mo .monmrugm areas... (8th cram? 003 65552:: 35:8: oom oow 009 00: _III L .i _ .1 _ _ d _ _+__ oom_ ocs 00: 009 —____ _ __.-. r ..__..._ —— .1 com I __ ___.. . 4 1 . . H W . + _ . . m . . * . H . o o 0 me we we we on mm .3 .mm .3 cm iaiaj uiaig buiraiin ui spioA tUSDJBd 38 for calculation of the mean cross sectional area of the grain bed, the air velocities through the drying tray were corrected to those through the vibrating grain layer. Grain Movement Calibration At increased depths of the grain layer, a grain move- ment sufficient to produce thorough mixing was required for satisfactory application of infrared radiant energy for dry- ing. Determination as to whether or not the vibration ap- paratus constructed produced thorough mixing or cycling of the corn kernels was made first by placing five dyed kernels on the bottom of a two inch layer of shelled corn. Vibra- tion at a frequency of 1,000 cycles per minute and ampli— tude of 3/32 inch was used. The average rate of cycling ranged from five to six cycles per minute per kernal. Thus it could be concluded that on the average each kernel was cycling at this rate from the bottom of a two inch grain layer to the surface, where it was exposed to infrared radi- ation for a short period of time before cycling again. Further confirmation to determine whether or not the frequency and circular type vibratory motion traced by the eccentricity of the cam (amplitude) were sufficient to pro— duce thorough mixing of the grain layer was made by a tem— perature distribution study. To do this a two point thermo— couple probe was constructed and attached to the base of the 39 drying tray which was filled with a two inch layer of high moisture Shelled corn. The leads from the thermocouples were connected to an automatic recording potentiometer. The temperature distribution was recorded for forty-five minutes during the drying period for both stationary and vibrating two inch grain layers being vibrated at 1,000 cycles per minute, amplitude of 3/32 inch, while receiving infrared radiant energy at the rate of 3,250 Btu/hr.ft2. The results of these tests are shown in Figure 10. From these graphical results it was confirmed that the vibrated or mechanically- fluidized grain layer was being thoroughly mixed Since the temperature distribution in the vibrating grain layer was essentially the same at the center of the mass as it was just below the exposed surface, much in contrast to the tem- perature distribution in the stationary layer. Calibration for Equivalent Effect Between Vibration and Forced Air Flow in Relation to Moisture Removal Conventional drying (heated air) uses forced air flow not only to aid in the rate of heat transfer but to carry away moisture as well. Tests were run to determine the equivalent effect of vibration in the relation to mois- ture removal by comparison to forced air through a station- ary layer of high moisture grain. Stationary grain layer tests were made by placing a two inch layer of high moisture shelled corn in the drying tray, then forced air at 70°F was drawn through the grain Temperature i°FI Grain 4(3 Stationary 2 in. grain layer (initial H.C. 34.46 d.b.) A. - T. C. 1 fully exposed to infrared energy A2 - T. C. l at subsurface level As - T. C. 2 at l in. below exposed grain surface (center) Vibrating 2 in. grain layer (initial M.C. 34.4% d.b.) B, — T. C. l at subsurface level 82 - T. C. 2 at l in. below exposed grain surface (center) __.---._- Vibrating 2 in. grain layer (initial H.C. 78.7% d.b.) Cl - T. C. l at subsurface level C2 - l. L. 2 at l in. below exposed grain surface (center) "5 r =I000cyc|es/min I i “i, T Ti ti 1 ‘T i 2:0 A : TézlnCh i I I i F _ I " I 23,2508iu/mn. * //%. ' . Amati I II6 microns //// 2 . . .2 - _ > . +- :r x . 1 +. ————— ——1 T — 70 F ' z / . I , A I r . CI C2 . J 3 c inches ’.// - /A2 . . r———— ;;r—— - . +~- . i 44: (\lC forced air I /z - ,J a / a’ I 'l’ 3 |"R - —-o---;—’ ‘ -—l- — + — +——-— /# y' I ' i,’ ’0 I W LICgQ" . - —+ + —( --—(—A.( I I T ” 6 energy / 2' r , . . . . - -7 . _ _. “\“0‘ l / //e/0l __. . \ / \ um I . - - . ~ . r ------ I ----- T III 2“ 75i . ' 2 I” i so . - ‘ 25 ‘ ' l i l [ 1 O l . l ( i l l ( i ‘ 5 I0 IS 20 25 30 35 4o 45 50 55 ea 65 70 Time (min) figure 10 Temperature distribution in two incn stationarv and vibrating grain layers of snelled corn versus time. 41 layer at a previously determined velocity. The test was run for a two hour period at which time the grain sample was reweighed and the moisture removal determined. Similar two hour drying tests were run at various forced air veloc- ities through two inch grain layers and the moisture re- moval determined. In comparison two inch grain layers were vibrated for two hours at room temperature (70°F), no forced air, using an amplitude of 3/32 inch and at various frequencies. In the same manner the amounts of moisture removed at the end of the two hour vibration drying periods at various frequencies were determined. A comparison was then made to determine the equiva- lent effect of vibrating the grain layer in relation to forced air through the grain layer in terms of moisture re- moval. The results of these data are shown in Figure 11. From these results it can be concluded that vibrating the grain in relation to the moisture removed is equivalent to a forced air velocity in the range of from 25 to 36 feet per minute or an average of approximately 30 feet per minute. Infrared Radiant Energy Source and Calibration The infrared radiant energy was produced by 375 watt, electrical resistance, tungsten filament, industrial type heat lamps. These lamps were mounted to the hemiSpherical shaped metal frame with the tip of the bulb being maintained Forced Air Velocity Through Groin (fl/min) 300 ~ 42 __li - i [4“ t f r T T r r "*T‘ *V‘L— "win I I I I I I ‘ I: I I I ’ I I 280~———¥—~——r—4—— - . -1 ll.ll._-__..l ~m—+~ I r ' I . ‘ | ‘ | 250A—_A__e+_ all” - +l__lr___r_lml __i --__.,, ll- _- a - _ + f - I l i 240 t + ~——~—-—¢- -r é-———— —-——9—~—— ——+— >———-—¢ — “—4—— ———.———~— —.— ————. .r 220___- ~—— , ~ —+ are fi .e-_..l _#l l _ -- , - N O 0 (To 0 6'» o E o |20 I00 80---- 60 40 20 F—-— ——~ 4-——— O —9—— -r——#-——-i-+--——.v——-w——-————-+— —— —r——-¢- ——~— -< I I Average initial MC. 45% (d b) 1 0 . 9—— ,,..l_-‘ n-7,, . , — . - *r ITTT' —— *~ --»-~—— +.______+__,_,___.. —- + - ~ iv- A if 4 -—7 O~ i +- 4 fif— ? + - I I I T; Edit val e ntVaiac—it refrain q’uemy‘ 'ranqe 600 to I450 cycles/min. I I i I t I l l I I I I0 20 30 40 50 60 70 80 90 I00 l|0 I20 Grams Moisture Removed in Two Hours Figure 11 Forced air veloci‘h' versus moisture removal from two incl: layer of shelled corn and equivalent velocity of vibration only 43 at a distance of one foot from the vibrating grain tray. The size of the apparatus was such that a maximum of seven of these infrared bulbs could be mounted at once to the hemiSpherical frame. Calibration tests for determining the intensity at which infrared radiant energy was being received at surface of the grain layer were made by use of a thermopile (Figure 16). The Eppley thermopile was used in conjunction with a Leeds and Northrup millivolt potentiometer. The infrared lamps were given several minutes to obtain maximum operating temperatures before calibrating. By exposing the thermopile in the infrared energy field, the maximum millivolt reading was determined by the manual millivolt potentiometer in ap— proximately thirty seconds exposure time. From this maximum millivolt reading one need only to multiply by the calibrated conversion factor of 117.4 Btu/hr.ft2mv, (value furnished by the manufacturer) to obtain the rate at which radiant energy was being received at the surface of the grain in terms of Btu/hr.ft2. Values were obtained for a series of from one through seven 375 watt infrared heat lamps centered over the drying tray at a distance of one foot from it. These maximum intensity values, shown in Figure 12, obtained at an input voltage of 115 volts, and measured at the center of the drying tray, were used in all calculations. However, the average energy distribution measured over the surface of the drying tray was approximately 10 per cent less. Infrared mtensaty recewed at grain surface (Btu/hrftz) eooorfl - — ~ 5500 — — .1 a 5000r-*—" —__a»___ __d _- __._4u- 11.1 h ()1 O O 4000 3500 3000 2500 2000 1 I500 -{————— v rooo————- ——4 4 4 4 fl soo~—-—-—— ~4——~+4 ~ ~ 4 _4 ~ « 4 ' ‘ L ' J l I 0 ll 2 3 5 6 7 Figure 12 Energy received at surface of grain laver versus number of infrared lamps centered at one foot above drying tray. Number of 375 watt heat lamps 45 Calibration for Varying7Wavelength at Peak Infrared Intensity' The wavelength at peak intensity of the infrared emitter, in this case 375 watt industrial type heat lamps, was varied by varying the input voltage. The intensity of infrared radiant energy received at the surface of the grain layer was held constant, while the input voltage was varied. This increased or decreased the temperature of the tungsten filament which in the same manner shortened or lengthened the wavelength at peak intensity of the emitter. Longer wavelengths required that more heat lamps be used to main— tain the same intensity, while in the same manner for a shorter wavelength with increased input voltage the number of heat lamps could be reduced. A Variac was used in series to vary the input voltage, while the Eppley thermopile and Leeds and Northrup millivolt potentiometer were used to determine when the infrared intensity being received at the surface of the grain layer had reached the previously cal— ibrated constant intensity value. Using the input voltage reading from the calibrated Variac, the percentage of the rated voltage of the lamp was calculated. From a log—log plot of the percentage input wattage and percentage color temperature versus the percent- age of rated voltage, shown in Figure 13, the output color temperature was calculated. Using these color temperature values and applying Wein's law, 7\ To = 2,900, on the max K Percent Watts and Color Temperature E: Q Tungsten 2500K (basis) --- Nickel Chromtum I090 K (basrs) Q be 8 9 2t0 I5 20 25 30 40 50 60 70 80 90 IOO I50 200 25C Percent of Rated Voltage Figure 13 Comparative performance of various infrared sources as percent volts versus percent input, output and temperature (Fosteria Pressed Steel Corporation, Fostoria, Ohio). 47 assumption that the infrared lamps emit radiant energy approximately as a black body, the wavelengths at peak intensity for various color temperatures were calculated. Method of DeterminingfiTotal Heat ‘Transfer Coefficient * The total heat transfer coefficient, ht’ included both the convection value, h and the equivalent radiation c7 coefficient, h The total heat transfer coefficient, ht’ r' was predicted through application of an empirical fluidized bed particle-to-fluid convection equation (Leva, 1959), hC = 2.2 x 10'3 (G)1'7(Dp)0°5 and the radiation equation ,_ SNTC4 for the equivalent radiation coefficient, hr (tc'too) The equivalent particle diameter of a kernel of corn, DP’ was determined on the basis of an equivalent Sphere with the same volume. A mercury diSplacement apparatus was used and an average equivalent diameter of a kernel of corn was found to be 0.33 inches. In the same manner the air mass flow rate, G, was determined from experimentally established air velocities through the grain layer and inlet air tempera— ture conditions. The equation for equivalent radiation coefficient was calculated by applying the radiation equation, using an established emissivity, 6 for shelled corn of 0.93. The c, absolute temperatures of the grain were determined both by 48 temperature distribution data and exhaust air temperatures after thirty minutes drying time. Similarly the denomina- tor was composed of the temperature difference between the grain, tC, and surrounding air temperature, t expresSed 00’ in degrees Fahrenheit. APPLICATION OF DIMENSIONAL ANALYSIS FOR DESCRIBING INFRARED VIBRATION DRYING Selection of Variables The Buckingham Pi Theorem was applied to establish dimensionless ratios containing what was believed to be all the pertinent variables involved in infrared vibration dry— ing of cereal grain. These variables were frequency, ampli- tude, depth, wavelength, infrared intensity, air velocity, initial grain temperature, heat capacity of grain, thermal conductivity of the grain, heat transfer coefficient, and drying time. The following symbols were used to denote these variables. F - frequency of vibration, cycle/min. A — amplitude of vibration, inches. D - depth of grain layer, inches. .Anmx.‘ wavelength at peak intensity of infrared radiant energy emitter, microns. I - infrared radiant energy intensity being received by product; Btu/hr.ft , V - air velocity through grain layer, ft/min. T. - initial grain temperature, OF. C — heat capacity of grain, Btu/lb.OF. k - thermal conductivity of grain, Btu/hr.ftOF. 49 w _ 50 heat transfer coefficient at surface of grain from convection and rgradiation, where ht = (hC + hr), Btu/hr.ft2 F. drying time, min. moisture content ratio of grain, ~E— Mo These variables or secondary quantities carry the following dimensions: Variable Symbol F A D Jlmax H < W Variable Name Dimension frequency 1/6 amplitude L grain depth L wavelength L radiant intensity H/0L2 air velocity L/B initial grain temperature T grain heat capacity H/MT grain thermal conductivity H/OLT total heat transfer coefficient H/OLZT drying time 6 moisture content ratio M/MO The symbols for the dimensions of the variables denote the following primary quantities: H - heat M — Mass L - length 51 T — temperature 6 — time From this listing, it was seen that the number of variables which was believed to be sufficient to describe infrared vibration drying was twelve, and the number of dimensions contained in these variables was five. Therefore, the number of dimensionless groups involved would be m = (n—b), or the number of variables minus the number of dimensions. Thus the number of Pi ratios (7T’ratios) would equal seven, m = (12-5) — 7. Combining Infrared Vibration Drying Variables In applying the Buckingham Pi theorem for combining the infrared vibration drying parameters, five of the twelve variables were selected which together included all of the dimensions involving heat, mass, length, time and tempera— ture. These five variables were the grain depth, frequency of vibration, grain thermal heat capacity, grain thermal conductivity, and initial grain temperature. This left the amplitude of vibration, wavelength at peak intensity of the emitter, infrared intensity, air velocity, heat transfer coefficient, time, and moisture content ratio to be intro- duced one at a time into the analysis. Thus solving one may write the equation for 1T1 as follows: (D)V(F)W(Cp)x(k)V(Ti)zA = H°M°L°T°e° 52 Introducing the dimensions for each of the variables into the equation, the analysis for determining the TTi dimension- less ratio was as follows: V(%)W(%)X(3%)Y(T)ZL = H°M°L°T°e° Solution for powers pertaining to each of the variables by dimensional analysis was: (a) Heat, H x + y = 0 (b) Mass, M -x = 0 (c) Length, L v - y + l = 0 (d) Temperature, T — x - y + z = 0 (e) Time, 6 - w - y = 0 Solving the equations simultaneously the powers were found to be v = —l, w = O, x = O, y = O, z = O. This yielded the value of the first dimensionless ratio, TTl = A/D. Similarly introduction of wavelength, infrared in- tensity, forced air velocity, total heat transfer coeffi- cient, time, and moisture content ratio into the analyses one at a time as in previous analysis for 1T1, the following seven dimensionless Trratios were determined: 77', =A/D, TF2 = A max/D, 1T3 = ID/kTi, TT4 = V/FD, 7T5 = htD/k, 7T6 = F6 and TC, = w. 53 These seven dimensionless Tr ratios were combined as T77 = fifil,TT2,TT3,TT4,TTS,7T6) or M/MO = flA/D, XmaX/D, ID/kTi, V/FD, htD/k, F6). A number of similar analyses were performed with each analysis obtaining a set of dimension- less ratios slightly different from the previous. .Each of the dimensionless ratios contained part of the twelve variables related to the infrared vibration dry- ing of shelled corn. Therefore, it was necessary to estab— lish experimentally which of the variables affect the drying rate of shelled corn most. Of the twelve variables involved in infrared vibra- tion drying, essentially two of them vary continually during every drying period. These are the moisture content ratio, M/MO, and the drying time, 9. Of the remaining ten varia- bles, it was decided to study the effect of eight of these on the drying rate of high moisture shelled corn. These variables were frequency of vibration, F; amplitude of vibra- tion, A; wavelength at peak intensity of the emitter, Atmax; intensity of infrared radiant energy received by the product, I; depth of the grain layer, D; initial grain temperature, Ti; the effect of concurrent forced air velocity, V; and the total heat transfer coefficient, ht; where ht includes both the convection value, h and an equivalent radiation value, c; hr' The grain thermal conductivity, kc,and thermal heat capacity, C were assumed to be relatively constant through— p7 out the drying period (Kazarian, 1962). 54 To study the effect of each of the variables on the drying rate of shelled corn it was necessary to vary one at a time while holding the others constant. Thus experiments were performed with this objective in mind. In each case the drying constant, k, was determined on the basis that the equation, M/MO = (3‘k9, was valid for describing the entire period, since the equilibrium moisture content, Me, was essentially zero. Thus the k-values were used as crite- ria for comparing the effect of each variable on the drying rate of shelled corn. DRYING PROCEDURE High moisture shelled corn used in this study had been harvested with a picker sheller. It was then placed in plastic lined bags, sealed and stored in a GOP freezer until which time the grain was needed for drying tests. At this time a quantity of the frozen grain was removed from the COP freezer, placed in a small plastic bag or sealed jar and allowed to thaw and warm to room temperature. Drying tests were run by weighing the proper amount of shelled corn, for example enough for a two inch layer in the six inch diameter drying tray, on a Mettler balance to the nearest 0.1 gram. The sample was placed in the drying tray and vibrated in the infrared field. Sample weights were taken every fifteen minutes, with the total drying time ranging from forty—five to sixty minutes depending upon the variable under study. All samples were then placed in an oven maintained at 2120F for forty-eight hours at which time samples were removed, the dry matter weighed and moisture contents calculated as percentage dry basis. When studying the effect of one of the variables, for example frequency variation, then the amplitude was held constant at 3/32 inch, intensity constant at 3,250 Btu/hr. ftZ, ,1, constant at 1.16 microns, grain depth constant at max 55 56 two inches, initial grain temperature constant at 700F, air velocity equivalent by vibration only, while the fre- quency was varied in the range of from 600 cycles per-minute to 1,450 cycles per minute and its effect on the drying rate determined. Similarly when studying the effect of the variable intensity of infrared radiation on the drying rate, the fre— quency was held constant at 1,000 cycles per minute, and all the other variables were maintained at the same previously mentioned values except the intensity which was varied in the range of from 1,500 to 4,600 Btu/hr.ft2. The same procedure was carried out until all the variables had been studied. The drying constant, k, was calculated as a criterion for determining the effect of each variable on the drying rate. RESULTS OF INFRARED VARIABLE STUDY Calculation of k Values The drying constant was determined by the relation, k = 2.303 [log (M2) - log (M1)] , which is the slope of a 92‘91 straight line of a semilogarithmic plot of log M versus 8. The tabulation of these values are listed in Table 1. Frequency Variation Effect The effect of varying the frequency of vibration (within range) of the grain layer during drying was shown to have essentially no effect upon the drying rate of high mois- ture shelled corn. A frequency of at least 600 cycles per minute (amplitude 3/32 inch) was required to bring about a reasonable amount of mechanical fluidization of the grain layer or kernel cycling. Also a vibration frequency of 1,000 cycles per minute yielded the smoothest operation of the equipment and grain movements. This value was recom— mended as the frequency to be used throughout. Figure 14 denotes that varying the frequency of vibration has essen- tially no effect upon the drying rate of high moisture corn. 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A c 3835 no: or: - €25 c Huoo .uc\:Hmo a He \HHV Ho sumo xmera < \mmHuHuV _ x 02 an > H m ;.coscHHcoo--H uHcoH kxIO2 LN 01 Drying Constant 60 55 50 45 .45 o 05 65 Frequency of Vibration (cycles/ min.) 4 _ I f. I w_—7—_ _~______. _ ' .-*7# A” _ _fi—fi “4 4 ' 4 4 D = 2 l0. gram layer . __l i t % A 3 3‘/32 m. . T - r * , -‘ r —k+*-— ot— _ . g .‘ 4 , l I : 3,250 Btu/hrftz l a t l f . 4 I 4 ; , ; __>\max = 4.46 mlcrans ; 4 E : » * T = 70°F - ___ in _;___ i_l._._L_ r“. V ’-" 30 ft./min.4vlbratlan ; 4 only) *4 *4 ’ * * ‘ ‘ T “ l . i 1 4 4 4 4 4 4 e H 4 1 : 4 4 C i - 4 . I I I i L .L - l l 4 4 I T S f I T j T , 4 at 4 fi—f—v—t a t—,—~. H—‘vs H H — — +——- gea—H—H— H—LH— m—HH—H—fl —+¥-m+—~ -' ; ’ ‘ 4 l , , t t l, - - Hi -H H - Evil iwl H__H_i_----i-:,—_ _- i- H- .i i l , 4 4 , i ‘ 4 l l__- ‘_”___fl_____rm_l.,l__c__. ; 1 li_ . - l I ’ C4 7 4 l . l : L 4 l » . l /| i i 4 l 1 l 4 l t L L 1 __4 500 600 700 800 900 |000 H00 l200 I300 I400 4500 I600 Figure 1h Effect of frequency of vibration on drying constant for shelled corn Percent Moistureldry basis) 60 55 (I‘ O .5 (fl 5 O (N m LN O N (.71 N O 66 _ '1 —--O-— Frequency = 600 cycles/min. __fim “fig . __7 —Cl—— Frequency ‘-' I000 cycles/min. ——-A— - Frequency 3 I200 cycles/min. ......... +_ , ___ D 3 2m grain layer A Z 3/32 In. __\. I : 3,250 Btu/hrfi.2 Xmm=IWmMMs _ T? : 70°F. V ‘3' 30 ft/min Ivibrctian I“ __ __enbL __- in- -_ -1- ,,_._l- - _ - c - - *x __ ..i., i__.+ \S: t __ ,1 _c , c _c _c __ 4;\:! ___l_mc " \ I 5 IO I5 20 25 30 35 4O 45 50 55 60 Time (min) Figure 15 Mcisture ccntent of shelled corn versus time in relation to vibration frequency variation 67 that frequency variation has essentially no effect on the drying rate of shelled corn. Amplitude Variation Effect The effect of varying the amplitude of vibration on the drying rate of high moisture shelled corn yielded one value which contributed most to optimum drying results. Of the three amplitudes studied, 1/16 inch, 3/32 inch, and 1/8 inch, optimum drying resulted when the 3/32 inch value was used. All replicate drying tests indicated that the drying constant, k, declined for both 1/16 inch and 1/8 inch ampli— tudes. These results are illustrated in Figure 16. Further .verification of these results are shown in Figure 17, which illustrates the relationship of moisture content of the shelled corn versus time at the three amplitudes under study. Infrared Intensity Variation Effect Varying the infrared radiant energy intensity pro— duced a definite effect on the drying rate of high moisture shelled corn. The infrared intensities studied, ranging from 1,500 to 4,600 Btu/hr.ft2, showed increased drying rates with increased infrared intensities. The relation was not linear over the range studied but appeared sinusoidal within limits as shown in Figure 18. The plot of moiSture content of the grain versus time of infrared vibration dry- ing as shown in Figure 19 also indicated increased drying Drying Constant - k x I02 5.0 r“ on P o .0" 01 9‘ o .N 01 .N o '01 0.5 68 Amplitude of Vibration (inches) Figure 16 Effect of amplitude variation on the drying constant for shelled corn I I I I I . __.c-_-_l___ __ _ _.__.-_ “J __________u___ _I_-r ' . f ' D = 2.in.grain layer2 I __I__ _.____ . _ _I_ _I__ _I_ _ __I I = 3,250-Btu/hr.ft. I__ . I 4 E>(max = I.I6 microns I ___-_.__ ______ _____I__ _ __I _ I ----I _I T : 70°F. I___. - l ' i v 2 30 tt./min.4vibratian ; I . = only) 4 — - *—-——I+--- -4 I :- - t _ "I" " I‘ ' ' I“' ‘ 'I‘ "—I _ _.__T_ ._ __I, .__ . .1”.-. __ -_.I__ __I _ _ _I_ _ _ _ _ — —— H I l ”Ix I I—-—— 4 —+—— —— ——--- -- -- / I- - \ - +I-- -+— - .L.. - — —— + —H I I // ' j \ I , I ' I I . . \‘ 4 I ' __ _ -l _ 4 .-_.-- I ' .- K I--. I I——-——L————— I I ' | ' I I 4 I --——-—- — I— I I» i + l 4 —I - —------- ~— I . I i I I . 4 I : r I v ) i ll 4 II i i 432 l/Iis 362 4/8 5’32 3/l6 MU I 4 I 4 63.3 955.02 285a M, n O n. I I h z . .nIU .l *l .Oul. M u - m, ..n. m .I 0 h .hlu . I/ 3/ y .m m 0 n. M I m 8 .PM W ,. _ g 0 m F. V I ,- +. _ e n... 5 6 o (I n , d i 2.. l O O . IN 2 3 4. 7 3 . . , InIV H .I. .. _ 4 l . -444 4444.1 m .. ._....~_ “We . I A o I m I v . _ , h _ m H _ A -I-.-4--.I IIIm _ _ . _ . _ . A3 flu WI; I..I4 “I I .. _I. 4.4T.I!II4,I.4 4+I 44. w e u _ . g . M A _ _ 4: 4 I. . I Iw _ , w . 44Iw IIII .- _I I ,. .. I, 4.15 e e I, ,. I 2 _ _ _ W __ _ II II LII g ._ I4.- I 4 IO _ W _ n g j . V 4.T4II 0:44 4 T4 4 4I+il 4 4 4444 4 4+fi444 4 441 w H B . V , , 44 w .417 ‘T I n 4444474II444+1444L m U fi __, M _ . A 44 . 4.4% 4,-4L4 s 4 . _ w _ E Time (min) Figure 1? Moisture content of sheljer' com versus time in relation +o amplitude variation Drying Constant k xlO2 5.0 f—‘gfl ‘7 V fi fi ’ ff *7 T' WG—1" r j 4 4.5L——~ + i 4* i— o ”_f WW W . __I 40»——~+~7 flV - 5 , i o thI 4 3.5——+—— —~ ~ + 4 zap— * W H 5 ~ ~ 2.5~ « — u 2.0~— «——~+~ * 45 *— —-#4 k ——~ + A 7‘ e —. —————~— __,__ -L ———_‘L -_- ._.__ ,, a D I 2 In, graIn layer I, 40"“ A ‘ i ‘; ._4 A 2 3/32 In, 4 >\ max = l.l6 microns § 05W.-- 0 , W_ WW; T1 = 70°F. I . v 2 30 II/mm IIIbIoIIon ‘ + L i _ A only) A O 500 I000 I500 2000 2500 3000 3500 4000 4500 5000 Infrared Intensity (Btu/Nit?) Figure 18 Effect of infrared intensity variation on the drying constant for shelled corn Percent Mousture (d.b.) 60 .5 O ()4 U1 CH O N U‘ N O .~ A ‘4 _—*—~é *—_ tote—n—sI-ty 72.230 BIu/III trim i-__s _--+_’- H 3 3,250 n n 4 G I. = 3,760 n '- 9 ___ 44 ——O——- .. ' 4,600 N n W A .W-_W “__ ____ D = 2 In grain layEr A : 3/324nCh W W I - 4_ >\ max = 4.46 microns TI 3 70°F. - - fi_#_ V ’1 30tt.[mIn.4_\IjbratI0n anty) +—-—~———- T Ti 4 4 Time (min) Figure 19 Moisture content of shelled corn :ersus time in reisiion to infrared intensity variation 72 rates with increased infrared radiant energy intensities. Wavelength Variation Effect Wavelength variation at the peak intensity of the infrared emitter, using the assumption that the infrared lamps were emitting as black bodies, produced a definite effect on the drying rate of high moisture shelled corn. Increasing the wavelength at peak intensity also increased the drying rate of shelled corn. Wavelengths at peak inten— sities of 1.08[(, 1.16L(, 1.32LL and 2.50;! were studied. Essentially a linear relationship resulted as shown in Fig— ure 20. Similarly Figure 21 illustrates a more rapid reduc— tion in moisture of high moisture shelled corn when infrared vibration drying is conducted with an infrared source emit: ting a longer wavelength at peak intensity. Initial Grain Temperature Effect Varying the initial temperature of the grain prior to drying with infrared radiant energy showed only a slight but positive effect on the drying rate. An increase in the value of the drying constant of a little over 12 per cent was observed when the initial grain temperature was varied from 320F to lZOOFc The results of these data are shown in Figure 22. In the same manner Figure 23 illustrates the change in moisture content as a function of time in relation to the initial temperature of the grain. Drying Constant -k x 402 5.0 ._ _. .45 on .5 0 pa (JT .04 O N 01 N 0 Ln 0 ()5 4 ? 4 D 3 2m. grain layer 4 ‘ j A : 3/32 In. 4 I" _ , I : 3,250 Btu/hrft? I ,, f I f .' T: : 70°F. . _ - J _. V 3 30 ft./mm.4vibrotion only) WW WW - .W ....... - __W-I___ a 4 I” . ‘ II I I ’4" I“ T I 4 : ' 4 . I 4 I 05 4.0 I5 20 25 Wave Length (microns) Figure 2‘0 Effect of wavelength at peak intensity variation on the drying constant for shelled corn 74 60f— ' fi—e—— _II'oIé—L‘éanIIIII ISIJII Intensi—iy :‘I‘0'8—m'IE70IIJ % ——A—— u u u n n H6 n a .. .. .. .. I32 .. I 50 __'__ .. ,. ,, .. ,, 2 _ ., * (gas intared) 45 = 2 at grain oner ‘ : Efizin. ‘ 4O 3 3,250 Btu /hr. ft.2 A, 3 70°F D . 3' 35 _ __i-‘i 30tt/mtnlwbroteaeruil_ Q) . I E a 50 + + _ - _WW 2 ‘E 825 +****" WW-W ES 4 4 Q 204——— + 7—-~——~v— . - ————— —«au — - e 45I—— —— + - a —a W — — ~7——« [O +————4-A v —.~ W7 — ~ —. fi - —— 4 _W_ -__. 5 >-——— _._i __.-_,.-,,_.,__ .7 . fl--- ._. ___.- ,_ El. _, »W_.. _ --“a i — -_.. h—r._a O W W4 l i 5 IO 45 20 25 3O 35 4O 45 50 55 60 TIme 4min.) wavelength of infrared energy at peak intensity .igure 21 Moisture content of shelled corn versus time in relation to 75 5'0 “_T __— _fi ' ‘Tu‘wf—"m '4’ _____.-._- . 4 T i i 4 . 4 D = 2m. groin layer i 4.5 . +-———-—- L- - . 4 ' A : 3 32 444' l ' . . l l I 3,250 Btu/hr. 41.2 4.0———~— -fi---—--—+——+n .__;____i__---.W >\max 2 4.46 microns : 4 I V ’-‘-’ 30fl./min.4vibraiion 4 35 ‘ . only) “£2 ' i 4 T:— T 4 x 30 ———-+ —«--—— —— _--_,_.-W__ _s. z— ——4 f -_-r__i-- —~———L~-— —4——-——-———JI 4 ‘ ' 4 4 ' ' ' E i I «9 i _ I- I- . --—'+—--—— I .1 E I W 5 “iv—d 4 g . - _I _ - L- ; _ .__—_I_--— .;K . 5 : 4 45—— -..t a- _I a ~_a - .L__- i ' E, 4 _ _c 4 IO— - a + ~ ~~ ~— ~+ - M4“ "44— — +— __W —+ — ~ . 4 , 05—— . - ._ - - _.-_ - I wimp—_I_ - I -- - _I_—-__I . ' . I ’ ' ; 4 4 i i 4 4 . 4 4 4 I_/1/ l l 4 l i4 l l 4 4 3 W 4 W4 30 4O 5O 60 7D 80 90 400 440 420 430 440 4 0 lnItial Grain Temoerature 40F.) Figure 2? Effect of initial grain temperature on the drying constant for shelled corn Percent moisture (d.b.) 60 T I — ' 4 u lniiiol groin temperature 32°F. H II II 3 50°F iI IOO°ond 420°F D = 2m qroin layer A = 3/32 inch I : 3,25081u/hr.f1. >\ mox : 4.46 microns V ’-‘—’ 30fi./mln.(vibroii0n only)i I0— I IIIII WW — I I W I I I— I ,W_ WW I f ‘ 5~~ T e—I— +~ I 4 i 4 4 4 I 4 L l i W‘ i ' W W' i O 5 40 IS 20 25 3O 35 4O 45 50 55 60 65 Time (min) Figure 23 Moisture content 31‘ shelled cor-n versus time in relation to the initial grain temperature 77 Forced Air Flow Effect Vibration of the grain layer (no forced air) was shown to have an equivalent forced air flow effect in rela- tion to drying of approximately thirty to thirty-one feet per minute. Using forced air flows concurrent to the direc— tion of infrared energy transfer throughout the entire dry- ing period reduced the drying rate of high moisture shelled corn, which indicated a cooling effect on the surface of the grain. Figure 24 illustrates the effect of forced air veloc- ities (values include equivalent vibration effect). Forced air flow decreased the drying rate and in a linear fashion. Using the vibration equivalent (30 ft/min) a larger drying rate was obtained. Further verification was seen in Figure 30 illustrating moisture content as a function of time for the various forced air velocities through the grain. The most efficient use of forced air flow used in conjunction with infrared vibration drying was obtained when intermit- tent air flows were used. A forced air flow of approximate- ly 115 feet per minute for the first fifteen minutes only 0f the infrared vibration drying period and then continuing with the vibration frequency of 1,000 cycles per minute (velocity equivalent 30 ft/min) for the remainder of the drying period produced superior drying results over the use of forced air flow during the entire drying period as shown in Figure 25. Drying Conslont -k x402 50 .5 m 9 o w C11 .04 O N U1 .N 0 Ln 05 if 4 m- ’7 l "l”; 4‘ '4 _ T. 4"— '. -*~—— W 4 4 4 : D 3 2m. grom loyer _» _ ~44le _ 4 -_4 _ *4 A 3 3/352 in. 4 l 4 4 4 l ' 3,250 Btu/hrfl.2 __Wl . lIII .I __l >\mox = 4.46 microns ' TI 3 70°F. l——- I A—fifi I - —4——fi— Hie-4 — ”IF—I ,_W ‘T — 4 — ————r————~—d I l- I—IIIII I— I II—I- I I ‘I 4e I . 4 l i 4 4 l 4 r: 4* -*———+——w-u+!—* t"*““f -** + 7——-+ ————— WWw_. l : 4 4 4 q 4 Vibrolion only ' l 4 l l . . 4 ——~.— 4 : i 4 4 : l ' 4 ' l l l l l i i - 50 400 450 200 250 300 350 400 450 500 550 Air Velocity (fl/sec.) Figure 214 Effect of forced air velocity (vilraticn effect plus forced air) on the drying constant for shelled corn Percent moisture (d.b.l 6O 55 50 45' 4O 35 30 25 20 .I. .4) —---6— *Forced air velocity - 3O tt./min.lvibrotion only) __W ——8— .. .. .. = 445 tt/min. -——5'-" .. .. .. =2|O ft./min. l .I 44 —-B-—- .. .. II = 285 8 355 ft/min. ____ 4 4 ----- 0"" Forced oir velocity = 4‘45 ft/min. for first 45 min, 1 vrbrotron only for remoinder I 4 *All forced air velocities include equivalent effect ‘ % w—w—Trw, ot opproximotely 30 tt/min due to vibrotion only F__ -__..I___e_ii. ,__II_—I—_ III. D = E Hinrcin layer 4\ “s i f l l A 1 /32 Inch 2 4 \ I I 1 4 3 3,250 Btu/hrft. __— .-__ I -__—f. Wi,__+____,fl TD 4 T1 3 70°F 4 , \\ ‘ 4 l I I )\mox ’-"- 4.46 microns ”F” \ “—"T f ‘ ‘ I 4 I \ 4 4 4 l \l ‘ 4 4 4 4 | 4 4 17— —- 4 \ 4 l 4 4' 4— I 4 \ ~ 4 I 4 \ \ M - 4 \ \ - . '45— l __+ W ,WW “W44_ \\ \ _4_ A l I \ ‘ -— f 4 l \ 4 — v e—fie- ~ ~* ~——— 4* ~+ ———+- \ ——v t 4 4 \ I‘ I 1 4 4 : \fi 4 4 l 4 4 * I I 1 4 E I 4 ”WWW ~~r-~— ar- >~ — — “—r + I ' l I ’ l l I r l l l l l l l 5 40 45 20 25 3O 35 4O 45 50 55 60 Time (min) Figure 25 Moisture content of shelled corn in relation to rate of forced air flow througt grain layer 80 Grain Depth Variation Effect Vibration of the grain layer, sufficient to produce thorough mixing, permitted satisfactory drying of high mois- ture grain at increased depths. Increasing the depth of the grain layer resulted in a decrease in the drying rate (hold- ing intensity constant) as shown in Figure 26. Considering the drying rate within the range of depths from one to four inches, the drying constant, k, appeared to follow a sinu— soidal relationship. In the same manner Figure 27 showed a decrease in the drying rate as the depth of the grain layer was increased. Effect of Total Heat Transfer Coefficient Variation The total heat transfer coefficient, ht, established from the sum of the convection and equivalent radiation 3 1.7 4 . . _ — 0.5 Ec‘iTc coeff1c1ent values, h - 2.2x10 (G) (D ) + , t p (tc - tag) increased sharply with increasing forced air velocities as shown in Figure 28. It was also seen that the equivalent radiation coefficient, h contributed relatively little to r' the value of the total heat transfer coefficient. Vibration equivalent (30 ft/min) at a frequency of 1,000 cycles per minute yielded a total heat transfer coefficient, ht = 8 Btu/hr.ft2P. Thus increased air velocities produced in- creased total heat transfer coefficients and reduced drying rates in infrared vibration drying. . -.. .~.. \..~ . up Drying Constont -k x IO2 31 5.0r r -__ _ A 3 3/32ll'l. . - 2 4.5 —-—-— —~ -- . . . +4 _ A I - 3,250 Btu/hrft, Xmox = |.|6 microns _ _ 0 404—-— + __._ __ _. __,__ +___ T " 7O F. v =2 30 ft./mrn.lvibrotion only) 3.5— -+ ~ -- _l__.______ _ _ 30’— e + 4— _ 25.- - _._ _ 2.0r-- . __ _ l5 - _ _ lO---—-+- --+ -~ + ___- _ __ . i .__ 05* - - . _ O 2 3 4 5 6 Groin Depth (inches) 11 the aiming constant. for Shelled :‘c-“n 4 3" 31' 3'1. '3 'v 1 \. a". ’T () Figure :6 Lf’cct of g. Percent moisture (d.b.) —B— l Inch groin loyer l_fl._ ,, , _ _,_ ——.‘—' 2 II II II 4 44 __A—' 3 II I. II 4 '" r 7 4 7-" W —e-— 4 II II n 4 I 4 4 A : 3/32 4n- 4 55 4 fir—qu—J— I I 4 : I = 3,250 ent/mu? 50— ,lili; 4 _-4 7 >\ mox = l|6 microns 4 4 T: = 70°F. V '3 30ft/minlvibrofron onlyl l l 4 45 I 4 e I 4 _ ..U _ l». _l._. b O ()4 (11 4 4 ,4 _e _ . ._ .__ng__i,i 7i y- / /1 g 44 f —4.. __‘l .— ll. 4- / [J W W I5 4 ‘I _ I 44 l 4 4 1 I0 I ff I I - e - I 4 I 4 4 4 I 4 5 . I I 4 4 a - 0 4 4. I 4 4 4 4 i A l 5 l0 IS 20 25 3O 35 4O 45 50 55 60 65 Time (mm) Figure 27 Moisture content. of shelled corn versus tine in relation to variation in grain depth 8.4 N A O N N O 200 - 2.2 x Io'3IoI"’Io.,I°'5 § 4 _ Ec‘r R “c ' '00) hc" hr (1) O O5 O A O /' 1’ Totol heot tronsfer coefficient, h, and convection heat transfer coefficient, hc Btu/hr. ft.'°F. O 40 80 I20 ISO 200 240 280 320 360 400 440 480 520 Air Velocity (ft/min.) Figure 28 A plot of total heat transfer coefficient and convection heat transfer coefficient versus air velocity through grain layer. 84 Efficiency of Infrared Energy Utilization The efficiency of infrared radiant energy utiliza- tion was improved by vibrating the grain layer as well as using forced air flows for both the prOper time interval and concurrent to the direction of infrared radiant energy transfer. A forced air flow of 115 feet per minute for only the first fifteen minutes of infrared vibration drying peri- od improved the efficiency of utilization of infrared energy being received at the rate of 3,250 Btu/hr.ft2 at the sur- face of a two inch vibrating grain layer from 76 per cent when vibration only was used (vibration equivalent to an air velocity of thirty to thirty-one feet per minute) to 83.5 per cent. The overall efficiency, including electrical energy to vibrate and for forced air flow was 60.4 per cent as compared to an overall efficiency of 59 per cent when vibration only was used. The results of these calculations are listed in Table 2. Figure 25, a plot of moisture content versus time, illustrates further the effect on efficiency of infrared energy utilization. The efficiencies of infrared vibration drying of high moisture shelled corn were compared when vibration only was used, forced air velocity of 145 ft/min (value includes vibration effect) for the first fifteen minutes only of the infrared vibration drying period, and for various forced air velocities used throughout the entire infrared vibration drying period. A.:ea we amnem one How :e2\nw man mo w.bo 5.00 m.Ho oo w.oain.ov 3oam awn Umouom mafia :oaumunfi>v v 4A.:fie ma vmufim on» How :fiE\pm mad mo do no cm 00 H.¢Hio.om 30am new Uoouom mafia coaumune>v m A.:ME ma pmuflw How :n2\nm mHH mo «.00 m.¢o m.mw we w.maio.nw 30am new Umouom mafia soapmunfi>v m Ii om on on o.maim.ow Axaco :oevmunfi>v m Ago Asv Agv 30am oumunfi> Uo>fioomu mfimmn sup new noouom now confisv Ow >muonm >muoco “no: “coo “on ion >wuoco mafia no mafia Uo>fimoou no woman Apcouqoo I>mH :fimuw opmunfl> ow >mumco ooh coaumufiaflps. Acflev chaumfloev Amonocfiv Ho>ma bonfisvou >muoco mafia imnwcfi no comma toumuwcfl mo use“ umcmu cfimum mo spawn Uo>flooou >wuoco non coewmufiaflp: >ocofloMMHm wafl>uo wce>um rmnwcfl no women COMP >muoco ooumumcw imNMpr: >muocm ooh mo >oaofloewmm Imumcfl mo >ocoeofimwm mum.un\sum onm.m mo one“ on» pm >muoco panacea Umumumufi mafi>fioomu :uou Umaaonm m wcfl>uo cofiumune> GM :oflpmmflawus >wuoco pcmfipmu mo mofloqmflUMMMo mo acmflnmaeoo .m manna COMBINING INFRARED VARIABLES AS THE RESULT OF VARIATION STUDY By experimentation the determination of the signif— icance of the variables involved in infrared vibration dry- ing was established by varying one at a time while holding the others constant. The trend as to whether or not an in- crease in a Specific variable had an increasing, decreasing, or negligible effect on the drying rate could thus be seen. From these results it was desired to manipulate several of the seven TT ratios so as to have three of the ratios containing the major variables under study and in dimensionless form. To accomplish this a combination of the original series of the seven dimensionless ratios was made. The first manipulation was for a new 7T8 dimensionless ratio, where 7T8 = 1Ti/1T; = (A/D)(FD/V) = FA/V. Similarly 7T9 = I Amax N2 7T3/ TT5 = (AmaX/DMID/k rink/11,13) = htD T Thus it was stated that of the seven original 1Thratios there were now three 7T ratios which contained nine of the twelve infra- red vibration variables. These dimensionless ratios were TF- ‘M/M TT-FA/v dTT-—I—A—m3-’-‘— d 7 — W — o, 8 - an 9 - ht DTi an were con- sidered to contain the most important. Thus it could be 86 stated that essentially 'W} = ,][2'né,‘"§), and that this function was sufficient to describe infrared vibration dry- ing. Infrared vibration drying tests made under various conditions and with no forced air flow indicated nearly linear drying rates could be obtained when drying high mois- ture shelled corn (initially in the range of 35 to 50 per cent moisture dry basis) to a moisture content of approx- imately 15 per cent. Drying beyond this point linearity ceased. Thus the overall drying curve was assumed to take form of the exponential drying equation. From indications of data collected and with a little manipulation it was shown that the value of 7T8 was essen— tially unity, when no forced air was used through the vibrat- ing grain layer. Since the amplitude of vibration was the maximum vertical distance traveled by the vibrating cam away from its zero reference point, then in the same manner the total vertical distance traveled in one cycle could be writ— ten as 4 A = C . d . . . . , FCd Rewriting the dimenSionless ratio as 778 = .__ V can now be shown that the value of this dimensionless ratio ,it was unity when no forced air was used. Optimum amplitude in relation to drying was found to be 3/32 inch, thus the optimum cycle distance was 3/8 inch or 3.125 x 10.2 feet. From previous data, as shown in Figure 11, the equivalent air velocity in relation to vibration of the grain layer 88 ranged between twenty—five to thirty—six feet per minute. The higher equivalent velocity occurred at the higher fre- quency and similarly the lower equivalent velocity at the lower vibration frequency, though in either case the dif- ference in equivalent velocities was quite small. For the frequency of vibration range of 600 to 1,450 cycles per minute and the range of equivalent vibra— tion velocity of twenty—five to thirty—six feet per minute, the value of 7T8 = EVEQ was essentially equal to unity. Illustrating, the average frequency within range was 1,000 cycles per minute and the average equivalent velocity was . . Tr F C thirty-one feet per minute, therefore 8 =-—V—Q = -2 , Min. 4 eyeles | Bl‘ft sults and taking into consideration forced air velocities as well, it could be stated that the value of the dimension— less ratio” 7T8 = E_%Q_ , would essentially always have a value less than or equal to one. Taking into consideration the entire period of infra- red vibration drying it has been shown that non—linearity exists, particularly when forced air velocities were used. To describe all variable situations it was assumed that infrared vibration drying took the form of the usual expo— M-Me _ —ke Mo‘Me 63 “ moisture content for a vibrating grain layer exposed to an nential drying equation, The equilibrium infrared source was essentially zero, thus the drying equa— . _ ~k9 tion became M/MO -— e 89 The previously established dimensionless parameters for infrared vibration drying were PC I M/M = 4 < d)<: >\max) 0 V htD T. 1R Thus, it was assumed that since the moisture content ratio, M/M was equal to some function of the other two dimension- 0’ less ratios, then it was proposed to show that the drying constant, k, for infrared vibration drying was also a func- tion of TT8 and 7T9. This was written in the form of k (Fig) (L__ >\max ht D TiR Therefore, the task was to establish an equation describing infrared vibration drying over the entire drying period for all variable situations and to place it into the form ejl— —$—>l . It was pr0posed to make the prediction equation for the drying constant dimensionless by introducing the drying constant ratio. This relation was introduced as k' = k/ko fKFCd)(ht§\$-:):4 , where k0 was the drying constant for high moisture shelled 90 corn for vibration drying without applying infrared energy. The RC value was determined as being approximately 2 x 10"3 min—1, and it was used throughout all calculations in the moisture content range studied. This yielded a dimension— less relationship with the drying constant ratio as a func— tion of the infrared vibration drying dimensionless ratios, from which the prediction drying constant for shelled corn could be determined. RESULTS OF DATA ANALYSIS FOR ESTIMATING DRYING CONSTANT AS A FUNCTION OF DIMENSIONLESS RATIOS BY USE OF REGRESSION EQUATION To establish the relationship between the drying constant, k, for high moisture shelled corn and the dimen- PC sionless ratios, <— Vd><'hDT I;\i ax , the methods of linear tD regression and correlation were used. To the experimentally determined values of drying constant ratio, k', versus the values of the dimensionless ratios determined by the infra- red variables under study, the linear regression analysis was applied. The regression analysis yielded an equation for a straight line, which gave an estimated value of the drying constant ratio, E}, from the known values of the dimension— less ratios containing the infrared vibration drying vari— ables. The linear regression equation was given by the relationship?= “k" + bk" (778172)) [(7787T9) - (W8 779)]. The slope of the regression equation or regression coeffi- cient was calculated by the equation, 1, _ NZCW8Tr9)(k‘)-(E(778779))(Elf') "(”8 9) ”ECW877932 -(E(7181T9))2 91 92 EfiJnilarly the correlation coefficient was determined by the relationship, NZ<7T8779>(1<')- (Ecflg "9)(Ek') 79>,k7‘[NE(1Tgfl9)5- >§1 [NEk'§-§ ~ where: k' = estimated or predicted value of the drying constant ratio, ka/kO k' = mean value of eXperimental drying constant ratios. . (1T'UT)= slope of regression equation or regression ’ 9 coeff1c1ent. (778179) = value of product of dimensionless ratios. (78 W9) mean value of products of dimensionless ratios from experimental data. N = number of observations. 7r) k} = coefficient of linear correlation. The calculations for the linear regression equation ~ for estimating the drying constant ratio, k', from the known values of the dimensionless ratios, . , %) (I ;\ max ht D TiR yielded a value for bk' (718 -n'), the lepe of regre551on equation, of 2. 22 x 105. The linear correlation coefficient illustrating the precision of the estimated drying constant ratio, k', from a known value of dimensionless ratios, PC ( Vd> (__21225 , calculated to be 0.66. From these results htD T 1R 93 the prediction linear regression equation for the prediction drying constant, ka, from a known value of the dimensionless FC ratios, <——- vId)( Am:____:> , produced the dimensionless pre- ht D T diction equation ,. k PC k'=-—a-=2.22x105(v)1d( A—fl—a") +6.42. k0 htD TiR The graphical results of this analysis are shown in Figure 29. The 95 per cent confidence interval was determined for the linear regression dimensionless prediction equation. The statistical relationship applied was of the form k'+t s 1+-1-+ (”871 9- 8W9)2< 1/20C (k' 7T8 W9) N (N-1) S2 («8 W9) (78m; "778N912 t1—1/20C Swans-119) 1+N (N-l) S2 cflgfig) 33E sagas 05 no 03.? 2308. a IPG 2338 was on» 3.35: .8» Conn-6w gamma?" on. g 5395: cognac.“ how no.3?" 33.53553 gang Boo “SQ—Hana .8.“ 03E. #6338 92.3 no peg mw 0.33.». ._E 5 > no: ASE/CV ”av m.m on in Nm 0.». m.~ QN ¢.~ N.~ o.~ m._ 3 v._ N. o._ 90 md to No ‘ \‘ \ \ \\ .\ L \ ... RI . 7 4 .... . \/\ 0. ..u \ o \T \ .I\ ..w +\mm.a a. L v mmé JW x m 0 :5; > mace + xcEKH fl hog-Nu.“ m .x - 6118's guossuo'f)‘ bqu 8 95 From this relationship the 95 per cent confidence interval for the drying constant ratio pertaining to the linear re- gression line was calculated and was found to be 12'! —4.35u om o m E oxo _ 3 .2355 a He > H x« d < \mmH V x o p m 2 a mandamGOU wcfi>uo How mGOMamsuo :ofluoflcmud mo >ufioflam> nmwdnmwmm Op >HmaooameSEwm muopoEaHmQ mad u>uo coapmuofi> ooumumcfi mca>um> >9 cocwsuouoo Guoo oofiaonm How mpqmumcoo wcfi>ua .m oHomH 98 m.me we m ow ooH oou.m mm.H mm\m ooo.H Owao.H m- o.oe as m ow OOH . ooa.m mm.H mm\m ooo.H m,OHme.H a.m¢ mm m ow oo ooe.m mm.H mm\m ooo.H m-Owae.H H.me mm m ow oo oou.m mm.H mm\m ooo.H m-Owa¢.H w.mq w m ow - om --ommum - wo.H mm\m coo.H m-Oonm.m m.eq w m 05 cm ome.m wo.H mm\m ooo.H m-Oerm.m o.me mm m ow oo ome.m wo.H mm\m ooo.H mloneo.H m.av co m oo omH omv.m mo.H mm\m ooo.H m-Omew.H o.Hq w m 05 om ooa.m mm.H mm\m ooo.H m-Omeo.m a.mq w m oq om ooa.m . mm.H mm\m ooo.H m-Omeo.m h.Hv om m oo mm ooa.m mm.H mm\m ooo.H m-on0H.m o.o¢ co m 00 OMH oou.w mm.H mm\m ooo.H m-onow.H m.He mm m 00 oo ooa.m mm.H mm\m coo.H m-onwo.m a.m¢ om m oe mm oou.m mm.H mm\m oom.H m-Oonw.H AmHmmn Amompw A.:Hv Aiov HcHE\uwv Ampm.ue\spmv AmaOHUHev A.ch HaHe . AcHex V >qu ..Hn\3pmv Q MB > H XNEK < \mmao>ov x 02 an m oosafiwooounm oHQmH 99 F.OO w O OO Om Ome.m OO.H mm\m OOO.H N.OmeaH m.OO «O O OO OOH Ome.m OO.H mm\m OOO.H m-OquO.H m.mv as m OO OOH Ome.m OO.H mm\m OOO.H m-OHxOF.H H.me OO O OO OmH Omv.m OO.H mm\m OOO.H N.OHxEH O.OO O O OO Om OOa.m mm.H mm\m OOO.H N.OHxOOH m.m¢ O O ‘OO Om OOO.m mm.H mm\m OOO.H N..OmemH O.mO mm .O OO OO OOO.O OH.H mm\m OOO.H m-Omem.m O.mq mm O OO OO OOO.O OH.H mm\m OOO.H m-OHxOO.m O.OO mm O OO OO OOO.O OH.H mm\m OOO.H m-OHxOm.m O.OO sq O OO OOH OOO.O OH.H mm\m OOO.H N.OmeOH m.OO OO O OO OOH OOO.O OH.H mm\m OOO.H N.OHxOO.m O.OO sq O OO OOH OOu.m mm.H mm\m OOO.H m-OHxOO.H m.ae mm O OO OO OOa.m mm.H mm\m OOO.H N.OHxOOH m.wq OO O OO OOH OO5.m mm.H mm\m OOO.H mlonmO.H O.OO «w O OO OOH OOu.m mm.H mm\m OOO.H N.OHxHOH HmHmmn Am A.OHO Am O AeHe\HmO- A Hm.ne\=HmO AmOoHOHeO A.cHO AOHE AaHex O >HUV .unwm O H0 > N H xme,d < \mmao>ov M. o on .H i E ooscfiyoOOunm maan 100 O.OO O O OO OO OOO.O OO.H OO\O OOO.H O.OHxOOH O.OO OO O OO OO OOO.O OO.H mm\O OOO.H N.OHxOOH O.OO OO O OO OOH OOa.m OO.H OO\O OOO.H O-OHxOO.H O.OO OO O OO OOH OOO.O mO.H OO\O OOO.H N.OHOHOOH O.OO OO O OO OOH OOO.O mO.H OO\O OOO.H N.OHxOOH O.OO OO O OO OO OOO.O mO.H OO\O OOO.H N.OHxOOH O.OO OO O OO OOH OOa.m OO.H OO\O OOO.H N.OHxOOH H.OO O O OO OO OOO.O OH.H OO\O OOO.H N.OHxHOH O.OO O O OO OO OOO.O OH.H OO\O OOO.H N.OHxOOH 0.00 O O OO OO OOO.O OH.H OO\O OOO.H O-OHan.H 0.00 O O OO OO OOO.O OH.H OO\O OOO.H OIOHOHOO O.OO O O OO OO OOO.O OH.H OO\O OOO.H O-OHOOO.O O.OO O O OO OO OOO.O OH.H OO\O OOO.H N.OHxOHO O.OO O O OO OO OOO.O Ome- -Ommm ----mOO.M-- m-mMWmme HOHOOO Ame Om A.OHO HmoO AOHO\OOO A “O.OO\OOOO AOOOOOHOO A.OHO HOHe HOHO\ O ifHUO .HQ\MumO D H > m H xOE K < \ono>oO x. o: O: .H i OOOOHHOOO--O OHOOH -..._;O_. 0.00 O O OO OO OOO.O OO.H NO\O OOO.H N.OHxOOH 0.00 OO O OO OOH OO0.0 OO.H OO\O OOO.H N.OHxOOH 1 0.00 OO O OO OOH OO0.0 OO.H NO\O OOO.H N.OHanH 0 1 0.00 O O OO OO OO0.0 OO.H OO\O OOO.H O-OHxOO.H AOHOOO Aiompm H.2HO AioO HOHe\HOO HOOO.HO\OOOO AOOOOOHEO H.OHO HOHE HOHOA O NHBOO Hua\:me O OH. > H xOEH\ < \mmHo>oO x 02 p: m OOOOHOOOO--O OHOOH 102 .Umm: mOz HHO Umouom cons UHHO> yo: mOS GOOpODUo cofiwoflomwm mag #Onw mchOoOUcO msnp .Umms OOS MOO Umouom can: muo>OH GHOHm wnOOOanO> nonH O nmsounw H How moamummmfio woOoHHOOmOm Omzonm OPHSOOO mocOOHO> Ho mOm>HOn< H no.0 u u H0.0H NO oo.omO cfiapfiz oo.onAmO HOm mo.o H mo.o cmwzgmm oo.OH MO mo.omO HOpoH oOpOmumo.om muOsvm :Omz Eovmmum mo mmmummm mmuOsvm Ho Sow GOOOOHMO> Ho mousom UmmD mO3 >Hao mcoHuOunH> awn: OHO>OH nocH O mcHUSHoaH UGO oH QD magmma GHOHG mow mpHSOOm HnoHOOsvm :OHpoOUmum may >9 UOHOHSUHOU OmonH UqO onoo OOHHmnm “om OOHpOm HQOpmcoo ch>HQ HOvnmEHuomxm on» 0p coayOHmm CH muHSOOm mocOOuO> mo mOm>HOq< .O OHDOH 103 (is—HOW ~ ,. --— -- u» H —H .11, Av . . l —0— 4 inch grain layer vibration only, experimental k l 1 60— _-_ .. .. .. u , .. -- , prediction k0 ' —x—-— .. u -- .. , forced air + vibration effect of lOOft/min experimental k1 _.*_— H II n n ’ II 'I t “ " " " " ,predeclion kg 55— —0— 3 .. " .. , vibration only, experimental k — _O._ .. .. .. .. , .. -- , predection ku 50_ _a_ 2 .. .. .. , -- " ,experimental k _ _9__ .. - -- .. , n " , predection ku —e.——— | -- .. .. , .. " ,experimental K ‘l 45%—- .. -- .. .. -- " , prediction ka 7 k \ Percent Moisture ldry basis) 4G \‘I I \\ \ F = IOOO cycles/min. i 2: y _ __ z 3 ' H o.» Q \\ A /32inch 45‘ L I = 2700 Btu/hrftz ! 30 \H\ \ k k0 2.22 x 0 [ V ) htD Ti 6.42, R T5 — 4.35 < k' < 4.35 + '1?" involving the dimensionless ratios is valid for all grain depths up to and including four inch grain layers when vibration only (no forced air flow) is used, but it is not valid for forced air velocities through the vibrating grain layer during drying. SUGGESTIONS FOR FURTHER STUDY 1. Determine the wavelength at peak emitter inten— sity at which shelled corn has maximum absorption of infra- red energy and the optimum wavelength—moisture content infrared absorption relationships for various grain moisture contents. 2. Study infrared vibration drying of deeper grain layers primarily four inches and larger, and the efficiency of infrared energy utilization in relation to the depth of the grain layer. 3. Study infrared vibration drying rates of other cereal grains such as oats, wheat and rice; compare these to the drying rates for shelled corn and adapt the drying constant prediction equations of these cereal grains to the one established for shelled corn. 4. Establish the forced air velocity—vibration combination for optimum infrared vibration drying results. 5. Determine the effect of infrared vibration drying on seed germination. 113 REFERENCES .Anonymous. 1958. Infrared processing is really catching on. Food Engineering, 30:110-112, February. Anonymous. 1960. Literature review of infrared energy produced with gas burners. Gas Association Laboratories. Research Bulletin, 83. Anonymous. 1963. 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