—' I8: (/3014 Thesis for* "Fine Degree 0? N1. Sc. ENCHZQN SE ATE L‘EE'EM TY 33.0.. *t 11.4 Hedfien 1956 Am FLOW FkQfiv‘é A mm QQCT EN GRAEN '1f;L51$ AIR FLOW FROM.A RAISED DUCT IN GRAIN By Scott L. Hedden AN ABSTRACT Submitted to the College of Agriculture of’Michigan State university of Agriculture'and Applied Science in.partial fulfillment of the-requirements fer the degree of MASTER OF SCIENCE -\ Department of Agricultural Engineering Year 1956 Approved (j;%béa£[ (3&41?2? ’0/7€791§ QCOTT L. HBDDEZ ABSTRACT The cost of early harvest and storing of grain using a ;>rced air dryer and storage combination to its full capacitv would be lowest if the storage could be increased and the power requirements to force air through the material were lowered. The purpose of this project was to determine the air flow characteristics of a raised duct of circular cross-section in shelled corn, including the air flow patterns surrountiing the L. O duct and the use of e: when t outlets to change the air dis er ‘1oution. A four feet square test bin twelve feet high was cons uraxcted with oressure taps szace< along its front and one side for l L measuring I ) Tare.) 3x0 (11.3? )3 U111 ugh tile L'I‘aln. Orifice plates and a vane ananometer were used to n (D {J U) S "3 CD ’1 flow from the bin. Smoke injectei through the pressure taps was used successfully to trace air flo m: oatte1.1s across a lucite section. Data were taken W1 h the circular duct 2 f:ct off the cf floor when the duct periphery was totally open, top half covered, and totallv Open with exllaust outlets on the zloor. Air mo ement from an Open periphery duct extended down to 1es oelow the duct and down to the floor hlth a half covered duct. Exhaust outlets in the bottom corners of the bin provided the most satisfactory air flow distribution with a raised d ct. A circular duct space! h feet on center and raised 2 feet off he floor will increase the storage cayaeitr by 6h bu"hels yer 16 foot length of duct if corner exhaust outlets are used. Air horse over computations from the observed data indicated that three to twelve times more horsepower was required to force a given amount of air through the grain in the test bin without corner exhaust ducts. AIR FLOW FROM A RAISED DUCT IN GRAIN By Scott L. Hedden A THESIS Submitted to the College of Agriculture of Michigan State university of Agriculture and Applied Science in.part1a1 fulfillment of the requirements fer the degree of 'MASTER.OF SCIENCE Department of Agricultural Engineering 1956 ACIQIOWIMTIMTS The author wishes to express his deepest appreciation to Doctor Carl w. Hall for his encouragement and guidance so freely given during the period of this research. To the Stran-Steel Corporation and in particular to Mr. Earl Anderson, Director of Extension, the author extends his sincere thanks for providing the necessary funds for a research assistantship and the emigrant used for the research. Sincere thanks goes to the Dairy Department and Mr. Edward Smiley for the loan of grain for conducting this study. The author is indebted to Doctor A. W. Farrell and his staff for their kind cooperation and the use of the Agricultm'al mmumg research facilities. TABLE OF COI-ITENTS Page Introduction .................................................... Review of Literature ............................................ Experiment ...................................................... laboratory Set-Up ........................................... Instrumentation ............................................. mead-m COOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOCO0.0000000000000CO Presentation and Discussion of Data ............................. SW oeeeooeeeeeeeeeoeeoeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeoeeeeeee 00116131310113 .QOOOOOOOOOOOOOOOOOO0000000000000.00000000000000.000. SuggeStionS for Mt‘me Iqork OOOOOOOOOOOIOOOOOOOOOOOOOOOOOOOOOOOOO Iiteratwe Cj-ted 00......OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO Appenm .0...OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOC.OOCOOOOOOOOOOCO III 17 23 25 25 26 27 LIST OF FIGURES Figure Page 1. Front View of Test Bin ...................................... 8 2. Exhaust Ducts Placed in Test Bin ............................ 9 3. Adjustable Outlet on Ethaust Duct ........................... 9 11. Rear View of Test Bin ....................................... 13 S. Vane Anemometer and Sleeve for Measuring Air Velocity ....... 16 6. Depth of Grain Below Duct Receiving Same Air Flow as Grain Above Duct for the Three Types of Ducts Used ................. l9 7. Power Reguirements for a Raised Duct ........................ _21 8. Air Flow Pattern Produced by Smoke Injection ................ 22 INTRODUCTION The drying and conditioning of grain is rapidly'becoming a necessary part of the production program on the farm. Reduction of field losses with early harvesting must be accompanied by a.means of reducing the moisture content of the product to a safe storage level or the proper moisture content fer marketing. The cost of drying is a sizeable factor in the production cost and may well become larger than the savings accrued.by early harvesting. It is therefore necessary to investigate possible ways of improving economically the drying and ventilation of grain in storage. 'Many existing storages are not used to their full capacity due to the limitations on the depth of grain that may'be placed over the duct systems on the floor. In drying with heated air, the factor limiting the depth of grain.to 18 to 2b inches in the drying unit is the overdrying of the grain next to the air duct due to the high temperature of the air. Little can be done to improve the capacity of the heated air dryer since most commercial units have the air duct in the center of the bin.and the bin.must be full to operate. These are usually batch bins and the grain must be cooled and moved to a larger storage. The factors limiting the depth of grain in a forced air system are different from the heated air situation. The same bin is usually used for both drying and storage when using forced air and the depth of grain over the ducts is limited to 6 to 8 feet because of the power requirements to overcome the resistance of the grain. The limitation on the depth of grain makes inefficient usage of a storage over ten feet in height. Another factor to consider is the limitation placed on the size of motor to drive a fan in areas where three-phase power is not available, which in turn limits the size of the drying operation. Providing a means of increasing the storage capacity of a bin and insuring sufficient air flow for drying or ventilation of the product will reduce the cost per bushel of grain dried. Early harvest and storage for optimun market conditions will then be justified. The objectives of this project were to: 1. Determine the value of a raised duct of circular cross- section to increase the capacity of a storage and reduce the power and energy necessary to force the air through the grain. 2. Obtain basic information on air flow patterns surrounding a circular duct in shelled corn. 3. Investigate the use of exhaust ducts placed below the raised duct to provide miform air distribution. REVIEW OF LITERAT URE No published information was found on the value of raised ducts or the effect of covering part of the duct as related to air flow patterns. Peterson (She presented data on a duct raised eighteen inches off the floor, and in an eight foot high bin measured the progression of the drying front with thernw’touples strung at different levels in the bin. The duct used by Peterson was of rectangular cross-section (10%; inches by 9% inches) with only the bottom Open for air movement. The results of Peterson's research recommend a maximum depth of six feet of grain above the bottom of the duct. Considerable work has been done by C.K. Shedd (6) in measuring the air pressure drop through grains (resistance to air flow) and a chart has been prepared relating pressure drop per foot of depth versus air flow. The pressure drop through a product increases as the air flow increases. and the smaller grains offer more resistance to air flow than larger sized products. Shedd found that foreign material increased or decreased the resistance to air flow, depending upon the amount and size of material present. A method of determining air flow distribution was reported by Collins (1) using a flow net determined by isopies'tic lines and normals. The isopiestic lines are detemined by measuring the *- Numbers in parentheses refer to appended references. static pressure at intervals throughout a transverse section of a bin and connecting lines of equal static pressure on a section drawing of the bin. Normal lines are then drawn perpendicular to the isopiestic lines with their starting points equally spaced on the periphery of the duct indicating paths of equal air flow. Using Shedd's data of cubic feet per minute per square foot of bin area versus static pressure multiplied by the width of the air path, the volume of air flow through a channel of grain can be determined. Hall (2) developed a method of rapidly and accurately deter- mining air flow values in grain drying structures by using the air flow net and Shedd's data. From Shedd's data, a chart was made of cubic feet per minute per square feet versus depth for different static pressure drops. Measuring the distance (depth) between isopiostic lines for a given pressure drop from the flow net drawing, the air flow in cubic feet per minute per square feet can be determined from the chart. '_ Using the equation cfln/acc. bu. '3 15 (Gilli/Sq. ft.) (1/3“): where cfm/sq. ft. is the air flow per square foot of area parallel to the surface of the duct and x' is the depth of accumulated grain in inches, an air flow value expressed in cubic feet fir minute per accumulated bushel of grain is obtained. Hukill and Ives (3) presented data on the radial air flow resistance of grain. These authors expressed the relation between apparent gelocity, (V) , and pressure drop (op) in the equation, a V Ap = Ioge (I4- bV) using Shedd's data and went on to verify this 5 equation through a range of observed data. The constants a and b differ for each kind of grain. A quarter round duct was placed in the corner of a square bin and the grain was confined to a quarter round shape by means of fly screen. It was noted that 75 percent of the pressm drop occurred next to the duct in less than 5 percent of the total grain mass, or 75 percent of the energy or fan and motor capacity was used to force the air through the first 5 percent of the grain. EXPERIMENT The prinaryproblem encountered in the study was the measurement of air movement entering, leaving and throughout the mass of grain. It was necessary to determine the total amount of air being forced through the grain and the distribution of the air flow within the mass of grain. Laboratory Set-Up Originally, it was planned to use a cormercial size storage to conduct the study. The difficulty in obtaining 1200 bushels of grain and maintaining its quality for a year seemed prohibitive and. would not allow changes to be made easily in the air flow system. Therefore, a laboratory size test bin was designed and constructed to rednimize the amount of materials handling and provide suitable controls on the variables affecting the study. The test bin was constructed of % inch plywood and designed to allow the height of the duct bottom to be varied up to 30 inches above the bin floor with a grain depth of 8 feet above the duct ( when 30 inches high). The bin walls were reinforced every 18 inches with a frame of 2 x h's placed edgewise and bolted at each corner. The bottom 1; feet of the front wall was made of 3/8 inch thick lucite with pressure tans drilled at 5 inch intervals. The possibility of using smoke to trace the air flow patterns prompted the incorporation of the lucite section into the bin. Pressure taps of 1/8 inch COpper tubing drilled to 5/61; inch inside diameter were placed in the front ( containing the lucite section) and right side wall of the bin. The tubes were spaced at 5 inch intervals in the bottom 5 feet of front wall and at 10 inch intervals in the top 8 feet of front wall and throughout the entire right-side wall. This arrangement is shown in Figure l. The test bin and fan platfom were mounted on skids to facili- tate moving while the bin was empty. The top of the bin was constructed in a pyramid shape, converging to hold the 10 inch diameter stove pipe containing an orifice plate. This provided the only air outlet during the first half of the study. Ther second half of the experiment was conducted with ducts of ~12- square foot cross-section placed in the lower corner on each side of the bin. The tOp,or hypotenuse side,of the ducts was 1/8 inch thick sheets of perforated steel and the other two sides of the triangular ducts were formed by the side walls and bottom of the bin. Figure 2 shows the arrangement of the ducts in the bin. The main duct was 16 inches .in diameter and 11, feet long, made of 1/8 inch iron rod covered with galvaxfized window screening. The canvas duct connecting the bin to the fan was removable to allow access to the inside of the duct. Part of the data was taken with the top half of the duct covered with brown paper on the inside. The paper was held in place with spring rings the same diameter as Fig. 1. Front view of test bin showing bin cross-bracing, pressure tap spacing, and orifice assembly at the top of the bin. Fig. 2. View of the perforated steel exhaust ducts placed in the bottom of the test bin. 0 '5'”, -' . '. .' _ I . ‘z ‘ Q5) ' Fig. 3. Adjustable outlet to exhaust duct at rear of the test bin. 10 the inside of the duct. The air outlet for each corner duct is shown in Figure 3. The sliding door was adjusted to give the desired air flow in each set of data and was located in the side opposite the wall used fer pressure measurements. Instrumentation The total air flow through the grain.was controlled by _ regulating the speed and intake of the fan. During the first part of the experiment, air flows of approximately 0.2, 2.5, 5.0 and 10 cfm/bu. were used at depths of 2, h, 6 and 8 feet of grain above the duct. A method of rapidly determining the air flow was necessary to avoid a needless waste of time in adjusting the fan to the desired air flow. Several methods of meaSuring air flow were used including a pitot tube traverse, vane type anememeter, and orifice plates. The use of’an orifice in a thin plate proved to be the most satisfactory method because a manometer indicating the pressure drOp across the orifice could be placed at eye level near the fan, eliminating the task of climbing to the top of the bin to take static pressure readings. By substituting the desired air flow into the orifice equation, a manometer reading could be obtained and reached'by adjusting the fan. Orifices of 1;, S and 6 inches in diameter, cut in 0.025 inch galvanized iron, were used to measure the range of air flows. A well-type inclined manometer having a magnification factor of eight was constructed to indicate the pressure drop across the orifice. A two feet rifle provided the scale and water was used as the fluid in the manometer. The equation for the flow of gases through a circular orifice is given in Appendix A and an aligiment chart to solve the orifice equation is presented in Appendix B. Atdepths of 6 and 8 feet of grain over the duct in the first half of the experiment, the bin cover was removed and a performance curve, Appendix C, was run for the fan of cfm vs. static pressure. The pressure drop through the grain and across the orifice became large enough to prevent reaching the higher air flows and necessitated the change in air flow measurement. The air flow was increased by eliminating the orifice pressure drOp when the bin cover was removed. The fan was then adjusted approximately to the desired air flow by measuring the duct static pressure with a micromanometer and referring to the perfomance curve. During the second half of the experiment, in which corner ducts were placed in the bin, the air flow was measured with a vane-type anemometer. The tOp was replaced on the bin without the orifice assembly and the area of the 10 inch pipe and the velocity used to determine air flow through the top of the grain. The outlet doors in the bottom of the bin were adjusted to give the desired air flow and the opened area and air velocity used to compute the air flow through the bottom of the bin; - The static pressure at each pressure tap was measured with a commercial micromanometer calibrated in inches of water. The first fan was a Clarldge size 3/h centrifugal. fan, capable of delivering 1700 cfm at 1 inch of water. When the capacity of the Claridge fan was reached, a larger fan made by the Grand Rapids Blower Pipe Company'was obtained. The smaller fan produced an uneven air flow and much time was spent in attempts to dampen the fluctuations at the micromanometer but with little success. This difficulty was overcome when the second fan was installed as shown in.Figure h. A.smoke gun producing white smoke was also used to visually trace the air flow patterns. A football valve needle was used on the end of the gun to inject the smoke through each pressure tap in the lucite section. Fig. h. Rear view of test bin showing (3) Variable speed mechanism (b) Adjustable inlet on fan (0) Sliding panel in the back of the test bin for adjusting duct height. 13 PROCEDURE The air flow study was divided into two parts. The original, or first part of the experiment was set up to study only the effect of a raised duct in a bin where the only outlet for air is through the top of the grain depth. The duct was set at 2 feet above the floor instead of starting at lower heights to detemine just how far below the duct air movement would occur. The fan was set to give a desired can/bu. as described under instrmnentation. Static pressure readings were taken at each tap on the front wall and recorded on a scale drawing of the bin. ISOpiestic lines were then drawn connecting points of equal static pressure in the bin cross-section. At each depth of grain over the duct, one set of pressure readings was taken along the side of the bin to check the mfiformity of air flow from the front to the back of the bin along the length of the duct. Smoke was injected at each pressure tap in the lucite section when the grain was 8 feet deep over the duct. The second part of the experiment was mdertaken after data from part one did not prove too interesting. The effect of exhaust ducts below the raised duct was investigated as described here. At each depth of grain over the duct, the two outlet doors in the bottom were adjusted to allow the same air flow per accmmllated bushel through the bottom 2 feet of grain as was flowing through 15 the depth of grain above the duct. The air flow adjustment was made by measuring the static pressure in the center duct, each corner duct, and above the grain and solving for cubic feet per minute per accmnulated bushel ( cfln/acc. bu.) using the curves presented in Appendix D, and the alignment chart in Appendix E. Static pressure readings were then taken and recorded as in the first part of the experiment. The air flow was measured at the pipe in the t0p of the bin and at the Opening of each corner door as shown in Figure 5 with the vane anemometer. Two readings were taken at each opening and averaged. The three average values ( two doors and tep) were added to get the total air flow from the bin. Three sets. of data were taken at each depth of grain. One set at the maximum air flow for that depth, one set at the minimum air flow, and the last set midway between the other two sets. anoke was again injected in the lucite section and the flow pattern obtained was followed with wax pencil. - \ . . .3: ' .0, ' ~_._ii '- Fig. 5 . Vane-type anemometer and sleeve for measuring air velocity from exhaust duets. 16 l7 PRESENTATION AN D DISCUSSION OF DATA Isopiestic lines were drawn on each set of data for each 0.1 inch difference in static pressure as an indication of the distribution and rate of air movement in a cross-section of the bin. A sample data sheet is included in Appendix F. From these observa- tions there was no air movement indicated through the grain below duct A.* A truer indication of air movement was obtained when the cfm/acc. bu. was computed for each 6 inch depth above and below the duct using the static pressure drop interpolated from the data sheets. These computations are summarized in Appendix G. The air movement extended 6 inches below duct A when the grain was 11, feet deep over the duct, but at greater depths there was slight air movement dom to the bottom of the bin. The same computations were made from the data with the t0p half of the duct covered (duet B) and air movement was noted at all depths to the bottom of the bin. Grain lower than 12 inches below the duct did not receive as much air in cfm/acc. bu. as the grain i’v The following notations will be followed in this discussion: Duct A - raised duct with total periphery Open - 60 percent openings Duct B - same duct with top half covered - 30 percent openings Duct C - same as Duct A with exhaust outlets placed on the floor Of the bin. All ducts were parallel to the bin floor. 18 above the duct. The depth of grain below the duct receiving the same cfm/acc; bu. as the grain above the duct is presented graphically in Figure 6. Smoke injected when the grain was 6 feet over the duct produced no distinct traces. At the taps along the bottom.and sides the smoke emerged from the cracks at the corners and through the emptying door. Data taken with the exhaust outlets in place was recorded when the outlet doors had been adjusted to distribute the same cfm/acc. bu. through the grain above and belOW'the duct. A definite relation was Observed between the area of the exhaust duct outlet and 'the depth of grain over the duct (Table 1). The area of the exhaust outlet was halved for each 2 feet increase in depth of grain over the duct. TABLE I Grain.Depth Over Duct 0 (ft.) 2 h 6 8 Manet Duct Opening (in?) 33.h 3 1.5 0.75 The horsepower requirements were computed for ducts A and B, using the equation: Air Hp 3 S.Pax cfm 46335 S.P. 3 static pressure drOp through grain, inches of water cfm ’ total air flow from bin cu. ft./min. Depth of Desired Air Movement Below Duct , inches 19 24“ "1 5 J Depth Above Duct, Ft. . Note: Range of air flows was 2-11 cm/bu. D Duct A - Open Periphery I Duct B - Top Half Covered E Duct C - Corner Exhaust Outlets Fig. 6 Graph shows depth of grain below duct receiving same air flow in cm/acc.tu. as grain above the duct. 20 The air horsepower requirements for each depth of grain were plotted against the total air flow for Figure 7. Comparing power requirements for equal depths of grain above the duct at 550 cfm, there was three times more power required to force air through 6 feet of grain without exhaust ducts. The air flow under duct A was small enough to be considered as a duct resting on the floor. At an air flow of 550 cfm, the horsepower requirement was 1/12 as great for duct 0 with 2 feet of grain above and below as for duct A with h feet of grain above it. Without the exhaust outlets there was comparatively little air flow (equivalent to a duct on.the floor). As the depth above duct C was increased, the power requirements became proportionally larger until they approached those of duct A or an equivalent duct on the floor. A duct 12 inches above the floor spaced titan center increases the storage capacity by 32 bushels for each 10 feet of duct length. This increase could be doubled using corner exhaust outlets. Smoke injected below the duct was traced with a grease pencil producing the lines of air flow, shown in Figure 8. 21 o a .o 9. 9269093.. .34 .0 zflon an 2H BBQ mama 4 figmfifl. mg Emma H: 0 HM .595. go. one .80..“ opens 2.5 m use 939,... oedema—flashes: .........., H. 2.. -11 ..1.,..-H«..r4 ~n..a443~ HHHHHH 4...». .HWUH n4. i .4: Q‘p \.O ‘Hou m term 22 Fig. 8. ' Tracings of an air flow pattern produced by smoke injection at, each pressm'e tap. 23 SUPMARI Three situations were analyzed in this study of a raised duct of circular cross-section. These were: 1. Air leaving the entire periphery of the cylindrical duct. - 2. Top half of the duct covered with air leaving through bottom half. 3. Periphery of duct open and adjustable outlet exhaust ducts placed in corner of the test bin. The range of data taken was limited by the size of fans . available. The most satisfactory analysis of data was on a cm/acc. bu. basis for different increments of depth. In the case of the open duct the air flow was not sufficient below 12 inches under the duct as compared to the air flow above the duct. 'Hhen the top half of the duct was covered there was air flow to the bottom of the bin but not uniformly distributed to the corners of the bin. Btthaust ducts on the test bin floor 2 feet below the duct allowed a uniform flow of air throughout the grain mass below the duct. The outlets on the exhaust ducts were adjusted at each depth of grain to allow the passage of the same airflow in cfln/acc. bu. below the duct as passed through it. The data showed that for an 2h increase in depth of 2 feet over the raised duct the outlet area of the exhaust duct was halved. Air horsepower computations from the observed data indicated that three to twelve times more power was required to force a given amount of air through the grain in the test bin without corner exhaust ducts. A raised 3 ‘ . «L ‘2'. k’;1(‘ L1") I n ch‘ - 4 "00 03.. 51; f" 9 Q. A.c‘—()\‘ (.llSJ ,\?v,‘ 1"!- (J H ITIJJ‘JJI duct c to 12 inches ahqvc inc 313.r nay bc tsri ‘lt;out ‘/\ c o ‘r‘f r-u ’ ("\‘I $1"?! \arf ~ --_ “L _ ' _‘. ,_ . -V -~.. * b ‘I m “Dhliitci sir. J’ V‘ 1 n p . ‘L 'Cn" . a -v a 9 "i on to; Jalf or duct lurccs air :13“ dsrnvarn ‘3 ) r J J O H- :‘3‘ .\l c.00vprinf. ' .L ~ .L .. , J- , '. W. .: ~JUS:QLlC outlet enhavst ducts prsvxcgs centre of a;r a Q L -' )1‘.; (‘11:; L”) T'. . over r'suir'mczcs are tim ac to t'clvc:3 times less with c “r “ c:::aust - .4 05"- mm“. . n . ' ad .1. t “user; ‘11?! 8. 18., 32' p120 o 't‘.' --. --, . -1. 4.” :\ ,4. -L :Lcn corner enlaust ducts below a «ac. spaced a fee: on center and raised ? ffict above the aloor, the storudc capacity would ' l a be increased 6; bushels “0‘ l0 foot '"r Investigate Air flow spheres, c th of (lust. patterns f:on lif iron a hayed raised ducts. raised duct sy't61 in a full scale drying Operation si.ilarity between drain-tile flow patterns and air crns from a raise d duet. patterns for particles of unown size and shape such as cubes, tetrahedrons,ctc. l. 2. 3. h. 26 LITERATURE CITED Collins, T. "Flow Patterns of Air Through Grain". Agricultural Ethneering, _3_l_1_:ll, November 1953. Hall, 0. W. "Analysis of Air Flow in Grain Drying". Agricultural Engineering , 1631; , April 1955. Hlfldll, W.V. and N. C. Ives. "Radial Air Flow Resistance of Grain". Agricultural Engineering , _3_§:5, May 1955. King, H. W. and others. aulics. New York: John Wiley and Sons, Inc., 19118. pg. 123 “Flow of Gases Through Orifices". Peterson, D. G. and others. "Methods of Conditioning Shelled Corn". Agricultural Engineering, 32:7, July 1952. Shedd, C. K. "Resistance of Grains and Seeds to Air Flow". Agricultural Engineering, 213:9, September 1953 A. B. C . D. E. F. G. 27 APPENDIX Page Derivation of Orifice Equation ........................... 28 Graphical 501111321011 0f Oflfice Equation 00000000000000.0009 30 F311 Perfoma-n-ce Cm ooooooooooooooooooooooo000000000000. 31 Air Flow Through Shelled Corn 32 Graphical Solution of Equation for Determining Air Flow Per Accm‘fl-ated BUShel OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOC 33 Saanle Data. Sheet sooooooooooooooooooooooooooooooooooooooo 3’4 Air Flow Measurements for Shelled Corn Expressed in OBI/Ace. B‘lo .0...O0.000.000.0000COOOOOOOOOOOOOOOOOOOO0.00 3S 28 APPENDIX A EQUATION FOR THE FLOW OF GASES THROUGH A CIRCULAR ORIFICE IN A FLAT PLATE (1;) I _ +1.2Dh Q CAJ'TgwlPZW E 2c (3a)] Where : Q A discharge, cfm ; C = orifice coefficient; ft orifice area, ft.2 3 g 3 acceleration of gravity,32.2 5302, P1 1'- air pressure upstream,psf; P2 w : specific weight of air,1b/ft3; D = orifice meter,ino; 3 air pressure downstream,psf; Da 3 pipe diameter, in. The term 14% 02 (gag proved to be less than 0.012 for the size of orifices used and was negligible in making slide rule computations. 2 The orifice area, A, is equal to 11% 2 . - P élbéft ) Pl-P2 Since h (ft) - , the term—T can be eXpressed by 3P1 .11 'Pz andh- = P14)? ft.ofair hl-w- 2 “w, 1’12 W Converting ft. of air to ft. of water: 1 p31 3 00016 ft. H20 = 13.07 ft. air (Std. 00nd.) 0.. 1 ft. H 0 ' 13.07 2 W5 3 816.9 fl}. Of air 111-112 = Ah (air) - 816.9 AH (H20) From a table of orifice coefficients for sharp edged circular orifices (h), C = 0.60 29 Substituting these values into the original equation: Q (cm) = 0.60 m2(1n2) a; 816. H ' 60 A): WIS-2:151:42 x 32.2 (3552) x 2 94 (m2 2: (13%) and solving for Q: 0 em = 13 DzJ—AH u l 1 D-omnc: DIAMETER,INCHES L.— .a—J Q-AIR FLOW, cm o/ / Ill 33: § 0 ITI'l'T'l l 3': Q=I3 D’s/AH — h 4 Apmmnc B AH -WATER COLUMN,INCHES Graphical Solution of Equation for Air Flow Through 3. Circular Orifice in a Thin Plate. 2.0 TIIFIIIIII IIIIIIITIII ‘ [IIIIIITIIIFIII 30 31 . O O 1’. 9+ H—o i .4 ~ X 4420 rpm ' o 8845f ‘ e 3075 A I920 Y q i 0 Fan Performance Against h ft. 0: $1011“ Corn 1 C W W W a a I. 5ft: fic Pressure,A,o 32 O a no Deffb of Grain, inches .. «km. ¥kuW>o\K&\v\ \ x x x \ \ .x \ \ \ \mm \P\\ \ x x \\ x \ x > x \. in \\ \NM K3. a- - .\ -1 we”. \ \\\ 513mb \ \.%&\\w\\. \\ e a? -1 s E \ \QsRewA. was“ ex. \ are? i 1 sC \ \\ \_ x \w a . \ \ \ v\\ x \ l \\\\\\ \.\ \ \x\ \ \\ c\ \ 5% H \\ \ \ \ r \\ \ .. \\ _ \ \\\ \ x \ 4 \\ r \ \\ x \ \ \\ .. \r\ . \\\ \ \ \ \\ Ea \KA \ t\ a 8 1 o .0 4 3 t (.1. APPENDIX D AIR FIDW THROUGH SHELLED CORN (Based on data by C.K.Shedd, "Resistance of Grains and Seeds to Air Flow". Agricultural Engineering, Vol. 3h, September, 1953.) 33 w W W N W... 7 O 6 4 8 2 l r. —_.-—-—- _b-—-P-bh _——-—-—-—P _ - —_-P——r-——-b-—bnbh— um 2.4mm k0 .Dm.00< mum 2&0 m. M V: a 5X .w/ I // =U v/ MB. /, FC .x/ CC 0 o o A an» manna” 0...... ............ J r_ . _..._ ______._b_._.__ _... . ._|_.fl._._._p_.—. _... p __.___._f—._._ . _...m_ 5...: moon... .5 .Edm mun. amou> o o o o o o m o e a 4 a m m a 5 4 a a r———_—-—- _ . —C.._.-._.-p_—b-.-_-p—-_.flL _ . _.-..bm-._ 3:022:25 ao :Pauonx. APPENDH E Graphical Solution of Equation for Determining the Air Flow per Accumulated Bushel of Grain Tm ~01]? mi} $1? -@—1 ‘5' Project 336-6 D3t33/6 Ju/j I176 _--—--—-._--_--—--—--—--_ o 00 007 a 00 ’¢ Tine: ”lo/14. T 07 9 07 6 Duct t: . W175 Efius 52” Depth of Grain over : 4ft .x' 07%} calL 49* 42.0: ./9 ,3 ‘ Air flow: To, C 400 cf»: 30”?!» ’34: cf»? ‘ = 276 cfm T m./ . mam. :35 “-34 .33 .33 ~33 I2 MI . [no 89.4 bu. [L4 57—; .4' .47 «’fl .47 .47 - 6’7 // ’3 35 APPENDIX 0 AIR FLOW MEASURDIENTS mm SHELLED com: EXPRESSED IN CFM/ACC. BU. Open Duct - (60% openings) Depth Under Duct Depth Over Duct 6 12 18 2h 2h A8 72 96 1 «x- 2 1.1 7.8 2.2 1.8 7.8 2.5 3.9 7.8 2.85 7.h 7.8 a- h 3.1 16 h.h5 8.25 16 5 8 16 5.7 21 16 * 8 5.9 31 8.9 8.3 31 10 17.5 31 11.h A9 31 - 2 r 2.7 27.5 5.5 * 5.5 h5 11.1 *1]. 32.5 21 3 a 2.1; 22.5 11.2 * 3.65 3.8 6.8 3.9 5.8 6.8 h.l 9.7 6.8 h.h 32.5 6.8 h * 205 30h hob 2.6 5.8 h.h 2.7 9.5 h.h 2.9 22.5 11.1: *- Origlnal test data APPENDIX G - (continued) Duct Half Covered - (30% Openings) Depth Under Duct Depth Over Duct Test GEM/Btu (in. ) (1110) No . 6 12 18 21; 2’4 148 72 1 * 2 107 907 2.2 2.7 907 2.5 7.1 9.7 2.85 13.7 9.7 e:- h 13 26 $.85 21 26 5.7 100 26 8.9 16 37.5 2.3 3.1 5.6 16.5 o o O\0\O\O\ 16. 25 32.5 12.5 23 35 BBSBEEEfimmmm 9h 3 m 2 2.2 201 ‘ 3.3 2.2 5.8 2.8 17.5 ho3 9.6 11.6 13 h.9 52.5 o o o o o o WWWUNNN‘Q \‘Iflslduwww O h m- 2.5 8.1 2.6 8.6 w 2.? 9.2 2.9 27.5 «- Original test data. £1127.- -)IX G - (contimmd) 3‘4 Open per/{erg .0qu @UCf Ha/f Co verea’ 60;”; aloe/1389: 30 )5, o/oen inf: 8' 8 6’ 6 4' 4 2' z' /*\\ h ----- 1 “““fl” t -4/ L. ______ 1 \"/I F- ----- 2’ 2' 0’08” DUC?‘ WI”) EX/70US7L OUf/E 7‘5 I ‘ , ‘ 8 \ .1“ \\ rm— — —-— 7 - .4 — -- ., \ -—---d “5"” “want, USE 0:51,! Date Due Demco-293