T'é'EE EFFECT OF HO? SUREACE mmsmas 0% THE HEAT TRANSFER AND THé DRY’ING RATE 0? SAND Thom for the D091» oi M. S. MfiCHIGAN STATE UNIVERSITY Le‘siie Erwin Lahfi 1958 THE EFFECT OF HOT SURFACE MOISTURE ON THE HEAT TRANSFER AND THE DRYING RATE OF SAND By LESLIE ERWIN LAHTI A THESIS Submitted to the College of Engineering of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Chemical Engineering 1958 (3, TABLE OF CONTENTS Page Abstract Acknowledgements Introduction ......................... 1 History .............................. 3 Equipment and Procedure .............. 10 Data ................................. 21 Presentation of Data ................. 49 Discussion of Results ................ 67 Conclusions ........................fl. 74 Appendix ............................. 75 Bibliography 0.00.00000000000000000... 78 ABSTRACT Recent work on the drying of sand on a hot sur- face, has suggested that thinner beds dry faster and have higher heat transfer coefficients, because of greater wetted areas at the hot surface. The problem of this study has been to evaluate that suggestion. Drying was done on a steam heated plate held at a constant temperature of 220°F. Three bed thicknesses of sand were used; namely, one-half inch, one inch and one and one-half inch. Layer moisture content, compo- site moisture content, amount of steam condensed, and sand bed temperatures over intervals of time were taken as primary data. Hot surface moisture contents, heat transfer coefficients and drying rates were obtained from this data. -The drying rates and heat transfer coefficients were the:highest with the one-half inch bed. The area of wetted hot surface was also the greatest for the one- half inch bed. Therefore, higher drying rates for the one-half inch bed are the result of higher heat trans- fer coefficients at the surface. These in turn are due to the greater area of hot wetted surface. 'I‘ n/ ’ Approved: W1) ,4{/ xicdf ACKNONLEDGEMENTS The author gratefully wishes to thank Dr. Randall w. Ludt for his willing assistance, excellent guidance and cooperation in the preparation of this work. Further thanks are expressed to Mr. D. T. Retford for his work on the original equipment design and to Mr. W. B. Clippinger for his work on making equipment alterations. INTRODUCTION INTRODUCTION Since the process of drying has been used by in- dustry for many years, it would seem that the mechanism of drying would be very well understood and described. A survey of the literature revealed that air drying, such as occurs ininature, has been very well described. However, very little has been written about hot surface drying. It has been only in recent years that the mech- anism of hot surface drying has been advanced, publicized and accepted. This study has been a continuation of the efforts in this field to more fully explain the hot surface dry- ing phenomenon. Sand was selected as the material to be dried, in an effort to lessen the number of variables in the process. The effects of bound water on the process were eliminated by use of a nonhygroscopic material like sand and it was possible to obtain a uniform particle size and shape by classification. Water was selected as the liquid to be removed, since it represents one of the major drying problems in industry. Purpose and Scope of This Investigation The purpose of this study has been to provide in- formation which could be used with other work to further explain the hot surface drying mechanism. It was hoped that relationships between hot surface moisture content, heat transfer coefficients and drying rates would aid in this explanation. Three sand bed thicknesses were dried; namely, one- half inch, one inch and one and one-half inch. The hot surface temperature was held constant at 220°F during all runs. Moisture content, layer moisture content, a- mount of steam condensed and sand bed temperatures mea- sured at periodic intervals were taken as primary data. HISTORY HISTORY Drying is not a new operation. For centuries, air drying has taken place in nature and the mechanism of air drying has been very thoroughly expounded in the literature. However, very little work has been done on hot surface drying. A brief description of air drying might help to explain some phase of the mechanism of hot surface drying and is for that reason repeated here. Air Drying, Essentially, it has been generally agreed that drying involves two steps; namely, the transfer of mois- ture as either liquid or vapor through the solid to the surface and transfer of water vapor from the surface of the solid into the main drying medium. Further, it has been generally accepted that during constant rate dry- ing the latter case is an evaporation process from a wetted surface. Vaporization later takes place from within the bed. However, the transfer of moisture through the sol- id to the surface created some controversy. Sherwood (18) from early work on drying, suggested that moisture trans- fer took place by means of diffusion. Ceaglske and Hougan (2) showed that flow of water in sand during air drying was due primarily to capillary forces. Hougan, McCauley and Marshall (10) showed wide discrepancies between diffusion equations and constant rate drying. Haines (8) previously had explained how moisture was held between particles by starting with a dry bed of soil and adding water to it. His first stage of wet- ness was called the pendular stage, wherein a small a- mount of water was held at the points of contact of the particles or suspended between the particles. More wa- ter added to the bed ledato his second stage of wetness, the funicular stage, wherein the particles were covered ' by a continuous water film but the pore spaces were still empty. After enough water was added to fill these pore spaces, he reached his last stage, the capillary stage, wherein all the cells between the particles were filled. Ceaglske and Hougan (2) used the above terminology and also the method of Haines to determine the effect of suction in the sand, expressed as percentage of satura- tion. Pearse, Oliver and Newitt (l6) concurred with Ceaglske and Hougan and expanded the theory of air dry- ing of granular materials. They explained that move- ment of moisture in the bed depended primarily on gra- vitational, capillary and frictional forces. From this study, a brief summary of air drying would be as follows: The bed was made up of small part- icles between which were interconnecting void spaces. As water started evaporating from the surface of the satura- ted bed, concave surfaces developed in the large pores, setting up suction within the bed. As more water evapora- ted, this suctional force increased until it was great enough to break the continuous water film. At this time the water was pulled down the large capillaries and sup- plied to the surface through the small capillaries, keep- ing the surface particles wet. The constant rate drying continued as long as there was sufficient moisture in the bed to cover the surface particles. When the small capillaries could not supply the sur- face with enough water to wet the particles, the critical moisture content was reached and the first falling rate period began. Vaporization continued at the surface at a reduced rate during this period. The second falling rate period commenced when the bed was sufficiently dry, such that particles through- out the bed were no longer covered with a continuous film of moisture. Water was said to exist in the pen- dular state and vaporization occurred within the bed. Newitt and Coleman (14) drying china clay, found increased drying rates and prolonged constant rate peri- ods in thinner beds. They felt the reason was due to a reduction in friction opposing the liguid flow. Hot Surface Drying In spite of the difference in the mechanism of heat and mass transfer between air and hot surface dry- ing, drying rate curves of similar shape have been re- ported. Ernst, Ardern, Schmied and Tiller (5) reported a constant rate period followed by a variable rate peri- od for the vacuum drying of Prussian blue on heated shelves. Ernst, Ridgway and Tiller (6) dried Sil-O-Cel in the same manner. They also reported a similar dry- ing rate curve and showed that in vacuum shelf drying, heat was supplied at both the top and bottom of the bed. Likewise, McCready (15), drying paper pulp on a hot surface, showed a constant rate period, followed by a first and second falling rate periods. Hougan, Mc- Cauley and Marshall (10) showed a few curves for mois- ture distribution within a granular bed, dried on a hot surface and introduced the phenomenon of vapor condensa- tion within the bed. King and Newitt (ll) found a pseu- do-constant rate followed by a falling rate while drying glass beads. Tambling (19), using salt solutions instead of water, showed that at 12 per cent moisture, 60 per cent of the salt concentrated near the hot surface and about 15 per cent at the open surface. This indicated that liquid was vaporized at the hot surface, rose through the bed and left the salt behind. Some of the vapor condensed in a region above the hot surface, picked up salt and moved toward the hot surface. Some liquid movement to the air surface also took place. Hadley and Eisenstadt (7) studied the movement of moisture in a granular material due to temperature gra- dients by using radioactive tracers. They also reported a liquid migration toward the hot end and a vapor move- ment away from it. Further, they observed that below a certain moisture content, migration was due to vaporiza- tion and not capillarity. Dreshfield (4) used dye migration to determine liqe uid migration in paper pulp. He measured the moisture content of the fibrous sheets using beta-ray transmis- sion and advanced the following description of the mech- anism of hot surface drying: At the start of drying, there was a short period of time during which the dry- ing rate and the temperature distribution adjusted from the initial conditions to the conditions of constant rate drying. Heat was added to the sheet at the hot surface and caused vaporization to take place. This vapor rose through the sheet and entered the air stream at the open surface. Partial condensation took place as this vapor rose and transferred heat to the sheet. This heat moved" by conduction in the direction of decreasing tempera- ture. At the open surface, a small fraction of the heat ' was transferred to the air by convection and the re- mainder caused vaporization. This process continued until the zone at the hot surface became too dry to maintain a steady rate of vaporization. At this time, the temperature drop across the hot zone increased and the rate of heat transfer to the sheet decreased. The temperatures of the rest of the sheet decreased and the drying rate decreased ac- cordingly. Below the critical moisture content, the zone in which vaporization occurred moved slowly away from the hot surface, and a continuous readjustment of temperature within the bed took place. Liquid migra— tion continued in the falling rate period, probably until the front of the zone of vaporization had reached the zone of maximum moisture content. By this time, the moisture content of the sheet was very low and re- maining water was removed by vaporization and diffusion of water vapor from the interior. Ludt (12), working independently of and simulta- neously with Dreshfield, dried sand and essentially con- curred with him in describing the mechanism of hot surface drying. Ludt however, pointed out that heat transfer through the sand bed-was due primarily to passage of hot vapors through the bed. Harbert, Cain and Huntington (9) reported transfer to be by some other means than con- duction. Ludt further explained that the hot surface was supplied by small capillaries and that the hot sur- face moisture content was constant during constant rate drying. Plate temperature was found to be the most im- portant factor in determining the constant drying rate. Both Ludt and Dreshfield concurred that the critical moisture content was primarily determined by the hot surface moisture content. Ludt stated that bed thickness influenced the crit- ical moisture content but had little effect on the con- stant drying rate. Retford (1?) expected a maximum dry- ing rate at some intermediate bed thickness. When dry— ing sand on a hot surface, he found the one-half inch bed dryed at a faster rate than either a one or a one and one-half inch bed. Ludt, Bohl and Retford commenced the work leading to this study and designed the equipment with which this study was made. EQUIPI‘JE ‘iT AND PROCEDURE EQUIPMENT AND PROCEDURE Equipment The drying process was carried out on a steel plate, heated with steam. This plate, one-quarter inch thick by 12% inches in diameter, was welded to a circu- lar steam chest (Diagram No. 1). On the underside of this plate was welded a cone shaped funnel with an up- per diameter of seven and one-half inches and a lower diameter equivalent to an one-half inch pipe. A pipe was welded to this end and extended through the bottom of the steam chest to an One-quarter inch needle valve. Steam entered the chest through an one-half inch, 18 psig. supply line equipped with a globe valve. A pipe was connected to the bottom of the chest, enabling excess steam and condensate to be removed. This line led through a needle valve to two glass condensers con- nected in series with capacity to condense the full out- put of the supply line. Steam entered the funnel inside the chest, through eight one-quarter inch inlet tubes. These tubes were L-shaped and welded to the side of the funnel in such a way that the portions of the tube on either side of the funnel pointed down. This permitted steam to pass freely through the tube but prevented con- 10 ll Diagram No. 1 Steam Heated Hot Plate Pressure Gage-\\ Drying Ring Three Thermocouples\§iSL Hot Surfaie ‘3, / s a; - :1 hfi I \ f I ‘x \ \ ‘ . \ U“ V Inlet {FUDGE—AS a \\\ \ \ \‘3‘; Ag :x /\ \ Funnel :: E3 Steam , ~\ .\ Inlet Insulationwv'1h'\\ :Q \ .. \\\ 3 Chest f ' \ Condensate-.——— . —‘ x. \\ I \\ 01 R\ Condensate \\ /////4/ Q‘ 5 Legs H) //////////////////////////////////// l2 densate from so doing. The chest, funnel, condensate pipe and valve were all well insulated with one inch magnesia block and rock wool insulation. The temperature of the hot surface was measured by use of three No. 20 gage Iron-Constantan, fiberglass over asbestos thermocouples.(Diagram No. 2). These ther- mocouples were soldered in grooves which ran radially at 120 degrees toward the center of the plate. One thermo- couple measured temperature at the center of the plate, the second measured it at a point one and three-quarters inches from the center and the third at a point three and one-half inches from the center. The centers of the hot junctions were approximately 0.05 inches below the surface of the plate. The thermocouple wire in the groove was covered with a strip of copper sheet, which was soldered to the plate. The iron lead wires were connected to a common ice bath cold junction, while the constantan lead wires were connected to individual throw type swithes. Sand bed temperatures were also measured by No. 20 gage Iron-Ccnstantan thermocouples. These thermocouples were mounted in a bridge, built of two parallel strips of micarta held together by two brass rods.(Diagram No. 3). The six thermocouples were arranged on the bridge in such a way that it was possible to measure tempera- tures throughout the bed. The hot junctions extended l5 Diagram No. 2 Top View - Drying Plate 10% inch Retainer Ring Thermocouple to center .“”__w 3333”,. ~\\ 7% inch Funnel /‘ ,/ ’/ ~ ,. .__, Soldered / - ' ’ \ \ Junctions . 2’ 1 I/ \ / 4 / 3/ \ ,f l / 3 ’ l i - ' 1 t \ 3 , \ o / , ./ \ x / - / ~ \ 3.- .“ / / 3 3 4 / .- ' / Thermocouple giggizé /3 1 " from center . .r’ /,/ M,~_M-/<.12% inch Drying Plate Tuermocouple - 3%" from center Brass Rods 14 Diagram No. 3 Thermocouple Bridge 6 Thermocouple Micarta Strips 2" VI; ‘Ix- lrrfS‘i/lé" %" 1 ___L Top View ll 3 u .,n ' l 1 . ' L' f -‘it- 3 - ‘iH—T h -oé.1.ué") I l ”W I 5 ‘1 ‘ Front View 15 three-quarters of an inch beyond the micarta face into the sand and ran at the same level for approximately three inches. The e. m. f. generated- was measuredon a Leeds and Northrup Portable Precision Potentiometer. Metal rings of 10% inch diameter were used on the plate surface to hold the sand in place. Glass tubes of one and one-half centimeters in diameter were used as sample tubes during the drying rate runs. Layer sam- ples were taken with iron tubes of 0.625 inches in diam- eter fitted with micarta liners or bushings 0.125 and 0.250 inches in height. The tubes and rings were of the height of the sand bed being investigated. Procedure Prior to each run the surface of the hot plate was cleaned with a course emery paper, followed by medium emery paper and finished with a fine emery paper; namely, 3-H emery paper of the wet-or-dry type, grit sizes 180, 280 and #00. The bottom of the retainer ring was also cleaned each time to assure a smooth fit on the plate. The retainer ring was placed on the plate and the sampling tubes were placed inside the ring at least one and one-half inches from it and two inches between tubes. Dry Ottawa sand of 40-60 U.S. Standard mesh size with a density of 102.6 pounds per cubic foot was poured into the tubes and around them to the height of the ring. 16 The bed was leveled smooth with a straight edge to the height of the ring and tubes. Eight layers of cheese cloth'wasIflaced on the bed to prevent erosion when the bed was wetted. All the air and the steam which had condensed in the chestand lines was removed by opening the inlet and blow down valves wide. After the pressure in the line had built up to 15 psig. again, the inlet valve was closed. The chest steam pressure was allowed to drop to three psig., at which time the blow down valve was closed. This allowed enough heat to remain in the bed and plate. to heat the distilled water, from room temperature to approximately 190°F, after it was carefully poured on the cheese cloth. If this pressure were not allowed to drop, addition of the water would cause blow holes to form as a result of the sudden vaporization at the hot surface. The bed was fully saturated and after the ex- cess water had drained off, the cheese cloth was removed. The steam inlet and blow down valves were opened slightly. The steam inlet valve had to be opened very slowly and the temperature of the plate held at 212°F long enough to allow the water above approximately 20 per cent moisture content (#water/#dry Sand) to be va- porized. Otherwise the excessive vaporization would, actually lift the sand bed in toto from the plate. It was necessary to puncture the thicker beds to allow this 1? vapor to escape. After the excess water was removed in this manner, the inlet and blow down valves were mani- pulated until the desired surface temperature of 220°F was reached. A record of chest pressure and surface temperature was made. During the run, the inlet and blow down valves were regulated to hold the surface tem- perature.constant. After the surface temperature was constant, the accumulated condensate from the funnel was drained off and a timed run started. A sample tube was taken from the bed at the same time and immediately placed in a numbered glass weighing bottle and sealed. These sam- ples were removed at periodic intervals by carefully extracting each sample with laboratory tongs. The condensate from the funnel was also collected at the same time as the moisture samples were taken. This was done by inserting the tip of the pipe leading from the funnel into a graduated cylinder, quickly cracking the needle valve and collecting all the accumu- lated condensate. When steam started to come through, the valve was closed and the liquid level in the gradu- ate read and recorded. Layer moisture samples were taken during separate runs. The hot surface was prepared as before. The mi— carta bushings were fitted into the iron tubes and placed. on the plate in the same manner as the glass tubes. 18 Sand was added, leveled with a straight edge and wetted as before. While the sand was drying, these units were removed at intervals with tongs. The micarta bushings were slipped from the iron tubes and separated into in— dividual weighing bottles. -Condensate samples were taken simultaneously. Sand bed temperatures were also taken during sepa- rate runs. After the surface was cleaned, the micarta thermocouple bridge with the six thermocouples, was placed on the plate. All strain was removed from the thermocouple wires, so that the bridge would stay in place and level with the plate. The height between eaCh thermocouple junction and the plate was measured and recorded. Several glass sampling tubes were placed on the plate also, keeping them at least two inches away from the thermocouple junctions. Sand was added as be- fore, covering the tubes and thermocouples completely. The sand bed was leveled and water added as before. After the plate temperature was brought up to 220°F again, a timed run was started. Sand bed temperatures and moisture samples were taken at timed intervals. No funnel condensate samples were taken because the temper- atures for the runs were correlated by use of the mois- ture samples. At the end of each run, the weighing bottles con- taining the moisture samples were weighed. They were .19 placed in a constant temperature oven and dried for twenty four hours at 105°C. A check for dryness, re— vealed that the samples were completely dry after eight hours in the oven. After drying, the samples were weighed dry and tared. Limitations of Equipment and Procedure The biggest drawback in the use of micarta bushings to determine layer moistures, was the breaking down of the resin at the temperatures used in the study. This resin deposited a thin film on the hot surface and cut. down heat transfer. The discrepancy caused by using these bushings, will be discussed in further detail un- der the section on Discussion of Results. In any future work, it might be advisable to use teflon or glass fiber reinforced epoxy tubing (if available in these small sizes). Also, it would be advisable to use brass tubes instead of iron, to reduce the corrosion of the tubes. Some vaporization may have occurred between the time the samples were removed from the bed and before they were slipped into the individual weighing bottles. However, this delay was shortened by making the buShings fit very loosely into the tubes, enabling them to be slipped out very rapidly. Also, the top bushings were slipped out first, with the bushings closest to the 20 hot surface being sealed in the weighing bottles first. As the condensate from the funnel was collected, some vaporization of liquid may have occurred, due to the pressure drop through the valve. Also, some flash evaporation may have taken place because of the high temperatures of the condensate. Counterbalancing this may have been some condensation of steam at the end of the collection. All three errors were small. The col- lection was accomplished quickly and the liquid level read immediately. From the behavior of the one inch bed on heat up; namely, rising from the plate, it is expected that the drying rates and heat transfer coefficients were lower than they probably would have been without the rising. This phenomenon might bear some future investigation. No provision was made for removal of non-condensa- bles from the steam. However, the continuous purging of the chest should have reduced this error. Condensate was removed from the steam in the line, preceding entry into the chest, with a trap. The design of the entry tubes into the funnel acted as a baffle in further re- moving any condensate before entry into the funnel. 21 Run #1 - ié inch Bed La er Hoisture Time Pressure Condensate .flater HeIgh£ Heater Kin. psig, m1, Airy S ins, # r? s' 0 4.6 ... .1832 .0625--—.1831 .1875--.-.1395 0575 ‘”'.-01902 2 404 1702 01342 00625 .fi .1318 .1875 m .1505 .375 “- .1375 4 4.3 14.8 .1209 .0625 --1.1744 .1875 —-- .1156 . 575 - .1127 6 4.5 804 01155 .0625 ... .1245 .1875 -~ .1102 0575 “" .1123 8 4.2 7.8 .0848 .0625 -- .0863 .1875 .-. 01192 .575 m .0754 10 4.2 5.6 .0714 .0625 ... .0918 .1875 - .0675 .375 - .0660 12 4.2 4.2 .0428 .0625 ~‘* .0778 .1875 -- .0486 .575 --- .0271 Run #2 - 1/3 inch Bed 0 4,3 ..... .1456 .0525 - .1409 01875 -.‘ .1443 0575 “*‘ 01483 3 4.2 2642 01044 00625 G‘. .1033 .1875 -—- .1081 0575 “‘ 01052 6 4.0 25.2 .0828 .0625 ... .0954 0575 “" 90763 9 3.8 15.8 .0576 Run 37:53 - % inch Bed Layer moisture Time Pressure Condensateg,fWater Height mffater mine 0 . p313: 5-5 5.0 5.0 5.0 4.5 4.2 31.13... m 54.0 Run 5654 - 3’: inch Bed \fi R) F” <3 \fl.'P 6.0 4.5 4.2 3.8 5.7 m 18.5 8.3 3.8 3.6 “11;; a yr .1452 61298 .0774 77: "n rm u.‘ w an m z 57:33.;‘1?’ I .A ma ‘ .0625 ... .1514 01875 “”“ ‘150 05125 ""91353 .4375 - .1572 .0625 ..¢ .1552 .1875 ... .1566 03125 ..‘ 51244 .4375 m . 1325 .0625 ¢** 60384 .1375 .** ‘0308 .5125 ... .0758 .4575 -- .0699 .0625 an. .0736 .1875 -~ .0654 3 e575 *" f0472 .0625 “fl. 30598 .1875 ... .0365 .5125 "’ .0463 .4575 ... .0449 Sample lost 01093 .0773 .0331 .0507 90133 .0118 00393 00625 ‘.* 90554 Ol§75 *.* 00611 .375 - .O4A3 .0625 ~“ .0404 .le75 -~ .0457 05?5 “” .0541 mm .2445 «— 3-5 inch Bed. Layer £30.13er Time Pressure Conaensate 4ffiater Height__#fiater A *IFT“ "'_, .. ‘ ' 7",“?- - ' P!fi‘|:‘— min . “r s 1;: ml, . \ m 111; ... PW,,1,‘J,_~.._~w.'__¢ O 4.4 m .1302 .0325 on. .1‘3’60 .1375 au- .1254 .3125 ~¢~ .1222 04375 W .1547 1 4.3 —-- .1157 .0625 ¢- .1218 .1375 -- .1145 .5125 -‘ .1075 2 4.2 21.2 .0918 .0625 u.. .0444’ .1375 *“' 0097? 0575 “““ 01055 5 4.0 -- .0978 .0625 -- .0825 .1375 -—~ .1045 .5125 ... .0947 .4375 -- .1047 .1875 ... .0574 .575 -- .0753 5 5.8 -—- .0442 .0625 ... .0526 .1375 -~ .0491 .375 -~ .0595 6 5.8 6.8 Sample lost - too dry. “ Part; of sample lost on plate. Run #6 «‘fi inch Bed Time minutes 0 mvaPWNl-i fressure 4.0 4.0 4.0 3.7 3.? Run #7 «- 352 inch Bed , 'QGWW1FUINHO 4.7 4.5 4.0 3.7 3.5 3.2 3.2 5.2 Condensate 1311 o m m M 18.8 16.5 7.8 2.2 24 fl \ v~ Agwfnéja Lil."— l- l .1613 . 244 .1015 _.o7?9 .0523 .0614 .0193 .0054 I’f' f j. .1 l Run 7,”;3 - #2 inch Bed Time minutes 0 \EOWUIP'UJNH Run #9 «- K2 inch Bed VOWUI'IPUBNI-‘O 4.3 4.3 4.5 4.2 4.0 3.6 3.5 3.5 Conéensate 121).: 9.8 7.4 4.5 5.8 5.4 300‘ 5.4 ' 10.4 10.2’ 9.6 7.4" 3.5 5.3 2.8 . 1572 . 1197 .0312 .0535 .0174 .0235 .0395 25 26 * . O¢H mvu ova and bad 00H and ”ma nod no new on» bad and ban and and ana and and and mod «ma non afiu no." 2.: 05 wbd mad n¢u mwd wad com mmn wad mad 5. . . E ,_ . no: .0 cu .m 9’ Dad Nod flan 09d 00H omd how how com .. p! _ 5.1; bo.l.onnuanoaaom nod awn Nbd find cam cum GHQ awniw oado. HAND. cane. avoo. Cowo. @bmo. Gama. mmmd. a.» $6 n.n HA 0.» OH a.n m 0.n m 0.” o b.” n m.n N a.» H o.¢ o lad-alliga- ohauoohm clan. 60m Soda “.0 OH% can and mad 5mH Hmfl add 00H aha mod mma ova man mom de nod de an #0“ wow and pan Omfi mad mad nod own wow wow and Hm” 90d mbd aha 00H 0H0 C Cam and mad Obs mad GHQ no I £33.05“. w§d 00m nomad cam cam awn Nbd ”mu wow cam 0am cam mmmo. Hmbo. onfid. 0000. Obmo. mane. same. mica. HNOH. 6.0 5.0 9.9 m.n ONOb den Soda & I_NH% can o.# NH o.v OH o.¢ O.v «.1 #.¢ 0.1 m.¢ 0031'me Iqmflmmlljdafll ans-aohm oaaa 009 noun &.t Haw In“ Run $13 - 1 inch Bed Time uressure Condensate min. 0 2 4 10 12 14 16 18 20 22 4.6 4.5 4.4 4.1 3.3 5.7 3.7 3.7 5.7 5.7 3.7 13.5 11.0 7.6 5.8 4.3 4.8 4.4 4.6 4.2 ' ' Height .0647 .1258 .0551 .0352 .0685 _. 1 f.‘ J. Layer m01SouPG 28 fiifitig 71' 5243‘" ._ LE .1375 no. . 0&2 . 575 m . ll ,1"? 0625 aun- . 1003 00625 a... . 12.34 '1375 -- .1193 '635 -- .1162 ’875 "‘ -1590 .375 -~ .0609 '37 -- .0731 ~1375 -- .0315 o 573 a... .0553]. .875 '“‘ .1050 ‘ Part of sample lost in transfer. Run {14 - 1 inch Rad Tina fressure Condensate r-*: 2n .t--4._ ;__A. O . 3 12 15 R3 77735.. ‘T o 6.0 5.2 5.0 4.7 5.8 3.6 5.5 5.5 3.5 ‘ Parts of sample lost. .r'll 0 22.8 22.4 20.2 15.8 10.5 7.4 4.5 .4. p ' 0.75.37" ,. u - -'M Lu?“ ll —.- I‘ .1172 .1004 .1002 .0792 00391 .0533 Layer moisture 1n 1“: .0732 .1072 a U ‘j 13 .1205 .O5L37' O O-5¢.35 . Ox} )2 .0175 .0774 .0277 .0931 .0825 .0693 .oym- .0555 .0491 .0529 00616 .0539 .0502 .0175' .0791 .0569 .0523 .1152 . .0566 Q 0“}:‘3‘1 .0453 '3 0 054.5 .“a {101? "‘7' 7",- 1.1 ‘v 29 Run 514 (cofl1 i If- i o 1 25 3.5 4.5 Run #15 - l 1n0h Bed 0 4.5 m 4 5.6 52.5 8 5.4 25.6 12 5.5 27.4 16 5.6 24.8 20 5.6 17.0 .) - 1 inch Bed .0215 .2119 .205 .145 .1152 .1478 01257 50 ISJBT 1011. re 130i? :ht 1.4111. in. """‘““TE .1375 .. .0735 0775 ““ .0616 .675 - .0450 .0625 “u‘ O 13) O .1375 -- ..11 0575 ““‘0207 .625 - .219 0875 “ 0219 .0625 cu- . 1615 0 1-375 ."' o 13:32 .575 -- .197 .625 v- .817 .375 -- .20. . :25 .. .1502 .575 -- .1521 “N" o 1413 .1375 - .1173 .375 *~-.1532 .875 ““ 01173 fl Qua w: [U 40 0313. :i38 306 10.8 5.6 6.8 305 608 3.5 6.4 505 4.3 Run #16 a 1 inCh Bed 0 4.6 ...;... 4.3 17.0 4.2 16.5 4.1 18.5 715 (cont.) - 1 inch Bed .0546 .1024 .0351 .1807 o 1643 .1456 .1552 .0625 .1375 .5?j «6&5 3:25 f\:“"\l" oUQd) 013(5 .375 .625 ~875. , moistvre J_ IIIII IIIIII IIIII IIIII Jn+nfl . ‘._ '-‘ J "I; P . I. ' d I- 1" -- '._..J b", I 1334 :03 )7 1.1.30 :lOCS .0734 91:77 oujJ} .0934 00/76 00352 .Gjl5 0225 .OJJ7 .0733 .06)? .146 .1342 ol}¥3 .lJJb .1331 .1374 olfio 1346 :1511 01555 VJ Run #16 (oont.) - 1 inch Bed Layer fioisture Time Pressure Condensate W"ate Height fijater min: 031?: ml, ; n sand in. y a 12 3.9 14.5 .1042 1825 .. 1586 0315 "" 01712 068.5 m .1444 .rlgs O. O 463 .v9/5 “'1' .1522 13 5.9 14.2 .1032 .125 - .1252 .625 ~ OOBJS .875 - .0317 21 5.8 802 00758 00625 a. .0975 .625 - .0579 .“75 - .0761 24 5.6 8.5 .0588 .125 -- .0661 0975 ." 006‘” 0875 u o '3 27 5.6 7.4 .0652 .125 - .0721 .575 - .0582 .4625 “'"' 00592 .8?5 ." 0061i 50 5.5 6.8 .0645 .125 - .0639 » 0275 "" 00355 0625 ~ .0633 53 5.5 7.4 .0612 .125 - .0625 .375 - .0570 o 6.3") 5 u 0 011167 0875 w 004-)3 33 5.5 6.4 .0141 Run #17 - 1 inch Bed Eime yressure Condensate min. 0 4 03 20 24 \N “I VJ C} 40 p513: 4.2 4.0 4.0 4.0 5-7 5-7 5-5 ml: 23.0 27.2 29.4 25.2 15.4 15.6 10.0 6.3 :{R‘u’ater mgry wand .2590 '02210 I. [.4 ~J U1 03 o ‘4 U1 y} R) .0939 .1458 .0077‘ ' Part of sample lost. 53 layer Eoisture Hei; ;ht fl; ~‘nr A in. ;=5éy 5and 0575 " .1353 .0625 - .1514 .1375 .. .168 o 3375 C. o 1462 .625 .. .1535 98125 " 01595 .9375 -* .1463 .0625 .. .1148 .1575 .. .1512 o 575 .. Q 1448 .525 - .1¢62 00625 .‘ .1293 013 75 .. ¢1564 .575 - .1556 o 025 a. .1422 0075 ~ 0 1526 00625 ‘* .1051 .1875 .. .1083 ”’75 " .1051 0625 *- 00999 .w(5 -- .0925 nun 518 - 1 inch Bed ’Lotc: These samples developed blow holes Time iressure Condensate fflater uiqutcs 252?. z :0, jiry bani O 4.2 -—-~ .1470 2 4.2 17.0 .1292 4 4.2 19.3 .0993 6 4.0 14.5 .0744 8 3.9 13.2 .0850 10 3.9 10.8 .05§4 12 3.8 6.5 .0317 14 3.8 5.4 . .0479 15 3.3 5.0 I .0331 18 5.7 4.8 ‘.0234 20 3.7 5.0 - .010 23 3-7 3.3 ..0082 £19 - 1 inch 30d 0 4.5 --~ .1612 3 3.6 18.5 .19£5* 6 . 5.4 1?.) .1553 9 3.4 15.4 .1065 12 3.4 14.3 .1277 15 3.5 15.5 -** during heat up and are discarded. Lun 319 (cont.) - 1 inch.Bed {,3 -—>~__ 4.1?»“9 "'3 rnf‘n 4.1..- . h 13 21 24. 27 53 Run #20 01 o: C) u} \N \J'l firessure COLJCfisaLo w_’ eter e 391:. vl.r ;»_1 ' E: 5.3 0.8 .Oegl 3’2 708 007ll 5.2 7.4 .0614 3.2 6.8 .0531 5.1 7.3 .0226 —»1 inch Bed (Silicone treated tubes) 4.3 -é- .1512 4.0 _ 19.7 .1522‘ 3.9 13.0 .1273 5.8 16.4 .115’* 5.6 18.1 .065? 01' U: 9 \i \N o \41 3-5 3.5 5'5 2 3.5 3.4 5.4 12.3 7&9 ..LU7 8.0 .O"30’ 7.2 .0635 6.4 .0513' 5.0 .0537 7.6 .04;(* 5.9 .0334 5.4 .0332‘ 4.8 .0136 'Sample tubes treated with silicone grease. V“ m Run 521 — 1 inch Zed Tire Pressure Coniensate .11.;1i931 ......l—‘;-..-._. wilf‘ij‘ . - TL- ; .2» sr 1...... 0 5.5 ——— .;3.0 5 4.4 10.8 .1c15 6 4.0 8.6 .1315 9 5.9 7.3 .1143 12 3'9 505 .1 lj 15 5-9 5.8 .0342 18 3.5 4.5 .1330 21 3.5 4.5 .1055 24 305 4.2 .033fi 27 5.5 5.4 .0749 330 3 . 5 5.8 . 0521 55 3.5 6.6 .0431 55 5.5 5.8 .363} 39 5-5 609 00245 42 3'5 505 .0214 Kote: 0n heat up of the bed, the entire bed raised from the hot surface about an one quarter inch. The 8am- plee seemed to be riding on a cushion of vapor as each tube would settle a fraction of an inch.when the tongs were put on to remove the sample. This run is tygical of the runs which were discarded for this reason. ##a find #3” 05H 55H own IIII. m.n 0m mmH 00H nbfi mma OmH mad vovo. N.w wm «DH NQH 05H nmfi emu «Om IIII n.n mm #md NmH 55H wwn mma mom mfimo. n.n om mMH oeH nma non mom QHN IIII n.n ma an obfl bmd mod mow 0am mmmo. n.n ma 59H Nod wad mom mom OHN IIII ¢.n #H baa an va New mew OHN mmHH. v.n NH and and bad wow wow cam IIII v.0 OH mmfi ”ma mad now mom CAN mmbo. m.n m moH «ma mod com OHN Dam IIII. m.n m mad fima mad mom OHN . OHN mbOfi. w.» v omH 0mm mad new mom OHN IIII. m.fl N and nfia mmd man now OHN ObNN. *.v 0 $493... 0.23.0.5 239 mo I 33930959 con fiend H I mm% dam ova mom awfi bra nae mmfl 0500. 0.0 cm and and aka aka mad omfi vmeo. n.n om mod mm“ men and bad nan nmvo. a.» ma tad *od aka «we own won Game. 0.» ma can bud med mma mad cow memo. n.n in cog me” am” mad How pom g... 0.» NH n3 9: 8H 8.. 8m 03 :1... ea. 3 emu we” cad new mom cam enao. a.n a flea med ewe” pom one cam u... b.» o and mad mad bow cam cam anew. b.n v and we” can pom cam cam .... m.n m and med can mom mom cam m.n 0 ..¢ . ,. . _.... .. .~ . ..an. naudmmnuv.aaq«mn sumac“ I evade opone pz.aom chauuQAm Gaga mo.I.0&=uwhomaoa com soda H I awn can 2’1 :."24 - 135: inch Bed. 355.1579}? 7.0. LC; ulLre KN Time Pressure Condensate j' 3:47:31" Roi-3:11: __ _-_{-_:_!:::-7? "in 09:1“ “-1. T...’ -. in. :13!" . .5.“ I107? - .1jt5 I, J’) ." gnu-1.30 :6;5 " OI-) )O .275 -- .2230 1.12 .. OQJUJO 1.575 - .dO)0 5 4.0 17.2 .1? "' 6 4.0 18. .1802 9 4.0 13.8 .1259 .153r -— .11)? ‘EVT ’- oiufa .041? w .10 )7 «QT/D "' o l4 .37 1.15:5 “'- .1510 1.3/5 “ Ql}\)3 15 3.9 13.0 -.1123 13 5.7 17.0 .1271 125 ~— .1517 .5?) v. .1253 ovu’ PM) u 01503 19125 a .1145 10575 ‘k' .1348 21 5.7 13.. .0370 24 3.6 15.3 .0707 27 7.6 15.0 .0494 30 . 11." .0553 33 3. 7.. .0342 Run #25 - 1% inch Bed Time Pressure Conflensate min. “I.“ O 10 20 n 001" . . _ \ G} 4. 4.5 4.5 4.5 ’3', -11. M a... 44.5 26.2 29.7 31.0 '2‘ I. (3 fr. 1.) #flater I ‘11-; .qu .1360 .1605 .1557 .1550 0 1233-3 40 Layer Loisture Height 112. .0625 .1375 j! .1 ‘5 1’ .«LJ and I I! I! ll :1 {I II I I! II 3! PI. _ {tater .1336 .1935 01932 .2170 .1365 .IDJG .1346 .1745 .1408 .1504 .1703 .1575 .1763 01573 01352 cllfil .1212 01292 .1455 .1533 .1533 .1237 .1258 .1150 .1592 .1560 .l4j2 01433 .1356 .1013 .1550 .1195 .1111 .1092 .0355 01066 01152 01457 91216 .1187 01213 Run 325 (cont.) - 1% inch Bed Time Uressure Co a La~ . n enaate AfWfltnfi HGiJFE L01sture . 4...; a]: u . ' min. 2“4fi Ei: Ex 34 : ~VJa-i‘ . r Y in ind 12 1":ij :“ . ,Mo - 1m 1nch Bod .0625 .18?5 .500 .750 loOFQ 1.250 1.4373 0125 0}?) U 02-?0 .. ’214’0 'bUO “"- 022:}; .750 “ ¢.') 1.000~ .. :2110 1.250 ." .2430 7 10457? ““ .21?0 .0625 ”'- .1??? nég75 ‘. :l/L - g? - .1" oéés .‘ oléég 00/5 .. .16 71 1.135 “ 01723 1.5185 .. .l/L .0625 -- .llfif :1375 “"I’ .1103 :3 3 ~ 3341 1:. .0 0 4'0 9§7S “‘ 9144; 101.25 n .1255 1.375 .0 .126 .) - 133 3ress: “e Condensate “L 40.2 14.8 10.0 6.8 Fun 326( (cont 335.319 11:11:. 7) 3i " 13 5.7 16 5.0 24 4.5 28 #.0 Run $27 - 1% inch Bed 0 9.0 inch Bed .1073 .1046 00755 .650 Layer Height 9 n 13.1. I II I II I fioishur3 "_. .L'.l.. c - J :.1.-.1 II I II I I I II‘I II I I II I‘II I I ‘Lcr 1;. 01155 .1300 .1033 .1101 qlle 01402 .10351 . ’L51 .1133 .1141 .1352 oOJlS .19d3 .0985 .0737 05795 00$)6 .0734 0 Q 06 EX) .0397 .0524 .0818 .072 .0.) if) .0731 .(\}I13 :(./‘\3/2 .0310 0054-8 .5310 02535 3711‘. ‘ cad) .170 .231 .221 ’) L... 1-1.111 _. L27 (0311.30) - 1:: non 130d ~—- 0 . 131').er 1.10.1.1.) L". -'. I .' ,...‘ - . Time :resaure 0111113333ta .3333 KC j.3f 1531. 133 3: :31. “43:13 3331 :ir. 10 6.0 34.2 .160 .259 15 5.0 2;.5 .092 .03 g 20 4- 5 113. 5 . 1005 . 06.323 25 503 705 00668 .1375 .- .750 ~- 1.033 -- 1 o .5125 “G. 30 3.6 5.2 .0622 .125 -— .750 ~- 19 :75 "' L3yers Lorct‘ \N \3’: \N 0 v1 0\ O a: O C) J L \fl 12 20 24 23 32 “"j o] . ,-__8 - 1 1“ , . ?un r—‘c 11:9 Fin. n V Eras inch red 'ture C owls: T7 5‘. 3- 3- . 4.4 4.3 41.2 4.0 §4.3 23.0 27.4 5.5 3.2 5.2 5.1 2.8 2.7 2.7 2.6 6.7 "9 I" :xijca 1'71]. . 'r , .1... J-~-.1J'\3 "H. " +("jfi‘ ?..C:i; ".1 - -- . y-fi' ' 1 “if; - 1.22.9-.. 1Y.0 .132 .2150 .1140 .1638 .08; .0626 .0544 .0654 C) ..' 't . 0 C . O C O u‘\ ;\V ‘ U.1. [a \RWU‘VWM'TN; {U \3 “I. o OIJC; . 5? 0.)!) 0 Chi). (3 DUI) 1.01:-) 1.325 \71 U1 ‘5 131Luure " '"T‘l‘ '-::tf7: '"" a 21.00 “m" o a-.-‘;‘0 "" 0 ...”IO “"’ 0 £2.1le .. .114” "" o elk/'1} - ..,; -'. .44.}, ‘”" o -l:3 ~¢ .1213 “'- 0 l J i3 ‘n' o 1-- 31-3 - .1“;O ." a 17-15 -- .G,¢O - .Cul3 ‘“ oll)5 c.- . '3 fig} 4' alu- .*:J J .3 .1- 9&3 (1.3.9:) "' cog/41.) Fun Time Pressure Condensate ml. min 44 48 Run 0 \D C‘ V! 12 27 50 #9 II.- 9-m x“??? T73 -10 6.5 5.5 5.4 5.4 5.4 4.7 4.7 4.2 5.8 3.8 5.8 inch 6.4 ’1‘ 0g) Bed 25.4 20.8 19.7 17.4 15.5 15.2 10.5 8.6 7.8 6.5 yea (COHto) - 1% inch Bed .syer Iai:fu.e 4 "77711745.? I <3-‘ «31.1 '= 601‘ “yr; “:1 in._ 1; -tni .0558 .0281 .1902 .125 .23) .1550 .1495 ..l455 .1275 .1440 .0658 .0955 .0350 .0266 .0585 .§?5 .{Jrrjb qr; 0'.) f 1.135 1.??5 .125 0575' .625 .875 1.125 1.3?5 .0625 .1375 '?(2 .059 .fi75 1.125 1.575 45 38 I! I: I! 8! 3! .1133 .1344 .1343 .1335 .1952 .1368 . 1 4-13.- 5 o 1433 .1595 .1472 .1527 .1102 .0?91 .C?71 alflffifi o '3 3 (“f-7f. r- o.{a .05}? Time .1121. O 4 8 Presaure v Run £30 - 1% inch Fed psig. 7.0 4.6 4.1 4.0 4.0 5.8 5.8 5.6 3.6 5.5 5.5 3.4 5.4 5.4 Condensate v 1.1045. .25.8 20.5 25.0 22.7 24.8 23.4 20.5 15.5 ”12.0 10.4 [8.5 '8.3 3.5 I: ‘1' New and 50H mmH mmH owH man and finfi and and nma and wad nmfl find vbn mbH mbd mbfi mbH mbH 06H mbH 16H vbfl mbd 50H omH .OmH HmH an wad «ma bmd bud mmH CON wow #0“ new mom .2 3m 8.... 8m 2m Sm 3m OHN OHN cam OHN OHN .. tun—muons: com com OHN cam OHN Dam OHN 0am ammo. ammo. mama. andfl. «mad. amen. ONON. O¢ON. cams b.n 0* fi.» at b.n m¢ r.n an b.n an b.n an b.n on §.n §N O.n ¢m «.0 am 0.! ma o.¢ nu o.v NH o.¢ o N.¢ b #.¢ 0 0.0 o Ida-.4441] 0.3.3.5 :3 no. noun «A I an‘ Ill and .3." 3H #3“ and H2" do." can and on." and mg” as" bad .3." om." 0099* 00H 05H wk." ”.me 2: 00m DON com CON mad on... 0’ o , 002. . mmd bk." va now no 0 Iguanas!— o.n me a.n m. a.» m. 0.6 an .0.» 6n m.n an w.» on 6.6 .m _..n .w .w.n aw, 6.6 ma 0.. 0H o.¢ NH H.« .m m.« o n.v n v.v o 13.3.... «a... 0.5:?!" and. ‘0‘ 3*“ I «9% a PRESENTATION OF DATA PRESENTATION OF DATA Four to six runs with glass tubes for moisture samples, were used to determine drying rates for each bed thickness. Each run was plotted on a moisture-time graph. The slope of the constant rate period was deter- mined by the method of least squares. Plots for each bed thickness were correlated to obtain similar mois- ture content at zero time. The correlated data was plot- ted on a composite moisture-time graph for each thickness (Graphs No. l, 2 and 5). The method of least squares was again used to determine the slope of the constant rate period. The curved portion of each plot was drawn in such a way as to represent the average of the points. Drying rates for each bed were calculated from these graphs, using the slope or dw/dO’to represent the rate, at any instant. The rates were plotted against moisture content on graph No. 4. Heat transfer coefficients were calculated from the amount of steam condensed and were plotted against average moisture content for each bed (Graphs No. 5A, 5B and 6A). A smooth curve was drawn through the points with a straight line to represent the average of the points during the period of constant hot surface moisture content. Four to six other runs with iron-micarta sample units 49 50 were used for each bed thickness to determine layer moistures. This data was grouped for each bed, in such a way that samples of similar composite moisture con— tent were averaged in two per cent moisture intervals. (For example: all samples between 14 and 16 per cent were grouped in one interval). These groups were all plotted on individual layer moisture content-height a- bove plate graphs. A smooth curve was drawn through the points. This was repeated for each group and the smoothed curves plotted on a composite layer moisture-height above plate graph (Graphs No. 7, 8 and 9). The moisture con- tent of the layer closest to the surface and the mois- ture content of the layer of maximum moisture were plot- ted against composite moisture for each bed (Graphs No. 10, 11 and 12). I Heat transfer coefficients were plotted against hot surface moisture contents (Graph No. 6B). These values were taken at the same average moisture contents. Two to four tests were made to determine tempera— ture distribution within the beds. Temperatures were plotted against height above the plate at various mois- ture contents (Graphs No. 15, 14 and 15). A special plot showing the difference in drying times between the iron-micarta units and the glass units was shown by graph No. 16. oh;a.v%uifll—"'-‘ 20w— g... m 1 -Dry Basic 5 E s: a: l J. L l Relaturt Percent: °1° Graph NO. 1 Moisture Content vs. Time % inch Sand Bed 51 5.. 4- .;' - . 2_. '\\\TT\“\;.“§~“-—___;. o 1 L J J 1 J l L 1 . o 1 r2 T5 '4 I5 e d 93 e ‘12) Time-Minutes Graph No. 2 Moisture Content vs. Time 1 inch Sand Bed L l J L J l L L 1 I l T U T J l 1 r 0 5 6 9 12 15 18 21 21+ 27 50 Time - Minutes 0 % 52 loin-ture Percentage - Dry Basis P‘ h: P‘ h’ n) n: A) e- o» «m <3 In 1 n_ l J { 1 g... 0 l Graph No. 3 ioisture Content vs. Time 1% inch Sand Bed Time - Minutes 53 54 Graph N00 1'" Drying Rates vs. Moisture Contents aw“ J 1 L L 1 T T j T l 10 12 11+ 16 18 ‘//1 inch Sand Bed Drying Rate - Water/Hr.-Yt2 1:111; 1012141618 //¥% ingh Sand Be§;__ 4 l 1 IL EU" 1 £6 12 1'4 lr618 Moisture Percentage - Dry Basis Graph No. 5 Heat Transfer Coefficients vs. Moisture Content 1 l T I l T _1 T J 1 F l 10 11 12 13 14 15 16- I? i I ._4._c»\ 2 '3 m m “”‘D '2 '2 e a! Ebb W U, s : +~o L": Q "—1 .4 H '1“ 1'“ I I q a: fl“? an "5 \an .- can-N I r I .1 4. .1 1 + : I. o 300 200 100 0 400 300 200 100 0 Heat Transfer Coefficients- Btu./Hr.-Ft.2~°F 55 Moisture Percentage -JDry Basis 56 Aoommndm pom map nag «flown ha: I omaaneouom.ouspe«oz ms nu on ma «H nfi NH MA on a w v o m w n F .1 F L p u _ __ +, u u _ _ _ _ _ _ _ . . n l _ 1 u.\n . [don Graph NO 0 6 Heat Transfer Coefficients Moisture Content VS. 0H rd fl 4 0.. ”m.~$ moon csom conga HHd I no A: A: .2" n." NH Anona w _ A b J p m _ m p _ . H — 1 p _ q . b — _ o F _ “41"“ com seem son“ 6“ a do I :1 o» N l d» O n J a O \‘l' a» Heat Transfer Coefficients- Btu./Hr.-Ft. 2_0F OOH cow con Layer Moisture Percentage - 9:: Basis 57 Graph No. 7 Layer Moisture vs. Height Above Plate % inch Sand Bed ' 22~~ 20-» 19%, . // ‘.\ 184b/z". , 16~~ Haul..- 1.44%“.h‘ 13%: . \\. K.\ 124.... \m \\ eh; 1.....0/ \o\.~].gz’a. ' ./ 10-: "‘ ° 8 .\. O--~alrgg§é Average Moisture 6% \° “"'/ __../ fl. 4%.\ ./ 4-4:” \I: 1......- 2.” 0 'r - J % : Jr 0 .10 .210 .30 .40 .50 Distance From Hot Plate - Inches Layer Hoiature Percentage - Dry Basia 58 Graph No. 8 Layer Moisture va. Height Above Plate 1 inch Sand Bed 22-— , /—-—-\ \ 20-”- /. 18~-;/‘/ 161+- /: 1 % '\-\I ,////:/”””fl.}3% .‘~“‘-~. 14-1:/0/./ \. \0\ 12 4%‘--——-—.\}1}’!}6 Average Moisture °\ .\, .10% e‘_____O#e/ 10";\ \. \.._ ”48% \OWO/ 8—0—— \ 6% 0M.#.’ “._______,.._, .\. 6“ % 4+ 2-v— o : 4 % I. % : : : : I. O .1 02 .3 e4 .5 ‘ e6 e7 .8 .9 1.0 Distance From Hot Plate - Inches Layer Hoieture Percentage . Dry Basie -— 59 Graph NO e 9 Layer Moisture vs. Height Above Plate 1% inch Sand Bed l J l 1 l L L L L l l l 1 1 1 I l .5 .4 .5 .6 .7 .8 .9 1.01.112 L3 1.4 1.5 Distance From Hot Plate - Inches Layer Moisture Bercentege -Dry leeie 20—» qur 16—— 14s~ lZsb 10~- 8+ 64- Graph No. 10 Layer Moisture vs. Composite Moisture % inch Sand Bed 1/16" Above ' Plate \ cad 5/8" Above Plate J L ll 6O #20 ~18 L-.‘l.6 ~14 p12 ~10 O I I I I J L I I r r 4 8 10 12 14 16 18 l I 2 l I 6 Composite Moisture Percentage - Dry Basis Layer Hoieture Percentage - Dry Basis Layer Moisture Percentage - Dry Basis 61 Graph No. 11 Layer Moisture vs. Composite Moisture 1 inch Sand Bed 20» 184— 16“- 1/16" Above /////// ' Plate . 14+ \ 124— Read 10—— 61 8+- '3 I5 m _ m 3.. C! I 4"_ 0 on . 95 . .p 2~~ -. g 0 y/// a . O 0'4- " —I- 8 9" / ° :7. Re d 3 / " I": ‘b 6 3 fl . o z: r_ z; a 0 v. ---1* 2 S l J I l J I L I 1 0 I I g I I I I I I O 2 4 8 10 12 14 16 18 Composite Moisture Percentage - Dry Basis Layer Moisture Percentage - Dry Basie Graph Ho. 12 Layer Moisture vs. 62 Composite Moisture 1% inch Sand Bed 20-. 18‘- 6l‘ 1/16" Above Plate l4