Ml l“ I ll‘hNMlHNMl \ ,— ‘ _,__’ 4’ ——f‘" __. ‘_ ___ _._ ‘ “WWW \ \Ix 144 670 THS EFFECT OF ULTRA§GHECS ON HEAT YRANSFER I.“ § I - P .2 m g ', P 2:29.313 1'3? 1:2 Dag-rag o: M. 3):. ‘e ‘I-(uéu? ; iq‘sr 11fi t‘fy,9?vfi"!€ «'9‘, :‘sil‘vizém 32.3.7232. u:‘¥:2‘“§.§‘ Anamdrac Fanciumng Deshmukh 1956 .29.“: II mum; 11:1»ng m: 1: g; :3 1171: it» will 11;: .‘fa (“mygg'gx (64:: €513 q Ch‘fieg‘W 5% 'fi “3’ OVERDUE FINES: 25¢ per day per item RETURNING LIBRARY MATERIALS: Place in book return to remove charge from circulation records EFFECT OF ULTRASONICS ON.HEAT TRANSFER By Anandreo Pendurang.ggehmukh A THESIS g I, u ‘ Submitted to the School of Agriculture of Michigan.3tete University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agriculturel Engineering 1956 EFFECT OF ULTRASONICS ON REAT TRANSFER By Anandrao Pandurang Deshmukh AN ABSTRACT Submitted to the School of Agriculture of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agricultural Engineering 1956 Approved by wfi/ M4 4/7/44 ACKNOWLEDGMENTS The author wishes to express his sincere appreciation to his major professor, Dr. Carl H. Hall of the Agricultural Engineering Department, under whose assistance and supervision the research work was conducted. The author is grateful to Dr. Arthur W. Farrell and his staff for making materials, equipment and facilities available for this study. The writer also appreciates the valuable assistance rendered by Mr. Leon J. Newcomer for acquainting the author with the ultrasonic generator. Thanks are due to Dr. Egon A. Hiedeman and Mr. Hack A. Breezeale of the Department of Physics for their valuable suggestions. Thanks is expressed to Mr. James Cawood, foreman of the Agricultural Engineering Research Laboratory, and laboratory workmen for their valuable assistance. Anandrao Pandurang Deshmukh ABSTRACT I The ulthmate goal was to study the effect of an ultra- sonic field on the rate of heat transfer. The specific tepics investigated were the application of ultrasonic waves parallel to and perpendicular to heat transfer surfaces. A commercially constructed ultrasonic generator was used to generate ultrasonic waves. An electric immersion pyrex glass sheathed cylindrical water heater was used to heat the water. Temperatures at various positions were measured by thermocouples. Ceramic discs and tube transducers were used to produce ultrasonic waves. The amount of heat input by ultrasonics was measured by the calorimetric method. With the disc transducer at a frequency of #00 kilocycles, there was no appreciable effect on the rate of heat transfer. At this frequency ultrasonic energy is low and has no advan- tage on the rate of heat transfer. Uith the transducer at a frequency of 1000 kilocycles there was a definite increase in the rate of heat transfer as compared to the results without ultrasonic energy. The rate of heat transfer was proportion- ately increased with an increase in ultrasonic power up to 50 ma ultrasonic generator output, and decreased above 50 me. In an ultrasonic field the system.came to steady state in 8 to 10 percent less time as compared to the time required to come to steady state without the ultrasonic field. The rate of heat transfer observed was 18.6 percent more with the heater output of h.watts and 50 ma ultrasonic energy than the sum of the individual effects. This percentage was decreased with Anandrao Pandurang Deshmukh 2 increased heater watts and increased ultrasonic energy. Low ultrasonic energy of 15 ma had no effect on the rate of heat transfer. Hhen the tube transducer with 6&0 kilocycle resonance frequency was used for a series of tests the temperature drop was 2-3 degrees F. higher on the heater surface in trials with heater only as compared to 50 me ultrasonic field and h watts heater power. This indicates reduction in fluid film resis- tance. The ultrasonic energy input per unit surface area was:much smaller with the tube transducer as compared to the disc trans- ducer. With the tube transducer at 25, 50, and'75 ma, water became heated in 25 percent less time than without ultrasonics with h, 6, and 8 watts heater power. There was no measurable variation in temperature at various distances from the trans- dhcer in liquids, which indicates uniform heating in ultra- sonic field with the tube transducer. TABLE OF CONTENTS INTRODUCTION . . . . . . . . . . . . OBJECTIWS C O O O O O O O O O O 0 REVIEW OF LITERATURE . . . . . . . . . Loss of Energy in Ultrasonics . . Ultrasonic Output . . . . . . Ultrasonic Velocities in Liquids and THEORETICAL PRINCIPLbS . . . . . . . . TEST I O O O O O O O O O O O O O O 0 Procedure . . . . . . . . . . . . Apparatus e e e e e e e e e e e e Re 8111138 e e e e e e e e e e e e Conclusions . . . . . . . . . . . EST I I O O O O O O O O O O O O O O 0 Procedure Results . . . Conclusion e e e e e e e e e e e TEST III 0 O O O O O O O O O O O O O 0 Procedure . . . . . . . . . . . . Re 81.11138 e Conclusions SUMMARY AND CONCLUSIONS . . . . . . . . Summary . . Conclusions . . . . . . . . . . . BI BLI WRAP II! I O O O O O O 0 O O O O ”PMDIX A O O O O O O O O O O O O ”PMDIX B O O O O O O O O O 0 O O O O O O O O O 0 O O O O O O 0 Cases 0 O O O O O O O O O O O 0 O O O O O O O O O O O 0 O O O 0 O O O O O O O O O O O O O O O O O O O O O . O o O O O O O O O 0 LIST OF FIGURES FIGURE PAGE 1. Principal apparatus used for procedure I and 11...... 16 2. Transducer assembly for procedure I and II........... 16 3. Section through transducer and tube showing agitation arrangement for procedure I and II.................. 17 h. Oscillator circuit................................... 19 5. Time temperature curves for different watts of heater element............................................. 20 6. Time temperature curves for ultrasonic energy only... 21 7. Time temperature curves for h heater watts and 0-75 ma ultrasonic energy................................ 22 8. Rate of heat transfer by ultrasonic energy only...... 25 9. Rate of heat transfer at h heater watts plus ultrasonic energy, 0-75 ma..................................... 27 10. Time temperature curves for ultrasonic energy........ 35 11. Time temperature curves for disc transducer.......... 36 12. Principal apparatus used for procedure III........... no 13. Time temperature curves for tube transducer (t2)..... N1 In. Time temperature curves for tube transducer.......... h2 LIST OF TABLES TABLE I. II. III. IV. V. VI. VII. Heater element performance......................... Ultrasonic wave length in water.................... Mean temperature difference at the outside surface or the tubOOOOOOOCOOOOOOOOOOOOOOOIOOOOOOOOOOOOOOOO Rate of heat transfer at 1000 kilocycles........... Saving of heat energy by ultrasonics............... Mean temperature difference per hour at the tube surfaCOOOOOOOOOO0.0.0.000...0.00.00.00.00...COO... Amount of heat transferred per hour by the tube.... PAGE 18 18 23 ‘3“ 26 33 31+ INTRODUCTION The field of ultrasonics is relatively new yet it has been found to have wide scientific technical applications. Over 1500 papers have been presented on different aspects of ultra- sonics. Ultrasonic waves are sound waves of a frequency above the audible range. In early literature concerning this sub- ject the term.'supersonics” and occasionally 'suprasonics" was used by some authors instead of ”ultrasonics." I There is no fundamental physical difference between ultra- sonics and audible sound waves. The human ear hears sounds up to 20,000 cycles per sec. Ultrasonic waves are compressional waves with frequencies ranging from 20 to 500,000 kilocycles per sec. It is apparent that the term.defines a tremendous range in both frequency and wave length. In the minimum.frequency range the length of ultrasonic waves in solids is about 8 in.; in liquids, about 2.h in.; in gases, about .63 in. In maximum.frequency range the wave length approached a value in solids of 3.2 x 10'“ in.; in liquids, l x 10'“ in.; in gases, 2h x 10’“ in. The higher the frequency the shorter is the wave length. Though there is no fundamental physical difference between sound waves of low, medium.and high frequencies, great differ- ences exist in the ease with which high intensities may be produced and the ease with which the sonic energy may be trans- mitted to the system under investigation. Absorption of high frequencies is much faster than or stronger than that of lower frequency waves. At extremely high frequencies the energy losses due to absorption become excessive. The amplitude necessary to transmit a given quan- tity of energy at low frequency is greater than those at high- er frequency. Sound waves of great intensity may bring about many kinds of phenomena such as emulsification of two bulk liquid phases, peptization, destruction of bacteria, disin- tegration of certain solids, coagulation, production of chemi- cal reactions, production of heating effects, agitation, stimulation of plant growth, submarine signaling, and communi- cations. All frequencies are suitable for the investigation of the physical properties of matter. There is a great concentration of energy in these waves. Bergman (21) shows intensity of 10 watts/sq. one is uiu;l, as compared to-lo”lo watts/sq. cm. with audible sound waves. The shorter ultrasonic waves are of the same order of magnitude as light waves. Ultrasonics is mostly used for agitation in this work. The writer's attention was directed to investigate the effects which ultrasonics mdght have upon heat transfer in liquids. Previous work (26) has shown that ultrasonics used in quenching oil bath has a good effect on the quality of metal and that the time of cooling is decreased as ultrasonics breaks down the gaseous layers along the metal surfaces. OBJECTIVES Numerous investigations have shown that the problem.in- volving gases and liquids in contact with heat transfer surface the overall heat conductivity of wall is greatly affected by the conductivity of surface film of the fluid to be heated. Thus the conductivity of the metal is less important than the conductivity of the surface film. The uniform heating is not always easy with conventional methods of heating, whether the heating may be water, oil or milk. The major difficulty lies in formation of layer of in- sulating liquid at the heater surface, the instant it is imp mersed, and as the layer may remain longer on some sections of a part than others, chances for uneven heating are increased. Experience has shown that the resistance can be reduced by any treatment which reduces the film.thickness. Agitation helped to break down liquid film and increases heating effec- tiveness. Any method of further increasing turbulence and re- ducing the film layer more quickly and uniformly would be an improvement. Liquid particles are in violent motion under ultrasonic vibration and should give rapid heating. More energy can be put into the liquid by ultrasonics than by agi- tation while keeping the solution in the vat. In consideration of these factors, a hypothesis is devel- oped wherein it is proposed that there will be 1) a decrease in the time of heating, 2) a uniform heating by ultrasonics, or 3) an increase in the rate of heat transfer. REVIEW OF LITERATURE Agitation by ultrasonic means is well known'in certain fields, especially in the chemical field. High frequencies are more readily absorbed in the agitated systemm (22). The field of ultrasonic agitation is one of the most promising. Ultrasonic waves have been found to cause pressure so large that the resulting mechanical stresses may be as much as 15,000 times the hydrostatic pressure. In agitation there is very little liquid to penetrate and therefore little ab- sorption. At the inter-face between the liquid and air the waves fly the liquid up into the air in the form.of fine drops. Emulsification by ultrasonic waves was first described by Hood and Loomis (21). However they dealt principally with qualitative observations of the phenomena and reported little concerning qualitative values of Optimum frequency, minimum.energy requirements, physical conditions for efficient irradiation. ‘H. T. Richards (21) has investigated such actions and it has been shown that the mixing is strongest at the boun- daries of the system, i.e., between the walls of the container and liquid and also between the liquid and vibrating system. Paulsen (2h) noticed heating as well as cavitation by ultrasonics. Lord Rayleigh originally pointed out that when a liquid is undergoing ultrasonic irradiation, a strong hissing noise should be heard. U. R. Weed and Loomis (23) showed the amount of power being impressed on a liquid bath can be meas- ured calorimetrically or electrically by noting the power I dissipated in the driving oscillator. The amount of energy needed to give the measured rise in temperature is the actual ultrasonic wattage. The larger the body of liquid.the greater the amount of total heat absorbed in it, although the tempera- ture rise may be greater in smaller amounts of material. Methods of measuring ultrasonic energy are l. Calorimetric method - mostly used in oil bath 2. Electric method 3. Glass disc method a. Suspending balance method 5. Echo method - pulse system According to flood the increase in temperature may reach a point where it increases a degree every few seconds. Ordi- narily, the center of oil exhibits the greatest amount of heat, and small bubbles of gas form.this point. Loss of Energy in Ultrasonics The dissipation of energy in an ultrasonic system is primarily due to the viscosity and damping of the liquid. The greatest amount of energy is commonly produced in ultra- sonics by the systems which are designed for agitation. Freundlich H. K. Seller (21), obtained about 300 watts in such a system, using transducer 60-70 cm. across their faces. Most of the ultrasonic energy measurements are made by noting the rise in temperature in the medium. A number of investiga- tors have reported obtaining energy of 10 watts per sq. cm. (22, 26). Ultrasonic Output Sokolove (2h) stated that the ultrasonic output is pro- portional to the square of amplitude of oscillation and to the cross-sectional area of the crystal. The larger the plate the more easily it is destroyed by excessive vibration because of its more homogeneous nature. Limitation to the output is set by the point at which the crystal ruptures. Polished faces and square edges give maximum output of ultrasonic energy. Almost instantaneous film elimination with marked improve- ment in quenching effectiveness, was the claim of Richard F. Harvey (26), Massachusetts metallurgist, who had used high fre- quency sound at high intensity for agitation. This method re- sulted in a greater uniform cooling. The range of vibration frequencies was wide from.100 kilocycles to 5 megacycles per second. Minimum.power requirement was about 25 watts per square inch of metal surface being quenched. Ultrasonic Velocities in Liquids and Cases Only longitudinal waves can be transmitted in liquids and gases. In such cases it is usually assumed that the vibrations take place too rapidly for heat to exchange. The velocity either in liquids or gases is then 2 )( ’““‘“ C V755 : 57%;; K -,ratio of specific heats, I I lb/cu. ft. Bis 8 compressibility at constant temperature Bad 8 adiabatic compressibility Measurement of velocities is made in liquids in order to get an idea of their chemical and physical characteristics. Ultrasonic velocity in liquids is the function of tempera- ture and pressure, and some methods of measuring ultrasonic velocities are as follows: 1) Interferometer is used for both liquids and gases, and 2) Pulse method has been more recently applied, and the time of travel of a pulse is measured. Frequency and Wave Length The usual relation among frequency, velocity, and wave- length holds for ultrasonic waves. They are related as 1.2 f A 8 wavelength, meter c c velocity, meter/sec. f - frequency, cycles/sec. THEORETICAL PRINCIPLES The basic principles upon which this study is based is the rapid removal of surface film which normally acts as a resistance to heat transfer. The overall conductivity of the heat-transfer wall is greatly affected by the conductivity of the surface film of the heating fluids. In a tin-walled apparatus such as pastuerizer, the actual heat transfer of stainless-steel vat is almost equal to that of tinned copper vat, even though the conductivity of copper is 9 to 10 times that of stainless steel. The conductivity can be greatly increased if the liquid film is removed rapidly. Viscous products heat or cool much slower in heating or cooling tank. In studying these problems it has been shown that when a liquid is in contact with a solid wall, there is a relatively stationery film.or fluid adhering on the surface of the solid. The film.thickness is decreased as the liquid is agitated and moved away from.the solid wall. Heat is transmitted only by conduction through this film, although as soon as heat pene- trates the film, the heated portion is picked up and moved into the main body of the fluid. . 10 TEST I Procedure The apparatus was set up as shown in Figure l. The trans- ducer used was 1000 kilocycle frequency and was fixed in a steel holder. Coaxial wire was connected to the transducer as shown in Figure l. A tinned cOpper tube which served as a water con- tainer, was fixed on the steel holder. In the beginning a few tests were made to determine the resonant frequency of the transducer. Then water heater was calibrated for h to 12 watts of power. The heater was immersed in water to l/u inch from the transducer. Four thermocouples were placed at various depths to measure the temperature of water. One thermocouple (t1) was on the heater surface, the second (t2) was in between the heater surface and inside sur- face of the tube, (t3) was on the inside surface of the tube, and (151;) was on the outside surface of the tube. All these thermocouples were at a distance of h in. above the transducer. The temperatures at various depths were recorded by means of a previously calibrated potentiometer. The input power of the heater was adjusted by means of variac and input ultrasonic energy was adjusted by means of variac which was on the generator. Tests were made to deter- mine the rate of heat gain and transfer by ultrasonics only by 11 noting the rise in temperature of water at regular intervals. Ultrasonic energy was used with a 15 to 100 ms of generator input. Output ultrasonic energy was measured by calorimetric and electric methods. The combination of heater and ultra- sonic energy was used to determine the rate of heat transfer. In all of these trials the initial temperature of water was 8h° F. and the amount of water was the same for procedure Tests I and II. Tests were run until steady state was reached. The maximum temperature of water was below 172° F. Room.temp perature was between 80-85° F. Variables studied in these trials were output of ultrasonic energy, power of heater watts, and temperature of water. Apparatus The apparatus shown in Figure l was used for Tests I and II. It consisted of ultrasonic generator (B), transducer assembly (A), in which the liquid was agitated with hOO and 1000 kilocycles/sec. The actual amount of ultrasonic energy was measured by calorimetric method. Thermocouples t1, t2, t3, and th were placed to measure the temperatures at various positions. Electric immersion pyrex brand glass sheath water heater (C) was used to heat the liquid; tinned copper tube was used as a water container; potentiometer (D) was used to measure the temperature of thermocouples. Variac (E) was used to change the voltage from 110 volts to desired voltage, i.e. 12 10-20 volts. Ammeter (F) was used to measure the current passing through the water heater. From knowing the current and the applied voltage to the water heater power input by the heater was calculated. Milliammeter on the generator in- dicates the current strength of the ultrasonic energy to the transducer. Since the physical dimensions of the barium titanate transducer element determines the ultrasonic frequency it is necessary to tune the generator output frequency to ‘match the natural frequency of the transducer. This was done with dial (G). The output current of the generator was ad- Justed with the dial (I). The ultrasonic energy was trans- mitted from.the generator to the transducer through the co- axial cable (J). The output of the generator through the water sample was also reported through milliammeters. The output current of the generator was reported here in milli- mmperee. Milliammeter is provided frome to 300 ma. This reads the cathode current of the oscillator. In Figure 2 a more detailed view of the transducer assembly is shown. Barium.titanate, (A), crystal holder, steel base (B), leads connecting to the coaxial cable (C), insulation which is around the crystal (D). The generator and the transducers have the following specifications: Generator: Model - Bu 20h Mfg. by Brush Electronic Company, Cleveland, Ohio 13 Power input c 115 volts, 6.5 amps., 660 watts, 60 cycles, single phase, A.C. Output frequency = tuning drawer (B), 300 to 1000 kc. Generator circuit = self-excited Hartley oscillator. Transducers (disc): Model = 5530143 and 553053 Mfg. by Brush Electronics Company, Cleveland, Ohio Type of element - barium titanate ceramic B, elements disc type. Resonance frequency 8 998 kc and hOO kc. Element thickness ' .10 in. and .27 in. 2.5 mm. 6.75 mm. Area of transducer - .785 sq. in. and .785 sq. in. including insulation. .628 sq. in. without insulation. wave length at resonance frequency t 'water I 100 kc #00 kc .06 in. .15 in. gas ' .OOlh in. .068 in. steel 8 .23h in. .58 in. Transducer (tgbgl: Model - 553h7B Mfg. by Brush Electronics Company Type of element - barium.titanate ceramic B Resonance frequency a 630 kc. Thickness 8 .125 in. or 3.125 mm. Inside area I 5.88 sq. cm. Have length at 6&0 kilocycles - 1.0 in. Tube specifications: Material - tinned copper Weight of tube: 387.6 gm. Specific heat of tube: .093 BTU/deg. F. per 1b. Emmissivity of tube: .28 ‘ Outside diameter I 1.5 in. Inside diameter I 1.37 in. Length of tube I 7 in. Outside area of tube I 33 sq. in. Inside area of tube I 30.1 sq. in. The following equation is used to find the amount of heat transferred to water: ‘1 . (At) (wt.) (sp. H ) <1 I heat transferred BTU/hr. At I mean temperature difference, deg. F. wt I weight of water in pounds Sp. H.I specific heat of material, BTU/lb. deg. F. q - (15) 118 (.998) - 3.9 BTU/hr. Amount of heat energy input by heater was measured by watt-meter. watts I E I cose E I applied volts I I current amps BI phase angle Ultrasonic energy was measured by calorimetric method and electric method. Calorimetric method: Heat given out by ultrasonic was used to raise the tem- perature of water and the container. Heat lost I (heat gained by water + heat gained by container) Heat gained by water [33%. 1 I? - 11.8 BTU/hr. Heat gained by the tube q IAt (wt.) (Sp. h.) I 10 x 89.6 x .093 x 60 ’33-'53. TE . .31 BTU/hr. Electric method: watts I volts x amps x cose I 38 x .078 x .9 x b.316 - 10.08 BTU/hr. __.—_~ Fig. 1:— Principal apparatus us;d for procedure I and II. Fig. 2. Transducer assembly for procedure I and II. 16 17 val N1 "’ Styrofoam ~-> Heater *—‘Thermocoup1e Tinned copper tube ~———+ Steel base coaxial cable I V // N f r".‘.:14‘ 11: /,'//:,/.3,§7 /» ' " ' ~ 11L ;.'.; ' I 1 9 J E .5 .F = 4 i I j 3' : ! ' E ' ' R :i I v . -4, J4..--. if V 6455 i5 V v s _l ; V c i In: N 5 5 i 5 L2 ” .--- .I -JIJ YSTAL F 7//////// Ill/If / F180 30 Section through transducer and tube showing agitation arrangement for procedure I and II. 18 TABLE I HEATER ELEMENT PERFORMANCE Watts nggtgggure Maxgmflz Tgmgggziure ( F) (mdnutes) h 106.5 . 120 5 110.5 110 6 115.5 120 7 121.0 110 8 126.0 130 9 130.0 120 10 133.0 130 11 137.0 120 12 180.0 120 TABLE II ULTRASONIC HAVE LENGTH IN HATER Frequency Wave Length 100 kilocycles . l.h3 cm 200 " .725 ' 500 8 .286 " 600 " .2hl " 700 " .26h * 1000 " .1h3 19 C ——1—— .-_:::_:. -_ -- _ (ma w H:- g E .1- I a LiNK CRYSTAL-1:13 ; - MC I‘I—J I ___ V .1. _____._-‘ -L I ”T is ‘ '. M wsv "15v 300v tooov (000‘ 300V -45y I|r Oscillator circuit. Fig. 14.. 20 .udofioao houses no apps: HGOHOHHHU sou oceans mopsuaz oo oadpsnoasop cede .maa do - eanqvaedmem 21 .hano amneCo 0H 0.: command: now mo>hdo mouse 0&5 peaches» 05 Ha do - eanqeaedmem 22 one .hwaomo camomsapas oases season 3 non aophdo oanpsaodaep cede mended: .5 .mE H H do - canqsaedmem NH 23 100 ma 75 ma 25 ma 50 ms TABLE III 15 ma SURFACE OF THE TUBE MEAN TEMPERATURE DIFFERENCE AT THE OUTSIDE 0 ma* Heater (watts) Time (min.) 20 80 120 39.0 19.0 .5 000 C C O 512 21 005 070 19.0 6.0 1.5 005 O C C 20 80 120 20 120 .75 h5.0 28.0 37.0 15.0 1.5 20 80 120 # mm - milliamps TABLE IV RATE OF hEAT TRANSFER AT 1000 KILOCYCLES BTU/hr Time Heater 0 ma 15 ma 25 ms 50 ma 75 ms 100 ms (min.) (watts) 20 O O 0.261 1.0h 2.87 5.00 6.82 80 0 0 0.196 0.65 2.61 n.16 h.95 120 0 O 0.131 0.261 1.uh 1.70 0.52 20 h h-h 8.95 5.21 6.52 7.8 -- 80 l). 1031 1057 1.86 2087 (+095 "" 120 h 0.39 0.39 .139 .531 .131 -- 20 6 6.8 8.35 9.1h 9.65 10.h -- 80 6 201.). 201]. 203“- ueLIJJ. -" "" 120 6 0.522 0261 e 261 0261 -- '- 20 8 8.6 8.86 9.h 9.65 11.72 -- 80 8 2.862 3.39 3.39 3.91 7.30 -- 120 8 .915 .261 .131 0.39 .21 -- 20 10 9.h 10.2 11.2 11.7 -- ~- 80 10 3.9 h.16 6.80 -- -- -- 120 10 1.31 1.31 1.56 3.0 -- -- 25 .maco hwuoce eacomah H5 ho noumaea soured amen Ho ow 26 mm.o mo.e one m.~e one mme . om mn.o me.o oee om.oe owe m.nne g mm oe.o no.o one m~.oe one m.mne a me o.o o.o mne oe mne :ne oe o mo.o oe.n ome o.me oee «me a ma on.o mo.e one m~.o ooe one a on oo.o me.o one ma.n oee one . mm nn.o ao.o ome :e.m oee m.-e g me o.o o.o owe o.one oee :me n o m .o me.n one o.oe ome .ome . mu m .o mo.e oee o.o owe o.ome 2 om mm.o me.o oee o.~ owe o.ome . mm ne.o ao.o one m~.o oo o.mee a me o.o o.o ooe o.o oee m.mee o o ~m.o oe.n owe o.m ome one . ma mn.e mo.e ome mo.~ oee m.eme g om mm.o me.o oee o.m oee ooe . mm nn.o ao.o one :.: oee m.aoe a me o.o o.o ome o.: owe o.ooe e o o a o m e n m e eaopsaes. .uopsses. ..a.. «n+mvum m m cadeoo me nonconsauab noncomsapap an as: cannon Ge egpsaodaea + Meadow he. + acumen mac A0305 ogpsaogoa modem om. 055090309 by monomer. 03.03 AmoSsSHeEv Ho .3905 modem poneeeaom .3 modem 0.2593385 maefim hwaenm mafia oecousaudb op 03am. upper. on 082. gang meadow canonsapab MOHzomdeqD Hm wag 95 mo 0555“ > H.349 27 oeeoasapes o..e mafia apps: acumen .ea mwuo .hmneao pa newsman» been no ovum sensed: cm 0 28 Results It appears from Figure 5 that the increase in temperature is proportional to the input power of the water heater. The rate of increase in temperature is higher in the beginning of the trial and gradually decreases with the increase in time of the trial. The tube comes to steady state after 110 to 120 minutes. At higher heater power the time for rapid in- crease in temperature is longer as compared to low power of the heater. Figure 6 shows ultrasonic energy increases the temperature of the tank. The increase in temperature at 15 milliamp output is negligible. As the output of ultrasonic energy was increased, the increase in temperature was increased. The rate of increase in temperature was much faster at higher output of ultrasonic energy. The proportion of increase in temperature is proportionately higher at higher output of ultrasonic energy. The time to come to steady state was less for 50 me of ultrasonic energy than 25 and 100 ma. The time for the tube to come to steady state was slightly less with the trial of ultrasonic energy than with the trial without ultrasonic energy. The rate of heat transfer was higher at 20 minutes time than 80 and 120 minutes. This rate was de- creased with increased time length of the trial. The rate of heat transfer increased with increased ultrasonic energy and with the increased power of the heater up to a certain limit. The combination of ultrasonics and heater has shown 29 higher rate of heat transfer than the sum of the individuals. Figure 7 shows the combination of heater and ultrasonic energy appears more effective at 50 ma ultrasonic energy output. It is clear that the change in temperature at h watts plus 50 me was much more than higher watts plus 50 ma. The temperature difference was 22° F as compared with 16° F in ultrasonic- energy only for the same heater power, though the more heat was given out by convection at higher temperature. Table V shows the amount of heat transferred in various 'trials. From column six it appears that more heat energy was transferred in the combination of h watts and 50 me. It ap- peared 50 ma might be critical ultrasonic energy for 1000 ’kilocycle frequency. Conclusions In conclusion it is believed that 1) Most of the tests required 110 to 120 minutes to come to the steady state. Tests with ultrasonic energy came to steady state 8 to 10 percent earlier than only heater watts. Output ultrasonic energy was not proportional to the input power of the generator. 2) Lower heater watts and 50 ms ultrasonic energy gave best advantage. The wattage combination of heater and ultrasonic 5.65 watts, which gave the same heating effect of 7 watts of heater alone. The above combination of heater and ultrasonics was for 118.h gm. cc's of water. The optimum combination for 30 this quantity of water was obtained with ultrasonics of 72 cc per watt and for heater, 30 cc per watt. 3) Lower heater watts of u and 50 ma ultrasonic energy gave best advantage. Low ultrasonic energy of 15 ma had negligible effect on the rate of heat transfer. In ultrasonic field, uniform heating was observed. Temperature drop on the heater surface waleSdegrees F higher in heater tests than with ultrasonic tests for h watts and 50 ma. 31 TEST II Procedure The apparatus used was the same as was used in procedure I except a transducer with a frequency of h00 kilocycles having .27 in. thickness. The outside diameter of transducer was 1.5 in. and made of barium titanate. The transducer was mounted as shown in Figure 2. Tests were run to find the effect of ultrasonic energy on the change in temperature of water. It has shown that low ultrasonic energy of below 50 ma has no effect on the temperature rise of water more than two degrees F. Tests were run to find the effect of 50, 75, and 100 ma. ultra- sonic energy and they were used in combination with low heater energy. Results In these trials 25 and 50 ma of generator output did not show appreciable change in temperature of water. At this fre- quency ultrasonic energy was not enough to cause rapid agitation. Ultrasonic energy is less concentrated as compared to 1000 kilocycle frequency. In trial of h watts of resistance heater and 25 and 50 ma ultrasonic had no advantage over only A watts of heater. 32 The change in temperature by ultrasonic energy was not more than 8 degrees F. at 100 ma generator output. The increase in temperature was 2.5 degrees F. per additional 25 ms ultra- sonic energy. The combination of heater watts and ultrasonic energy did not show any better results at hOO kilocycle fre- quency on the rate of heat transfer. Mean temperature differ- ence was higher at 20 minutes time and gradually decreased with increased length of time. The mean temperature difference at 20 minutes time was almost the same for 50, 75 and 100 ma ultra- sonic energy. All of the tests came to steady state after 110 to 120 minutes. Below 50 ma ultrasonic energy had no effect on the rise in temperature of water. The rate of heat trans- fer was the same in tests of heaten,and combination of heater and ultrasonics. Conclusion For frequency of h00 kilocycles there was no increase Vin the rate of heat transfer for using electric resistance heater. Heater power was from 0-10 watts and ultrasonic power for O to 100 ma. At hOO kilocycles the ultrasonic energy may not be enough to cause rapid agitation and to break down the fluid fihm. Ultrasonic energy raised the temperature of water by 7.8° at 100 ms generator output. 33 TABLE VI MEAN TEMPERATURE DIFFERENCE PER HOUR AT THE TUBE SURFACE Frequency - ROO kc. Disc transducer Combination of heater watts and ultrasonic energy Time Heater 0 ms 50 ms 7 ma 100 ma (min.) (watts) (°F) (°F) (°F) (°F) '20 0 o 3.5 3.5 3.5 80 0 O 2.5 2 2.5 120 0 0 0.5 1 1 20 1+ 21 2h 21+ 21+ 80 h 7.5 5.5 7 12 120 h 1 1 1 3 20 6 25 30 38 36 80 6 15 1ho5 13 12 120 6 1.5 .2.0 2.5 2.8 20 8 39 39 39 39 80 8 10 '10 13 13 120 g 8 1.5 1.5 2.5 2.5 3h TABLE VII RATE OF HEAT TRANSFERRED PER HOUR BY THE TUBE ‘t— .3 I _‘— Time Heater BTU/hr. (min.) (watts) 0 ma 50 ma 75 ma 100 ma 20 0 0 .91 0.92 .92 80 0 0 .65 .522 .65 120 0 o .13 .261 .261 20 u 5.15 6.25 6.25 6.25. 80 u 1.95 1.63 1.82 3.12 120 u .261 .261 .261 .783 20 6' 6.5 7.8 9.9 9.35 80 6 3.9 3.77 3.38 3.12 120 6 .39 .52 .65 .775 20 8 10.15 10.15 10.15 10.15 80 8 2.61 2.61 3.38 3.38 120 8 .39 .39 .65 .65 35 .hwaece oncommApH: one eon m0>9§o cannons mopanaz age» cans .oe .mea do - eanqsaedmem .aooscmceap omen pom m0>amo 0a: mousse: «E0680» oaee .ee .mea do - oaneaedmem 37 TEST III Procedure From the previous trials it has been shown that lower heater energy had better results from.the standpoint of heat transfer so only low heater watts were tried. In these trials the tube transducer was used with a frequency of 630 kilo- cycles. .The basic apparatus was the same as procedure I and II. The apparatus is shown in Figure 12. Amount of water was one-seventh times as compared to the procedure I and II. Ther- mocouples t1, t2, t3, and th were placed at various locations. Thermocouple t1 was on the surface of the heater, t2 was in between the heater surface and the inside surface of tube transducer, t3 was on the inside surface of the transducer, and th was on the outside surface of the transducer. The transducer itself was used-as a water container and was sealed with waterproof cement on a plastic sheet. Trials were run until they came to steady state. Most of the trials were run from.60 to 80 minutes. Results It has been found that all tests came to steady state with cylindrical transducer in less time than with the disc transducers. Testsof ultrasonic energy only came to steady 38 state earlier than with heater only, or combination of heater and ultrasonics. In this transducer, the output ultrasonic energy was less per unit surface area than the disc trans- ducers. This means the transducer produces low concentrated ‘ultrasonic waves. The energy output by 75 ma was much higher as compared to 50 and 25 ms generator input. As ultrasonic energy was increased, the time to come to steady state was 5 percent decreased. The temperature differ- ence between t1 and t2 was small in trials of ultrasonic energy onlg and in combination of heater and ultrasonic energy as comp pared to heater only trials. This means the temperature drOp on the heater surface is more in trials of heater only and less in trials of ultrasonics only and combination trials. The temperature drop between t3 and th decreased with in- creased ultrasonic energy only. This temperature difference was much smaller in ultrasonic energy only,as compared to heater and combination trials. Heat transfer was higher in trials of 75 ms and h watts combination. Below this ultrasonic energy was not advan— tageous. The temperature drop between t2 and t3 was negligible with ultrasonic trials and in combination trials. 0n the other hand the difference was much higher in trials with heater only which indicates uniform heating by ultrasonic WBVGB e 39 Conclusions 1. The temperature drop on the heater surface was 1.5 degrees F. higher in trials with heater only. This dr0p de- creased as ultrasonic energy increased. Ultrasonic energy was less concentrated with tube transducer as compared to disc transducer energy. 2. Rate of heat transfer was slightly higher at 75 me generator input than lower inputs. Heating was uniform in trials with ultrasonics only and in combination of heater and ultrasonic trials. 3. The time to came to steady state was 8 to 10 percent less in ultrasonic trials and combination trials, as comp pared to heater trials. This time was 25 percent less as compared to disc transducer for u watts of heater and 50 ma. Fig. 12. no Principal apparatus used for procedure III. Al . may use: once a p 09:» now mo>as o 0 have no mousse: Sop caea ne .mem d. ‘ sands Jedme I E2 0 use mom can a code no H m 0>a so one askedaop can a mousse: do ' can qsaed mom 1+3 SUMMARY AND CONCLUSIONS Summary The effect of ultrasonics on the rate of heat transfer was studied. The approach consisted of passing ultrasonic energy through water parallel and perpendicular to the liquid film.on a heater element. The variables studied were heater power, ultrasonic energy and temperature of water. A commercially available standard generator was used to obtain the ultrasonic waves. An immersion pyrex glass sheath cylindrical resistance heater was used to heat water. For longitudinal waves, parallel to the film, a disc transducer were used with frequencies of hOO and 1000 kilocycles. For transverse waves perpendicular to the film, a tube transducer having a frequency of 6&0 kilocycles was used. The amount of heat input by ultrasonics alone was measured by the calori- metric method and the amount of heat produced from the container was calculated. The amount of heat input by the heater was measured by a wattmeter. Several tests were run to calibrate the heater to determine wattage output. The study was divided into three groups. The first con- sisted of work done with 1000 kilocycles disc transducer; the second, of work done with EOO kilocycles disc transducer; and the third, of work done with 6&0 kilocycles tube transducer. The disc transducer with a frequency of HOO kilocycles had no appreciable effecc on the rate of heat transfer. At this frequency ultrasonic energy is low and had no advantage for the transfer of heat. A disc transducer with a frequency of 1000 kilocycles showed a definite increase on the rate of heat transfer over the tests without ultrasonic energy. The rate of heat transfer is proportionately increased up to a certain nmux above which it has no additional advantage. In an ultrasonic field of 50 ma and h heater watts, the system comes to a steady state of 120 degrees F. in 8 to 10 percent less time than without the ultrasonic field. The rate of heat transfer was 18.6 percent higher at four heater watts and 50 ma ultrasonic energy, than the sum of the individual effects. The rate of heat transfer was decreased with increased heater watts and increased ultrasonic energy beyond the above range. Low ultrasonic energy of 15 ms had negligible effect on the rate of heat transfer at all heater wattage from 0 to 10 watts. Low heater power of h watts and 50 ma ultrasonic energy was most effective. The ultrasonic energy was 72 cc/ watt at 50 ms and 30 cc/watt, at h.heater watts. The ratio of ultrasonic to heater power for optimum rate of heating at this level was 1 to 2.h. A tube transducer with a frequency of 6h0 kilocycles was used for a series of tests such that the ultrasonic energy input per unit surface area of transducer was one- 115 eighth that of disc transducer. In these tests the time re- quired to come to steady state of 120 degrees F was 20 to 25 percent less than that of the disc transducer. The heat transfer was not appreciably higher at & watts and 0 to 100 ma ultrasonic energy. Conclusions 1, The rate of heat transfer is higher with increased ultrasonic frequency. A heater wattage of & and ultrasonic energy of 50 ma has maximum advantage. Above 50 ma ultrasonic energy it has no additional advantage in 118 cc water. 2. Due to agitation of liquid by ultrasonic energy there is uniform heating of liquid. with ultrasonics the maximum temperature difference in the water container was 1 to 2 degrees F. as compared to 3 to & degrees F. without ultrasonics. 3. Temperature drop in between heater surface and liquid is 2 degrees F. less in ultrasonic field which indicates the reduction in film resistance to heat transfer. &. With the tube transducer at a frequency of 6&0 kc, at 25, 50 and 75 ms, the water became heated in 25 percent less time than without ultrasonics with &, 6 and 8 watt heater power. us a SUGGESTIONS FOR FUTURE WORK From the experience gained.in this work, further studies should be undertaken to further develop the relationship be- tween ultrasonic energy and heat transfer. 1. More study is needed with the frequencies above 1000 kc. It was shown that with increased frequency of ultrasonic energy, the rate of heat transfer increases. This work was limited to a maximum frequency of 1000 kc. 2. Determine the effect of applying ultrasonic energy for improving heat transfer for continuous flow of fluid over heater surface. 3. Analyze the relationship of wave length of ultrasonic energy and film thickness of fluid. &. Additional studies are needed to evaluate the per- formance of the tube transducer at different frequencies. 5. Further efforts should be directed toward develop- ment of devices for measurement of ultrasonic energy. 6. Further consideration should be given to develop- ment of the theory involved in using ultrasonic energy to change the film thickness or to change the heat transfer char- scteristics. 7. After getting sufficient basic data and minimum frequency at which ultrasonic energy will be most advantageous, this principle should be applied to grain drying, seed treat- ment, and other agricultural processes. 1. 2. 3. 9. 10. 11. 12. &6 BIBLIOGRAPHY American Institution of Physics. Egoceedinggas of the §ymposium.on Temperature, itngeagprement and Control in Science. 1939. 13 pp. Bates, 0. K., G. Hazzard and G. Palmer. Thermal Conductivit of Liquids, Industrial and Engineering_Chem1§t . 33 (19&1) PP. 375'3760 Birth, 0., and C. W. Hall. Ultrasonics in Quality Control. Unpublished M. 8. special research problem, Michigan State University, 1955, 2 pp. Brown, A. I. Intpgggcpion t9 Reg: Transfer. Ed. New Iork: MCGraw-Hill Book Company, l9&2, 232 pp. Cardinell, H. A. Refrigerator cans as farm storage. Michigan State College Agricultural Research Experiment Corlin, B. Ultrasonics. Ed. New York: McGraw-flill Book Company, 1959, 270 pp. Clarke, L. N. Methods of Measuring Thermal Conductivity of Poor Conductors. Australian Journal of Applied Scienceg. 5 (June. 195%). pp. 173-32. Davis, A. H. Thermal Conductivityado ondpanodaop 0548 nausea: 03 on 06 o LIFII on 00 00H 0 H do - omqeaedmax. 60 use one mupw3 m pom ONH OCH '6‘ a 691’ a. mo>nfie manpmnoQan cede nopdnaz om oo o I,” I \ 17$-v‘l' .- Im ‘1- 1.]. H H N H H do - oanqsaedmem 61 .hmaoao oHcomepHs a8 omao and moods 0H how mobhdo ondpmnoQSop nopsnuz co m OHH In N H o H H - eanqeaedmam 62 . -nomo oficomman: as mmuo new maps: 0 no newsman» noon ho opwm .mlm .mHm mopsnax . a - u . . 1 .... .. ... . . ...-r... . . .. . . . .... . . . . ... .. .- ... . . . . . 0 III.-- a _ -. .. . ..... .. . .. . . . .. __ . . . .. . . . . . . . . . ... .. ”HUN. 2 +... .. ... -. .. . .. o . .. .9..+49.¢ .... ...!1001. .an n.6> n 01v95091960 fl... .H. . .. ... ..0. 1. . .. . . ..19 01‘s. .1..19..0 boo. .... ....wvo . to... ...6 o.-. 161.11.1Y.Y'1.~.61v-n§1+r~L§-.rdo.. c v V69.-lvv1 O... .0. . . . . .. .. . .9 ..ncvbé‘T .6.0 .60. 6..# ...: 7.61 .69118.1011.t¢|?.¥71?§1f '91-6 9.0. 10+‘ .00911010111v..1o.. .7 .1 .761 61.1.0 60’. > 1 » r|1 . 4] 4 .. . .. .. . .. . .... ... ... ...§ IIY- 171.41.... 1.1... ..J. ..O.or..o.1..f~. .... 94.. .o.0..09v1 16.17 ...Y‘io. 101clo1oLon.vn .......r. .00. 6.....o1... , , o. .. .. .... u. . .... ...nv..ov -6 Avokcofi A .... .... ...r .10.. A... 16.16 to... n... o... o... .... ...- ..-. ....-..rn.0.1.o.. ..1.--....1 ... . . . . . .. . ... ., . .- 1. .. 4. .A .... .... -... .... ...: ..11 ...1 ....g.... .... .... ...- .... .... -........ ...- ..1. , * .. . .. . -. .. 1110?. .. yuan o... .... v.1.1..o ...16 ....1.... ...b .... .... .... .... ...-T.v-. v...:9..16... .. r . ~11 . 1 1 A , 4 . . - .. . .9 .909 471- .....96.0 vvtvvv.o' ...? .... -... a.-. 0...I-...w11oq-o+1..vo nvv. ~.-.> I... y... .... .. . .... ....17...11T.117th.. ... . . .. .... .... .... ..no .... ....1. .- ...: v... ..-.r1v.¢ ....L..qo ....-..ol-.61.:o:...v .... .... ..vg1i-.nAY..O.-I.v. c-.. .-.. .... . . 1 . .. .... .1~. .... ......cv. .u9v10.90wovoo n... .o.. .... o-.4 ..e. .b.. unto .... ...o-L¢'.a ... .... .16. r... c... .11. .--. ..u. . .. . 6b .... ... .... ...v ..9.fi....YI... ct..-.T.av1.110.e10.691.... ..9.v;ov71+¢-oi 6.09.1v1e10voV9.61ll1v1o1.11ov>. v... 6... .... .... .Vv. 1r » 6 > 41 . . 4 1 , A y . * .o ... . .e .. . . .. . . ..~-- 0... ....111.0 $..Y .....I.-. 06¢. a... tea..........#J-...T1.L0.v1.¢.p.1Toc+1n..6 '11.. .1?~11$1.lv.7511.0111116o 10-3- ..v. .... a ...-11 ‘... ... . . .. 1. . .. . I... ... .... .... 1.... ...-11v9..6 .766 e... o.6911.119|..1v-c.1+¢e1.491oLY9..e .... .... 7411.111 -... .. . 1111 6-1. 11|6 o ... 1.. ... . . .. . . 1. . .... . .... .... .007¢..V.....vee.069o..l+699w$loif..~w11L-¢ot.rb.r.6.-.. .... 1.491;..>.01.art .6 o... .v.. n... I .n u an . . v 1 . , ., .... I. H N r . .. . .. .... .... .... ......... .... v... ...a ...er.vl.+1&..+§.a 6ovw...w..o.. o...11.f1+..2.5. rev. .... .... .7. .... . . r 71» .1 b .H w .1 u . r ° 111/11.1.8 cacommnpas a8 «and: housed m OOH .hwuoco pa houzdhp paon no opam nouznnz o elm 611 cacomdnpas we om: .hwnoco can wands hopaoa 0H pa nouuaduu paw: mo onwm mouzndz .num .m-E °m/n1-a .oaap mounaaa om pa hwnoco cacomanpaa hp nouncdnp anon no ovum need: nouaom 66 moacomaapa 0.5 5 saw .QE ooauo m pm: acumen 0 you mm>ndo ondawhoqaou cede .mam .me mouscfiz om ‘ ' 4 7 .. .. 1. 11. ... . v .. .1. 11.1 . 1. . .. .. 1 ..1 .. .... .... I... ..1 ... .... . 1. 1 . . . .. . . . o . . .. 1. ..1 .. . .. . 1 _ .11 . ..1 .. ...» ... .... . . . . ,. . .... . .. . . . . .. 1. .... .... . .. .. . ... .. .1. . .... .... . . .1 .. . .. . .1 . 1 1 . . - . . 1 . 1.. 1 1 .. . 1.... . .1.. . ... ...... . .. . . . - .1 b . . . 1. 1 . . . ... .. ... . .... .. .. . ... .. 1 .. . . . .. . . . . .. . . .... ... ... .. . ... .. . .. . . o . . .. . .. . . . . . ... 11 . . .. 1 . . » . a A . . . . . . . 1. - 1... ..1. . .... .... .. . ... .. .. o .. .. . ... .. 1. .... p p . . . . ... .... .. ... ... . .1 .... .1 . 1. 1.. 1. . .1. .. w . . o. .. 1... .... 1.11 .... .. ... .... .1.. ...1 11.1 . .. .. . . .. .. . .. . 1 . 1 .1 . . . . .... .... .. . .. .1.. .. . 1 .. ..1. .. . . .... ... ..1. . . .. .. 1m .. . .1. .. ..1 ...I.... .... .... .11. ...1 v... ..1. ... .. . 1 . 1.... ... 1 ... . .Lfi .. .. 1.. . .. 1. . .1 .... .. . .. . .... . .1 .1.. .... .... .111 .... ... .... 1... 1... .... 1 . w . ... . .. . .. ... . 1. 1. 1... 1. . . .. .1.. 1. 1 ..1.. . . .... . . . ..111.. . y . ...1 . ... . .1 ..1. .... .... ..1 . .. .... 1.. .... ....1.... .. .. ...14... . .. 1 . . 1 1... .... .... .11. .. . . .. _ . . .. 1. .... .. . ..1 . ........ ... . 1. 1 1. + . _. .. . 1 . .. . .. 1 ..k. . . 1. . .. . ..1. .1.. .. . .1 .... . .. 1 .1 . ... t m. . . .1 . 1... .. 1A.. . . .. .... ... ... . . ..1. .. .... .1.. 1.1 1.. V . r 1 1 .. o. -. . . fi . . . . .1 .. .. . 1... ..1 v... 1... .1.. 1.. .u111111 . ... 1. . 1 11 .1. 11 1 1.. .. . 1.. r . . .... .. . . ..1 . . .1 . . .1 ......1. 1... . .. . .. . . . .. 1 . . . . 1 1 . . . 1 ..1 .11 . . ..11 . .. .... . .. ..1. .1.. .1.. ..1. 1 . . . 1.. 1.. . . 1 1 H. .. .. . -. . 11.1 11.. . . .. 1 111 . 11.1 1111 . . 1v. 1. 1 .1 ..11 19“ .w. . . .1.. 1 1 . A. . 1.1 .1. r «. .. 1. . 1 ..1. .111 o . 1 . . 11.1 . 11 . 1 .. . . . . &o1l. can. u 1 1. . . 1 . 111. 1.11 k 111 m 1 1 . . . - ... 1 . .... -311 u . 1 .... . . .1. . . 1.>1D.A'1.I < . 1 . . 1. . - . ...1 11.. . 1 A.... 1. 11. . 1 #.>1 01.111 . 1 .- 1.. ..1 1| 1 . 1110 11.. a . .. .. .... .... 1. o . . . 1 1.1.1.... . + . .11..-- 1 . _p 1 1 . 1 1 111155.111. . .4 . 1- . .1.-111.111. .. 1. . 1 . . 1.-.. ..1- 1»! H ... ... 1... 0.11. vbl" . 1 +1 ... 11.. .... ... 1 1 111.1..111 a. . . . . . .111 . .. .1 . .. . 1.. .1 . . 11. 1 ..11 11. 1 .1 .. 1 111. 1. LID H . . . 1 ....46.1 ... .1. . .111 .. r .1 4 1 .1 . 1 1. .. . . ..1..... a 1 .- .. .. . 1.. 1.1 .1 . 1 ..1 .. .. . .1 1 ... .r. . . 11 .. -.1 . .111 ..1. I OIII tn! ‘1‘ A .IILA‘AI. . 1 . v1b11 B 1 v 1. ...1 ‘I. . . .11.4..11 11 . r1... ... . 11.. - .. .- . .1.. 1 1. . 1.1vm* . .. .161 . . ... .. 1 ..11 .. . . . 1 .. .. . .1.. 1... . . .1. . 1 L 1- . 1. - .. . ..1 1.. 1. . 1111...1. 1 . H 4 4 . o. 1- 1 -119A1111 v. v 1 - . ..11Ir.1.. . + ... .. 1 1 . 11.. 111.. H. .4 1 .111311911 1n 41 T H . . . 21.1-.-. . ¢. 1. . . ...11111. . . - . . . 11.. 1. 1 r 11 . .». 1 .11 1 111711111! . *1 ... u . .1... 11. ... . .11. .v 1.11 .111 u» .H .1 1 .11. t v1l10 .0!- q. * .. . 1.. . .11. 1.... .. . . .... 1. . . 11.1.1.1.1 . .. . 1. . .1- 1 . 11.1911.-. H 1.. 1.1 . - .1... 1.1.1 .1 .m. 1H. . .... .1 1 1 1119111111» I... . 1 1.11 11 1 TU... 7". .1 H. . ..1.. . ......1....1 1 . * *1.. .1. ..1 1 . 11I¢AVII51 4 1 . .M. a .. . .. .. 1 . lb1$1¢10l>1bl§11 v 1 .~. ‘ .1. . ...IT"I0.$1 . ... ~ .1 . . 1 . 1 Yot.16..orr1 . . . . . . H > A¢w411v1711 do - oanqnaodmam 67 «8 ooauo vca nova: ONH .hmnoco oHQOmmnuaz nopaoz m now mmpndo ohdpahoqaop cede .oanm .wdm . _ b g x \ . nousaax. .1 1 C. :LILIL. - 11 .F MINI 11f .lultE om 00 c: 3 <3 14 14 - Oanaaedmom oma a”. OMH I '[II'IFII'I‘ 'I'11 1.33.2 \US E 0521!. Date Due I 1" l X I \ Demco-293 Ilmuuumlmmuuulmflijtlfiglgfl mm 795