Laboratory/Demonstration Experiments in Heat Transfer: Forced Convection

Transcription

1 Laboratory/Demontration Experiment in Heat Tranfer: Forced Convection Edgar C. Clauen, W. Roy Penney, Alion N. Dunn, Jennifer M. Gray, Jerod C. Hollingworth, Pei-Ting Hu, Brian K. McLelland, Patrick M. Sweeney, Thuy D. Tran, Chritopher A. von der Mehden, Jin-Yuan Wang Ralph E. Martin Department of Chemical Engineering Univerity of Arkana Abtract Laboratory exercie or demontration which are deigned to compare experimental data with data or correlation from the literature are excellent method for reinforcing coure content. A part of the requirement for CHEG 3143, Heat Tranport, and CHEG 3232, Laboratory II, junior level chemical engineering tudent were required to perform imple heat tranfer experiment uing inexpenive material that are readily available in mot engineering department. The deign, implementation and analyi of three of thee experiment are decribed. Experimental forced convection heat tranfer coefficient were determined by flowing air over an upward facing horizontal plate, pat the bulb of a mercury/gla thermometer and through an annulu. In each cae, the apparatu (the plate, cylinder or inner cylinder) wa allowed to cool or heat in the flowing air, while recording temperature a a function of time. The experimental heat tranfer coefficient were then determined from a heat balance over the heat tranfer urface. Finally, the experimental coefficient were compared to thoe obtained from appropriate literature correlation. The experimental forced convection heat tranfer coefficient for parallel flow over flat plate were time higher than literature correlation coefficient, mot likely reulting from the high turbulence generated by the fan. The experimental forced convection heat tranfer coefficient for two different ize of mercury/gla thermometer bulb, were within 20% of the literature correlation coefficient. The experimental forced convection coefficient from flow of hot air over a bra rod centered in an annulu were time higher than literature correlation coefficient, mot likely reulting from the the hair dryer jet velocity being 3.6 time higher than the annulu velocity. Introduction A number of paper have been written recently on method for improving or upplementing the teaching of heat tranfer including the ue of preadheet to olve two-dimenional heat tranfer problem 1, a new tranport approach to teaching turbulent thermal convection 2, the ue of

2 2 computer to evaluate view factor in thermal radiation 3, and a new computational method for teaching free convection 4. Supplemental experiment for ue in the laboratory or claroom have alo been preented including rather novel experiment uch a the drying of a towel 5 and the cooking of French fry-haped potatoe 6. A part of the combined requirement for CHEG 3143, Heat Tranport, and CHEG 3232, Laboratory II, junior level chemical engineering tudent at the Univerity of Arkana were required to perform imple heat tranfer experiment or demontration uing inexpenive material that are readily available in mot engineering department. The deign, implementation and analyi of three of thee experiment, forced convection heat tranfer coefficient by flowing air over an upward facing horizontal plate, pat the bulb of a mercury/gla thermometer and through an annulu, are decribed below. Thi exercie ha everal benefit: It provide an opportunity for tudent to have additional hand-on experience; It demontrate a phyical application of correlation found in the textbook; and, It help to develop an appreciation for the limitation of the correlation. Experiment 1. Forced Convection Heat Tranfer by Air Flowing Over the Top Surface of a Horizontal Plate Objective Forced convection heat tranfer occur when the fluid urrounding a urface i et in motion by an external mean uch a a fan, pump or atmopheric diturbance. Thi tudy wa concerned with forced convection heat tranfer from a fluid (air) flowing parallel to a flat plate at varying velocitie. The objective of thi experiment were to: 1. Determine the experimental forced convection heat tranfer coefficient for parallel flow over a flat plate. 2. Compare the experiment heat tranfer coefficient with the coefficient calculated from the correlation preented by Cengel 7. Experimental Equipment Lit Four mill finih aluminum plate (1.5 in x 12 in x 18 in) Four 13 in x 19 in heet of ½ in thick Styrofoam inulation Thermocouple reader (Omega HH12) 1/8 in diameter x 12 in long, Type K, heathed thermocouple Anemometer-thermometer (Kane-May, model KM4107, erial # 34095) 1,600 W hair dryer (Hartman Protec 1600) Styrofoam inulated heating box (13 in x 20 in x 23 in) Stopwatch, graduated in 0.01 time interval 3-peed Black & Decker window fan, model DTS50D/B

3 3 Experimental Procedure The chematic drawing of experimental apparatu are preented a Figure 1 and 2 and photograph are preented a Figure 3 and 4. Setup/Teting 1. Weigh each of the aluminum plate on an electronic balance. The average weight wa kg. 2. After placing two aluminum plate inide the inulated heating box, place the nozzle of the hair dryer into the hole in the lid, and heat the plate to ~150 F. 3. Place Styrofoam inulation on a tabletop. 4. Place a heated plate in the firt poition on the Styrofoam inulation, with the long (i.e., 18 in) dimenion in the flow direction (ee Figure 2 and 4). 5. Place two additional cold plate end-to-end (again, ee Figure 2 and 4), along the 18 in dimenion, and wrap the two 12 in x 1 ½ in and three 18 in x 1 ½ in vertical face with inulation. Leave a 1cm pace between plate to avoid conduction between the plate. 6. Connect the heathed thermocouple to the thermocouple reader and inert them into the firt plate. 7. Start the fan and chooe one of three fan peed. 8. Start the topwatch a oon a the temperature change 0.5 C from it original temperature. 9. Record the time at each ucceive 0.5 C change in temperature. 10. Ue the anemometer to meaure the air velocity over the plate at five different lateral poition to determine the average air velocity. 11. Repeat the above procedure for the two other fan peed etting. 12. Remove the econd heated plate from the heating box and place it in the fourth and lat poition from the firt plate (once again, ee Figure 2 and 4). 13. Repeat the above procedure for the fourth plate. 14. Ue the anemometer to meaure the air velocity over the fourth plate at five different lateral poition to determine the average air velocity. Safety Concern 1. Wear afety glae at all time. 2. Be very careful when handling the aluminum plate ince they each weigh 32 lb (14.35 kg), and can break bone if dropped. 3. Alway wear glove when handling the hot aluminum plate. 4. Keep finger away from the guard around the fan blade.

4 4 Figure 1. Inulated Wooden Box for Heating the Aluminum Plate Figure 2. Location of Plate for Flat Plate Heat Tranfer Experiment

5 5 Figure 3. Photograph of Inulated Wood Box ued to Heat the Aluminum Plate Figure 4. Photograph of Experimental Horizontal Plate Heat Tranfer Experiment

6 6 Data Reduction 1. A heat balance on the cooling plate, with no heat generation, yield: q = (1) Out q Acc 2. The plate i cooled by free convection and radiation a follow: q Out = q + q = ha ( T T ) + εσa ( T Conv Rad a 4 T 4 a ) (2) 3. The plate accumulate heat a it cool toward room temperature a follow: q ACC dt dt ( p ) = ρv ( C p ) dt = M C (3) dt 4. Thu, the heat balance of Equation 1 become: 4 4 dt ( ha ( T Ta ) + εσa ( T Ta )) = ρv ( CP ) dt Although mall, the heat balance wa alo corrected for the heat flow by conduction from the aluminum plate through the inulation to the table a q Cond = k I A(T - T a )/Δx I. (4) 5. The experimental data of plate temperature v. time (in Table 3) were plotted uing TK Solver and were curve fitted uing a econd order polynomial (i.e., T = a + bt + ct 2 ). Thi equation wa differentiated to determine dt/dt = b + 2ct Cengal give the following correlation for local heat tranfer coefficient for forced convection flow over a horizontal plate: Nu = h x = x Nu x x 0.5 / k Re x = h x / k = Re x 1 / 3 The integrated average coefficient are given by Nu = hx = 0.5 / k Re x Pr 0.8 Pr Pr 1 / 3 for laminar condition, i.e., Re < 500,000 (5) 1/ 3 for turbulent condition, i.e., 5x10 5 < Re < 10 7 (6) for laminar condition, i.e., Re < 500,000 (7) Nu = hx / k = (0.037 Re 871)Pr 1/ turbulent condition, 5x10 5 < Re < 10 7 (8) Comparion of Experimental Reult with Value from the Literature

7 7 Table 1 give all of the experimental data of temperature v. time for the ix experiment. Figure 5 preent a plot of T v. time for the firt plate at V = 4.82 m/. All of the data were curve fitted, a hown in Figure 4, and the lope of all ix of the individual plot wa determined at the fifth data point. Thi lope wa ued in Equation 4 to determine the experimental heat tranfer coefficient. Table 1. Experimental Data for Cooling of Flat Plate with Parallel Flow of Air 1 t Plate 1 t Plate 1 t Plate 4 th Plate 4 th Plate 4 th Plate V = 4.92 m/ V = 6.00 m/ V = 7.24 m/ V = 3.75 m/ V = 4.63 m/ V = 5.54 m/ Time () T ( C) Time () T ( C) Time () T ( C) Time () T ( C) Time () T ( C) Time () T ( C) Table 2 preent the experimental and reduced data for all of the experiment. For the firt plate, the ratio of h Exp /h Corr wa 2.72, 3 and 3.29 for air velocitie of 4.82, 6 and 7.24 m/, repectively, and, for the fourth plate, the repective value were 1.71, 2.36, 2.25 for air velocitie of 3.75, 4.64 and 5.54 m/, repectively. Thu, for the firt plate the average ratio of h Exp /h Corr wa 3 and for the fourth plate the average ratio wa 2.1. Table 2. Reduced Data for All Experiment Air Flow over Flat Plate Plate V Re Nu x h CORR T dt/dt q F CONV F RAD F COND h EXP 1 t E t E t E th E th E th E

8 8 Figure 5. Temperature v. Time Experimental Data from the Firt Plate at an Air Velocity of 4.82 m/ Thee reult indicate that the experimental apparatu did not come cloe to producing laminar flow over the plate. Thi i not very urpriing, conidering that the fan produce ignificant turbulence. The fan act like an agitator in a mechanically-agitated veel. It produce turbulence in addition to producing directed flow along the plate. In fact, it mut produce a great deal of turbulence for the meaured coefficient to be % higher than thoe which would be produced by non-turbulent laminar flow. Experiment 2. Forced Convection Cooling on a Mercury/Gla Column Objective Thi econd tudy wa concerned with forced convection heat tranfer from a fluid (air) flowing pat the cylindrical bulb of a mercury/gla thermometer. The objective of thi experiment were: 1. Determine the experimental forced convection heat tranfer coefficient for two different bulb ize at two different air velocitie, and 2. Compare the experiment heat tranfer coefficient with the Churchill/Berntein correlation for forced convection over a circular cylinder 8.

9 9 Experimental Equipment Lit Two mercury thermometer, one with a bulb diameter of 6 mm and a length of 1.5 cm and the other with a bulb diameter of 4.1 mm and a length of 1.4 cm Hot tap water Stop watch, graduated in 0.01 time interval Fan with two peed etting Anemometer Experimental Procedure 1. Heat the thermometer by holding it bulb under hot tap water until the temperature tabilized at about 70 C. 2. Remove the thermometer from the tap water and quickly wipe it dry with a paper towel. 3. Poition the thermometer horizontally in front of an operating fan, uing a laboratory ring tand and clamp. 4. Record thermometer with time a the thermometer cool toward room temperature. Safety Concern 1. Wear afety glae at all time. 2. Be careful not to drop the thermometer or to get burned by the hot water. 3. Keep finger away from the fan guard. Data Reduction Equation 1-4 were once again ued to calculate the experimental heat tranfer coefficient a in the previou experiment. The heat tranfer coefficient from the literature wa determined uing the Churchill/Berntein correlation for forced convection over a circular cylinder 8 : Nu = Re 1/ 2 Pr 1/ 3 3 [ 1+ ( 0.4 / Pr) ] 2 / 1/ Re 282,000 5 / 8 4 / 5 (9) In Equation 9, all propertie are evaluated at the film temperature, T Fiilm, which i defined a: T Film = T + T a 2 (10) Comparion of Experimental Reult with Value from the Literature Figure 6-9 how plot of experimental temperature profile for the 4.1 mm bulb at air velocitie of 500 and 920 ft/min and the 6 mm bulb at air velocitie of 500 and 920 ft/min, repectively. A tranient TK Solver Model wa developed to calculate the tranient profile uing a heat tranfer

10 10 coefficient calculated from Equation 9, but the coefficient wa ratioed to give the bet fit to the experimental data. The ratio of h exp /h corr to bet fit the experimental data are given in Table 3. Table 3. Ratio of h exp /h corr to Produce the Bet Fit to the Experimental Data for the Cooling of 4.1 and 6 mm Thermometer Bulb in Front of a Fan Blowing Room Air Bulb Diameter Air Velocity h EXP /h CORR Re Nu h CORR (mm) (ft/min) , , Thee ratio are likely a bit low becaue radiation effect were aumed to be negligible. Even with ome radiation effect, the literature correlation (Equation 9) yield reult which are quite cloe to the experimental coefficient. The mall ize of the thermometer bulb relative to the turbulent eddy ize produced by the fan are mot likely the reaon that the literature correlation better fit the experimental data for the thermometer bulb than for the flat plate for which h exp h corr varied from 2 to 3. For the flat plate, the turbulent eddy ize i likely maller than the dimenion of the flat plate and the turbulence in the flow field i very different than the laminar flow over a flat plate. Figure 6. Thermometer Temperature v. Time for the 4.1 mm Bulb at an Air Velocity of 500 ft/min (2.54 m/). LEGEND: (+) 1 t Experiment; (o) 2 nd Experiment; Solid Curve Predicted Profile with Ratio h EXP /h CORR = 1.

11 11 Figure 7. Thermometer Temperature v. Time for the 4.1 mm Bulb at an Air Velocity of 920 ft/min (4.67 m/). LEGEND: (+) 1 t Experiment; (o) 2 nd Experiment; Solid Curve Predicted Profile with Ratio h EXP /h CORR = 1. Figure 8. Thermometer Temperature v. Time for the 4.1 mm Bulb at an Air Velocity of 500 ft/min (2.54 m/). LEGEND: (+) 1 t Experiment; (o) 2 nd Experiment; Solid Curve Predicted Profile with Ratio h EXP /h CORR = 1.15

12 12 Figure 9. Thermometer Temperature v. Time for the 6 mm Bulb at an Air Velocity of 920 ft/min (4.67 m/). LEGEND: (+) 1 t Experiment; (o) 2 nd Experiment; Solid Curve Predicted Profile with Ratio h EXP /h CORR = 1.25 Experiment 3. Forced Convection Heat Tranfer from Hot Air in An Annulu to the Inner Cylinder Objective Another important geometry for forced convection heat tranfer i the heating or cooling of a fluid flowing through an annulu between an outer pipe and an inner cylinder. The objective of thi experiment were to: 1. Determine the experimental forced convection heat tranfer coefficient for the heating of a bra rod, contained in an annulu, a air flow through the annulu, and 2. Compare thee reult with the heat tranfer coefficient from the Dittu-Boelter equation 7. Experimental Equipment Lit 3 in inide diameter x 72 in long PVC tube 1 in diameter x 42.5 in long oak dowel 1 in diameter x 8.1 in long bra rod with a 1/8 in diameter x 3 in long center hole Omega HH12 thermocouple reader 1/8 in diameter by 12 in long heathed thermocouple Hair dryer (Hartman Protec 1600) Stopwatch, graduated in 0.01 time interval Window Fan (3-peed Black & Decker, model number DTS50D/B) Anemometer (Kane-May, model number KM4107)

13 13 Experimental Procedure The experimental apparatu i hown in the chematic of Figure 10 and the photograph of Figure Determine the weight (0.88 kg) of the bra rod and it dimenion (1in dia. x 8.1 in long). 2. Ue ice to cool the rod until it i cooled below room temperature. 3. Place the wood and bra rod into the PVC tube a hown in Figure 7. NOTE: The wood rod i ued to provide an inide cylinder which i much longer than the bra rod, o that fully etablihed turbulent flow exit prior to the hot air reaching the bra rod. 4. Inert the thermocouple into the 1/8 in center hole in the bra rod. 5. Turn on the hair dryer at it highet peed, and immediately tart the topwatch. 6. Record the time for each ucceive 1 o C change in temperature of the rod. 7. At a point after the air flow ha reached teady tate, record the velocity and ambient air temperature of the air exiting the annulu. 8. Repeat thi procedure a neceary, with the ame or different hair dryer peed. Safety Concern 1. Wear afety glae at all time. 2. Be on guard when the fan i ued. 3. Be extra careful that the PVC outer tube i held firmly vertical againt a upporting tructure. Figure 10. Schematic of Annulu Heating Apparatu

14 14 Figure 11. Schematic of Annulu Heating Apparatu Experimental Data Table 4. Experimental Data of Bra Rod Temperature v. Time for Heating of the Rod with a Hair Dryer Inerted into a Pipe with the Rod in it Center Run #1 V air = 4.22 m/ T air,out = 62 C Run #2 V air = 2.56 m/ T air,out = C Run #3 V air = 4.43 m/ T air,out = 64.2 C Time () T r ( C) Time () T r ( C) Time () T r ( C)

15 Data Reduction 1. A heat balance on the rod with no heat generation yield: q q = q (11) In Out Acc 2. The bra rod i heated by forced convection from below room temperature, thorough room temperature and to above room temperature. The heat tranfer coefficient i determined when the rod temperature i equal to the room temperature when heat tranfer by radiation to/from the pipe wall i either 0 or negligible. Thu, Equation 11 become q In = ha ( Ta T ) (12) 3. The bra rod accumulate heat a follow: dt ( p ) dt qacc = m C (13) 4. Therefore, the heat balance reduce to: dt ha( Ta T ) = m( C p) (14) dt 5. Equation 14 may be olved for the heat tranfer coefficient: dt m( C p ) h = dt (15) A( T T ) a 6. The experimental data, preented in Table 4, were plotted a T v. time and the data were curve-fitted with a econd order polynomial fit uing TK Solver; i.e., T = a + bt + ct 2. The lope of the curve wa determined at room temperature for inertion into Equation 15. The plot of T v t, for Run # 1, i preented in Figure 12. For thi run, the quadratic curve fit wa T = (t) 6.346E-6(t 2 ), giving dt /dt = ºC/. 7. The heat tranfer coefficient from the literature wa determined uing the Dittu- Boelter equation 7 for turbulent flow through tube with the hydraulic diameter of the

16 16 annulu (D h = D pipe D rod ) ued a the characteritic length in both Re (= vd h ρ/μ) and Nu (= h ccorr D h /k). Nu = Re 0.8 Pr 0.4 (16) 8. Finally, the heat tranfer coefficient from the literature correlation i calculated a follow knu h Corr = (17) D h Figure 12. T v. Time for Experiment # 1 with the 1 in Diameter x 8.1 in Long Bra Rod Heated by a 62 C, 81 ft/min (4.22 m/) Air Stream in a 3 in Pipe. Reult from the annulu heat tranfer experiment are ummarized in Table 5. Table 5. Reduced Data for All Experiment Air Flow through an Annulu Run V Re T a T dt /dt q Nu h CORR h EXP h CORR /h EXP (m/) ( C) ( C) , , ,

17 17 Comparion of Experimental Reult with Value from the Literature The experimental coefficient are ignificantly higher than the correlation predicted coefficient. Thi reult i not urpriing conidering: (1) the flow from the hair dryer i quite turbulent, (2) the velocity profile from the hair dryer i not flat, and (3) the jet exiting the hair dryer i only 1 ½ in diameter; wherea, the outide annulu pipe diameter i 3 in. The exit velocity from the hair dryer i 3.6 time the annulu velocity; thi high jet velocity entering the outide annulu pipe i probably the major reaon that the experimental heat tranfer coefficient i o much higher than the predicted value. Thi entering jet would produce coniderable turbulence a hear layer reduce the high jet velocity to an annulu velocity, which i only 28% of the jet velocity. Concluion Three imple forced convection heat tranfer experiment were developed for: 1. Air flowing over an upward facing cooling horizontal plate 2. Air flowing over the cooling bulb of a mercury/gla thermometer. 3. Hot air from a hair dryer flowing over a heating bra rod within an annulu. The experimental heat tranfer coefficient were compared with literature correlation predicted value. The experimental coefficient for the flat plate in parallel flow were time higher than the literature correlation coefficient, primarily becaue the flow from the fan wa highly turbulent and the literature correlation were for laminar condition. The experimental coefficient for the bulb of the mercury/gla thermometer in parallel flow were time higher than the literature correlation coefficient. Thi good agreement between experiment and correlation wa mot likely a reult of the bulb dimenion being ignificantly maller than the cale of turbulence produced by the fan. The experimental coefficient for the rod within an annulu were 1.6 to 2.2 higher than the literature correlation prediction. Thi finding likely reult from the entering jet velocity from the hair dryer being 3.6 time the annulu velocity. Thi high velocity jet produce coniderable turbulence a hear layer reduce the entering jet velocity to an annulu velocity which i only 28% of the jet velocity. Although the effect of thee experiment on tudent learning ha not yet been quantified, anecdotally tudent remarked, after the completion of the exercie, that they really learned a lot from thee aignment. It i planned to offer thi exercie again thi fall, at which time the tudent will be urveyed relative to the value of the exercie.

18 18 Nomenclature A S heat tranfer area, m 2 C p pecific heat, J/kg K D cylinder diameter, m F CONV fraction of total heat tranfer by convection F COND fraction of total heat tranfer by conduction F RAD fraction of total heat tranfer by radiation h area average convection heat tranfer coefficient, W/m 2 K h CORR heat tranfer coefficient from literature correlation, W/m 2 K h EXP heat tranfer coefficient from experimental data, W/m 2 K h x local heat tranfer coefficient at length x along a flat plate, W/m 2 K k fluid thermal conductivity, W/mK M ma of the plate or cylinder, kg Nu area average Nuelt number, hx/k or hd/k Nu x local Nuelt number at location x along flat plate, hx/k Pr Prandtl number of the fluid q In heat tranfer into the ytem, W q Out heat tranfer from the ytem, W q Acc heat accumulated within the ytem, W q conv heat tranfer by convection, W q Rad heat tranfer by radiation, W Re Reynold number, = VDρ/μ for cylinder & Vxρ/μ for a flat plate T a ambient temperature of urrounding, K T Film film temperature = (T + T a )/2, K T urface temperature, K v fluid velocity, m/ V volume of plate or cylinder, m 3 x length along flat plate in flow direction, m ε urface emiivity ρ fluid denity, kg/m 3 σ Stefan-Boltzmann contant, W/m 2 K 4 Reference 1. Beer, R.S., 2002, Spreadheet Solution to Two-Dimenional Heat Tranfer Problem. Chemical Engineering Education, Vol. 36, No. 2, pp Churchill, S.W., 2002, A New Approach to Teaching Turbulent Thermal Convection, Chemical Engineering Education, Vol. 36, No. 4, pp Henda, R., 2004, Computer Evaluation of Exchange Factor in Thermal Radiation, Chemical Engineering Education, Vol. 38, No. 2, pp Goldtein, A.S., 2004, A Computational Model for Teaching Free Convection, Chemical Engineering Education, Vol. 38, No. 4, pp Nollert, M.U., 2002, An Eay Heat and Ma Tranfer Experiment for Tranport Phenomena, Chemical Engineering Education, Vol. 36, No. 1, pp Smart, J.L., 2003, Optimum Cooking of French Fry-Shaped Potatoe: A Claroom Study of Heat and Ma Tranfer, Chemical Engineering Education, Vol. 37, No. 2, pp , Cengel, Y.A., 2003, Heat Tranfer: A Practical Approach, McGraw-Hill Book Company, New York. 8. Incropera, F.P., DeWitt, D.P., 1996, Fundamental of Heat and Ma Tranfer, 4 th edition, John Wiley & Son, New York.

19 19 EDGAR C. CLAUSEN Dr. Clauen currently erve a Adam Profeor of Chemical Engineering at the Univerity of Arkana. Hi reearch interet include bioproce engineering (fermentation, kinetic, reactor deign, bioeparation, proce cale-up and deign), ga phae fermentation, and the production of energy and chemical from bioma and wate. Dr. Clauen i a regitered profeional engineer in the tate of Arkana. W. ROY PENNEY Dr. Penney currently erve a Profeor of Chemical Engineering at the Univerity of Arkana. Hi reearch interet include fluid mixing and proce deign. Profeor Penney i a regitered profeional engineer in the tate of Arkana. ALISON N. DUNN, JENNIFER M. GRAY, JEROD C. HOLLINGSWORTH, PEI-TING HSU, BRIAN K. MCLELLAND, PATRICK M. SWEENEY, THUY D. TRAN, CHRISTOPHER A. VON DER MEHDEN, JIN- YUAN WANG M. Dunn, M. Gray, Mr. Hollingworth, M. Hu, Mr. McLelland, Mr. Sweeney, M. Tan, Mr. von der Mehden and Mr. Wang are either current or former chemical engineering tudent at the Univerity of Arkana. All four tudent participated with their clamate (in group of two) in performing experimental exercie a part of the requirement for CHEG 3143, Heat Tranport, and CHEG 3232, Laboratory II.