EXPERIMENT NO. 5 FREE AND FORCED HEAT CONVECTION OBJECTIVE OF THE EXPERIMENT: To investigate the transfer of heat by con

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Experiment No 5 Free And Forced Heat Convection Objective Of The Experiment To Investigate The Transfer Of Heat By Con 1 (124.4 KiB) Viewed 47 times

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DATA COLLECTED

Experiment No 5 Free And Forced Heat Convection Objective Of The Experiment To Investigate The Transfer Of Heat By Con 8 (53.49 KiB) Viewed 47 times

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QUESTION
6. Plot the heat transfer coefficient vs velocity for forced
convection.
7. Plot temperature vs position (1, 2, and 3) for forced
convection.
EXPERIMENT NO. 5 FREE AND FORCED HEAT CONVECTION OBJECTIVE OF THE EXPERIMENT: To investigate the transfer of heat by convection both naturally and by force. To determine effect of fin addition on the heat transfer characteristics. THEORY Heat energy can be transmitted by three methods: Conduction, convection, and radiation. In this experiment, transfer of energy by means of convection method will be investigated. Convection is the transfer of thermal energy between a solid and a moving fluid. Convection is governed by two phenomena: the movement of energy due to molecular vibrations and bulk fluid motion. In general, Convection is of two types, forced convection and free (natural) convection. When heat is transferred by the circulation of fluids due to buoyancy from the density changes induced by heating itself, then the process is known as free or natural convective heat transfer. On the other hand, if heat is transferred by circulating fluid due to external devise (such as fan, blower, pump, etc), then the process is called forced convective heat transfer. Addition of extended surfaces increase the heat transfer rate from a surface to a fluid wherever it is not possible to increase the value of the surface heat transfer coefficient or the temperature difference between the surface and the fluid. The use of fins has variety of shapes; however, in this experiment only flat fin type will be investigated (see Figure 1). The rate of heat transfer from a surface to a fluid by convection given by Newton's Law of Cooling: Q = AhTm (1) Where, A is the cross section area, h is the heat transfer coefficient, Tm is the mean temperature. The other related formulae and their descriptions are list in the table shown below. BMM3511 Engineering Thermo-Fluid Lab-05-C01 - Free and Foreced Convection

Page 2 of 8 Descriptions Remarks -Using perfect gas assumption -AT is the temperature difference and can be calculated from the difference between the average inlet and outlet temperatures. Heat transfer rate Q=mC₂AT (2) - The specific heat capacity of the air C, is also dependent on the air temperature and should be found from thermodynamics tables. p= Density of air Mass flow rate m = pVA (3) V = Average velocity of air A Cross sectional area Average temperature in the duct Tave = (4) Can be used to calculate the specific heat capacity C, value -Pe is the amount of power that is consumed by the heaters, and it can be considered as a measure of the amount of heat released. Efficiency (5) 7- Pe The efficiency factor indicates the portion of the input energy that is transferred to the fluid T = (6) - This is called Log Mean Temperature (LMT) Mean temperature -T, and Ts represent air and surface temperatures respectively. - the heat transfer coefficient, h, can be evaluated from Eqns. (1), (2), and (6). - μ = Air viscosity and L= Characteristic length Reynolds number Re= -The heat transfer depends not only on the temperature difference and the surface material of the heater, but is also influenced by the flow regime, i.e., laminar or turbulent flow. -Reynolds number is a criterion for defining whether a flow is turbulent or laminar. - The Nusselt number is dimensionless and is used in measuring heat transfer rates. -k is the thermal conductivity hL Nu (8) k -The Nusselt number can be calculated once the heat transfer coefficient, h, is known. Nusselt number Nu=0.664√ Re Pr. 033 (9) -Using the values obtained from this equation it is possible to check the accuracy of experiments for flat plate heater. BMM3511 Engineering Thermo-Fluid Lab-05-CO1 Free and Foreced Convection Formula Tin + Tout 2 T-TA T., -TA TS-TA In pVL μ

T₁ T ● T₁3 (a) (b) Figure1. Heat transfer plate (a) with and (b) without fins EXPERIMENTAL APPARATUS Figure 2 depicts the schematic diagram of the apparatus used in the experiment. It comprises the following 1) Fan Air Flow 2) Air duct 3) Finned and flat plate heater inserts Plate sensor Fan 4) Power regulator control o Wattmeter Plate and probe temperature switch 5) Digital power meter Temperature. indicator 6) Anemometer 7) Plate heater placement. Heater 8) Fan speed regulator 9) Temperature sensors 10) Data logger with Dasy lab software Thermal anemometer Figure 2. Schematic of Convention Heat Transfer Rig BMM3511 Engineering Thermo-Fluid Lab-05-CO1- Free and Foreced Convection Probe sensor Page 3 of 8 Heater control

Page 4 of 8 PROCEDURE - Make sure that you understand the explanations for general start-up and experimental procedures given during the lab session. - Write the complete procedures in your report. PRECAUTIONS 1. Beware of hot surfaces!!! Make sure that the heater power supply is first switched off before replacing the heater insert. 2. Do not touch the fan while conducting the experiment. 3. Wait until the hot plate is cool before you try to take it out from the air duct. 4. Keep away the anemometer once the velocity has been measured. 5. Be careful when connecting the heat socket to the power source. 6. The parallax error should be avoided while taking readings DATA COLLECTION 1. Complete the following table. 2. Show all the necessary calculations. A) Free Convection 1. Plate without fin: Heat Source:- Q = 75 W Time T₁ (C) T₂ (C) h (J/kg.K) (min) 0 4 8 12 16 2. With plate fin: Heat Source: Q = 75 W Time T₁ (C) T₂ (C) T3 (°C) 77 h (J/kg.K) (min) 0 4 8 12 16 BMM3511 Engineering Thermo-Fluid Lab-05-CO1 Free and Foreced Convection T3 (°C) 77 Remarks Remarks

3. With cylindrical fins: Heat Source:- Q = 75 W Time T, (C) T₂ (°C) (min) 0 4 8 12 16 B) Forced Convection 1. Without fin: Heat Source:- Fan Speed:- Time (min) 0 1 2 3 4 5 6 7 8 9 10 2. With fin: Q = 75 W V=0.2 m/s T₁ (°C) T₂ (°C) Heat Source: Fan Speed:- T3 (°C) T, (°C) 77 77 h (J/kg.K) (J/kg.K) Q = 75 W V=0.2 m/s Time T₁ (°C) T₂ (°C) T3 (°C) 77 h (J/kg.K) (min) 0 1 2 3 BMM3511 Engineering Thermo-Fluid Lab-05-CO1 Free and Foreced Convection Remarks Remarks Remarks Page 5 of 8

4 5 6 7 8 9 10 3. With fin: Q-75 W V=0.4 m/s T₁ (°C) T₂ (°C) T3 (°C) h (J/kg.K) Heat Source:- Q = 75 W V=0.6 m/s Fan Speed:- Time h T₁ (°C) T₂ (°C) T3 (°C) 17 (min) (J/kg.K) 0 1 2 3 4 5 6 7 8 9 10 BMM3511 Engineering Thermo-Fluid Lab-05-CO1 Free and Foreced Convection Heat Source:- Fan Speed:- Time (min) 0 1 2 3 4 5 6 7 8 9 10 4. With fin: 77 Remarks Remarks Page 6 of 8

Page 7 of 8 RESULTS 1. Plot graphs of temperature against time for free convection a. with plate fins, b. without fins, and c. with cylindrical fins. 2. Plot graphs of temperature against time for forced convection in the plates a. with fins, and b. without fins. 3. Calculate the mass flow rate of the air and the heat transfer rate. 4. Plot of efficiency vs time for each convection mode in one graph. 5. For the flat plate heater, plot the experimental Nusselt number data with comparison of the measured values to the one obtained from Eq. (9). 6. Plot the heat transfer coefficient vs velocity for forced convection. 7. Plot temperature vs position (1, 2, and 3) for forced convection. 8. Include any other necessary graphs. DISCUSSION 1. Discuss variation of heat transfer in free and forced convection modes. 2. In your discussion, indicate the differences between laminar and turbulent flows. Moreover, elaborate which one has the highest heat transfer coefficient. 3. Discuss the difference in the measured values of heat transfer coefficient if one uses linear average temperature (Eqn. 4) instead of LMT (Eqn. 6). 4. Discuss the effect convection mode on the efficiency. 5. Discuss the effect of extended surfaces on the heat convection. 6. Discuss the results you obtained during the experiment. CONCLUSIONS - Draw your own conclusion based on the experimental data. Comment on the performance of free and forced heat convection. Comment on the addition of extended surfaces for heat convection. REFERENCES State references you used to write the report BMM3511 Engineering Thermo-Fluid Lab-05-CO1 Free and Foreced Convection

EXPERIMENTS LEGEND A B C, D, H E F G Q T J K L M EZ OP N A B с D H E F I = Fan = Air duct = Temperature points (H = T1, D = T2, C = T3) = Anemometer point = Finned plate heater = Flat plate heater = Cylindrical plate heater = Power regulator = Digital power meter = ON/OFF switch = Fan speed regulator = Fan ON/OFF switch = Digital handheld temperature probe and meter = Digital handheld anemometer = Plate heater placement Q 0 N M K

Experiment 1 Free Convection Safety / Precaution 1. Do not touch the heat plate or air duct when conducting the experiment. 2. Do not touch the fan when conducting the experiment. 3. Ensure the heat plate is cooled down before remove away from the air duct. 4. Be careful when using the handheld digital anemometer. Keep it away once the air velocity is measured. 5. Be careful when connecting the heat socket to the power source. 6. Do not attempt to change the setting of the digital power meter. 7. Ensure the fan is switched OFF when conducting the free convection experiment. Pre-experiment procedure 1. Read the safety instruction given before conducting the experiment. 2. Read and understand the theory for free convection before lab session. 3. Prepare the accessories needed for the experiment. Objective Demonstration of free convection. • Determination of free convective heat transfer to air from flat plate heater. • Determination of free convective heat transfer to air from cylindrical plate heater. • Determination of free convective heat transfer to air from finned heat plate. Relationship between dissipated power with surface temperature. . Comparison between the three different type of surfaces heater. • Determination of Rayleigh Number, Nusselt Number and heat loss of surface heater. Accessories 1. LS-17004-FFC Free and Forced Convection Apparatus 2. Handheld temperature probe and meter 3. Vertical plate heater 4. Cylindrical plate heater 5. Finned plate heater Procedure 1. Place the LS-17004-FFC Free and forced convection apparatus on a level table. Adjust the adjustable levelling foot is necessary. 2. Plug the 3 pin plug to the 240VAC main power supply. Turn ON the power supply. 3. Switch ON the power supply unit (K) in front of the control panel. 4. Select the desired test specimen (i.e F, G, Q). Record down the shape of the selected test specimen. Please find appendix for the dimension of the test specimen. 5. Place the test specimen to the plate heater placement (P). Lock it with the wing nuts provided. 6. Connect the test specimen heater cable to the heater socket which is located at the back of

the control panel. 7. Take the digital handheld temperature probe and meter, measure the initial temperature (T.) in the air duct by putting the temperature probe into temperature point E. (Ensure the fan is OFF). 8. After read the temperature at point E, place the temperature probe to point D. 9. Regulate the power supplied to 50W by turning the power regulator (I). Keep an eye on the digital power meter (J). 10. For every five minute elapsed, measure the temperature (T..) at point D and record it into a table. 11. Continue the experiment until steady state achieved (where the temperature reading at point D became constant). 12. Repeat the experiment with other power. 13. Repeat the experiment with different type of test specimen. (Ensure the previous heat plate is properly cooled before removing it). 14. From the temperature result obtained, calculate the film temperature (T.). Then, from the thermophysical properties of gases at atmospheric pressure table provided, extract out all the relevant information. 15. From the information obtained, calculate the volumetric thermal expansion coefficient (3), Rayleigh Number, Nusselt Number using the correct equation. 16. Finally, calculate the coefficient of convection heat transfer (h) and hence the heat loss by convection (q) using the correct equation. Result Type of test specimen: Dimension of test specimen: Initial temperature reading: Power t (min) T₁2 (°C)

Power T. (°C) T. (°C) T. (K) T. (K) (W) k.10³ a.10⁰ Cp μ. 10¹ v.10⁰ (KJ/kgK) (N.s/m2) (m2/s) (W/m.K) (m2/s) T. (K) Pr B (K¹) Ra g (m/s²) Nu D (m) h (W/m².K) P (kg/m3) AT

q (w) Nq(w) Useful information and equation: = Power, T. (temperature at point D), T. (Initial To be obtained from experiment temperature) T₁ = [T.(K) + T. (K)] / 2 3 = 1/T D = diameter of rod or cross sectioned length perpendicular to flow direction To be obtained from thermophysical properties of gases at atmospheric pressure = Cp, u, v, k, a, Pr For Ra, Nu, h and q equation, please refer to theory section. Nq = only application for finned and bundle of cylinder whereby N for cylinder is 24 N for finned is 6 Experiment 2 - Forced Convection

Safety / Precaution 1. Do not touch the heat plate or air duct when conducting the experiment. 2. Do not touch the fan when conducting the experiment. 3. Ensure the heat plate is cooled down before remove away from the air duct. 4. Be careful when using the handheld digital anemometer. Keep it away once the air velocity is measured. 5. Be careful when connecting the heat socket to the power source. 6. Do not attempt to change the setting of the digital power meter. 7. Ensure the fan is switched OFF when conducting the free convection experiment. Pre-experiment procedure 1. Read the safety instruction given before conducting the experiment. 2. Read and understand the theory for forced convection before lab session. 3. Prepare the accessories needed for the experiment. Objective Demonstration of forced convection. Determination of forced convective heat transfer to air from vertical plate heater. • Determination of forced convective heat transfer to air from cylindrical plate heater. • Determination of forced convective heat transfer to air from finned heat plate. Relationship between air velocity with surface temperature. • Comparison between the four different type of surfaces heater. Accessories 1. LS-17004-FFC Free and Forced Convection Apparatus 2. Handheld digital anemometer 3. Handheld temperature probe and meter 4. Vertical plate heater 5. Cylindrical plate heater 6. Finned plate heater Procedure 1. Place the LS-17004-FFC Free and forced convection apparatus on a level table. Adjust the adjustable levelling foot is necessary. 2. Plug the 3 pin plug to the 240VAC main power supply. Turn ON the power supply. 3. Switch ON the power supply unit (K) in front of the control panel. 4. Select the desired test specimen (i.e F, G, Q). Record down the shape of the selected test specimen. Please find appendix for the dimension of the test specimen. 5. Place the test specimen to the plate heater placement (P). Lock it with the wing nuts provided. Connect the test specimen heater cable to the heater socket which is located at the back of the control panel. 7. Take the digital handheld temperature probe and meter, measure the initial temperature (T)

in the air duct by putting the temperature probe into temperature point E. (Ensure the fan is OFF). 8. After read the temperature at point E, place the temperature probe to point D. 9. Switch ON the fan switch (M). Place the anemometer to the point E. Set the fan speed to 0.2m/s. 10. Regulate the power supplied to 100W by turning the power regulator (I). Keep an eye on the digital power meter (J). 11. For every one minute elapsed, measure the temperature (T.) at point D and record it into a table. 12. Continue the experiment until steady state achieved (where the temperature reading at point D became constant). 13. Repeat the experiment with other power. 14. Repeat the experiment with different type of test specimen. (Ensure the previous heat plate is properly cooled before removing it). 15. From the temperature result obtained, calculate the film temperature (T.). Then, from the thermophysical properties of gases at atmospheric pressure table provided, extract out all the relevant information for initial temperature (T.), film temperature, (T.) and temperature at point D when steady state (T.). 16. Calculate Reynold's number (Re), Nusselt number (Nu), heat transfer coefficient (h) and overall heat transfer (q). Result Type of test specimen: Dimension of test specimen: Initial temperature reading: Air velocity t (s) T. ("C)

T. (°C) T.(K) Cp (KJ/kgK) p (kg/m3) u. 10 (N.s/m2) v.10 (m2/s) k.10³ (W/m.K) Pr

Velocity (m/s) Velocity (m/s) Velocity (m/s) T.(°C) T. ("C) Re C m Cp T.(K) (KJ/kgK) p (kg/m3) T. (°C) Cp T, ("C) T.(K) (KJ/kgK) p (kg/m3) T. (K) T. (K) Nu h (W/m²K) μ. 10' (N.s/m2) v.10° (m2/s) H. 10/ (N.s/m2) v.10° (m2/s) T₁(K) q (W) k.10³ (W/m.K) Pr. k.10% (W/m.K) Pr Rep.m V (m/s) Nq(W)

Useful information and equation: To be obtained from experiment = Power, T., T., velocity T₁ = [T.(K) + T. (K)] / 2 D = diameter of rod or cross sectioned length perpendicular to flow direction To be obtained from thermophysical properties of gases at atmospheric pressure = Cp. H. v, k, a, Pr For Re, Nu, h and q equation, please refer to theory section. Nq = only application for finned and bundle of cylinder whereby N for cylinder is 24 N for finned is 6 Appendix (Test Heater Dimension): Cylindrical Rod: 09,53 14,85 10,50 10,50 Ø O 8 O Qo 0 0 0 0 0 Length = 110mm

Finned Plate: Vertical Plate: 110,00 6,35 19.05.

MANUFACTURER'S DATA Experiment 1 Free Convection - Test specimen = Cylindrical Power 25W t (min) TRON (°C) 0 31 10 34.5 15 36.9 20 39.4 25 41.4 30 43.1 35 44.2 40 45.4 45 46.4 50 47.4 55 48.1 60 48.8 65 48.8 70 49.5 75 49.4 80 50.2 85 50

90 95 Power t (min) 0 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 50 50 50W Tid ("C) 32.7 40.8 44.7 48.3 50.9 53.1 54.7 56.1 57.4 58.1 59 59.5 59.7 60.1 60.4 60.5

15 20 25 30 35 40 45 50 55 60 65 70 56.2 62.4 66.8 70 71.3 71.9 72.8 74.3 75 75.6 76.1 75.8 T. (°C) T. (°C) Power (W) T. (K) T.(K) T. (K) g (m/s) D (m) p (kg/m3) 25.0000 50.2000 31.0000 323.2000 304.0000 313.6000 0.0032 9.8000 0.0095 1.1161 50.0000 60.5000 31.0000 333.5000 304.0000 | 318.7500 0.0031 9.8000 0.0095 1.0990 75.0000 66.4000 31.0000 339.4000 304.0000 321.7000 9.8000 0.0095 1.0892 0.0031 31.0000 349.1000 304.0000 326.5500 0.0031 100.0000 76.1000 9.8000 0.0095 1.0730 Pr Ra Nu AT Cp H. 10 V.10⁰ k.10⁹ a.10⁰ (KJ/kgK) (N.s/m2) (m2/s) (W/m.K) (m2/s) h (W/m².K) 1.0075 191.0192 17.2582 27.3064 24.5128 0.7051 1227.5595 2.7249 7.8076 19.2000 1.0078 193.4500 17.7763 27.6875 25.2750 0.7044 1747.2107 2.9388 8.5382 29.5000 1.0079 194.8424 18.0730 27.9058 25.7116 0.7040 2008.6171 3.0291 8.8700 35.4000 1.0081 197.1316 18.5609 28.2647 26.4294 0.7033 2388.0565 3.1461 9.3309 45.1000 B (K¹)

q (w) Nq(w) 0.4938 11.8501 0.8296 19.9108 1.0342 24.8215 1.3861 33.2662 Sample Calculation for the Case free convection of Cylindrical Rod (Power = 25W), T. (C) = 50.20 T. (C) = 31.00 T, (K) = T (C) + 273 = 323.00 T. (K) = T. (C) + 273 = 304.00 T, (K) = [T. (K)+ T. (K)] / 2 = 313.60 B (K.) = 1/T₁ = 0.003 D (m) = Diameter of the rod = 9.53mm p (kg/m3, Cp (KJ/kgK), μ. 10 (N.s/m2), v. 10 (m2/s), k.10 (W/m.K), a.10 (m2/s) and Pr (all obtained from the gas properties table. (You may use interpolation method or take the reading close to the film temperature (T.).

gB(T. -T.)L' VOC Using equation (4), Ra= Gr_Pr = 0.387 Ra Nu-0.60+ [1+ (0.559/Pr)/16 18:37 Using equation (11), = 2.725 hD Nup = CRa", Using equation (12), , h = 7.808 AT = T. (K)+ T. (K) = 19.20 Using equation (1), q=hoverage A, (T. -T.). = 7.808(3.142 0.00953*0.110)19.20 = 0.4938 W Nq = 24 0.4938 = 11.85W Experiment 2 Forced Convection Test specimen = Cylindrical; Power = 100W Air velocity 0.2m/s t(s) T. (C) 0 66.7 30 72.5 60 76.7 90 79.6 120 81.9 150 83.8 180 85.8 = 1227.559

210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780 810 840 870 Air velocity 87.3 88.5 89.5 90.2 90.9 91.6 91.9 92.2 92.4 93 93 93.2 93.2 93.1 93.3 93.4 93.6 93.9 93.9 94 93.8 94 94.3 0.6m/s

t (s) 0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 T("C) 71.2 78.8 84.7 89.2 92.7 95.5 97.5 99 100 100.7 101.2 101.3 101.4 101.3 101.1 100.7 100.5 100.2 99.8 99.5 99.2 98.9

660 690 720 750 780 810 840 870 Air velocity t (s) 0 30 60 90 120 150 180 210 240 270 300 98.4 97.9 97.6 97.3 97 96.7 96.4 96.1 0.9m/s Tinal ("C) 67.1 74.7 81.2 85.4 88.4 90.3 91.4 91.7 91.7 91.6 91.1

330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780 810 840 870 900 Air velocity t (s) 0 90.7 90.1 89.5 88.7 88 87.1 86.5 85.9 85.1 84.3 83.7 83.3 82.7 82.2 81.6 81.2 80.5 80.3 79.7 79.3 1.1m/s Tunn (°C) 66.3

30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 74.5 79.4 81 83.6 84.7 84.9 84.5 84 83.3 82.4 81.7 80.7 79.7 78.8 77.9 77.3 76.5 75.8 75.1 74.3 73.8 73.1 72.6 72

750 780 810 840 870 900 T. (°C) 33.2 Velocity (m/s) 0.2 0.6 0.9 1.1 Velocity (m/s) 0.2 0.6 0.9 1.1 71.5 71 70.6 70.3 69.8 69.5 T. (K) Cp (KJ/kgK) p (kg/m3) u. 10 (N.s/m2) v.10° (m2/s) k.10³ (W/m.K) 306.2 1.007248 1.1407664 187.5264 16.51372 26.7588 Cp (KJ/kgK) p (kg/m3) T. ("C) T.(K) μ. 10/ (N.s/m2) v.10° (m2/s) 206.2176 20.49748 72.8 345.8 1.008832 1.0089776 29.6892 0.70058 62.1 335.1 1.008404 1.0445872 201.1672 19.42106 28.8974 0.70208 58.4 331.4 1.008256 1.0569008 199.4208 19.04884 28.6236 0.70260 54.4 327.4 1.008096 1.0702128 197.5328 18.64644 28.3276 0.70316 Cp H. 10' k.10³ T. (°C) T.(K) (KJ/kgK) P (kg/m3) (N.s/m2) v.10° (m2/s) (W/m.K) Pr 53 326 1.00804 1.074872 196,872 18.5056 28.224 0.70336 47.65 320.65 1.007826 1.0926768 194.3468 17.96739 27.8281 0.70410 45.8 318.8 1.007752 1.0988336 193.4736 17.78128 27.6912 0.70436 43.8 316.8 1.007672 1.1054896 192.5296 17.58008 27.5432 0.70464 Pr 0.706132 k.10% (W/m.K) Pr

Velocity (m/s) T. (°C) T. (°C) T. (K) T. (K) T. (K) Vmax (m/s) Reoman 0.2 94.8 31 367.8 304 335.9 0.666666667 389.9568715 0.6 101.4 31 374.4 304 339.2 2 1169.870615 0.9 91.7 31 364.7 304 334.35 3 1754.805922 1.1 84.9 31 357.9 304 330.95 3.666666667 2144.762793 Re C m Nu h (W/m²K) q (W) Nq(W) 98.53435409 0.9 0.4 4.98176603 13.9029433 2.14597340 51.50336171 290.2441647 0.35 0.6 9.28192107 25.9036698 4.41195282 105.8868678 447.2232207 0.35 0.6 12.0224169 33.5517525 33.5517525 4.92720697 118.2529675 556.9639848 0.35 0.6 13.7076125 38.254739 4.98851077 119.7242587 Sample Calculation for the Case forced convection of Cylindrical Rod (velocity = 0.2m/s), Data for table 1, 2 and 3 obtained from the gas properties table. V... = S/(SD)* velocity = 1.381 Re.. =VD/v₁. = 808.13 Re = p.(velocity)(D)/u = 98.53 C and m, refer to table 5 Using equation (20), Nu= 4.98 hl) Nu₂ = Using equation (12), k = CRa , h = 13.90

Using equation (1), q="overage A, (1, -T.) Ng = 24 * 2.92 = 70.08W = 13.9(3.142*0.00953*0.110)63.8 = 2.92

1.0 OBJECTIVES AND BASIC EQUATIONS 2.0 EXPERIMENT PROCEDURE 3.0 DATA TABLE AND CALCULATIONS Experiment 1 Free Convection 1) With cylindrical plate; Power = 25W Time(min) T. (K) T, (K) 0 304 304.00 10 304 305.75 15 304 306.95 20) 304 308.20 25 304 309.20 30 304 310.05 35 304 310.60 40 304 311.20 304 311.70 304 312.20 45 50 Ts (°C) Tę (K) 31.0 304.00 34.5 307.50 36.9 309.90 39.4 312.40 41.4 314.40 43.1 316.10 44.2 317.20 45.4 318.40 46.4 319,40 47.4 320.40 B = (K-¹) 0.0033 0.0033 0.0033 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032

55 48.1 60 48.8 65 48.8 70 49.5 75 49.4 80 50.2 85 50.0 90 50.0 95 50.0 2) With cylindrical plate; Power = 50W Time(min) 0 10 15 20 25 30 35 40 45 50 55 60 321.10 321.80 321.80 322.50 322.40 323.20 323.00 323.00 323.00 Ts (°C) Ts (K) 32.7 305.70 40.8 313.80 44.7 317.70 48.3 321.30 50.9 323.90 53.1 326.10 54.7 327.70 56.1 329.10 57.4 330.40 58.1 331.10 59.0 332.00 59.5 332.50 304 304 304 304 304 304 304 304 304 Too(K) 304 304 304 304 304 304 304 304 304 304 304 304 312.55 312.90 312.90 313.25 313.20 313.60 313.50 313.50 313.50 T, (K) 304.85 308.90 310.85 312.65 313.95 315.05 315.85 316.55 317.20 317.55 318.00 318.25 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 P = (K-¹) 0.0033 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0032 0.0031 0.0031 0.0031

332.70 333.10 333.40 333.50 Ts (C Ts (K) 34.0 307.00 45.6 318.60 49.8 322.80 53.6 326.60 56.6 329.60 59.9 332.90 61.9 334.90 63.5 336.50 66.0 339.00 65.8 338.80 65.6 338.60 65.6 338.60 66.2 339.20 66.4 339.40 66.4 339.40 65 59.7 70 60.1 75 60.4 80 60.5 3) With cylindrical plate; Power 75W Time(min) 0 10 15 20 25 30 35 40 45 50 55 60 65 70 75 304 304 304 304 T. (K) 304 304 304 304 304 304 304 304 304 304 304 304 304 304 304 318.35 318.55 318.70 318.75 T, (K) 305.50 311.30 313.40 315.30 316.80 318.45 319.45 320.25 321.50 321.40 321.30 321.30 321.60 321.70 321.70 0.0031 0.0031 0.0031 0.0031 B = (K-¹) 0.0033 0.0032 0.0032 0.0032 0.0032 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031

4) With cylindrical plate; Power 100W Time(min) 0 10 15 20 25 30 35 40 45 50 55 60 65 70 Ts (°C) Ts (K) 32.2 305.20 49.1 322.10 56.2 329.20 62.4 335.40 66.8 339.80 70.0 343.00 71.3 344.30 71.9 344.90 72.8 345.80 74.3 347.30 75.0 348.00 75.6 348.60 76.1 349.10 75.8 348.80 T... (K) 304 304 304 304 304 304 304 304 304 304 304 304 304 304 T, (K) 304.60 313.05 316.60 319.70 321.90 323.50 324.15 324.45 324.90 325.65 326.00 326.30 326.55 326.40 B = (K-¹) 0.0033 0.0032 0.0032 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031

Free Convection Calculated Data POWER T(°C) T(°C) Ts(K) T(K) T(K) B(K-¹) g D(m) kg (W) (m/s²) P m 25 50.2 31 0.0095 1.1248 50 60.5 31 0.0095 1.1065 323.2 304 333.5 304 339.4 304 349.1 304 313.60 0.0032 9.81 318.75 0.0031 9.81 321.70 0.0031 9.81 326.55 0.0031 9.81 75 66.4 31 0.0095 1.0964 0.0095 1.0803 100 76.1 31 u. 10/ V. 106 k. 10³ Cp a. 106 Pr Ra Nu h (W/m²K) (KJ/kgK) (N.s/m²) (m²/s) (W/mK) (m²/s) 1.0070 192.0760 17.0776 26.6644 1.0070 194.4300 17.5720 27.0440 1.0070 195.7280 17.8552 27.2564 1.0070 197.8975 18.3279 27.6092 23.7161 0.7253 1995.2218 3.0339 8.5156 24.3867 0.7239 2800.2863 3.2689 9.3056 24.7707 0.7231 3250.9264 3.3794 9.6958 25.4725 0.7219 3923.7353 3.5253 10.2454 AT q(W) Nq (W) 19.2 0.5368 12.8840 29.5 0.9013 21.6321 35.4 1.1270 27.0472 45.1 1.5171 36.4114 Experiment 2 - Forced Convection 1) With cylindrical plate; Power 100 W Air velocity = 0.2 m/s Ts (°C) T, (K) B = 7/₁1 ( (K-¹) 66.7 322.95 0.0031 72.5 325.85 0.0031 76.7 327.95 0.0030 79.6 329.40 0.0030 81.9 330.55 0.0030 83.8 331.50 0.0030 85.8 332.50) 0.0030 87.3 333.25 0.0030 88.5 333.85 0.0030 89.5 334.35 0.0030 Time(min) 0 30) 60 90 120 150 180 210 240 270 Ts (K) 339.70 345.50 349.70 352.60 354.90 356.80 358,80 360.30 361.50 362.50 Too(K) 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2

300 90.2 330 90.9 360 91.6 390 91.9 420 92.2 450 92.4 480 93.0 510 93.0 540 93.2 570 93.2 600 93.1 630 93.3 660 93.4 690 93.6 720 93.9 750 93.9 780 94.0 810 93.8 840 94.0 870 94.3 2) With cylindrical plate; Power 100 W Air Velocity 0.6 m/s = Time(min) Ts (° C) 363.20 363.90 364.60 364.90 365.20 365.40 366.00 366.00 366.20 366.20 366.10 366.30 366.40 366.60 366.90 366.90 367.00 366.80 367.00 367.30 T's (K) 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 Too(K) 334.70 335.05 335.40 335.55 335.70 335.80 336.10 336.10 336.20 336.20 336.15 336.25 336.30) 336.40 336.55 336.55 336.60 336.50 336.60 336.75 T, (K) 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 B = (K-¹)

0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780 712 78.8 84.7 89.2 92.7 95.5 97.5 99.0 100.0 100.7 101.2 101.3 101.4 101.3 101.1 100.7 100.5 100.2 99,8 99,5 99.2 98.9 98.4 97.9 97.6 97.3 97.0 344.20 351.80 357.70 362.20 365.70 368.50 370.50 372.00 373.00 373.70 374.20 374.30 374.40 374.30 374.10 373.70 373.50 373.20 372.80 372.50 372.20 371.90 371.40 370.90 370.60 370.30 370.00 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 325.20 329.00 331.95 334.20 335.95 337.35 338.35 339.10 339.60 339.95 340.20 340.25 340.30 340.25 340.15 339.95 339.85 339.70 339.50 339.35 339.20 339.05 338.80 338.55 338.40 338.25 338.10 0.0031 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0029 0.0030 0.0030 0.0030 0.0030 0.0030

810 96.7 840 96.4 870 96.1 3) With cylindrical plate; Power 100 W Air Velocity = 0.9 m/s Ts (°C) 67.1 74.7 81.2 85.4 88.4 90.3 91.4 91.7 91.7 91.6 91.1 90.7 90.1 89.5 88.7 88.0 87.1 86.5 85.9 85.1 Time(min) 0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 $10 540 570 369.70 369.40 369.10 TS (K) 340.10 347.70 354.20 358.40 361.40 363.30 364.40 364.70 364.70 364.60 364.10 363.70 363.10 362.50 361.70 361.00 360.10 359.50 358.90 358.10 306.2 306.2 306.2 Too(K) 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 337.95 337.80 337.65 Tf (K) 323.15 326.95 330.20 332.30 333.80) 334.75 335.30 335.45 335.45 335.40 335.15 334.95 334.65 334.35 333.95 333.60 333.15 332.85 332.55 332.15 0.0030 0.0030 0.0030 B = (K-¹) 0.0031 0.0031 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030

600 84.3 630 83.7 660 83.3 690 82.7 720 82.2 750 81.6 780 81.2 810 80.5 840 80.3 870 79.7 900 79.3 4) With cylindrical plate; Power 100 W Air Velocity 1.1 m/s Time(min) Ts (° C) 0 66.3 30 74.5 60 79.4 90 81.0 120 83.6 150 84.7 180 84.9 210 84.5 240 84.0 270 83.3 300 82.4 330 81.7 360 80.7 357.30 356.70 356.30 355.70 355.20 354.60 354.20 353.50 353.30 352.70 352.30 Tę (K) 339.30 347.50 352.40 354.00 356.60 357.70 357.90 357.50 357.00 356.30 355.40 354.70 353.70 306.2 331.75 306.2 331.45 306.2 331.25 306.2 330.95 306.2 330.70 306.2 330.40 306.2 330.20 306.2 329.85 306.2 329.75 306.2 329.45 306.2 329.25 Too(K) T, (K) 306.2 322.75 306.2 326.85 306.2 329.30 306.2 330.10 306.2 331.40 306.2 331.95 306.2 332.05 306.2 331.85 306.2 331.60 306.2 331.25 306.2 330.80 306.2 330.45 306.2 329.95 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 B = (K-¹) 0.0031 0.0031 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030

600 84.3 630 83.7 660 83.3 690 82.7 720 82.2 750 81.6 780 81.2 810 80.5 840 80.3 870 79.7 900 79.3 4) With cylindrical plate; Power 100 W Air Velocity 1.1 m/s Time(min) Ts (° C) 0 66.3 30 74.5 60 79.4 90 81.0 120 83.6 150 84.7 180 84.9 210 84.5 240 84.0 270 83.3 300 82.4 330 81.7 360 80.7 357.30 356.70 356.30 355.70 355.20 354.60 354.20 353.50 353.30 352.70 352.30 Tę (K) 339.30 347.50 352.40 354.00 356.60 357.70 357.90 357.50 357.00 356.30 355.40 354.70 353.70 306.2 331.75 306.2 331.45 306.2 331.25 306.2 330.95 306.2 330.70 306.2 330.40 306.2 330.20 306.2 329.85 306.2 329.75 306.2 329.45 306.2 329.25 Too(K) T, (K) 306.2 322.75 306.2 326.85 306.2 329.30 306.2 330.10 306.2 331.40 306.2 331.95 306.2 332.05 306.2 331.85 306.2 331.60 306.2 331.25 306.2 330.80 306.2 330.45 306.2 329.95 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 B = (K-¹) 0.0031 0.0031 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030 0.0030

390 420 450 480 510 540 570 600 630 660 690 720 750 780 810 840 870 900 79.7 78.8 77.9 77.3 76.5 75.8 75.1 74.3 73.8 73.1 72.6 72.0 71.5 71.0 70.6 70.3 69.8 69.5 352.70 351.80 350.90 350.30 349.50 348.80 348.10 347.30 346.80 346.10 345.60 345.00 344.50 344.00 343.60 343.30 342.80 342.50 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 306.2 329.45 329.00 328.55 328.25 327,85 327.50 327.15 326.75 326.50 326.15 325.90 325.60 325.35 325.10 324.90 324.75 324.50 324.35 0.0030 0.0030 0.0030 0.0030 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031

FORCED CONVECTION CALCULATED DATA Too. (°C) Too. (K) C₂ kg P (KJ/kgK) 'mª 33.2 306.2 1.007 1.1518 Velocity T, (°C) T,(K) C₂ (m/s) (KJ/kgK) 0.2 72.8 345.8 1.0073 0.6 62.1 335.1 1.0070 0.9 58.4 331.4 1.0070 1.1 54.4 327.4 Velocity T,(°C) T,(K) (m/s) 0.2 0.6 0.9 1.1 Velocity T,(C) T. (°C) T₂(K) (m/s) 0.2 72.8 33.2 0.6 62.1 33.2 0.9 58.4 33.2 1.1 54.4 33.2 Re C 104.0218 0.9 321.0975 0.35 486.4282 0.35 601.1012 0.35 μ. 107 k. 10³ P₁ (N.s/m²) (W/m.K) 188.6720 26.1168 0.7273 kg. u. 10 V. 106 Pm3 k. 103 Pr, (N.s/m²) (N.s/m²) (m²/s) 1.0200 1.0525 (W/m.K) 206.4320 20.2356 29.0116 0.7171 201.7240 19.1679 28.2333 0.7197 200.0800 18.8032 27.9632 0.7206 198.2800 18.4112 27.6712 0.7217 1.0643 1.0070 1.0775 kg. H. 107 V. 106 Pr k. 103 (N.s/m²) (m²/s) (W/m.K) 772 53.00 47.65 320.65 1.0070 Cp P3 (KJ/kgK) 326.00 1.0070 1.0821 197.6500 18.2740 27.5690 0.7220 1.1000 195.2660 17.7544 27.1808 0.7234 1.1063 194.4520 17.5768 27.0476 0.7239 193.5480 17.3848 26.9012 0.7244 45.80 318.80 1.0070 43.80 316.80 1.0070 1.1133 T... (K) T, (°K) Vmax (m/s) Rep.max 345.8 306.2 326.00 0.6667 346.5762 335.1 306.2 320.65 2.0000 1070.1573 331.4 306.2 318.80 3.0000 1621.4556 327.4 306.2 316.80 3.6667 2003.6660 q (W) Nq(W) 3.1282 75.0759 5.5466 133.1194 6.1761 148.2253 5.8680 140.8310 II 0.4 0.6 0.6 0.6 V. 106 (m²/s) 16.3808 Nu 8.2904 20.4301 26.2170 29.7701 h (W/m².K) 24.0587 58.4534 74.6428 84.3002