hmt lab manual (heat and mass transfer lab manual)

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radial conduction through the wall of a cylinder 5

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To measure the thermal conductivity of liquids and gases. 7 To demonstrate the relationship between power input and surface temperature in free convection 8 T

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d counter current Shell & Tube Heat Exchanger.

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7

Heat and Mass Transfer Lab

2

Experiment 1: Fourier’s Law study for linear conduction of heat along a homogeneous bar

Objective: To investigate Fourier's Law for the linear conduction of heat along a homogeneous bar Procedures: 1. Make sure that the main switch initially off. Then Insert a brass conductor (25mm

diameter) section intermediate section into the linear module and clamp together. 2. Turn on the water supply and ensure that water is flowing from the free end of the

water pipe to drain. This should be checked at intervals. 3. Turn the heater power control knob control panel to the fully anticlockwise position and

connect the sensors leads. 4. Switch on the power supply and main switch; the digital readouts will be illuminated. 5. Turn the heater power control to 40 Watts and allow sufficient time for a steady state

condition to be achieved before recording the temperature at all six sensor points and the input power reading on the wattmeter (Q). This procedure can be repeated for other input power between 0 to 40 watts. After each change, sufficient time must be allowed to achieve steady state conditions.

6. Plot of the temperature, T versus distance, x. Calculate the theoretical and actual thermal conductivity. Note: i) When assembling the sample between the heater and the cooler take care to

match the shallow shoulders in the housings. ii) Ensure that the temperature measurement points are aligned along the

longitudinal axis of the unit. Results:

Heater Power, Q (Watts)

T1 (°C)

T2 (°C)

T3 (°C)

T4 (°C)

T5 (°C)

T6 (°C)

T7 (°C)

T8 (°C)

T9 (°C)


3

Experiment 2: Conduction of heat and overall heat transfer along a composite bar

Objective: To study the conduction of heat along a composite bar and evaluate the overall heat transfer coefficient

Procedure:

1. Make sure that the main switch initially off. Insert the stainless steel section or any

other metals (without sensor) into the linear module and clamp together. 2. Turn on the water supply and ensure that water is flowing from the free end of the

water pipe to drain. This should be checked at intervals. 3. Turn the heater power control knob control panel to the fully anticlockwise position. 4. Connect the six sensor leads (T1, 2, 3 & 7, 8, 9) to the plugs on top of the linear

conduction module. Connect the left-hand sensor lead from the module to the place marked T1 on the control panel. Repeat this procedure for the remaining five sensor leads, connecting them from left to right on the module and in numeral order on the control panel.

5. Switch on the power supply and main switch; the digital readouts will be illuminated. 6. Turn the heater power control to 40 Watts and allow sufficient time for a steady state


7. Plot of the temperature, T versus distance, x. Calculate the Overall Heat Transfer Coefficient, U based on the knowledge of kbrass and kstainless steel and distances x1, x2 and x3.

Note: When assembling the sample between the heater and the cooler take care to match the surface.

Results:

Test Heater

Power, Q (Watts)

T1 (°C)

T2 (°C)

T3 (°C)

T7 (°C)

T8 (°C)

T9 (°C)

A

B

C

D


4

Experiment 3: The effect of a change in cross-sectional area on the temperature profile along a thermal conductor

Objective: To investigate the effect of a change in the cross-sectional area on the temperature profile along a thermal conductor. Procedure: 1. Make sure that the main switch initially off. Insert a brass or any other metals

conductor (13mm diameter) section into the linear module and clamp together. 2. Turn on the water supply and ensure that water is flowing from the free end of the

water pipe to drain. This should be checked at intervals. 3. Turn the heater power control knob control panel to the fully anticlockwise position. 4. Connect the six sensor leads (T1, 2, 3 & 7, 8, 9) to the plugs on top of the linear

conduction module. Connect the left-hand sensor lead from the module to the place marked TT1 on the control panel. Repeat this procedure for the remaining five sensor leads, connecting them from left to right on the module and in numeral order on the control panel.

5. Switch on the power supply and main switch; the digital readouts will be illuminated.

6. Turn the heater power control to 20 Watts and allow sufficient time for a steady state condition to be achieved before recording the temperature at all six sensor points and the input power reading on the wattmeter (Q). This procedure can be repeated for other input power between 0 to 20 watts. After each change, sufficient time must be allowed to achieve steady state conditions.

7. Plot of the temperature, T versus distance, x. Comment on the trend and slope of the graph.

Note: When assembling the sample between the heater and the cooler take care to provide a good surface contact.

Results:

Test Heater Power, Q (Watts)

T1 (°C)

T2 (°C)

T3 (°C)

T7 (°C)

T8 (°C)

T9 (°C)

A

B

C

D


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Experiment 4: The temperature profile and rate of heat transfer for radial conduction through the wall of cylinder

Objective: To examine the temperature profile and determine the rate of heat transfer resulting from radial conduction through the wall of a cylinder

Procedure:

1. Make sure that the main switch initially off. 2. Connect one of the water tubes to the water supply and the other to drain. 3. Connect the heater supply lead for the radial conduction module into the power supply

socket on the control panel. 4. Connect the six sensor (T1, 2, 3 & 4, 5, 6) leads to the radial module, with the T1

connected to the innermost plug on the radial. Connect the remaining five sensor leads to the radial module correspondingly, ending with T6 sensor lead at the edge of the radial module.

5. Turn on the water supply and ensure that water is flowing from the free end of the water pipe to drain. This should be checked at intervals.

6. Turn the heater power control knob control panel to the fully anticlockwise position. 7. Switch on the power supply and main switch; the digital readouts will be illuminated. 8. Turn the heater power control to 40 Watts and allow sufficient time for a steady state


9. Plot of the temperature, T versus distance, r. Calculate the amount of heat transferred.

Results:

Test Heater Power, Q (Watts)

T1 (°C)

T2 (°C)

T3 (°C)

T4 (°C)

T5 (°C)

T6 (°C)

A

B

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D


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Experiment 5: To determine the overall heat transfer coefficient of non-metallic materials

like glass, wood, plastic etc. And compare it with the theoretical value.

Objective: To measure the thermal conductivity of the samples, we’ll use the apparatus of Thermal

Conductivity of Building Materials apparatus.

Procedure:

1. Connect the apparatus unit with the Indicator Service Unit with the each connector to the desire point mentioned on the back of the indicator box.

2. Connect the cold plate water supply connection to the lab cold water hose bib and adjust the flow to maintain a limited flow through the unit. Direct the discharge hose to the lab’s drain.

3. Measure the thickness of each sample at several locations prior to inserting them into the apparatus. This will allow you to determine the average thickness of the sample.

4. Insert the sample into the apparatus and position it for testing. 5. Note the temperature of the cooling water being supplied to the cold plate by the shop water. Set

the PID controller to maintain the hot plate at 15°C to 20°C above this temperature. 6. Monitor the TC and heat flux meter readings for stability. When these readings reach steady-

state, record the information to use in your calculations. 7. Repeat these procedures for each of the samples. 8. The heat flux sensor is used to display he thermal conductivity directly on the display.

Test Heat Input Q Temperature Measurement

Volt Amp Watt T1 T2 T3 T4 T5 T6 Tw-i Inlet of water

Tw-o Outlet of water

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Temperature indicator for the hot plate. T1, T2, and T3 (Temperature Hot Plate) Th=(T1+T2+T3)/3 Temperature indicator for the cold plate. T4, T5, and T6 (Temperature cold Plate) Tc=(T4+T5+T6)/3


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Experiment 6: To determine the thermal conductivity of liquids and gases.

Objective: To measure the thermal conductivity of liquids and gases.

Procedure:

1 Use air as the sample of the experiment. 2 Make sure there is cooling water supply to the water jacket and it is 5-10 LPM. 3 Turn on the main switch and the heater switch. 4 Record the power and temperature readings T1,T2. When all readings stabilized for about 10

minutes. 5 Calculate the thermal conductivity of air by applying Fourier’s Equation. Use the incidental heat

loss correction value for accurate thermal conductivity determination. 6 Repeat the experiment by substituting the air with aceton with the heating power of 175 watt.

Sample Power

supply to heater Q(W)

T1 (oC)

T2 (oC)

∆T (oC)

Qgen (W)

Qc (W)

Qlost (W)

K (W/mk)

Error (%)

Air

water

Outer radius of the inner cylinder, R (m) 0.01665

Inner radius of the outer cylinder, L (m) 0.01695

Length of the cylinder, L (m) 0.10

Theoretical thermal conductivity, k of air 0.026

Theoretical thermal conductivity, k of water 0.16


8

Experiment 7: To determine the relationship between power input and surface temperature

in free convection.

Objectives: To demonstrate the relationship between power input and surface temperature in free convection.

Procedures:

1. Remove the fan assembly from the top of the duct. 2. Place the finned heat exchanger into the test duct. 3. Set the heater power control to 20 Watts (clockwise). 4. Allow sufficient time to achieve steady state conditions before noting the heated plate

temperature (tH) and ambient temperature (tA) into the table below. 5. Repeat this procedure at 40, 60 and 80 Watts. 6. Plot a graph of power against temperature (tH-tA).

Input Power Watts

Plate Temp (tH) C

Ambient Temp (tA) °C

tH – tA C

20 40 60 80


9

Experiment 8: To determine the relationship between power input and surface temperature in forced convection.

Objectives: To demonstrate the relationship between power input and surface temperature in forced convection.

Procedures:

1. Place the fan assembly on to the top of the duct. 2. Place the finned heat exchanger into the duct. 3. Set the heater power control to 50 Watts (clockwise). Allow sufficient time to achieve

steady state conditions before noting the heated plate temperature (tH) and the ambient temperature (tA).

4. Set the fan speed control to give a reading of 0.5m/s on the thermal anemometer, allow sufficient time to achieve steady state conditions. Record heated plate temperature (tH) and ambient temperature (tA).

5. Repeat this procedure by setting the fan speed control to give 1.0m/s and 1.5m/s. 6. Plot a graph of air velocity against temperature. ( tH –tA)

Power input = 50 Watts

Air Velocity m/s

Plate Temp (tH) C


tH – tA C

0 0.5 1.0 1.5


10

Experiment 9: To determine the use of extended surface to improve heat transfer from the surface.

Objectives: To demonstrate the use of extended surface to improve heat transfer from the surface.

Procedures:

1. Place the fan assembly on to the top of the duct. 2. Place the flat plate heat exchanger into the duct. 3. Set the heater power control to 75 Watts. Allow the temperature to rise to 800C, and

then adjust the heater power control to 15 Watts until a steady reading is obtained. 4. Set the fan speed control to give 1m/s using the thermal anemometer. Record heated

plate temperature (tH) and the ambient temperature (tA). 5. Repeat this procedure at 2 and 2.5m/s for the flat plate. Repeat the experiment by

replacing the flat plate with the finned plate and pinned plate. 6. Plot graphs of velocity against temperature (tH - tA) for each of the plates.


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Input power = 15 Watts

Velocity m/s

Plate Temp (tH) C


tH - tA C

0 1 2

2.5

Note: Comment on the correlation between total surface area of the heat exchanger and the temperature achieved.

Further Experiments: Increase power input and repeat experiments


12

Experiment 10: INVERSE SQUARE LAW FOR HEAT

Objective: To show that the intensity of radiation on a surface is inversely proportional to the square of the distance of the surface from the radiation source Procedure: 1. Follow the basic instruction as written in this section. 2. Connect one of the thermocouple of the target plates BLACK to the panel and place

the plate on the bench, to record ambient temperature. 3. Position the radiometer on the test track at 800mm from the heat source. 4. Set heater temperature to 150°C by using heater controller. Monitor TH reading on the

indicator. 5. When TH value has stabilized, record BLACK, TH, the distance, x and the radiometer

reading, R. 6. Next, move the radiometer position to 700mm from the heated surface and monitor the

reading on the display panel. When the value has stabilized, record BLACK, TH, the distance, x and the radiometer reading, R.

7. Repeat the above procedure by reducing the distance by 100mm until the radiometer is 300mm from the heated surface.

Observations:

Distance, x(mm)

Radiometer Reading, R(W/m2)

BLACK (°C) TH (°C)

800 700 600 500 150 300

Assignment: Plot the Log of the corrected radiometer reading R versus Log10 x graph and calculate the slope. Compare the result with the theoretical value.


13

Experiment 11: STEFAN-BOLTZMANN LAW

Objective: To show that the intensity of radiation varies as the fourth power the source temperature. Procedure: 1. Follow the basic instruction as written in this section. 2. Connect one of the thermocouple of the target plates BLACK to the panel and place

the plate on the bench, to record ambient temperature. 3. Position the radiometer on the test track at 800mm from the heat source. 4. Set the heater temperature to 150°C by heater controller. Monitor TH reading on the

panel. 5. When TH value has stabilized, move the radiometer to 300mm from the heated plate.

The reading of the radiometer should start to rise. When the value has stabilized, record BLACK, TH, the distance, x and the radiometer reading, R.

6. Next, move the radiometer to 800mm from the heated plate again. 7. Repeat the above procedure with an increment of 50°C from 250°C to 150°C.

Observations:

Heater Temperature

(°C) Distance,

x(mm) Radiometer

Reading, R(W/m2)

BLACK (°C) TH (°C)

150 300 125 300 100 300 75 300

Assignment: Calculate the relationship between the Stefan Boltzmann Law and the corrected radiation reading (Rc), given as a factor of F.


14

Experiment 12: Co-Current and counter current Shell & Tube Heat Exchanger.

Co-Current: In this experiment, cold water enters the shell at room temperature while hot water enters the tubes in the same direction. Students shall study the heat exchanger under different flow rate and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state.

Counter current: In this experiment, cold water enters the shell at room temperature while hot water enters the tubes in the opposite direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state. Procedure:

1. Perform general start-up procedures in Section 5.1. 2. Check all valves are in co-current position (Please refer to Section 5.0). 3. Switch the valve position to Shell & Tube Heat Exchanger. 4. Switch on pumps P1 and P2. 5. Open and adjust valves V29 and V30 to obtain the desired flow rates for hot water and

cold water streams, respectively. 6. Allow the system to reach steady state for 10 minutes. 7. Record FT1, FT2, TT1, TT2, TT3, TT4 and differential pressure across the tube and

shell. 8. Repeat steps 5 to 7 with different combinations of flow rates FT1 and FT2 as in the

results sheet. 9. Switch off pumps P1 and P2. 10. Proceed to the next experiment or shut-down the equipment.

Results:

FT1 FT 2 TT 1 TT 2 TT 3 TT 4 DPhot DPcold

(LPM) (LPM) (°C) (°C) (°C) (°C)

Assignments: 1. Calculate the heat transfer and heat loss for energy balance study. 2. Calculate the LMTD. 3. Calculate heat transfer coefficients. 4. Calculate the pressure drop and compare with the experimental result 5. Perform temperature profile study and the flow rate effects on heat transfer.


15

Experiment 13: Co-Current and counter current Concentric Heat Exchanger Co-Current:

In this experiment, cold water enters the shell at room temperature while hot water enters the tubes in the same direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state. Counter current: In this experiment, cold water enters the shell at room temperature while hot water enters the tubes in the opposite direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state.

Procedure:

1. Perform general start-up procedures in Section 5.1. 2. Check all valves are in co-current position (Please refer to Section 5.0). 3. Switch the valve position to Concentric Heat Exchanger. 4. Switch on pumps P1 and P2. 5. Open and adjust valves V29 and V30 to obtain the desired flow rates for hot water and cold

water streams, respectively. 6. Allow the system to reach steady state for 10 minutes. 7. Record FT1, FT2, TT1, TT2, TT3, TT4 and differential pressure across the tube and shell. 8. Repeat steps 5 to 7 with different combinations of flow rates FT1 and FT2 as in the results

sheet. 9. Switch off pumps P1 and P2. 10. Proceed to the next experiment or shut-down the equipment.

Results:

FT 1 FT 2 TT 1 TT 2 TT 3 TT 4 DPhot DPcold

(LPM) (LPM) (°C) (°C) (°C) (°C)

Assignments: 1. Calculate the heat transfer and heat loss for energy balance study. 2. Calculate the LMTD. 3. Calculate heat transfer coefficients.

Perform temperature profile study and the flow rate effects on heat transfer


16

Experiment 14: Co-Current and counter current Plate Heat Exchanger Co-Current:

In this experiment, cold water enters the heat exchanger at room temperature while hot water enters the heat exchanger in the same direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state. Counter current: In this experiment, cold water enters the heat exchanger at room temperature while hot water enters in the opposite direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state.

Procedure:

1. Perform general start-up procedures in Section 4.1. 2. Check all valves are in co-current position (Please refer to Section 5.0). 3. Switch the valve position to Plate Heat Exchanger. 4. Switch on pumps P1 and P2. 5. Open and adjust valves V29 and V30 to obtain the desired flow rates for hot water and cold

water streams, respectively. 6. Allow the system to reach steady state for 10 minutes. 7. Record FT1, FT2, TT1, TT2, TT3 and TT4 and differential pressure. 8. Repeat steps 5 to 7 for different combinations of flow rates FT1 and FT2 as in the results


Results:


(LPM) (LPM) (°C) (°C) (°C) (°C)

Assignments:

1. Calculate the heat transfer and heat loss for energy balance study. 2. Calculate the LMTD. 3. Calculate heat transfer coefficients. 4. Perform temperature profile study and the flow rate effects on heat transfer.


17

Experiment 15: Co-Current and counter current coil Heat Exchanger Co-Current:

In this experiment, cold water enters the heat exchanger at room temperature while hot water enters the heat exchanger in the same direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state. Counter current: In this experiment, cold water enters the heat exchanger at room temperature while hot water enters in the opposite direction. Students shall vary the hot water and cold water flow rates and record accordingly the inlet and outlet temperatures of both the hot water and cold water streams at steady state.

Procedure:

11. Perform general start-up procedures in Section 4.1. 12. Check all valves are in co-current position (Please refer to Section 5.0). 13. Switch the valve position to Plate Heat Exchanger. 14. Switch on pumps P1 and P2. 15. Open and adjust valves V29 and V30 to obtain the desired flow rates for hot water and cold

water streams, respectively. 16. Allow the system to reach steady state for 10 minutes. 17. Record FT1, FT2, TT1, TT2, TT3 and TT4 and differential pressure. 18. Repeat steps 5 to 7 for different combinations of flow rates FT1 and FT2 as in the results


Results:


(LPM) (LPM) (°C) (°C) (°C) (°C)

Assignments:

5. Calculate the heat transfer and heat loss for energy balance study. 6. Calculate the LMTD. 7. Calculate heat transfer coefficients.


18

8. Perform temperature profile study and the flow rate effects on heat transfer.

THE END

hmt lab manual (heat and mass transfer lab manual)

Engineering

desired flow rates

perform general start

energy balance study

cold water streams

cold water enters

flow rates ft1

fan speed control

hand sensor lead