MEC4408: Thermodynamics and heat transfer 2023-S1
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HEAT TRANSFER MEASUREMENT LABORATORY
Academic in charge Professor Mainak Majumder
Teaching Associates Ms Sahar Shahali
Mr Adrian Cordero Obando
Lab Overview This laboratory activity will consist of three separate experiments to introduce and
demonstrate basic principles and applications of thermodynamics and heat
transfer. You will undertake the experiments in groups, then submit a brief report
including answers to the questions for each experiment.
Learning Outcomes • Predict temperature rise of an object during unsteady state heat conduction
and compare with experimental data
• Evaluate the relative magnitude of heat transfer by natural and forced
convection modes
• Determine the heat transfer rates by convection and radiation modes from
experimental data
• Identify the sources of error in the experiments and estimations
Assessment Overview Formal lab report
Assessment Weighting 10%
Assessment Due Date Due by 11.55 pm of Monday week 12
Relevant unit content Content from weeks 6-11
Health and Safety Information • Wear Personal Protective Equipment (PPE) as instructed (lab coat,
covered legs, safety glasses)
• Some parts of the equipment can be dangerously hot!
• Spatial awareness with equipment and people around you
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Introduction
This experiment uses two pieces of equipment, the first of which is a flow-controlled water bath (Unsteady State Heat
Transfer (USHT) rig). The rig consists of a 30-litre insulated bath with a heating element mounted in the base and a pump
to control the velocity of the water. Objects can be mounted on a sting and plunged into the water bath. Thermocouples
are positioned such that the core temperature of the object can be monitored as well as the bath temperature and the
water temperature adjacent to the object.
The other piece of equipment is the Blower Rig. In this rig, a scroll fan is used to blow air over a heated cylinder. The air
velocity is measured by a hot-wire anemometer and controlled by the butterfly gate. The cylinder is mounted such that
conduction to the duct is minimised. It can be heated by a heating element at its core and the surface temp can be
measured by a thermocouple. It can also be rotated to measure the surface temperature at different positions on a
cylinder. A matt black coating is applied to the cylinder which gives an emissivity close to 1.
Figure 1 Experimental equipment
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Part 1 – Water Bath Rig
In this experiment, you will use the Water Bath Rig to explore the convection and conduction methods of heat transfer.
Figure 2 Water Bath Rig in situ with schematic
1. First, familiarise yourself with the experimental setup. There is a control box, which is connected to three
thermocouples within the water bath setup. One thermocouple detects the temperature of the water bath (T1),
one detects the temperature of our sample core (T2) and one detects the temperature of the water just below
the sample (T3). Your TA will have turned the water bath on before class (by setting the thermostat to 6), so it
should be well on its way toward heating to a temperature of ~85°C. Make sure your heat resistant gloves and a
plastic beaker of cold water are nearby.
Figure 3 Stings
2. Observe the control box and wait until the water bath temperature reaches 85°C. Then, carefully lift out the
sting/rod. Be gentle when doing this, as parts of the assembly will have expanded slightly while the bath has been
heating.
3. Attach the 20mm diameter (smaller) brass cylinder to the sting by screwing the parts together securely. Insert the
T3 thermocouple into the centre of the cylinder and the T2 thermocouple adjacent to the cylinder. Switch the
control box viewer to the appropriate channel, to observe the change in temperature of the rod/sting (T3).
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4. Record the initial temperature of the rod/sting, then plunge the cylinder into the water bath.
5. Record the temperatures and time until T3 reaches the same temperature as the water bath. You may like to take
a short video of the control box to refer back to.
6. Carefully remove the cylinder from the water bath and place in the beaker of cold water.
7. Repeat this process for the 20 mm stainless steel cylinder and larger 30 mm diameter brass cylinders.
8. You may like to collect your results for Part 1 in a table similar to the one below;
Table 1. Water bath experimental data
Time
(s)
Bath
Temp
(˚C)
Core Temp (˚C)
Brass 20 mm cylinder Brass 30 mm cylinder Steel 20 mm cylinder
Predicted Actual Predicted Actual Predicted Actual
0
1
2
3
4
5
10
15
25
40
55
70
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Part 2 – Blower Rig
In this experiment, you will use the Blower Rig to explore the forced/natural convection and radiation methods of heat
transfer.
Figure 4 Blower Rig in situ, with schematic
2a - Natural Convection and Radiation
1. First, familiarise yourself with the experimental setup. There is a control box, which is connected to two
thermocouples within the Blower Rig setup. Ensure the heater power is set to zero (all the way anticlockwise),
open the butterfly valve completely and check that the control box is showing the right channel of data.
2. Adjust the control box to supply 50 volts, to start the Blower Rig heating process.
3. Wait for the cylinder surface temperature (T2) to stabilise, then record T1, T2, V and I.
4. Increase the voltage to 80 V and repeat the above. Do this for 120, 150 and 185 volts as well. Note that T2 should
not exceed 500˚C, so keep a careful watch on the temperature at the highest voltage level. If required, you may
use a lower final voltage to ensure max temperature is not exceeded
You may like to collect your results for Part 2a in a table similar to the one below;
Table 2. Natural convection experimental results
V (volts) I (amperes) T1 (˚C) T2 (˚C)
50
80
120
150
~185
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2b - Forced Convection
Note: The hot wire anemometer measuring the duct velocity may take up to 15 seconds to respond to changes in butterfly
valve position
1. Turn the fan on and adjust the adjust the duct air velocity () to approximately 0.5 -1 by adjusting the butterfly
valve. Record the initial Voltage and Amperage in Table 3. below. Note that you will not be able to get the Ua to
exactly 0.5, this is why you must record the actual value (compared to the nominal value).
2. Set the heater power to 200 volts. This is safe to do now as the butterfly valve is open
3. Wait for the cylinder surface temperature to stabilise (approx. 10 seconds), then record T1, T2, V, I and .
4. Increase to 1.0 ms-1 and repeat measurements once T2 stabilises
5. Repeat process in increments of 1 ms-1 until = 8 ms-1 .
You may like to collect your results for Part 2b in tables similar to the ones below;
Table 3. Forced convection experimental results actual nominal (record at the beginning only)
Volts
Amps
Ua – nominal (ms-1) Ua – actual (ms-1) T1 (˚C) T2 (˚C)
0.5
1
2
3
4
5
6
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Part 3 – Theoretical calculations
3a – calculations for the water bath experiment
We will be comparing the experimental data with theoretical predictions. To calculate the theoretical values, you will need
to use the following equations;
= − ∞
− ∞ Equation 1
where θ is the non-dimensional temperature
Tc is the geometric centre temperature
Ti is the geometric centre temperature before immersion (Tc at time zero)
T∞ is the bath temperature
= = 2 Equation 2
where α is the thermal diffusivity (refer to Appendix 1 for brass and stainless-steel values)
t is the time
l is the characteristic length for the geometry (here we are using cylinders, and so l is the radius of the cylinder)
= ℎ 0 Equation 3
where h is the heat transfer coefficient
r0 is the characteristic length for the geometry (here we are using a cylinder, and so ro is the radius of the cylinder)
k is the thermal conductivity (refer to Appendix 1 for brass and stainless-steel values
1. Calculate the Fourier number, Fo. for dimensionless time, τ, using Equation 2.
2. Calculate the Fourier number for all of the experimental timepoints using Equation 2.
3. Refer to the Heisler chart (Appendix 1) to find the reciprocal of the Biot number (1/Bi) for each point.
4. You should now be able to calculate the heat transfer coefficient, h, using Equation 3.
5. Once you have found the heat transfer coefficient, h, you should be able to determine the Bi number for the other
cylinders. You will find that the heat transfer coefficient, h, is constant across all three scenarios. Why is this the
case?
6. Use the same h for the other two cylinders and find 1/Bi
7. Calculate the Fourier number for the other two cylinders using Equation 2.
8. Use Equation 1. to find θ and Tc, using the Fourier numbers and 1/Bi, values.
9. Now, referring to the Heisler chart (Appendix 1), determine the dimensionless temperature θo. Remember, you
can use Equation 2, as you have the characteristic length and thermal diffusivity, and you can set the time you
want to estimate.
10. Finally, you can predict the cylinder centre temperature using Equation 1, as you now have all of the required
values (θ is the non-dimensional temperature found via the Heisler chart, Ti is the geometric centre temperature
before immersion (Tc at time zero) and T∞ is the bath temperature).
11. Gather your data for the water bath, for measured cylinder temperature with time, and graph the predicted and
measured cylinder temperature with time
12. Comment on the accuracy of the prediction.
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3b – calculations for the blower rig experiment
We will be comparing the experimental data with theoretical predictions. To calculate the theoretical values, you will need
to use the following equations;
= ℎ∆ Equation 4
where Qconv is the convective heat loss
As is the surface area
T is the temperature
ℎ =
Equation 5
where h is the heat transfer coefficient (for natural convective heat loss)
k is the thermal conductivity
Nu is the Nusselt number
D is the diameter of the cylinder
= () Equation 6
where Nu is the Nusselt number (for natural convective heat loss)
Ra is the Raleigh Number (refer to Table 2. In Appendix 1)
c is the …
α Is the characteristic length for the geometry (here we are using a cylinder, and so ro is the radius of the cylinder)
k is the thermal conductivity (refer to Appendix 1 for brass and stainless-steel values
= (2− 1 )3 2 Equation 7
where g is gravity,
β is
1
; , where = 1+ 22
D is the cylinder diameter
= 4.810 × 10−7 2 − 5.236 × 10−4 + 0.82155
= 1.346 × 10−10 2 − 2.443 × 10−9 + 4.614 × 10−6 unit is m2/s
= 9.4457 × 10−5 − 2.9619 × 10−5 2 + 5.826 × 10−4 unit is W/mK
= 0.3 + 0.62 1/2 1/3
�1+ �0.4
�
2/3
�
1/4 �1 + � 282000�5/8�4/5 Equation 8
where Nu is the Nusselt number (for forced convective heat loss)
Re is …
= 4.810 × 10−7 2 − 5.236 × 10−4 + 0.82155
. = ∈ (24 − 14) Equation 9
where
. is the radiative heat loss
As is surface area
ε is emissivity of the surface
σ is Stefan- Boltzmann constant
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1. Calculate the heat transfer coefficient by rearranging Equations 4 and 5.
2. For natural convection, calculate Ra and therefore Nu by rearranging equations 5 and 6 (refer to Appendix 1 for
natural convection coefficients)
3. For forced convection, calculate Re and therefore Nu by rearranging equations 7 and 8
4. Use equation 9 to calculate the radiative heat loss.
5. Gather your data for the blower rig, for measured cylinder temperature with time
6. Produce graphs illustrating;
a. the effect of surface temperature on heat loss due to convection and radiation from the natural
convection data
b. the effect of air velocity on heat loss due to convection and radiation
c. the effect of location on the temperature at different air velocities
7. Comment on the heat input vs total calculated heat out (convection and radiation)
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Assessment
The post-lab activity for this laboratory is a formal report worth 10%, due in week 12.
Your report must be a maximum of 10 pages (including any appendices, which should include your raw data). It should
include the following sections;
• Introduction – include aims of the experiments
• Results and Discussion
o Plots of
 WATER RIG: Predicted and Measured Cylinder temperature vs Time
• Comment on accuracy of predicted vs measured temperatures
 BLOWER RIG: Effect of surface temperature on heat loss due to convection and radiation from
the natural convection data
 BLOWER RIG: Effect of air velocity on heat loss due to convection and radiation
 BLOWER RIG: Comment on the heat input vs total calculated heat out (convection and radiation)
o Correct results (include sample calculations in the appendix)
o Discussion of trends in the data and brief explanations for what was observed
o Comments on sources of error
• Conclusion – summary of findings (including key numerical values) and comment on any future work required
• References – any style is acceptable, just be consistent.
Your report will be marked according to the marking guide below;
Section Marks (out of 30)
Pre-lab Quiz 4
Introduction 2
Results and Discussion 8
Conclusions 4
References 2
Quality of Figures 4
Overall presentation 2
Writing Style 4
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References and resources
1. Çengel, Yunus A., and Michael A. Boles. Thermodynamics : An Engineering Approach, McGraw-Hill Higher
Education, 2014. ProQuest Ebook Central,
https://ebookcentral.proquest.com/lib/monash/detail.action?docID=5471325.
2. P. A. Hilton Ltd. H112G Manual. 2012, accessed 2023-04-26 from https://www.p-a-hilton.co.uk/products/heat-
transfer/unsteady-state-heat-transfer-module, 2012
3. P. A. Hilton Ltd. H112D Manual. 2012, accessed 2023-04-26 from https://www.p-a-hilton.co.uk/products/heat-
transfer/combined-convection-and-radiation-module, 2012
4. P. A. Hilton Ltd. H112 Manual, 2012, accessed 2023-04-26 from https://www.p-a-hilton.co.uk/products/heat-
transfer/heat-transfer-service-unit
Acknowledgements
This laboratory exercised was developed at the Mechanical and Aerospace Engineering Department, Monash University,
by M. Majumder.
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APPENDIX 1 – REFERENCE DATA FOR EXPERIMENTS
The following tables and figures contain information that you will need to use in your calculations.
Table A1-1. Properties of brass and stainless steel relating to heat transfer
Brass Stainless Steel
Thermal Conductivity , or k (W m-1 K-1) 121 16.3
Specific Heat Capacity, or c (J kg-1) 385 460
Density, or ρ (kg m-3) 7930 8500
Thermal Diffusivity, or α (m2s-1) 3.7 x10-5 0.45 x 10-5
Table A1-2. Natural Convection Coefficients
c a
− − 0.675 0.058
− 1.020 0.148
0.850 0.188
0.480 0.250
0.125 0.333