Ashford University Chemistry Heat Transfer Lab Reports

Thermal conductivity of given test materials –Single plate method
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
OBJECTIVE
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
To determine the thermal resistance and thermal conductivity of the given different building materials and
understand the heat conduction process involved.
WORKING PRINCIPLE
A known rate of heat is conducted through a specimen of the material in the form of a slab of cross
sectional area ‘A’ placed between an electric heat source generating heat supply at a constant rate and heat sink (cold
fluid chamber or cooler). The entire assembly is embedded in low conductivity insulation in order to minimize lateral heat
leakage from the exposed surface of the specimen.
PROCEDURE
1. Make sure that the heat flux sensor and the thermocouples for Th and Tc are connected to the display unit
2. Check the water supply and water hoses for incoming water and outgoing water in the cooler unit.
3. In order to insert specimen, turn the spindle anti-clockwise and lifting the heater plate. Place the specimen to be tested
on the cooling plate via the front of the unit.
4. Then clamp the specimen in between the heater plate and cooling plate.
5. Switch on the unit using the main switch. Make sure that the temperature set point on Th is set to 50oC, and then switch
on the heater.
6. Note the temperature readings at frequent intervals till consecutive readings are same indicating that steady state has
been reached.
7. After your experimental work, turn off water supply & main switch and then turn the spindle clockwise and lifting the
heater plate to remove the specimen(s).
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
FORMULAE
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
The Fourier’s law of heat conduction is given by
dT
dX = − k A
Where,
temperature
quantity of heat conducted per unit time,
=
=
area of cross section normal to the direction of heat flow [m2] dT
thermal conductivity
=
thickness of test material thickness, [m] k
=
A
= drop,(Th – Tc) [o C] dX
of the material, [W/moC]
EXPERIMENTAL LAYOUT
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
Time, t
in min
Heat
Flux
/A =q
(W/m²)
Hot Plate
Temperature
Th (ºC)
Cold Plate
Temperature
Tc (ºC)
0
2
4
6
8
10
12
14
16
18
20
Sl.
No
Test
Sample
Heat
Flux
/A =q
(W/m²)
Thermocouple Readings, [ o C]
Hot Plate
Cold Plate
Temperature
Temperature
Temperature
difference
(Th)
(Tc)
(dT)
Thermal
Thermal
conductivity
Resistance
( k)
(Rth)
[W/moC]
[oC/W]
1
2
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
TABLE OF MEASUREMENTS
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
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Test material
Dimension
Polystyrene (Expanded)
Poly oxyethylene (POM)
300×300 mm
300×300 mm
Maximum service
temperature °C
60
100
Plaster
Corkboard
PMMA
Armaflex
300×300 mm
300×300 mm
300×300 mm
300×300 mm
100
80
80
70
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
Figure. 2 Temperature distribution along the Length (heat transfer direction) of slab*
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
[*A straight line is drawn to fit the data and its slope gives the temperature gradient]
Specification of the test materials
1. Thickness of test sample, dX
=
m
2. Area of the test sample, A
=
m2
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
MODEL
k
CALCULATION
Q
,
=
A
dTdX
=
=
Rth
o
C/W
dX
=
k.A
=
=
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
Heat Transfer Lab (CHEE3101P) 16 Jan 2019
S.
No.
Test Material
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Heat Flux
Thermal conductivity, k
(W/m2)
= Q/A(ΔT/ΔX)
1
2
Remarks of the Faculty in-charge:
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
Date:
Faculty Signature:
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
TABLE OF RESULTS
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
ANALYSIS OF RESULTS /
CONCLUSIONS
1.
2
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
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Heat Transfer Lab (CHEE3101P) 16 Jan 2019
. Forced convection heat transfer in a vertical stainless steel plate
Obtained Mark
OBJECTIVE
To determine the heat transfer coefficient between the given fluid and the solid surface and thereby
compare the heat transfer coefficient with fluid velocity.
EXPERIMENTAL SET UP
The experimental unit consists of a vertical plate made of S.S material enclosed in a rectangular duct open
at both top and bottom. The duct is of sufficient dimensions as not to interfere with the convection process while
at the same time preventing external disturbances to affect the data. The blower/ fan is mounted on the top or
bottom of the duct to enhance the fluid flow over the plate and velocity is measured by anemometer. The surface
temperature of the plate and ambient temperature is measured using thermocouples. The surface of the plate is
polished to minimize radiation heat losses.
SPECIFICATION
Stainless steel plate: height =
mm
width =
mm
PROCEDURE
1. The system is switched on.
2. The amount of heat input is measured by using the wattmeter.
3. The blower is switched on and a particular amount of air flow is fixed.
4. The system is allowed to reach the steady state and the temperatures for the plate and surrounding fluid
medium are noted.
5. The above procedure is repeated for various air flow rates, keeping the heater input same.
FORMULAE
For a vertical plate transferring heat to the surroundings with the aid of velocity at constant heat flux, the following
empirical relations hold.
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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Nux
=
0.453 Re L0.5 . Pr 0.333
for
Re < 5 x 105 (Laminar flow) Nux = 0.031 Re L0.8 . Pr 0.33 for 105 < Re < 107 (Turbulent flow) Reynolds number, = V L along flow / γ Re Where γ V = kinematic viscosity, m2/s = velocity of air through the duct, m/s All the properties for air are evaluated at the film temperature given by Tf Ts = +T = Heat Transfer Lab (MIME4212P) 16 Jan 2019 oC Page 3 of 11 2 EXPERIMENTAL LAYOUT TABLE OF MEASUREMENTS Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 4 of 11 Sl.No Rate of heat flow Fluid velocity Surface temperature (V) ( ) watt (Ts) m/s oC Ambient Temp.Diff Temperature T (T∞ ) oC 1. 2. 3. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 5 of 11 oC CALCULATIONS: (for reading no: ) Velocity of the air through the duct, V = m/s Mean film temperature, Tf = Ts +T = 2 oC Properties of air at Tf are as follows: k γ Pr = = W/m oC m2/s = Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 6 of 11 γ Reynolds number, Re =VL/ = = = = = = hemp L / k (W/m2 oC) Nux Nux k / L = = Nux W/m2 oC = Nux hx hx Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 7 of 11 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 36 of 80 TABLE OF RESULTS: The local heat transfer coefficient was determined under forced convection mode for various air flow rates and the results are given below. S. Heat input Velocity Re Nux No. Q (W) V (m/s) 1. 2. 3. ANALYSIS OF RESULTS 1. 2 . Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 8 of 11 hx (W/m2K) Remarks of the Faculty in-charge: Date: Signature: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 9 of 11 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 10 of 11 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 11 of 11 EXPERIMENT 7: Counter flow type Double pipe heat exchanger- Energy balance and overall efficiency. Introduction: Double pipe heat exchanger is a device used to exchange/transfer heat from one fluid to another without mixing of the two fluids. It consists of two pipes; one pipe with a hot fluid (small diameter) and another pipe with a cold fluid (larger diameter). The small pipe is held inside the larger pipe. As the cold and hot fluids are allowed to flow there will be a heat transfer from hot temperature to cold temperature therefore there should be an energy balance where; heat lost by hot fluid equals heat gained by the cold fluid. This is theoretical. There are two types of flows in double pipe heat exchanger; counter-current flow or co-current flow. Counter-current flow is when both fluids flow in opposite directions with each other while co-current flow both fluids flow in the same direction (parallel). The objective of this experiment is to determine the overall efficiency of the double pipe heat exchanger at varying fluid flow rates. Efficiency = Qc / Qh Qh = mh * Cph * ▲Th (heat lost by hot fluid) Qc = mc * Cpc * ▲Tc (heat gained by cold fluid) Where; m = mass of the respective fluids Cp = specific heat capacity of the respective fluids ▲T = change in temperature of the respective fluids. Materials: Double pipe heat exchanger device. In our experiment this device will be aided by a computer software program service. Results and Calculations: Volume flow rate of hot fluid is fixed. The fluid used in both pipes is water. Observation table: HOT FLUID Valve % COLD FLUID Volume flow rate lits/min Inlet temp 0 C T1 Mid temp 0 C T2 Outlet temp 0 C T3 Volume flow rate lits/min Inlet temp 0 C Mid temp 0 C Outlet temp 0 C T4 T5 T6 50 3.5 47.7 45.0 43.0 3.28 24.6 26.5 28.7 60 3.5 56.7 53.0 50.0 3.43 24.4 27.0 30.0 70 3.5 55.6 52.1 49.2 3.54 24.5 26.8 29.6 80 3.5 55.1 51.7 48.8 3.81 25.1 27.2 29.8 Calculations: Mass flow rate (kg/s) = volume flow rate (m3 / s) * density of fluid (kg/m3) (Lit/min * 1.667*10-5)= m3/s Reading no 1: At T2 of 450C for hot fluid: ρh = 990.1kg/m3, Cph = 4180 J/ kg. K mh = (3.5*1.667*10-5) * 990.1 = 0.058 kg/s Qh = mh * Cph * ▲Th Qh = (0.058)*(4180)*(4.7) Qh = 1139.5 J /s (W) At T5 of 26.50C for cold fluid Temperature 0C ρc (kg/m3) Cpc (J/kg. K) Upper limit 30 996.0 4178 Lower limit 25 997.0 4180 T5 26.5 993.6 4173.3 mc = (3.28*1.667*10-5) * 993.6 = 0.054kg/s Qc = mc * Cpc * ▲Tc Qc = (0.054)* (4173.3) * (4.1) Qc = 923.9 J/s (W) Heat power lost = Qh – Qc = 1139.5 - 923.9 = 215.6 W Overall Efficiency = (923.9/1139.5) *100 = 81.08% Reading no 2: At T2 of 530C for hot fluid Temperature 0C ρh (kg/m3) Cph (J/kg. K) Upper limit 55 985.2 4183 Lower limit 50 988.1 4181 T2 53 983.3 4184.3 Temperature 0C ρc (kg/m3) Cpc (J/kg. K) Upper limit 30 996.0 4178 Lower limit 25 997.0 4180 T5 27 994.5 4175 mh = (3.5*1.667*10-5) * 983.3 = 0.057 kg/s Qh = mh * Cph * ▲Th Qh = (0.057) * (4184.3) * (6.7) Qh = 1598 J/s (W) At T5 of 270C for cold fluid mc = (3.43*1.667*10-5) * 994.5 = 0.0568 kg/s Qc = mc * Cpc * ▲Tc Qc = (0.0568) * (4175) * (5.6) Qc = 1328 J/s (W) Heat power lost = Qh – Qc = 1598 – 1328 = 270 W (1328/1598)*100 = 83.1% Reading no 3: At T2 of 52.10C for hot fluid Temperature 0C ρh (kg/m3) Cph (J/kg. K) Upper limit 55 985.2 4183 Lower limit 50 988.1 4181 T2 52.1 981.2 4185.7 mh = (3.5*1.667*10-5) * 981.2 = 0.0572 kg/s Qh = mh * Cph * ▲Th Qh = (0.0572) * (4185.7) * (6.4) Qh = 1532.3 J/s (W) At T5 of 26.80C for cold fluid Temperature 0C ρc (kg/m3) Cpc (J/kg. K) Upper limit 30 996.0 4178 Lower limit 25 997.0 4180 T5 26.8 994.2 4174.4 mc = (3.54*1.667*10-5) * 994.2 = 0.0587 kg/s Qc = mc * Cpc * ▲Tc Qc = (0.0587) * (4174.4) * (5.1) Qc = 1250 J/s (W) Heat lost = Qh – Qc = 1532.3 – 1250 = 282.3 W (1250/1532.3) * 100 = 81.6% Reading no: 4 At T2 of 51.70C for hot fluid Temperature 0C ρh (kg/m3) Cph (J/kg. K) Upper limit 55 985.2 4183 Lower limit 50 988.1 4181 T2 51.7 979.6 4186.9 mh = (3.5*1.667*10-5) * 979.6 = 0.0572 kg/s Qh = mh * Cph * ▲Th Qh = (0.0572) * (4186.9) * (6.3) Qh = 1508.8 J/s (W) At T5 of 27.2 for cold fluid Temperature 0C ρc (kg/m3) Cpc (J/kg. K) Upper limit 30 996.0 4178 Lower limit 25 997.0 4180 T5 27.2 994.7 4175.4 mc = (3.81*1.667*10-5) * 994.7 = 0.0632 kg/s Qc = mc * Cpc * ▲Tc Qc = (0.0632) * (4175.2) * (4.7) Qc = 1240.2 J/s (W) Heat lost = Qh – Qc = (1508.8 – 1240.2) = 268.6 W (1240.2/1508.8) * 100 = 82.2% Table of results: Mass flow rate (kg/s) mh Heat emitted Qh (W) Mass flow rate (kg/s) mc Heat gained Qc (W) Heat exchanger efficiency % 50 0.0580 1139.5 0.0540 923.9 81.08 60 0.0570 1598 0.0568 1328 83.10 70 0.0572 1532.3 0.0587 1250 81.6 80 0.0572 1508.8 0.0632 1240.2 82.2 Valve % HOT FLUID COLD FLUID Conclusion: Theoretically the value of Qc is equal to the value of Qh where the efficiency is 100%. Experimentally the values of Qc and Qh are not equal as shown in the table of results above but the overall average efficiency is around 82% this means there is heat loss of 12%. This difference might be caused due to heat loss to the surroundings. All the readings shows that heat was lost to the surroundings because the value of Qc is less than Qh and no heat gained from the surroundings. As the flow rate of the cold fluid increased the value of Qc also increased. This indicates that more heat was gained from the hot fluid to cold fluid because of the increase in flow rate of cold fluid. References. THOMAS, All About Double Pipe Heat Exchangers,n.d, https://www.thomasnet.com/articles/process-equipment/double-pipeheatexchangers/. Accessed on October 28th, 2020. Remarks of the faculty in-charge Date: Faculty signature: Guidelines “The experiment Report “ EXP. 1, 2 1) Title Includes the experiment title, your name, ID and the submission date 2) Introduction A brief article about the experiment and objectives You might include external references if needed 3) Materials This includes the specimens, equipment and the experimental apparatus, specification of the test materials etc. You might include photos of the apparatus or scan the apparatus if provided in the lab note 4) Results and discussion This part should include your data input and results For example as Exp.1 You need to fill in the table of Measurements Time 0 2 4 . . etc Heat flux Thot Tcold And all other experiment tables …………. You need to include all the calculations mentioned in the lab notebook Plus you need to include graphs (all should be in Excel or any graphic software, graph sheet not accepted) 1) How hot plate temperature changes with time 2) How Heat flux changes with time Discuss the results 5) Conclusion State at least two points in a paragraph At the end include the following Remarks of the faculty in-charge Date Facility signature Thermal conductivity of given test materials – Single plate method Page 1 of 17 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 OBJECTIVE Page 2 of 17 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 To determine the thermal resistance and thermal conductivity of the given different building materials and understand the heat conduction process involved. WORKING PRINCIPLE A known rate of heat is conducted through a specimen of the material in the form of a slab of cross sectional area ‘A’ placed between an electric heat source generating heat supply at a constant rate and heat sink (cold fluid chamber or cooler). The entire assembly is embedded in low conductivity insulation in order to minimize lateral heat leakage from the exposed surface of the specimen. PROCEDURE 1. Make sure that the heat flux sensor and the thermocouples for Th and Tc are connected to the display unit 2. Check the water supply and water hoses for incoming water and outgoing water in the cooler unit. 3. In order to insert specimen, turn the spindle anti-clockwise and lifting the heater plate. Place the specimen to be tested on the cooling plate via the front of the unit. 4. Then clamp the specimen in between the heater plate and cooling plate. 5. Switch on the unit using the main switch. Make sure that the temperature set point on Th is set to 50oC, and then switch on the heater. 6. Note the temperature readings at frequent intervals till consecutive readings are same indicating that steady state has been reached. 7. After your experimental work, turn off water supply & main switch and then turn the spindle clockwise and lifting the heater plate to remove the specimen(s). Page 3 of 17 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 FORMULAE Page 4 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 The Fourier’s law of heat conduction is given by dT dX = − k A Where, temperature quantity of heat conducted per unit time, = = area of cross section normal to the direction of heat flow [m2] dT thermal conductivity = thickness of test material thickness, [m] k = A = drop,(Th – Tc) [o C] dX of the material, [W/moC] EXPERIMENTAL LAYOUT Page 5 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Time, t in min Heat Flux /A =q (W/m²) Hot Plate Temperature Th (ºC) Cold Plate Temperature Tc (ºC) 0 2 4 6 8 10 12 14 16 18 20 Sl. No Test Sample Heat Flux /A =q (W/m²) Thermocouple Readings, [ o C] Hot Plate Cold Plate Temperature Temperature Temperature difference (Th) (Tc) (dT) Thermal Thermal conductivity Resistance ( k) (Rth) [W/moC] [oC/W] 1 2 Page 6 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 TABLE OF MEASUREMENTS Page 7 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 8 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 of 80 Test material Dimension Polystyrene (Expanded) Poly oxyethylene (POM) 300x300 mm 300x300 mm Maximum service temperature °C 60 100 Plaster Corkboard PMMA Armaflex 300x300 mm 300x300 mm 300x300 mm 300x300 mm 100 80 80 70 Page 9 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Figure. 2 Temperature distribution along the Length (heat transfer direction) of slab* Page 10 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 [*A straight line is drawn to fit the data and its slope gives the temperature gradient] Specification of the test materials 1. Thickness of test sample, dX = m 2. Area of the test sample, A = m2 Page 11 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 MODEL k CALCULATION Q , = A dTdX = = Rth o C/W dX = k.A = = Page 12 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 S. No. Test Material Page 13 of 80 Heat Flux Thermal conductivity, k (W/m2) = Q/A(ΔT/ΔX) 1 2 Remarks of the Faculty in-charge: Page 13 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Date: Faculty Signature: Page 14 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 TABLE OF RESULTS Page 15 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 ANALYSIS OF RESULTS / CONCLUSIONS 1. 2 Page 16 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 17 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Sultanate of Oman University of Technology and Applied Sciences Department Stamp For Educational Purposes Only Higher College of Technology Heat Transfer Practical (CHEE3101 P) Semester II Academic Year 2020-2021 Laboratory Manual ENGINEERING DEPARTMENT Student Name Section # Name of Faculty (Laboratory): ID # Mr. Magd Ahmed Day/Time Office Hours: E-mail Address: Magd.gehad@hct.edu.om Version No. Last Date of Revision Name of Course Coordinator (Lecturer): Dr. Ibrahim Al-Siyabi Signature Date Signature Date Name of Faculty Head (Lab): Approved by: Program Coordinator’s Name: Verified by: Curriculum Committee Member: Specialization Signature Section Signature Date CAE EEE Date MIE Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 2 of 80 After successfully completed this course, students should be able to manifest the following ticked College Graduate Attributes (GA): o 1. Are well-disciplined and committed to hard work and a high standard of productivity; o 2. Are able to apply the knowledge and skills to a diverse and competitive work environment; o 3. Are able to think critically, analyze and solve problems; o 4. Have a high degree of competence in using information and communication technology; o 5. Are professionally competent and up-to-date in their field of specialization in a changing global environment; o 6. Can gather and process knowledge from a variety of sources, and communicate effectively in written and spoken English; o 7. Can effectively demonstrate and apply good interpersonal skills in teamwork and leadership roles; o 8. Are committed to self-development through lifelong learning; o 9. Are socially responsible citizens aware of contemporary issues in contributing to national development; and o 10. Are able to demonstrate and apply their entrepreneurial skills. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 3 of 80 DEPARTMENT OF ENGINEERING MECHANICAL & INDUSTRIAL ENGINEERING SECTION Higher College of Technology, P O BOX 74, AL-KHUWAIR, CODE 133  24473600 fax 24485364 Course Name: HEAT TRANSFER Practical Course Code: MIME 4212P & CHEE3101P List of Experiments S/N Experiment Title Page # Objectives No. Learning Outcome No. Graduate Attribute No. 1 Thermal conductivity of given test materials – single plate method 7 1-5 1-9 1-10 2 Thermal conductivity of given test materials – Multi plate method (composite wall) 15 1-5 1-9 1-10 3 Natural convection heat transfers in a vertical stainless steel plate 22 1-5 1-9 1-10 31 1-5 1-9 1-10 4 Forced convection heat transfer in a vertical stainless steel plate 5 Radiation: Inverse Square Law for Heat 39 1-5 1-9 1-10 6 Radiation: Stefan– Boltzmann law 45 1-5 1-9 1-10 53 1-5 1-9 1-10 60 1-5 1-9 1-10 7 8 Counter flow type Double pipe heat exchanger- Energy balance and overall efficiency Overall Heat Transfer Coefficient for Cocurrent (Parallel) flow type double pipe heat exchanger by LMTD method Heat Transfer Lab (MIME4212P) 16 Jan 2019 Date Completed Page 4 of 80 Marks Technician’s Signature LABORATORY/WORKSHOP SAFETY RULES 1. Attentively LISTEN TO THE INSTRUCTIONS of the laboratory/workshop staff before starting with any laboratory/workshop work. 2. LISTEN TO the laboratory/workshop staff as he discusses the SAFETY ARRANGEMENT for the activity and keep in mind the required precaution and KNOW THE HAZARDS involved in the performance of the laboratory/workshop activity. 3. READ AND UNDERSTAND THE PROCEDURE as written in the laboratory/workshop manual before beginning with any activity. If you have doubts do not hesitate to ask the in-charge laboratory/workshop staff. 4. Always think of safety. EXECUTE THE LABORATORY EXPERIMENT WITH EXTRA CARE AND AVOID PLAYING WHILE DOING THE ACTIVITY. Fooling around or "horse play" in the laboratory/workshop is absolutely forbidden. Students found in violation of this safety rule will be dealt accordingly. 5. NEVER energize circuits or turn on equipment and devices without approval of the in-charge laboratory/workshop staff. 6. Do not use devices and equipment if you DO NOT KNOW how to use it. Ask for HELP! 7. OBSERVE BEST PRACTICES for MANUAL HANDLING when working. Do not try to move heavy objects alone or without the use of the appropriate equipment. Use trolley and/or lifting tools as necessary. ASK FOR HELP! 8. HOUSEKEEPING RULE is fully implemented in all laboratories and workshops. Keep your work area clean and organized. Return all devices and equipment in their proper storage. 9. WEAR THE APPROPRIATE ATTIRE while inside the laboratory or workshop (LABORATORY COAT OR COVER ALL) 10. FOOD AND DRINKS are not allowed inside the laboratory or workshop. 11. FAMILIARIZE yourself with all safety arrangement in the laboratory/workshop. Know the emergency procedures, evacuation procedures, location of first aid kit and location of the fire extinguisher. 12. If an INCIDENT/ACCIDENT happened, immediately call the attention of the laboratory instructor/laboratory technician in charge. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 5 of 80 EMERGENCY SERVICES S.N. OFFICE CONTACT NO. Royal Oman 9999 1 Police 2 3 4 Civil Defense Control Room Al-Khuwair Health Center Royal Hospital COLLEGE EMERGENCY NUMBERS S.N. OFFICE ROOM NO. College Clinic Main Campus 24473866/ext. 5266 24473754/ ext. 5154 24480567 ELC College Emergency Hotline College RHS 24599000 Engineering RHS 5242 24343666 92920203 5053 EMERGENCY CONTACT INFORMATION Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 6 of 80 UNDERTAKING ON THE USE OF ENGINEERING LABORATORY/WORKSHOP I, , with ID No.: is currently registered in (Student Name) ( ) (Course Name) (Course Code) have read, understood and agreed with all the laboratory and workshop safety rules implemented by the Engineering Department. I assure that: • I shall follow all written and oral instructions given to me by the faculty in-charge; • I shall give my full cooperation to maintain a safe working environment ensuring my safety, safety of my fellow students and safety of staff members; and • I shall use the laboratory/workshop equipment and tools in accordance with the specification. Further, I am aware that I shall not be allowed to participate in the activity and receive failing mark if I have violated any of the laboratory and workshop safety rules. Lastly, I am also fully aware that I shall be held liable for whatever damage I may have caused inside the laboratory premises. Semester : Academic Year : Student Signature : Date : Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 7 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Experiment I. Thermal conductivity of given test materials – Single plate method Obtained Mark Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 8 of 80 OBJECTIVE To determine the thermal resistance and thermal conductivity of the given different building materials and understand the heat conduction process involved. WORKING PRINCIPLE A known rate of heat is conducted through a specimen of the material in the form of a slab of cross sectional area ‘A’ placed between an electric heat source generating heat supply at a constant rate and heat sink (cold fluid chamber or cooler). The entire assembly is embedded in low conductivity insulation in order to minimize lateral heat leakage from the exposed surface of the specimen. PROCEDURE 1. Make sure that the heat flux sensor and the thermocouples for Th and Tc are connected to the display unit 2. Check the water supply and water hoses for incoming water and outgoing water in the cooler unit. 3. In order to insert specimen, turn the spindle anti-clockwise and lifting the heater plate. Place the specimen to be tested on the cooling plate via the front of the unit. 4. Then clamp the specimen in between the heater plate and cooling plate. 5. Switch on the unit using the main switch. Make sure that the temperature set point on Th is set to 50oC, and then switch on the heater. 6. Note the temperature readings at frequent intervals till consecutive readings are same indicating that steady state has been reached. 7. After your experimental work, turn off water supply & main switch and then turn the spindle clockwise and lifting the heater plate to remove the specimen(s). Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 9 of 80 FORMULAE The Fourier’s law of heat conduction is given by = −kA dT dX Where, A = = quantity of heat conducted per unit time, area of cross section normal to the direction of heat flow [m2] dT = temperature drop,(Th – Tc) [o C] dX = thickness of test material thickness, [m] k = thermal conductivity of the material, [W/moC] EXPERIMENTAL LAYOUT Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 10 of 80 TABLE OF MEASUREMENTS Time, t in min Heat Flux /A =q (W/m²) Hot Plate Temperature Th (ºC) Cold Plate Temperature Tc (ºC) 0 2 4 6 8 10 12 14 16 18 20 Sl. Test No Sample Heat Flux /A =q (W/m²) Thermocouple Readings, [ o C] Hot Plate Cold Plate Temperature Temperature (Th) (Tc) Thermal Thermal Temperature conductivity Resistance difference ( k) (Rth) (dT) [W/moC] [oC/W] 1 2 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 11 of 80 Figure. 2 Temperature distribution along the Length (heat transfer direction) of slab* [*A straight line is drawn to fit the data and its slope gives the temperature gradient] Specification of the test materials Test material Dimension Polystyrene (Expanded) Poly oxyethylene (POM) Plaster Corkboard PMMA Armaflex 300x300 mm 300x300 mm Maximum service temperature °C 60 100 300x300 mm 300x300 mm 300x300 mm 300x300 mm 100 80 80 70 1. Thickness of test sample, dX = m 2. Area of the test sample, A = m2 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 12 of 80 MODEL CALCULATION k = Q dT A    dX  , W/moC = = Rth  dX  =   k.A  o C/W = = Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 13 of 80 TABLE OF RESULTS S. Test Heat Flux Thermal conductivity, k No. Material (W/m2) = Q/A(ΔT/ΔX) 1 2 ANALYSIS OF RESULTS / CONCLUSIONS 1. 2 Remarks of the Faculty in-charge: Date: Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Faculty Signature: Page 14 of 80 Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 15 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Experiment 2. Thermal conductivity of given test materials – Multi plate method (composite wall) Obtained Mark Heat Transfer Lab (CHEE3101P) 16 Jan 2019 Page 16 of 80 OBJECTIVE To determine the thermal resistance and thermal conductivity of the given different building materials and understand the heat conduction process involved. WORKING PRINCIPLE A known rate of heat is conducted through a specimen of the material in the form of a slab of cross sectional area ‘A’ placed between an electric heat source generating heat supply at a constant rate and heat sink (cold fluid chamber or cooler). The entire assembly is embedded in low conductivity insulation in order to minimize lateral heat leakage from the exposed surface of the specimen. PROCEDURE 1. Make sure that the heat flux sensor and the thermocouples for Th and Tc are connected to the display unit 2. Check the water supply and water hoses for incoming water and outgoing water in the cooler unit. 3. In order to insert specimens, turn the spindle anti-clockwise and lifting the heater plate. Place the specimen to be tested on the cooling plate via the front of the unit. 4. Then clamp the specimens in between the heater plate and cooling plate. 5. Switch on the unit using the main switch. Make sure that the temperature set point on Th is set to 50oC, and then switch on the heater. 6. Note the temperature readings at frequent intervals till consecutive readings are same indicating that steady state has been reached. 7. After your experimental work, turn off water supply & main switch and then turn the spindle clockwise and lifting the heater plate to remove the specimens. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 17 of 80 FORMULAE Figure1. One dimensional heat flow through a composite wall (samples are connected in series). The Fourier’s law of heat conduction is given by = − k A dT = − k1 A (T − T ) = − k 2 A (T − T ) = .......= − k m A (T − T dX x1 2 1 x2 3 2 xm m ) m−1 Where, A = = quantity of heat conducted per unit time, area of cross section normal to the direction of heat flow [m2] dT = temperature drop,(Th – Tc) [o C] dX = thickness of test material thickness, [m] k = thermal conductivity of the material, [W/moC] EXPERIMENTAL LAYOUT Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 18 of 80 TABLE OF MEASUREMENTS Specification of the test material Test material Dimension Polystyrene (Expanded) Poly oxyethylene (POM) Plaster Corkboard PMMA Armaflex 300x300 mm Maximum service temperature °C 60 300x300 mm 100 300x300 mm 300x300 mm 300x300 mm 300x300 mm 100 80 80 70 Thickness mm 1. Thickness of test samples, X1 = X2 2. Area of the test sample, A Sl. No Heat Flux /A =q (W/m²) m = m m2 = Thermocouple Readings, [ o C] Temp. Hot Plate Cold Plate Temperature Temperature (Th) (Tc) difference (dT) Equivalent Thermal conductivity ( km) o Thermal Resistance (Total Rth) [oC/W] [W/m C] 1 2 3 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 19 of 80 MODEL CALCULATION q = −k A q= dT kA k A k A = − 1 (T − T ) = − 2 (T − T ) = ....... = − m (T − T ) 2 1 3 2 m m −1 x2 xm dX x1 Toverall (T1 − Tm ) = x1 x x2  Rth + .... m + km .A k1.A k2 .A q=− km A xm (T − Tm−1 ) m q km = dT A    dX  W/moC , = = = Rtotal = Toverall     q  o C/W = = Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 20 of 80 TABLE OF RESULTS S. No. Test Heat Flux Equivalent Thermal Material (W/m2) Conductivity, k = Q/A(ΔT/ΔX) (composite) 1 2 ANALYSIS OF RESULTS / CONCLUSIONS 1. 2. Remarks of the Faculty in-charge: Date: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Faculty Signature: Page 21 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 22 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Experiment 3. Natural convection heat transfers in a vertical stainless steel plate Obtained Mark Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 23 of 80 OBJECTIVE To determine the free convective heat transfer coefficient between the given fluid and the solid surface by both experimental and empirical methods EXPERIMENTAL SET UP The experimental unit consists of a vertical plate made of S.S material enclosed in a rectangular duct open at both top and bottom. The duct is of sufficient dimensions as not to interfere with the convection process while at the same time preventing external disturbances to affect the data. The surface temperature of the plate and ambient temperature is measured using thermocouples. The surface of the plate is polished to minimize radiation heat losses. SPECIFICATION Stainless steel plate: height = mm width = mm PROCEDURE 1. Switch on the mains. 2. Allow the unit to stabilize. 3. Note down the readings of the SS plate shown in the digital display. 4. Note down the local chamber temperature shown in the digital display. 5. Repeat the experiment for different heat inputs and tabulate the readings for calculations. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 24 of 80 FORMULAE Energy input, = watts The convection law is given as = hexp As (Ts – T∞) Where h – – Rate of heat transfer; Heat input, W Average heat transfer coefficient, W/m2K As – Surface area of the plate, m2 Ts – surface temperature of hot body, oC T∞ – Temperature of the fluid, oC Hence, hexp. = ( Q ) As Ts −T For a vertical plate transferring heat to the surroundings the following empirical relations hold. Nuav = 0.59 (GrL . Pr)0.25 for 104 < GrL Pr < 109 (Laminar flow) Nuav = 0.10 (GrL . Pr)0.33 for 109 < GrL Pr < 1013 (Turbulent flow) Where Nuav = Average Nusselt number = hL k f L - Height of cylinder, m kf - Thermal conductivity of fluid, W/m K Gr = Grashof number based on length = g β ΔT L3 γ2 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 25 of 80 Where β - β = Coefficient of thermal expansion, 1   Where Tf is mean film temperature in K    Tf  Tf = (Ts + T ) 2 Where Ts and T∞ are in oC ΔT - Temperature difference, Ts - T∞ γ - Kinematic viscosity in m2/s Pr - Prandtl number, Cp  k The fluid properties k, , , , Cp are all evaluated at the mean film temperature Tf EXPERIMENTAL LAYOUT Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 26 of 80 TABLE OF MEASUREMENTS Sl.No Rate of heat flow Surface temperature (Ts) o watt C Ambient Temperature (T∞ ) o T o C 1. 2. CALCULATIONS: (for reading No: ) To find hexp  Ts = C T∞ = o As = hexp = C m2 ( Q As Ts −T hexp = ) = W/m2 oC Heat Transfer Lab (MIME4212P) 16 Jan 2019 Temp.Difference Page 27 of 80 C To find hemp Tf = Ts +T 2 o = C = K From data sheet, properties of air at Tf Pr =  = m2/s k = W/m oC  = Gr = 1 = Tf K-1 g  T L3 = 2 GrL Pr = Since GrL Pr = Nuav = = Nuav = Nuav = hemp L / k hemp = Nuav k / L (W/m2 oC) = hemp = W/m2 oC Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 28 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 29 of 80 TABLE OF RESULTS Sl. Heat Input hexp hemp No. (W) (W/m2 K) (W/m2 K) 1. 2. ANALYSIS OF RESULTS/ CONCLUSIONS 1. 2. Remarks of the Faculty in-charge: Date: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Signature: Page 30 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 31 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Experiment 4. Forced convection heat transfer in a vertical stainless steel plate Obtained Mark Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 32 of 80 OBJECTIVE To determine the heat transfer coefficient between the given fluid and the solid surface and thereby compare the heat transfer coefficient with fluid velocity. EXPERIMENTAL SET UP The experimental unit consists of a vertical plate made of S.S material enclosed in a rectangular duct open at both top and bottom. The duct is of sufficient dimensions as not to interfere with the convection process while at the same time preventing external disturbances to affect the data. The blower/ fan is mounted on the top or bottom of the duct to enhance the fluid flow over the plate and velocity is measured by anemometer. The surface temperature of the plate and ambient temperature is measured using thermocouples. The surface of the plate is polished to minimize radiation heat losses. SPECIFICATION Stainless steel plate: height = mm width = mm PROCEDURE 1. The system is switched on. 2. The amount of heat input is measured by using the wattmeter. 3. The blower is switched on and a particular amount of air flow is fixed. 4. The system is allowed to reach the steady state and the temperatures for the plate and surrounding fluid medium are noted. 5. The above procedure is repeated for various air flow rates, keeping the heater input same. FORMULAE For a vertical plate transferring heat to the surroundings with the aid of velocity at constant heat flux, the following empirical relations hold. Nux = 0.453 ReL0.5 . Pr 0.333 for Re < 5 x 105 (Laminar flow) Nux = 0.031 ReL0.8 . Pr 0.33 for 105 < Re < 107 (Turbulent flow) Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 33 of 80 Reynolds number, Re Where γ V = V L along flow / γ = kinematic viscosity, m2/s = velocity of air through the duct, m/s All the properties for air are evaluated at the film temperature given by Tf = Ts +T = 2 o C EXPERIMENTAL LAYOUT Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 34 of 80 TABLE OF MEASUREMENTS Sl.No Fluid velocity Rate of heat flow (V) Surface temperature (Ts) ( ) watt o m/s C Ambient Temperature (T∞ ) o C 1. 2. 3. CALCULATIONS: (for reading no: ) Velocity of the air through the duct, V = Mean film temperature, Tf m/s = Ts +T 2 = o C Properties of air at Tf are as follows: k = W/m oC γ = m2/s Pr = Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 35 of 80 Temp.Diff T o C Reynolds number, Re =VL/γ = = Nux = = Nux = Nux = hemp L / k hx = Nux k / L (W/m2 oC) = hx = Heat Transfer Lab (MIME4212P) 16 Jan 2019 W/m2 oC Page 36 of 80 TABLE OF RESULTS: The local heat transfer coefficient was determined under forced convection mode for various air flow rates and the results are given below. S. Heat input Velocity No. Q (W) V (m/s) Re Nux hx (W/m2K) 1. 2. 3. ANALYSIS OF RESULTS 1. 2. Remarks of the Faculty in-charge: Date: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Signature: Page 37 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 38 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 39 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Experiment 5. Radiation: Inverse Square Law for Heat Obtained Mark Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 40 of 80 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. THEORY: An ideal black surface is one which absorbs the entire radiation incident on it and its reflectivity and transmissivity are zero. The radiation emitted per unit area per unit time from the surface of the body is called emissive power. It is denoted by the term ‘E’. Black surface has the maximum amount of emissive power for a given temperature. The ratio of emissive power of given surface at a given temperature (E) to that of the emissive power of a black body at the same temperature (Eb) is defined as emissivity (ε). For a black body, emissivity is 1. Emissivity depends upon temperature, wavelength and nature of the surface. The intensity of radiation on a surface is inversely proportional to the square of the distance of the surface from the radiation source. This law equally applicable to heat, light and electromagnetic (radio waves) radiation. EXPERIMENTAL SET UP: The experimental set up consists of a circular plate provided with heating coil and a radiometer mounted on a bench with measuring scale. The heat input to the heater is varied by dimmerstat and is measured by an ammeter and voltmeter. The temperature of the plate is measured by thermocouple. One thermocouple is kept open to the atmosphere to read the ambient temperature. The radiometer measurements can be viewed from control and measurement system. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 41 of 80 EXPERIMENTAL LAYOUT PROCEDURE: 1. Give power input to black body (circular plate) surface by adjust the dimmerstat . 2. Set the radiometer at a specified distance and measure the scale on the bench and allow the system to reach steady state. 3. Measure the steady state heat flux from radiometer. 4. Repeat the experiment for the same power input and varying the radio-meter scale. FORMULAE: The power input given for black surface, b = Ib × Vb Watts ___ Radiometer reading (intensity of radiation) = q rad W/m ___ Inverse square law, q rad  2 1 r2 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 42 of 80 TABLE OF MEASUREMENTS The power input given for black surface, Patm = 1.0 atm ___ Distance r (m) q b = Ib × Vb Watts Tambient = °C r² 1/r² m² m-2 rad Radio meter reading (W/m²) Theater Tradiometer °C °C 0.2 0.4 0.6 0.8 CALCULATIONS: (for reading no: Heat Transfer Lab (MIME4212P) 16 Jan 2019 ) Page 43 of 80 ANALYSIS OF RESULTS 1. 2. Remarks of the Faculty in-charge: Date: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Signature: Page 44 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 45 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Experiment 6. Radiation: Stefan – Boltzmann law Obtained Mark Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 46 of 80 OBJECTIVE: To show that the intensity of radiation varies as the fourth power of the source temperature and compare the actual & calculated heat flux. THEORY: An ideal black surface is one which absorbs the entire radiation incident on it and its reflectivity and transmissivity are zero. The radiation emitted per unit area per unit time from the surface of the body is called emissive power. It is denoted by the term ‘E’. Black surface has the maximum amount of emissive power for a given temperature. The ratio of emissive power of given surface at a given temperature (E) to that of the emissive power of a black body at the same temperature (Eb) is defined as emissivity (ε). For a black body, emissivity is 1. Emissivity depends upon temperature, wavelength and nature of the surface. The intensity of radiation varies as the fourth power of the source temperature. EXPERIMENTAL SET UP: The experimental set up consists of a circular plate provided with heating coil and a radiometer mounted on a bench with measuring scale. The heat input to the heater is varied by dimmerstat and is measured by an ammeter and voltmeter. The temperature of the plate is measured by thermocouple. One thermocouple is kept open to the atmosphere to read the ambient temperature. The radiometer measurements can be viewed from control and measurement system. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 47 of 80 EXPERIMENTAL LAYOUT PROCEDURE: 1. Give power input to black body (circular plate) surface by adjust the dimmerstat . 2. Set the radiometer at a specified distance and measure the scale on the bench and allow the system to reach steady state. 3. Measure the steady state heat flux from radiometer. 4. Repeat the experiment for changing power input at a constant radio-meter scale. FORMULAE: The power input given for black surface, b = Ib × Vb Watts ___ Radiometer reading (intensity of radiation) = q rad W/m 2 Net energy exchange between two bodies: Q =   A F 1−2 (T 4 − T 4 ) 1−2 1 2 Where Q1-2 A F1-2 σ  = Rate of heat transfer by Radiation (Watt = J/s) = Area on which the air will be flow (m²) = View factor = Boltzmann’s constant (= 5.67 10−8 W/m² K 4 ) = Emissivity Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 48 of 80  = Absorptivity In general for black body  =  =1.0 The view factor can be calculated by the following approach: For old system r1 = 7mm r2 = 52.5mm For the new system r1 = 5.5mm r2 = 50mm Definitions: R = r/a; R1 = r1 / a and R2 = r2 / a X = 1 + (1 + R22)/R12 Governing equation Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 49 of 80 TABLE OF MEASUREMENTS The power input given for black surface, b = Ib × Vb Patmosphere = 1.0 atmos Power input to the black surface qb (Watt) ___ q Tambient = Theater Tradiometer °C °C °C F1−2 Qcalculated W Radio meter reading (W/m²) CALCULATIONS: (for reading no: Heat Transfer Lab (MIME4212P) 16 Jan 2019 rad Watts ) Page 50 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 51 of 80 ANALYSIS OF RESULTS 1. 2. Remarks of the Faculty in-charge: Date: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Signature: Page 52 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 53 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Exercise 7- Counter flow type Double pipe heat exchanger- Energy balance and overall efficiency Obtained Mark Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 54 of 80 Objective To perform an energy balance across a Tubular Heat Exchanger and calculate the Overall Efficiency at different fluid flow rates. Method By measuring the changes in temperature of the two separate fluid streams in a tubular heat exchanger and calculating the heat energy transferred to/from each stream to determine the Overall Efficiency. Equipment Required HT30X/HT30XC Heat Exchanger Service Unit HT31 Tubular Heat Exchanger Equipment Setup Before proceeding with the exercise ensure that the equipment has been set up and the accessory installed as described in this manual, with a cold water supply connected and the pressure regulator adjusted. The apparatus should be switched on, and if using the HT30XC the service unit should be connected to a suitable PC on which the software has been installed. Computer operation is optional with the HT30X. If using the HT30XC, or the HT30X with the optional software, run the HT31 software for the service unit used (HT30XC software must be used with the HT30XC and HT30X software with the HT30X, as the calibration for the sensors differs between the two service units). If using the HT30XC, select the counter flow (Counter current) exercise. If using the HT30X, select Exercise A and then select Counter current Operation on the software display option box. Theory and Relations Note: For this demonstration the heat exchanger is configured for countercurrent flow (the two fluid streams flowing in opposite directions). Mass flow rate (kg/s) = Volume flow rate (m3/s) × Density of fluid (kg/m3) Conversion factor for volume flow rate Heat power (Rate of Heat) = (mass flow rate × Specific heat capacity × Change in temperature) W Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 55 of 80 Therefore: Heat power emitted from hot fluid Qh = [W] Heat power absorbed by cold fluid Qc = [W] Where h = (T1 - T3) and c = (T6 – T4) Heat power lost (or gained) Qf = Qh – Qc [W] Overall Efficiency  = Theoretically Qh and Qc should be equal. In practice these differ due to heat losses or gains to/from the environment. Note: In this exercise the cold fluid is circulated through the outer annulus, if the average cold fluid temperature is above the ambient air temperature then heat will be lost to the surroundings resulting in h100%. Working Fluid: WATER in both stream Observation Tabulation for Counter flow arrangement HOT FLUID Reading Volume Number flow rate [Lits/min] Inlet temp o C T1 COLD FLUID Mid temp o C T2 Exit temp o C T3 Volume flow rate [Lits/min] Inlet temp o C T4 Mid temp o C T5 Exit temp o C T6 1 2 3 4 Note down the following water properties corresponding to mid average temperature of the fluid from property table. at T2= o C for hot fluid = kg/m3 = J/kg K at T5= o C for Cold fluid = kg/m3 = J/kg K Note: If necessary use interpolation technique Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 56 of 80 Calculation For each set of readings, the relevant derived results are should be calculated and presented. Reading 1 Reading 2 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 57 of 80 Reading 3 Reading 4 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 58 of 80 Resultant Tabulation Hot Fluid Reading Number mass flow rate kg/s Cold Fluid mass flow rate kg/s Heat emitted W Qh Heat gained W Qc Heat Exchanger efficiency % Write your conclusion by answering the following, Explain any difference between Qh and Qc in your results. Comment on the effects of the increase in the cold fluid flow rate. Compare the heat power emitted from/absorbed by the two fluid streams at the different flow rates. Conclusion 1. 2. 3. Remarks of the Faculty in-charge: Date: Heat Transfer Lab (MIME4212P) 16 Jan 2019 Signature: Page 59 of 80 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 60 of 80 Course Name: Heat Transfer Course Code: MIME 4212P & CHEE 3101P Exercise 8 - Overall Heat Transfer Coefficient for Cocurrent (Parallel) flow type double pipe heat exchanger by LMTD method Obtained Mark Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 61 of 80 Objective To determine the Overall Heat Transfer Coefficient for a Tubular Heat Exchanger using the Logarithmic Mean Temperature Difference to perform the calculations (for concurrent/parallel flow). Method By measuring the temperatures of the two fluid streams and calculating the LMTD from which the overall heat transfer coefficient can be calculated for each flow configuration. Equipment Required HT30X/HT30XC Heat Exchanger Service Unit and HT31 Tubular Heat Exchanger Equipment Setup Before proceeding with the exercise ensure that the equipment has been set up and the accessory installed as described in this manual, with a cold water supply connected and the pressure regulator adjusted. The apparatus should be switched on, and if using the HT30XC the service unit should be connected to a suitable PC on which the software has been installed. Computer operation is optional with the HT30X. If using the HT30XC, or the HT30X with the optional software, run the HT31 software for the service unit used (HT30XC software must be used with the HT30XC and HT30X software with the HT30X, as the calibration for the sensors differs between the two service units). If using the HT30XC, select the counter flow (Counter current) exercise. If using the HT30X, select Exercise A and then select Counter current Operation on the software display option box. Theory and Relations Cocurrent operation (Parallel flow) When the service unit is configured for cocurrent operation the hot and cold fluid streams flow in the same direction across the heat transfer surface (the two fluid streams enter the heat exchanger at the same end). In PC, select ‘Load New Experiment...’ from the ‘File’ menu and click on the Cocurrent Operation exercise radio button then select the ‘Load’ button. The connections to the heat exchanger are now configured for cocurrent operation where the hot and cold fluid streams flow in the same direction across the heat transfer surface (the two fluid streams enter the heat exchanger at the same end). Adjust the cold water flow control valve setting to 1 litre/min (hot and cold water flowrates remain the same as before). When the temperatures are stable select the icon or manually record the following: T1, T2, T3, T4, T5, T6, Fhot, Fcold. Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 62 of 80 Note: To eliminate the effect of heat losses/gains in the cold water stream the heat emitted from the hot fluid stream will be used in the calculations. Because the temperature difference between the hot and cold fluid streams varies along the length of the heat exchanger it is necessary to derive an average temperature difference (driving force) from which heat transfer calculations can be performed. This average temperature difference is called the Logarithmic Mean Temperature Difference (LMTD) Mass flow rate (kg/s) = Volume flow rate (m3/s) × Density of fluid (kg/m3) Conversion factor for volume flow rate Heat power (Rate of Heat) = (mass flow rate × Specific heat capacity × Change in temperature) W Heat power emitted from hot fluid – T1 ) For LMTD [W] where h = (T3 Qh = calculation: LMTD AND Note: This equation cannot produce a result if The heat transmission area in the exchanger must be calculated using the arithmetic mean diameter of the inner tube. Arithmetic mean diameter Hot fluid tube (inner tube) outer diameter and inner diameter Heat transmission length L = 0.660 m Heat Transmission area A [m2] = Note: (dm can be used since r2/r1 5 x 105 flow -- Turbulent Nux = 0.0296 (Re)0.8 (Pr)0.333 Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 70 of 80 1. Metals are good conductors of heat because a. their atoms collide frequently b. their atoms are relatively apart c. they contain free electrons d. they have high density e. all of the above 2. which of the following is a case of steady state heat transfer? a. IC engine b. Air compressor c. heating of building in winter d. cooling of orange in refrigerator e. all of the above f. none of the above 3. Heat transferred by all three modes of heat transfer, viz, conduction, convection and radiation in a. electric heater b. steam condenser c. melting of ice d. refrigerator condenser coils e. boiler f. none of the above 4. Emissivity of a white polished body in comparison to a black body is a. higher b. lower c. same d. depends upon shape of body e. none of the above 5. A black body is one whose absorptivity a. varies with temperature b. varies with wavelength of the incident ray c. is equal to its emissivity d. does not vary with temperature and wavelength of incident ray e. none of the above 6. A non-dimensional number generally associated with natural convection heat transfer is a. Nusselt number b. Webber number c. Grashoff Number d. Prandtl Number e. Reynlod Number f. All of the above Heat Transfer Lab (MIME4212P) 16 Jan 2019 Page 71 of 80 7. Heat transfer takes place as per a. Zeroth law of thermodynamics b. First law of thermodynamics c. Second law of thermodynamics d. Kirchoff's law e. Stefan's law 8. One side of a 1 cm thick stainless steel wall (k1 = 19 W/moC) is maintained at Th=180oC and the other side is insulated with a layer of 4 cm thick fiberglass. The outside of the fiberglass is maintained at Tc=60oC and the heat loss through then wall is 300 W. Determine the thermal conductivity of fiber glass if the area of the wall is 2.5 m2. [3 marks] 9. Air at 20oC and Pressure of 1.0132 bar is flowing over a flat plate of 1 m long, 0.5 m wide due to density difference. If the plate is at 80oC. Calculate Grashof number and Type of flow. [5marks] g=9.81m/s2 ; = Criteria for flow type Gr Pr < 1 x 109 Gr Pr > 1 x 109
— Laminar flow
— Turbulent flow
1. Thermal conductivity of solid metals with rise in temperature normally
a. increases
b. decreases
c. remains same
d. may increase or decrease based on temperature
2. which of the following is a case of steady state heat transfer?
a. IC engine
b. Air compressor
c. heating of building in winter
d. cooling of orange in refrigerator
e. all of the above
f. none of the above
3. Thermal conductivity of a material may be defined as the
a. quantity of heat flowing in one second through one cube of material when
opposite faces are maintained at a temperature difference of 1oC
b. quantity of heat following in one second through a slab of the material of
area one cm square, thickness 1 cm when its faces differed in temperature
by 1oC
c. heat conducted in unit time across unit area through unit thickness when
a temperature difference of unity is maintained between opposite faces
d. all of the above
e. none of the above
Heat Transfer Lab (MIME4212P) 16 Jan 2019
Page 72 of 80
4. When heat is transferred from hot body to cold body, in a straight line, without
affecting the intervening medium, it is referred as heat transfer by
a. conduction
b. convection
c. radiation
d. conduction and convection
e. convection and radiation
5. Emissivity of a white polished body in comparison to a black body is
a. higher
b. lower
c. same
d. depends upon shape of body
e. none of the above
6. A black body is one whose absorptivity
a. varies with temperature
b. varies with wavelength of the incident ray
c. is equal to its emissivity
d. does not vary with temperature and wavelength of incident ray
e. none of the above
7. Heat is closely related with
a. Liquids
b. solids
c. energy
d. temperature
e. enthalpy
f. entropy
8. Select the wrong case. Heat flowing from one side to other depends directly on
a. face area
b. time
c. thickness
d. temperature difference
e. thermal conductivity
9. A black plate is heated by resistance heating by transferring 1.5 A current with a
drop in voltage of 60V when the distance between the plate and radiometer is
15cm. The diameter of the circular black plate is 19mm.If the distance between
the plate and radiometer is doubled what will be the value of Q? (Use inverse
square law).
[3]
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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Radio meter
Black plate
Distance =r
12. Air at 25oC and Pressure of 1.0132 bar is flowing over a flat plate of 1 m long, 0.5
m wide due to density difference. If the plate is at 80oC. Calculate Grashof
number and Type of flow. [4marks]
Criteria for flow type
g=9.81m/s2 ; =
Gr Pr < 1 x 109 Gr Pr > 1 x 109
1.
— Laminar flow
— Turbulent flow
heat conducted through unit area and unit thick face per unit time when
temperature difference between opposite faces is unity is called
a. thermal resistance
b. emissivity
c. temperature gradient
d. heat transfer rate
e. thermal conductivity
2. Heat transfer takes place as per
a. Zeroth law of thermodynamics
b. First law of thermodynamics
c. Second law of thermodynamics
d. Kirchoff’s law
e. Stefan’s law
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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3. When heat is transferred from one particle of hot body to another by actual
motion of the heated particles. it is referred to as heat transfer by
f. conduction
g. convection
h. radiation
i. conduction and convection
j. convection and radiation
4. When heat is transferred from hot body to cold body, in a straight line, without
affecting the intervening medium, it is referred as heat transfer by
k. conduction
l. convection
m. radiation
n. conduction and convection
o. convection and radiation
5. Heat is closely related with
p. Liquids
q. solids
r. energy
s. temperature
t. enthalpy
u. entropy
6. Which of the following is the case of heat transfer by radiation?
v. blast furnace
w. heating of a building
x. cooling of parts of engine
y. heat received by a person from fire place
z. all of the above
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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7. Air, at a pressure of 1 bar is flowing over a flat plate at a velocity of 3 m/s. If the
plate is maintained at 60oC, calculate the heat transfer co-efficient per unit width
of the plate taking the length of the plate along the flow of air is 2 m.
[5]
Air
temperature
oC
W
Hot plate
temperature
oC
Air
Velocity
m/s
Criteria for flow type
Re < 5 x 105 -Laminar flow Nux = 0.332 (Re)0.5 (Pr)0.333 Re > 5 x 105
193.2
20
60
Heat Transfer Lab (MIME4212P) 16 Jan 2019
3
— Turbulent flow
Nux = 0.0296 (Re)0.8 (Pr)0.333
Page 76 of 80
COURSE ASSESSMENT MARKS DISTRIBUTION
Heat Transfer (MIME4212P) & (CHEE3101P)
PERFORMING EXPERIMENT (Handwritten) – Submit same day [5 Marks]
Experiment Procedure (Complete & Detailed in Own Words)
1
[Marks]
1
Skills (Dexterity in handling equipment)
1
Complete, Well Presented (clean) Data Collection with Teacher’s Signature
1
Initial Partial Calculations (correct clear step by step), Unit Conversions
1
Clean & Maintained Workspace / Equipment
0.5
Attend On Time / Lab Discipline / Safety / Personal Protective Equipment (PPE)
0.5
REPORT SUBMISSION (Word Processed) – Submit thru E Learning [10 Marks]
Aim and Experiment Procedure (Complete & Detailed in Own Words)
Equipment / Apparatus / Tools / Components Used
Table & Graphs (complete, correct & clear)
2
[Marks]
1
2
Complete Calculations (correct clear step by step), Unit Conversions
2
Conclusion in Reference to the Aim / Objective of Experiment
1
Remarks based on the Outcome/Evidence & Reasoning with Errors & Uncertainty
2
Assignment correct & complete with proper Reference
1.5
Report Presentation, Correct Format and File type
0.5
2 PRACTICAL ASSESSMENTS (Average) [15 Marks]
[Marks]
Short Questions / Definition / Basic Applications / Equipment Use & Function
5
Procedure / Data Outcome / Graph Interpretation / Equipment Comparison
5
Calculations / Detailed Solutions / Unit Conversions
5
3
Obtained
Marks
Total Marks [30]
*Submission of Manual marking scheme:
Submission Day
a) On Time
b) 1-day Late
c)
2-day Late
d) 3 or more days late
Deduction of Marks
0
3
5
10
Notes:
✓ Lab Experiment should be accomplished on a 2-hour session only.
✓ Failure to comply will be subjected to the *Submission of Manual marking scheme.
✓ Use black or blue pen only. Reduction will be imposed for not following instructions.
✓ In case of absence, only with valid reasons submitted within 1 week are allowed to perform the missed
Laboratory Experiment.
✓ Reports will be uploaded to Turnitin software for Plagiarism.
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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References
1. Solteq, Malaysia: HE110 – Thermal Conductivity of Building Material Apparatus Manual, Equipment for Engineering Education.
2. Solteq, Malaysia: HE106 – Free and Forced Convection Apparatus – Manual,
Equipment for Engineering Education.
3. P.A.Hilton, UK: H111, H111C & H111P –Thermal Radiation Apparatus – Manual,
Equipment for Engineering Education.
4. HT30X/HT30XC Heat Exchanger Service Unit and HT31 Tubular Heat Exchanger
user manual, www.armfield.co.uk
5. Yunus A.Cengel, “Heat Transfer” 2nd Edition Reprint, McGraw Hill Higher
Education, 2002.
6. J. P. Holman, “Heat Transfer” 8th International Edition, McGraw Hill Higher
Education INC, 1997.
7. R. C. Sachdeva, “Fundamentals of Engineering Heat and Mass Transfer” Reprint, New
Age Science, Limited, 2007.
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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Linear Interpolation using Calculator
Suppose you have the following straight line: – and you need to calculate the value of Y?!
To do this using calculator fx991-ES, please follow this procedure: 1.
2.
3.
4.
5.
6.
7.
8.
Press Mode Button.
Press 3 “Stat “.
Press 2“A+BX”.
Enter the value of limits in X column, 0 and 20.
Enter the value of limits in Y column, 10 and 5.
Press AC button.
Press Shift.
Press 1.
If you want the value of Y at x = 8.
9. Press 8.
10. Press Shift.
11. Press 1.
12. Press 7” Reg”.
13. Press 5.
14. Press =.
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To do this using calculator fx100-MS, please follow this procedure: –
1. Press Mode Button.
2. Press “REG “(2)
3. Press “Lin” (1)
4. Press “AC”.
5. Press “shift+Mode”.
6. Press “Scl” (1) and “=” and “AC”.
7. For data entry follow the below steps
a. Enter “X” and “,” and “Y” and press “M+”.
b. Enter “X” and “,” and “Y” and press “M+”.
8. Press AC.
You want the value of Y at x = 8.
9.
Press 8.
10.
Press Shift.
11.
Press 2.
12.
Press replay button right arrow thrice.”>” ”>” ”>”.
13.
Press 2 “ ”.
14.
Press =.
For the next data repeat steps from 6.
Heat Transfer Lab (MIME4212P) 16 Jan 2019
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