Download Anna University B-Tech ME 5th Sem Thermal Engineering TE Lab Manual Question Paper

DEPARTMENT OF

MECHANICAL ENGINEERING

ME6512 - THERMAL ENGINEERING LABORATORY

V SEMESTER - R 2013

LABORATORY MANUAL

Name : _______________________________________

Register No.: _______________________________________

Section : _______________________________________

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COURSE OBJECTIVES

• To study the heat transfer phenomena predict the relevant coefficient using implementation. To study the performance of refrigeration cycle / components

LIST OF EXPERIMENTS:

HEAT TRANSFER LAB:

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1. Thermal conductivity measurement using guarded plate apparatus
2. Thermal conductivity measurement of pipe insulation using lagged pipe apparatus
3. Determination of heat transfer coefficient under natural convection from a vertical cylinder
4. Determination of heat transfer coefficient under forced convection from a tube
5. Determination of Thermal conductivity of composite wall

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6. Determination of Thermal conductivity of insulating powder
7. Heat transfer from pin-fin apparatus (natural & forced convection modes)
8. Determination of Stefan - Boltzmann constant
9. Determination of emissivity of a grey surface
10. Effectiveness of Parallel / counter flow heat exchanger

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REFRIGERATION AND AIR CONDITIONING LAB:

1. Determination of COP of a refrigeration system
2. Experiments on Psychrometric processes
3. Performance test on a reciprocating air compressor
4. Performance test in a HC Refrigeration System

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5. Performance test in a fluidized Bed Cooling Tower

COURSE OUTCOMES

1. Able to find out the thermal conductivity of various materials.
2. Able to determine the heat transfer through lagged pipe using lagged pipe apparatus

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3. Able to find out the surface heat transfer coefficient of a vertical tube losing water by natural convection experiment.
4. Able to conduct and find out the heat transfer coefficient by forced convection apparatus
5. Able to find out the rate of heat transfer through different materials
6. Able to find out the thermal conductivity of insulating powder by conduction
7. Have attain the practical knowledge and able to find out the pin fin efficiency and net heat transfer rate.

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8. Have attain the practical knowledge and able to find out the pin fin efficiency and net heat transfer rate.
9. Able to find out the Stefan Boltzman constant value.
10. Able to find out the emissivity of the given test plate.
11. Able to conduct the load test on a refrigeration test rig and find out the volumetric efficiency and co-efficient of performance for any type of refrigerant.
12. Have attain the practical knowledge on pscychrometric processes with air conditioning system

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13. Able to find out the values of isothermal and volumetric efficiency by conducting the experiments at various delivery pressures
14. Able to conduct the experiment and find out the coefficient of performance.
15. Able to conduct the experiments and to find out the performance test in cooling tower of various FBC Boiler.

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CONTENTS

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Expt. No.1

THERMAL CONDUCTIVITY MEASUREMENT

USING GUARDED PLATE APPARATUS

Aim:

To conduct an experiment to find the thermal conductivity of a given plate using two slab guarded hot plate method

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Apparatus required:

1. Experimental setup
2. Thermocouple
3. Ammeter
4. Voltmeter

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Theory:

The heater plate is surrounded by a heating ring for stabilizing the temperature of the primary heater and to prevent heat jobs radially around its edges. The primary and guard heater are made up of mica sheets in which is a wound closely spaced Nichrome wire and packed with upper and lower mica sheets. These heaters together form a flat which together with upper and lower copper plates and rings form the heater plate assembly.

Two thermocouples are used to measure the hot face temperature at the upper and lower central heater assembly copper plates. Two more thermocouples are used to check balance in both the heater inputs. Specimens are held between the heater and cooling unit on each side of the apparatus. Thermocouples No.5 and No. 6 measure the temperature of the upper cooling plate and lower cooling plate respectively.The heater plate assembly together with cooling plates and specimen held in position by 3 vertical studs and nuts on a base plate are shown in the assembly drawing.The cooling chamber is a composite assembly of grooved aluminum casting and aluminum cover with entry and exit adaptors for water inlet and outlet.

Formulae used:

1. Power input, Q = V × A/2 W

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2. Thermal Conductivity, K = (Q × dx)/(Ax dt) W/mK
3. Area, A = (p/4) d² (10 + x) cm²
4. Average Temperature, dT = (T1+T2+T3+T4)/4 – (T5+T6)/2

Precautions:

1. Keep dimmer stat to zero volt position before start.

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2. Increase the voltage gradually.
3. Start the cooling circuit before switching ON the heaters and adjust the flow rate so that practically there is no temperature rise in the circuiting fluid.
4. Keep the heater plate undisturbed and adjust the cooling plates after keeping the samples with the help of nuts gently
5. Keep the loosely filled insulation (Glass wool) packets gently and remove them slowly so that they do not disturb the thermocouples terminals and heater wires.

Specifications:

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1. Diameter of the heating plate = 100 mm
2. Width of the heating ring = 37 mm
3. Inside diameter of the heating ring = 106 mm
4. Outside diameter of the heating ring = 180 mm
5. Maximum thickness of the specimen = 25 mm

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6. Minimum thickness of the specimen = 6 mm
7. Diameter of the specimen = 140 mm
8. Mean temperature range = 40°C - 100 °C
9. Maximum temperature of the hot plate = 170°C
10. Diameter of the cooling plates = 180 mm

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11. Central Heater: Nichrome strip type sandwiched between mica sheets (400 W)
12. Guarded Heater Ring: Nichrome strip type sandwiched between mica sheets (400 W)
13. Dimmer stat 2 Nos. = (0 – 2 A) – 240 V
14. Voltmeter = 0 – 100 / 200 V
15. Ammeter = 0-2 A

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16. Thermocouples = 6 Nos. (Chromel Alumel)
17. Insulation Box = 375 mm x 375 mm (Approx)
18. Temperature indicator = 0 - 200°C
19. Width of gap between two heater plates (x) = 2.5 mm
20. Specimen thickness (L) = 12.5 mm

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21. Specimen used = Press wood

Tabulation:

Schematic view of the test set-up:

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[Diagram of the test setup would be inserted here]

Procedure:

1. Place the specimens on either side of the heating plate assembly, uniformly touching the cooling plates. Fill the outer container with loose fill insulation such as glass wool.
2. Open the cooling water valve before switching ON the apparatus, and ensure that enough cooling water is passed through the cooling plates.

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3. Switch ON the apparatus and heat input to the central and guarded heaters through separate single phase supply lines with dimmer stat.
4. Provide correct heat input to the central and guarded plates for adjusting the dimmer stat switch.
5. Adjust the guarded heater input in such a way that there is no radial heat flow which is checked from thermocouple readings and is adjusted accordingly.
6. Observe and record the current, voltage and thermocouples readings every 10 minutes till a reasonably steady state condition achieved.
7. Write the readings in the observation table.

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8. Take the final steady state values for calculations.

Result:

Thus the experiment was done and thermal conductivity of given material was found to be

k = ___________ W/mK.

Outcome:

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From this experiment, finding the thermal conductivity of a given plate using two slab guarded hot plate method is learnt and this experiment could be used in the areas such as Pipe lines, IC engines, heat exchangers, etc. where thermal conductivity is to be found.

Applications:

Pipe lines, IC engines, heat exchangers

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Viva – voce

1. Define - Thermal Conductivity
2. State Fourier's law of heat conduction.
3. State the applications of fins.

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4. Define - Fins
5. State Newton's law of cooling or convection law.
6. What are the factors affecting the thermal conductivity?
7. What is the value of thermal conductivity for wood?
8. What are the various modes of heat transfer?

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9. What is meant by conduction?
10. Define - Heat Transfer
11. State the purpose of heating ring provided in this experiment.
12. What is meant by transient heat conduction?
13. How heat transfer occurs through insulated medium?

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14. What are the material used for making the guarded plate?
15. How many thermocouples were mounted in this experiment?
16. Specify the thermocouple numbers which was used to measure the cooling plate temperature.
17. What is unit for thermal conductivity?
18. What is meant by Newtonian and Non-Newtonian fluids?

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19. What is meant by dimensional analysis?
20. State the advantages of dimensional analysis.

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