LMMEC334

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MEC334

IC ENGINES AND REFRIGERATION LABORATORY

LAB Manual

Mechanical Engineering Department

Lovely Professional University, Phagwara

Jalandhar, Punjab 144402

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S. No. Title of the Experiment Page No. 1. Petrol Engine :

To study the constructional details and working principles of four stroke Petrol Engine.

3-4

2. To draw valve timing diagram of a Petrol Engine and study of Its impact on the performance of IC Engine.

5-6

3. Diesel Engine : To study the constructional details and working principles of four Stroke Diesel Engine.

7-8

4. To draw valve timing diagram of a Diesel Engine and study of Its impact on the performance of an IC Engine.

9-10

5. Morse Test : (a) Determine the brake power, indicated power and friction power of a Multi cylinder petrol engine running at constant speed (Morse Test). (b) Determine the mechanical efficiency of a multi cylinder petrol engine running at constant speed (Morse Test).

11-15

6. Performance of Diesel Engine : (a)Performance of a diesel engine from no load to full load (at constant speed) for a single cylinder engine in terms of brake power indicated power, mechanical efficiency and SFC (Specific fuel consumption). (b)To obtain power consumption curves and draw the heat balance sheet.

16-19

7. Vapour Compression system : To evaluate experimentally the Performance of a vapour compression test rig using R-134a (Tetra fluoro ethane) as refrigerant.

20-21

8. Domestic Refrigerator and Window Air Conditioner : (a) To study and identify the various components of a domestic refrigerator and window type air conditioner and to learn their functioning.

22-24

9. Vapour Absorption system and Air Conditioning test rig : To calculate the Coefficient of Performance of a vapour absorption refrigeration system.

25-27

10. To calculate the Coefficient of Performance of air-conditioning test rig during Heating/Cooling/Humidification/Dehumidification and Mixing of air streams.

28-30

11. Motor Controls and Safety Devices : To study and learn the functioning of thermostatic switch, low pressure and high pressure controls, over load protector, fusible plug, pressure relief valve & water failure switch.

31-33

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Experiment No. 1

Aim: To study the constructional details and working principles of four stroke Petrol Engine.

Equipments and apparatus: Single-Cylinder Petrol Engine Test Rig

Learning Objective:

(1) Study of various component of four stroke petrol engine.

(2) To know the working of four stroke petrol engine.

Theory: When the cycle is completed in two revolutions of the crankshaft, it is called four stroke cycle engines. A mixture of fuel with correct amount of air is exploded in an engine cylinder which is closed at one end. As a result of this explosion, heat is released and this heat causes the pressure of the burning gases to increase. This pressure forces a close fitting piston to move down the cylinder. The movement of piston is transmitted to a crankshaft by a connecting rod so that the crankshaft rotates and turns a flywheel connected to it. Power is taken from the rotating crank shaft to do mechanical work. To obtain continuous rotation of the crankshaft the explosion has to be repeated continuously. Before the explosion to take place, the used gases are expelled from the cylinder, fresh charge of fuel and air are admitted in to the cylinder and the piston moved back to its starting position. The sequences of events taking place in an engine are called the working cycle of the engine. The sequence of events taking place inside the engine is as follows 1. Admission of air or air-fuel mixture inside the engine cylinder (suction) 2. Compression of the air or air fuel mixture inside the engine (compression) 3. Injection of fuel in compressed air for ignition of the fuel or ignition of air-fuel mixture by an electric spark using a spark plug to produce thermal power inside the cylinder (power) 4. Removal of all the burnt gases from the cylinder to receive fresh charge (exhaust) Note: Charge means admitting fresh air in to the cylinder in the case of compression ignition engines (diesel engines) or admitting a mixture of air and fuel in to the cylinder in the case of spark ignition engines.

Suggested readings for student:

Books: Internal Combustion Engine by M.L. Mathur and R.P. Sharma, IC Engine by V. Ganesan

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Worksheet of the student

Date of performance: Registration No:

Aim: To study the constructional details and working principles of four stroke Petrol Engine.

Observation table: Study of four stroke petrol engine

S.No. Components Working 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Learning Outcomes:

S.No. Parameter Marks obtained Max. Marks 1. Understanding of the student about the procedure

/apparatus 20

2. Observations and analysis including learning outcome 20 3. Completion of the experiment, Discipline and

Cleanliness 10

Signature of Faculty

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Experiment No.2

Aim: To draw valve timing diagram of a Petrol Engine and study of its impact on the performance of IC Engine.

Equipments and apparatus: Single-Cylinder Petrol Engine Test Rig, Stop Watch, and Digital Tachometer, Filler gauge.

Learning Objective:

1. The purpose of this experiment is to study the working of four stroke Petrol Engine

2. To know the valve timing diagram of petrol engine.

3. To know the effect of valve timing diagram

Theory: In four- stroke S. I. Engine the opening and closing of the valves and the ignition of the air fuel mixture do not take place exactly at the dead centre positions. The valve open slightly earlier and close after their respective dead centre positions. The ignition also occurs prior, to the mixture is fully compressed, and the piston reaches the top dead centre position. Similarly in a C. I. Engine both the valves do not open and close exactly at dead centre positions, rather operate at some degree on either side in terms of the crank angles from the dead centre positions. The injection of the fuel is also timed to occur earlier. Outline of the procedure 1) Fix a plate on the body of the Engine touching the flywheel. 2) Mark the positions of both the dead centers on the flywheel with the reference to the fixed plate, TDC and BDC in case of vertical Engines, IDC and ODC in case of horizontal Engines. 3) Mark on the flywheel when the inlet and exhaust valves open and close as the flywheel is rotated slowly. 4) Measure the valves (Tappet) Clearance. 5) Mark the spark ignition timing in case of petrol. 6) Measure the angles of the various events and plot the valve timing diagram. Results: - Based on final calculation valve timing diagram is drawn and compare with the standard valve timing diagram. Suggested readings for student:


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Aim: To draw valve timing diagram of a Petrol Engine and study of its impact on the performance of IC Engine.

Observation Table:

S.No. Engine Type Tappet Clearance Valve Timing Inlet Valve (mm)

Exhaust Valve (mm)

Inlet Valve Exhaust Valve Injection Timing

Open (0)

Close (0)

Open (0)

Close (0)

1. Four-Stroke, Single- Cylinder (Vertical) Petrol Engine.

Result and Discussion:

Error Analysis:

Learning Outcome:


/apparatus 20


Cleanliness 10


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Experiment No. 3

Aim: To study the constructional details and working principles of four stroke Diesel Engine.

Equipments and apparatus: Diesel Engine Test Rig

Learning Objective:

(1) Study of various component of four stroke Diesel engine.

(2) To know the working of four stroke Diesel engine.

Theory:

SUCTION STROKE: With the movement of the piston from T.D.C. to B.D.C. during this stroke, the inlet valve opens and the air at atmospheric pressure is drawn inside the engine cylinder; the exhaust valve however remains closed. This operation is represented by the line 5-1 COMPRESSION STROKE: The air drawn at atmospheric pressure during the suction stroke is compressed to high pressure and temperature as the piston moves from B.D.C. to T.D.C. Both the inlet and exhaust valves do not open during any part of this stroke. This operation is represented by 1-2 POWER STROKE OR EXPANSION STROKE: As the piston starts moving from T.D.C to B.D.C, the quantity of fuel is injected into the hot compressed air in fine sprays by the fuel injector and it (fuel) starts burning at constant pressure shown by the line 2-3. At the point 3 fuel supply is cut off. The fuel is injected at the end of compression stroke but in actual practice the ignition of the fuel starts before the end of the compression stroke. The hot gases of the cylinder expand adiabatically to point 4. Thus doing work on the piston. EXHAUST STROKE: The piston moves from the B.D.C. to T.D.C. and the exhaust gases escape to the atmosphere through the exhaust valve. When the piston reaches the T.D.C. the exhaust valve closes and the cycle is completed. This stroke is represented by the line 1-5.

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Aim: To study the constructional details and working principles of four stroke Diesel Engine.

Observation table: Study of four stroke Diesel engine

S.No. Components Working 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Learning Outcomes:


/apparatus 20


Cleanliness 10


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Experiment No. 4

Aim: To draw valve timing diagram of a Diesel Engine and study of its impact on the performance of IC Engine.

Equipments and apparatus: Single-Cylinder Diesel Engine Test Rig, Stop Watch, and Digital Tachometer.

Learning Objective:

1. The purpose of this experiment is to study the working of Diesel Engine

2. To know the valve timing diagram of Diesel engine.

3. To know the effect of valve timing diagram on engine performance.

Theory: In four- stroke S. I. Engine the opening and closing of the valves and the ignition of the air fuel mixture do not take place exactly at the dead centre positions. The valve open slightly earlier and close after their respective dead centre positions. The ignition also occurs prior, to the mixture is fully compressed, and the piston reaches the top dead centre position. Similarly in a C. I. Engine both the valves do not open and close exactly at dead centre positions, rather operate at some degree on either side in terms of the crank angles from the dead centre positions. The injection of the fuel is also timed to occur earlier. Outline of the procedure 1) Fix a plate on the body of the Engine touching the flywheel. 2) Mark the positions of both the dead centers on the flywheel with the reference to the fixed plate, TDC and BDC in case of vertical Engines, IDC and ODC in case of horizontal Engines. 3) Mark on the flywheel when the inlet and exhaust valves open and close as the flywheel is rotated slowly. 4) Measure the valves (Tappet) Clearance. 5) Mark the injection timing in case of Diesel Engine. 6) Measure the angles of the various events and plot the valve timing diagram Result: - Based on final calculation valve timing diagram is drawn and compare with the standard valve timing diagram. Suggested readings for student:


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Aim: To draw valve timing diagram of a Diesel Engine and study of its impact on the performance of IC Engine.

Observation Table:

S.No. Engine Type Tappet Clearance Valve Timing Inlet Valve (mm)

Exhaust Valve (mm)

Inlet Valve Exhaust Valve Injection Timing

Open (0)

Close (0)

Open (0)

Close (0)

1. Four-Stroke, Single- Cylinder (Vertical) Petrol Engine.


Error Analysis:

Learning Outcome:


/apparatus 20


Cleanliness 10


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Experiment No 5

Aim: Determine the brake power, Indicated power and frictional power of a Multi cylinder petrol Engine running at a constant speed. (Morse Test)

(b) Determine the mechanical efficiency of a multi cylinder petrol engine running at constant speed (Morse Test).

Equipments and apparatus: - Multi-Cylinder Petrol Engine Test Rig, Stop Watch, Hand Gloves and Digital Tachometer.

Learning Objective: To know the performance parameter of engine at different loads.

Theory: - The purpose of Morse Test is to obtain the approximate Indicated Power of a Multi-cylinder Engine. It consists of running the engine against a dynamometer at a particular speed, cutting out the firing of each cylinder in turn and noting the fall in BP each time while maintaining the speed constant. When one cylinder is cut off, power developed is reduced and speed of engine falls. Accordingly the load on the dynamometer is adjusted so as to restore the engine speed. This is done to maintain FP constant, which is considered to be independent of the load and proportional to the engine speed. The observed difference in BP between all cylinders firing and with one cylinder cut off is the IP of the cut off cylinder. Summation of IP of all the cylinders would then give the total IP of the engine under test.

Formula Used:-

(i) Brake Power, BP = ଶగே்

KW

(ii) Torque, T = WxR, Where W is the load on dynamometer and R= R1 + R2

R1 = Diameter of the flywheel

R2= Diameter of rope

(ii) Indicated Power (IP) of each Cylinders:

IP1 = (BPT - BP2, 3, 4) KW

IP2 = (BPT - BP1, 3, 4) KW

IP3 = (BPT - BP1, 2, 4) KW

IP4 = (BPT - BP1, 2, 3) KW

(iii) Total IP of the Engine, IPT = (IP1 + IP2 + IP3 + IP4) KW

(iv) Mechanical efficiency, η mechanical = BPT / IPT

Procedure: - 1. Before starting the engine check the fuel supply, lubrication oil, and availability of cooling water.

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2. Set the dynamometer to zero loads.

3. Run the engine till it attains the working temperature and steady state condition. Adjust the dynamometer load to obtain the desired engine speed. Record the engine speed and dynamometer reading for the BP calculation.

4. Now cut off one cylinder. Short-circuiting its spark plug can do this.

5. Reduce the dynamometer load so as to restore the engine speed as at step 3. Record the dynamometer reading for BP calculation.

6. Connect the cut off cylinder and run the engine on all cylinders for a short time. This is necessary for the steady state conditions.

7. Repeat steps 4, 5, and 6 for other remaining cylinders turn by turn and record the dynamometer readings for each cylinder.

8. Bring the dynamometer load to zero, disengage the dynamometer and stop the engine.

9. Do the necessary calculations.

Observations:

Engine Speed, N = _________rpm

No. of Cylinders, n = ______

General Calculation:

Torque, T = (W1 – W2) x 9.81xR

Where R = R1 + R2

R1 = Diameter of flywheel

R2 = Diameter of rope

W1 = Dead weight

W2 = spring weight

Now, Brake Power BP = ଶగே்

KW

And indicated power IPi = BPT – BPi

Where IPi = Indicated power for ith cylinder cutoff

and i= 1,2,3,4

Now, total indicated power IPT = IP1 + IP2+ IP3 + IP4

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ᶯm (mechanical efficiency) = ூ

Result:

BPT (Total brake power) =

IPT (Total Indicated Power) =

FPT (Total Frictional Power) =

ᶯm (Mechanical Efficiency) =



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Aim: Determine the brake power, Indicated power and frictional power of a Multi cylinder petrol Engine running at a constant speed. (Morse Test)

(b) Determine the mechanical efficiency of a multi cylinder petrol engine running at constant speed (Morse Test).

Observations:

Engine Speed, N = _________rpm

No. of Cylinders, n = _______

Observation Table:

Calculation:

S. No. Cylinder Working Dynamometer Reading, (KW)

Brake Power, BP (KW)

IP of the cutoff cylinder, (KW)

1. 1-2-3-4 BPT = 2. 2-3-4 BP2,3,4 = IP1 =

3. 1-3-4 BP1,3,4 = IP2 =

4. 1-2-4 BP1,2,4 = IP3 =

5. 1-2-3 BP1,2,3 = IP4 =

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Learning Outcomes:


/apparatus 20


Cleanliness 10


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Experiment No 6

Aim: Performance of a diesel from no load to full load (at constant speed) for a single cylinder engine in terms of brake power, indicated power, mechanical efficiency and SFC (Specific fuel consumption) and to obtain power consumption curves and draw the heat balance sheet.

Apparatus Used: - Four-Stroke, Single-Cylinder (Constant Speed) Diesel Engine Test Rig, Stop Watch, and Digital Tachometer.

Learning Objective: The purpose of this experiment is to study the flow of heat and performance of engine at different load.

Theory: - Under some circumstances (i.e. Electric Generator) C. I. Engines are required to run at constant speed. For this purpose the test is to be performed at constant speed and the load is varied from zero to maximum. When load on the engine increases its speed decreases. Accordingly the fuel supply is adjusted to keep the engine speed constant. Corresponding to each load setting, dynamometer readings and fuel consumption rate are measured. The BP, BSFC, BMEP, A/F, and Mechanical Efficiency are calculated from measured data and plotted against the load.

Procedure: - 1. Before starting the engine check the fuel supply, lubrication oil, and availability of `cooling water.

2. Set zero loads by switching off all the bulbs.

3. Run the engine till it attains the working temperature and steady state condition.

4. Adjust the load to obtain the desired engine speed. Note down the fuel consumption rate.

5. Change the load so that the engine speed Change, to maintain the engine speed constant fuel consumption increases.

6. Note down the fuel consumption rate, speed, air inlet temperature, at this load setting.

7. Repeat steps 5 and 6 for various loads.

9. Do the necessary calculation.

General Calculation:

Fuel consumed: Wf = ௫௧

× ௦௧௬ ௨ଵ

× ݊݅݉/݃ܭ 60

Where x = Volume of fuel consumed (ml)

And t = Time taken in second

Specific fuel consumption:

SPC = ி௨ ௦௨ௗு

Kg/BHP

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Heat supplied:

Hf = Wf × C.V kJ/min

Brake Power:

BP = ௗ.ହ

KW

Heat Equivalent to BP:

HBP = BP × 60 kJ/min

Air Consumption:

Qa = Cd a0 ඥ2݃ܪ m3/sec

Heat carried away by cooling water:

Hw = mCW × 4.2 × (T2-T1) kJ/min

Where mCW = mass of cooling water

T1 = water inlet temperature

T2 = water outlet temperature

Heat carried away by exhaust gas:

Hg = mEG × 1.02 × (TG – TR)

Where mEG = mass of exhaust gases = (wf + Qa), Qa = mass of air consumed

Tg = temperature of exhaust gas

TR = Room Temperature

Unaccountable Heat loss:

HUN = Hf – Total heat used

Results: Performance curve are plotted and they are similar to the standard performance curve



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Aim: Performance of a diesel from no load to full load (at constant speed) for a single cylinder engine in terms of brake power, indicated power, mechanical efficiency and SFC (Specific fuel consumption) and to obtain power consumption curves and draw the heat balance sheet.

Observations:-

S.No Engine Speed, N (rpm)

Load (kW) Time taken for 10 ml of fuel, t sec

Engine cooling water flow rate, mw (Kg/hr)

Engine Cooling water temperature, (oC)

Exhaust gas temperature, Tfg (0C)

Manometer Reading

twi two 1. 1500 2. 1500 3. 1500 4. 1500

Calculation:-

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Result and Discussion

Learning Outcomes


/apparatus 20


Cleanliness 10


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Experiment No 7

Aim: - To evaluate experimentally the Performance of a vapour compression test rig using R-134a (Tetra fluoro ethane) as refrigerant.

Equipment Required: Vapor compression test rig with evaporator, reciprocating device, condenser and receiver, throttling device and R134A as refrigerant. Material Required: Refrigerant R134A etc. Learning Objective: To find the coefficient of performance of a Vapor Compression Refrigerator (VCR).

Outline Procedure:

1) Switch on the main supply of the trainer

2) open the valves so that the refrigerant can flow through expansion valves/capillary tube.

3) Switch on the condenser, fan, and compressor and solenoid valves

4) Run the test rig at least for 15 minutes.

5) Note down the temperature before entering compressor (T1) temperature after exit from compressor (T2) Temperature after condenser, (T3) and temperature after expansion valve (T4).

6) Note down suction pressure (P1) and delivery pressure (P2)

7) Note down the Rota meter reading (m) i.e. mass flow rate

8) Note down the voltage and Ampere meter readings

9) Calculate COP

Results: COP

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Aim: - To evaluate experimentally the Performance of a vapour compression test rig using R-134a (Tetra fluoro ethane) as refrigerant.

Observation table:-

S.No. P1 P2 T1 T2 T3 T4 M

Calculation:-

Result/ Discussion:-

Learning Outcomes:


/apparatus 20


Cleanliness 10


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Experiment 8

Aim: - (a) To study & detect the various troubles or faults in domestic type refrigerator and window air conditioner.

Equipment Required: - Setup of Domestic Refrigerator and Setup of Window Air Conditioner.

Learning Objectives: To know about faults there causes and remedies of Domestic type refrigerator and window air conditioner

Procedure:

Domestic Refrigerator: To check the causes of faults in the following cases:

a) If the unit does not run at all.

b) If the unit runs but does not produces cooling at all.

c) If the unit runs but does not produce proper cooling.

d) If the interior light is defective.

e) If the unit runs continuously.

f) If the unit freezes ice cubes but does not cool food stuff properly.

g) If refrigerator is noisy.

h) If the unit trips or short cycle through over load protector.

Window Air Conditioner:

a) If the unit does not start.

b) If the unit runs but does not produce cooling at all.

c) If unit runs continuously.

d) If operation is noisy.

e) If unit trips or short cycles through over load protector.

f) If cooling is insufficient.

Results: Troubles and faults/ possible cause/ Remedies

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Aim: - (a) To study & detect the various troubles or faults in domestic type refrigerator and window air conditioner.

Observation Table:

S.No Possible Cause Test and Remedy

Results and Discussion

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Learning Outcomes


/apparatus 20


cleanliness 10


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Experiment No. 9

Aim: - (a) To calculate the Coefficient of performance of a Vapor Absorption Refrigeration System.

Equipment Required: Vapour absorption test rig with generator evaporator, condenser.

Learning Objectives: To calculate COP of vapour absorption system and compare the result with COP of vapour compression system.

Materials Required: Absorbent required etc.

Procedure:

a) Switch on the main supply of the trainer.

b) Run the test rig at least for 30 minute

c) Note down the evaporator temperature (T1) Condensing temperature (T2) Generator temperature (T3). General Calculation

COP = [T1/T2-T3] / [T3-T2/T1]

Results: COP

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Aim: - (a) To calculate the Coefficient of performance of a Vapor Absorption Refrigeration System.

Observation Table:

S.No T1 T2 T3

Calculation:-

COP = [T1/T2-T3] / [T3-T2/T1]


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Learning Outcomes


/apparatus 20


Cleanliness 10


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Experiment No.10

Aim: (b) To calculate the COP of a air conditioning test rig during (i) Heating (ii) cooling (iii) Humidification (iv) Dehumidification (v) mixing of air stream.

Equipment Required: Vapor compression air conditioning test rig, with evaporator, reciprocating device, condenser, receiver, throttling device.

Learning Objectives:

i. To understand Psychometric chart

ii. To know about air conditioning

Material Required: Refrigerant required, air required etc. Procedure:

a) Switch on the main supply of the trainer

b) Open the valves so that the refrigerant can flow through expansion valves/capillary tube.

c) Switch on the condenser, fan, and compressor and solenoid valves

d) Run the test rig at least for 15 minutes.

e) Note down the temperature before entering compressor (T1) temperature after exit from compressor (T2) Temperature after condenser, (T3) and temperature after expansion valve

f) Note down suction pressure (P1) and delivery pressure (P2)

g) Note down the Rota meter reading (m) i.e. mass flow rate

h) Note down the voltage and Ampere meter readings

i) Note the readings of DBT and WBT

j) Repeat this procedure and calculate COP during (i) ) Heating (ii) cooling (iii) Humidification (iv)

Dehumidification (v) mixing of air stream by using heater and steam generator

Results:

COPheating =

COPCooling =

COPhumidification =

COPDehumidification =

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Aim: (b) To calculate the COP of a air conditioning test rig during (i) Heating (ii) cooling (iii) Humidification (iv) Dehumidification (v) mixing of air stream.

Observation Table:-

S.No P1 P2 T1 T2 T3 T4 m

Calculation:

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Learning Outcomes


/apparatus 20


Cleanliness 10


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Experiment No. 11

Aim: -To study and learn the functioning of thermostatic switch, low pressure and high pressure controls, over load protector, fusible plug, pressure relief valve & water failure switch.

Equipment Required: Low pressure and high pressure control switch, thermostatic switch, Overload protector, filters and strainers, filter driers.

Learning Objectives: To study the functioning of control switch, thermostatic switch, overload protector and various filters and strainers.

Procedure:

a.) Take the equipment required.

b.) Check if it is working properly.

c.) Note down the temperature and pressure reading of the various equipment.

Results: Study the functions of control switch, thermostatic switch, overload protector and various filters and strainers.

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Aim: -To study and learn the functioning of thermostatic switch, low pressure and high pressure controls, over load protector, fusible plug, pressure relief valve & water failure switch.

Observation Table:-

S.No Equipment Function

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Results and Discussion:

Learning Outcomes


/apparatus 20


Cleanliness 10


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