VIDYA PRATISHTHAN’S COLLEGE OF ENGINEERING, BARAMATI DEPARTMENT OF MECHANICAL ENGINEERING LABORATORY MANUAL SUBJECT: REFRIGERATION AND AIR-CONDITIONING [SUBJECT CODE: 302051] CLASS: T.E. MECHANICAL YEAR: 2011-12 APPROVED BY: H.o.D. [Mech] PRINCIPAL Prof. P. R. Shinde Dr. S. B. Deosarkar VALIDITY UP TO: ACADEMIC YEAR 2012 – 2013 PRAPARED BY: PROF. P. R. Chitragar, K.M. Jadhav
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VIDYA PRATISHTHAN’S
COLLEGE OF ENGINEERING, BARAMATI
DEPARTMENT OF MECHANICAL ENGINEERING
LABORATORY MANUAL
SUBJECT: REFRIGERATION AND AIR-CONDITIONING
[SUBJECT CODE: 302051]
CLASS: T.E. MECHANICAL
YEAR: 2011-12
APPROVED BY: H.o.D. [Mech] PRINCIPAL Prof. P. R. Shinde Dr. S. B. Deosarkar
VALIDITY UP TO: ACADEMIC YEAR 2012 – 2013
PRAPARED BY: PROF. P. R. Chitragar, K.M. Jadhav
VIDYA PRATISHTHAN’S
COLLEGE OF ENGINEERING, BARAMATI
DEPARTMENT OF MECHANICAL ENGINEERING
List of Experiments
FACULTY: PROF.K. M. JADHAV SUBJECT: REFRIGERATION AND
AIR-CONDITIONING
YEAR: 20011-12 CLASS: T.E. (MECH)
1. Test on Vapour compression Test Rig.
2. Test on ice plant test rig.
3. Test on air conditioning test rig.
4. Trial on vapour absorption refrigeration system.
5. Study of installation/operatio/maintenance practices for refrigeration systems.
6. Determination of refrigeration load in cold storage (case study/visit).
7. Visit to any refrigeration or air conditioning plant.
8. Thermal analysis of any refrigeration or air-conditioning cycle.
Prof. K M. JADHAV
[SUB-Incharge]
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
EXPERIMENT NO. 1
TITLE: TRIAL ON VAPOUR COMPRESSION TESTS Objective: Trial on vapour compression test rig to find out actual and theoretical
COP. Theory: VAPOUR COMPRESSION REFRIGERATION SYSTEM
A vapour compression system is improved type of air refrigeration system in which
suitable working substance termed as refrigerant is used, it condensates and
evaporates at temperature and pressure close to atmospheric conditions. The refrigerants used for this purpose are ammonia, carbon dioxide, and sulphur dioxide.
The refrigerant used does not leave the system, alternatively condensing and
evaporating. In evaporation, the refrigerant absorbs it’s latent heat from which it is used for circulating it around the cold chamber while cost during it gives latent heat to the circulating water of the cooler. The VCS is thus latent heat pump as it pumps
its latent heat from brine end and delivers it to the cooler. It is generally used for all individual purposes from small domestic refrigerator to a big air conditioning plant.
ADVANTAGES:
1. It has similar size for given capacity of refrigerator. 2. It has less running cost. 3. It is employed for large range of temperature. 4. The COP is quite higher.
DISADVANTAGES:
1. The initial cost is higher. 2. The leakage of refrigerant is difficult to avoid.
ESSENTIAL PARTS OF THE SYSTEM:
1. Compressor: The low pressure and temperature of the vapour refrigerant from evaporator is
drawn into the compressor through IV or suction valve where it is compressed to high pressure and temperature. Refrigerant is discharged into the condenser through delivery or discharge valve.
2. Condenser It consists of coils of pipe in which high pressure and temperature vapour refrigerant gets cooled and condensed. The refrigerant while running through
the condenser gives up its latent heat to the surrounding condensing medium
which is normally air or water.
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
3. Receiver The condensed liquid refrigerant from the condenser is stored in vessel known as
receiver from where it is supplied to the evaporator through the expansion valve. 4. Expansion Valve: It allows the liquid refrigerant under high pressure and temperature to pass at a
controlled rate after reducing its pressure and temperature. Some of the refrigerants evaporate and pass through expansion valve but their greater portion is vapourised in the evaporator at low pressures and temperatures.
5. Evaporator: It consists of coils of pipe in which the liquid refrigerant at low pressure and
temperature. In evaporation, the liquid vapour refrigerant absorbs its latent heat of vapourisation from the medium which is to be cooled.
ANALYSIS OF VAPOUR COMPRESSION SYSTEM:
It depends upon: 1. Load on refrigerant plant in Tonnes.
2. Temperature of refrigerant. 3. Atmospheric temperature.
The temperature of refrigerant required and atmospheric conditions decide the
temperature of the refrigerant entering into the condenser and automatically it
decides the pressure ratio. Similarly, the working cycle is represented on T-S and P-h diagram, where the
process 3-2 represents superheating and 4-5 represents undercooling. The COP of
this cycle increases as it approaches near to the Carnot cycle. This is explained as
follows: The absorption of heat in evaporation and rejection of heat in the condenser are in the form of the latent heat. This heat transfer is carried out by maintaining the
temperatures differences as low as possible in evaporator and condenser. By comparing with the refrigerant cycle where high temperature cycle is necessary to carry out into compressor isolating it from the atmosphere. Irreversibility only
exists in the throttling process. The VCS approaches Carnot cycle as compared with air refrigeration system and COP of VCS is higher than air refrigeration system.
SPECIFICATIONS:
1. Cooling capacity: 30 kg of ice in 24 hours. 2. Insulation: PUF Insulation 3. Number of ice cans: 12 4. Size of tank: (0.83*0.345*0.345) m3.
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
5. Height of the tank: 0.27 m 6. Size of the ice can: (0.325*0.116*0.078) m3.
PROCEDURE:
1. Fill the tank in vapour compression test rig with the brine solution.
2. Switch ON the main supply. 3. Start the compressor and stirrer supply button. 4. Take initial energy meter reading of both compressor and stirrer. 5. Wait for about 50 minutes so that the system gets stabilized.
6. After stabilization take all readings at required temperature. 7. Measure evaporator (L.P) and condenser (H.P) pressures.
FIGURES:
VAPOUR COMPRESSION SYSTEM
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
SIMPLE VCC (T-S Graph) OBSERVATIONS:
1. Inlet temperature of brine at the start = 30°C.
2. Total weight of brine solution = 110.9 kg 3. Specific heat of brine = 23.32 kJ/kg°C 4. Final temperature of the brine at time of loading ice plant = -6°C 5. Final temperature of brine = 0°C
OBSERVATION TABLE:
Sr.
NO.
TIME T1 T2 T3 T4 T5 T6 Energy
meter
reading
(amp)
Energy
Meter
Reading
kW
LP
(bar)
HP
(bar)
CALCULATIONS:
1. Refrigeration Effect = m*Cp*(dT/dt) a. Size of can = 0.325*0.116*0.078
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
= 0.0294 m3 b. Total size of the can = 12*0.00294 = 0.3528 m3 c. Size of the tank = 0.83*0.395*0.395 = 0.1295 m3
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
RESULT:
1. Theoretical COP =
2. Actual COP =
p-h diagram for refrigerant 134a
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
EXPERIMENT NO. 2
TITLE: TEST ON ICE PLANT TEST RIG
Objective: 1. Test on ice formation
2. Calculation of actual and theoretical COP
Apparatus: Ice plant test rig.
Specifications:
1. Compressor: hermetically sealed kirloskar made. 2. Condensor: Forced convection air cooled 3. Expansion valve: thermostatic expansion valve 4. Evaporator: Immerse type direct expansion 5. Cooling capacity: 30 kg of ice in 24 hours 6. Insulation: PUF insulation 7. Number of ice cans: 12 8. Flowmeter: GPs flow make rotameter 9. Size of tank: 0.83*0.395*0.395 m3. 10. Size of ice can: 0.35*0.166*0.078 m3.
Procedure:
1. Place machine in proper position where its level is horizontal and it is well insulated.
2. Machine must have atleast 1.5 m clearance from all sides. 3. Give 230 V, 50 Hz, 1 phase supply. 4. Prepare brine solution of water with approximate 20% of NaCl and mix it
thoroughly with water in the tank.
5. Start the compressor by putting switch ON. 6. Check the solution and discharge pressure and note down energy meter
reading.
7. Allow unit to run for some hours to bring down the temperature of brine in the range of -15°C to -120°C.
8. After attaining the temperature, fill ice can with water in each can and insert the ice can.
9. Now start agitator. Take all the readings of temperature at various point and pressure flow rate.
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
10. Allow the unit to run between the periods of 4 hours to 10 hours. Take all the readings until ice formation takes place.
11. After formation of ice remove the ice blocks.
Figures:
Ice plant test rig
Observations:
1. Time required to obtain temperature = 2 hours 2. Total weight of water in ice can = 30 kg 3. Initial temperature of water in ice can = 25°C. 4. Final temperature = 0°C. 5. Final temperature of brine when ice is formed = -2°C. 6. Time required = 5 hours
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
7. Initial temperature of brine start up = 15°C. 8. Total weight of brine solution = 110.9 kg 9. Specific heat of brine = 23.32 kJ/kg°C 10. Final temperature of the brine at time of loading ice plant = -6°C
Observation Table:
Sr.
No.
TIME T1 T2 T3 T4 T5 T6 Energy
Meter
Reading
kW
LP
(bar)
HP
(bar)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Where,
T1= Discharge gas temperature
T2= Liquid line temperature condenser output
T3= After expansion Temperature
T4= Suction gas Temperature
T5= Temperature of brine
T6= Ambient Temperature
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
Conversions:
PSI = 0.06897 bar
P1 = 23*0.6897 bar = 1.5 bar
P2 = 51*0.6897 = 10.25 bar
Calculations:
1. Refrigeration Effect
2. Compressor work =
3. Stirrer work =
4. COP (actual)
5. COP (from p-h chart)
Result:
1. Theoretical COP = 2. Actual COP =
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
p-h diagram for 134a refrigerant
REFRIGERATION AND AIR-CONDITIONING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
EXPERIMENT NO. 3
TITLE: TEST ON AIR CONDITIONING TEST RIG
Objective:
1. Study of vapour compression cycle for conditioner.