The document summarizes an experiment conducted on a vapor compression refrigeration unit. The objectives were to study the refrigeration cycle, saturation pressure-temperature relationship, effect of compressor pressure ratio on performance, and effect of evaporating and condensing temperatures on refrigeration rate and heat output. The experimental setup was used to collect data on evaporator and condenser pressures, temperatures, heat transfer rates, and overall heat transfer coefficients. The results showed some deviation from theoretical values likely due to heat loss, pressure drops, and non-ideal charge and insulation of the system. In conclusion, refrigeration systems are useful for food preservation, air conditioning, and other industrial processes.

1. Study of a Refrigeration
Unit
Presented By-
Abdullah Al Masud (1202019)

2. Objectives
 To study vapor compression refrigeration cycle with visual observations
 To investigate the saturation pressure-temperature relationship during
evaporation and condensation
 To determine the effect of compressor pressure ratio on system
performance
 To Determine of the effect of evaporating and condensing temperatures
on the refrigeration rate and condenser heat output
 To Determine of the overall heat transfer between R141 b and water in
the evaporator and condenser
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3. Theory
 Refrigeration is a process of transformation heat from a
lower temperature region to higher one.
 The coefficient of performance of a refrigerator is expressed
as COP
COP =
Desired output
Net work
=
Qc
W
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4. Theory (continued)
Vapor-Compression Refrigeration Cycle
(a) Schematic (b) T-s diagram12/19/2015 4

5. Theory (continued)
Actual Vapor-Compression Refrigeration Cycle
(a) Schematic (b) T-s diagram12/19/2015 5

6. Experimental Setup
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7. Observed Data
Observation No 1 2 3 4 5
Evaporator Gauge Pressure,Pe (KN/m2 ) -62 -65 -68 -68 -65
Absolute Evaporator Pressure, Pe (KN/m2 ) 39.378 36.378 33.325 33.325 36.378
Evaporator temperature,t5( oC) 11 10 9.8 10.5 11.5
Evaporator water flow rate, me (g/s) 4 4 4 4 4
Evaporator water inlet temperature,t1( oC) 16 15.2 15.2 16 17
Evaporator water outlet temperature,t2( oC) 12 10 10 10 11
Condensed liquid temperature, t8( oC) 26.2 28 29.8 30.4 32
Condensed gauge pressure, pc (KN/m2 ) 120 130 138 141 149
Absolute condenser pressure, pc (KN/m2 ) 221.378 221.378 221.378 221.378 221.378
Compressor discharge temperature,t7( oC) 52 54 55 56 56
Condenser temperature,t6( oC) 26 28 30 31 32
Condenser water flow rate,mc (g/s) 28 24 20 16 12
Condenser water inlet temperature,t4( oC) 14.5 15 15 16 16.5
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8. Sample Calculation
Actual pressure
• Absolute
pressure of
evaporator,
Pe=pe+P
• absolute
pressure of
Condeser,
Pc=pc+P
Compressor
pressure
ratio =
𝑃𝑐
𝑃𝑒
Calculation of
rate of Heat
transfer
Rate of heat
transfer
=mCpΔt
Calculation of
Overall heat
transfer
coefficient
Ue =
Qe
Ae ∆TLMTD (evaporator )
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9. Sample Calculation ( Continued)
Here,
ΔTLMTD =
𝑇 𝑖𝑛−𝑇𝑜𝑢𝑡
𝑙𝑛
𝑇 𝑖𝑛
𝑇 𝑜𝑢𝑡
 Tin=temperature difference between water inlet and R141b
 Tout= temperature difference between water outlet and R141b
 For evaporator,
Tin=t1-t5 , Tout= t2-t5
 For condenser,
Tin=t6-t4 , Tout= t6-t3
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10. Experimental Outcomes
Experimental and therotetical saturation pressure vs. saturation temperature curve for both
evaporator and condenser.
Experimental Theoretical
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11. Experimental Outcomes (continued)
Experimental and theoretical curve for rate of heat transfer vs. condensing temperature
Experimental Theoretical
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12. Experimental Outcomes (continued)
Exeprimetal and theoretical curve for rate of heat transfer vs. compressor pressure ratio
Experimental Theoretical12/19/2015 12

13. Experimental Outcomes (continued)
No of obs
Heat transfer
rate,Q
Compressor
Pressure ratio,r
Overall heat transfer
co-efficient,U
Evaporator, Qe
(kN/m2)
Condenser, Qc
(kN/m2)
Evaporator,
Ue (W/m2.°C)
Condenser, Uc
(W/m2.°C)
1 66.880 58.520 5.622 839.360 162.582
2 86.944 150.480 6.360 1223.500 384.358
3 86.944 167.200 7.172 1719.600 373.851
Results
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14. Deviation and clarification
Experimental results fluctuate from the theoretical ones because of some reasons.
Some of them are discussed below :
 System was not perfectly insulated and refrigerant exchanged heat with the
surroundings
 Introduction of huge source of pressure drop by valves.
 The system must be fed with an accurate charge of refrigerant
 The system must be air free.
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15. Why we use refrigeration system?
 Food preservation
 Air conditioning system
 Compressed air purification
 In chemical plants
 Reduction of moisture content
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16. Thank you!
The End
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