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A Presentation on
STUDY OF A REFRIGERATION UNIT
Prepared ByMuhammad Shafiul Munir
Student ID: 0902049A2 (Group 04)
Partner’s: 0902046090204709020480902050
Department of Chemical Engineering, BUETDate: 05.06.2013
Presentation at a Glance
What is Refrigeration
Vapour- Compression Refrigeration Cycle
Why we are so concerned about Refrigeration
Experimental Set-up
Schematic Diagram
Graphs
Result
Thermodynamic Significance of Refrigeration
Conclusion
What is Refrigeration ??
Transfer of heat from a Lower Temparature region from a higher one
The device that works cyclically to perform this job is Refrigerator
The working fluid used in refrigerator is called refrigerant.
Ideal Vapour Compression Cycle
1. (1-2) Isentropic Compression in a Compressor
2. (2-3) Constant Pressure Heat Rejection in a Condenser
3. (3-4) Throttling in an expansion device
4. (4-1) Constant Pressure Heat Absorption in an Evaporator
The Actual Vapour Comoression Cycle
Irreversibility
• Fluid Friction
(Pressure Drop)
• Heat Transfer
Why Study Refrigeration ??
Food Preservation
Gas Liquefaction
Used in Oil
Refineries
Chemical Plants
Petro-Chemical
Plants
Why Study Refrigeration (Continued) ??
Steel and Cutlury
Meats, Fish and
Poultry
Dairy Industry
Transporting
Temperature
Sensetive foodstuffs
or pharmaceuticals.
Experimental System
Schematic Diagram
Calculation Process
1. Rate of Heat Transfer in both Evaporator and Condenser-
Q= ṁCp(Δt)
2. Overall Heat Transfer Co-efficient for both Evaporator and
Condenser-
U= Q/ AΔt LMTD
3. Compressor Pressure Ratio-
P= Pc/Pe
Results
Observation
Number
Rate of Heat
Transfer to
Water in
Evaporator,
Qe (W)
Rate of
Heat
Transfer to
Water in
Condenser,
Qc (W)
Overall Heat
Transfer
Coefficient,
Ue(W/m2.0C)
Over all Heat
Transfer
Coefficient,
Uc(W/m2.0C)
Compressor
Pressure
Ratio,
( Pc / Pe)
01 20.5 41.8 52.25 375.8 10.77
02 167.2 41.8 435.78 529.7 10.49
03 12.54 83.6 31.75 1435.4 10.45
04 83.6 125.4 227.37 1810.9 11.41
05 41.8 125.4 104.5 1810.9 11.55
Graph 01: Saturation Pressure Vs. Saturation Temperature
0
50
100
150
200
250
300
0 20 40
Satu
rati
on
Pre
ssu
re
Saturation Temperature
Evaporator
Condenser
Actual Experimental
Graph 02: Heat Transfer Rate Vs. Condensing Temperature
0
20
40
60
80
100
120
140
160
180
20 25 30
He
at T
ran
sfe
r R
ate
Condensing Temperature
Heat Transfer Rate Vs. Condensing Temperature
Heat TransferRateEvaporator
Heat TransferRateCondenser
Actual Experimental
Graph 03: Heat Transfer Rate Vs. Compressor Pressure Ratio
0
20
40
60
80
100
120
140
160
180
10 11 12
He
at T
ran
sfe
r R
ate
Compressor Pressure Ratio
Heat Transfer Rate Vs. Compressor Pressure Ratio
HeatTransferRateEvaporator
HeatTransferRateCondenser
ExperimentalActual
Refrigeration- Thermodynamic Point of View
Refrigeration operates on a true Thermodynamic cycle
It Involves-
Nucleate Boiling and Filmwise Condensation
Steady Flow processes like throttling, compression and Heat Exchange.
Flow Control
Conclusion
In this experiment our main objective was to study
refrigeration unit.
After the Experiment it is quite clear that the
objectives were quite fulfilled.
Performance of refrigeration can be increased using-
Cascade Refrigeration System
Multistage Refrigeration System
Questions ???
Cascade Refrigeration
Reversed Carnot Cycle
Multistage Compression Refrigeration System
