This chapter discusses refrigeration and refrigeration systems. It describes refrigeration as maintaining a system or body at a lower temperature than its surroundings using mechanical or heat energy. The key components of a refrigeration system are identified as the compressor, condenser, expansion valve, and evaporator. Common refrigerants are also discussed, along with their ideal properties. The refrigeration cycle operates by absorbing heat in the evaporator and rejecting heat in the condenser.

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2. The maintenance of a system or body at a temperature lower than that of its surroundings.
• The system maintained at the lower temperature is known as refrigerated system
• The equipment used to maintain this lower temperature is known as the refrigerating system.
(Refrigerator)
PRINCIPLES.
1. By chemical means
2. By bringing the substance to be cooled directly or indirectly in contact with cooling medium
3. By using mechanical or heat energy
APPLICATIONS OF REFRIGERATION
1. The industrial processes.
2. Preservation of perishable goods.
3. Providing comfortable environments
UNIT OF REFRIGERATION
Refrigerant Ton: 1 RT = 3.517 kW
REFRIGERATION CYCLE
1. Natural methods
2. Artificial or Mechanical methods
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3. T
Qout
2
3
win
4 1
Qin
S
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7. A. Compressor:
To pumps the refrigerant through the system
1. Reciprocating compressor
2. Centrifugal compressor
3. Rotary compressor
B. Condenser
To de-superheat and condenses the compressor discharge vapor and frequently to sub cool the
resultant liquid while introducing a minimum pressure drop
1. Water cooled condensers
2. Air-cooled condensers
3. Evaporative condensers
C. Evaporator
To absorb heat into the refrigeration system
1. Flooded evaporators
2. Dry-expansion evaporators
D. Expansion valve
I. To reduce the pressure and temperature of the refrigerant coming from the condenser
II. To regulate the flow of the refrigerant as per the load
1. Capillary tube. 4. Constant pressure expansion valve.
2. Thermostatic-expansion valve. 5. Solenoid valve.
3. Low and high side float valves.
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8. REFRIGERANTS
The substance carrying the heat from low temperature region and discharging the same to
the, higher temperature sink is known as "refrigerant".
An ideal refrigerant:
1. The condensing pressure should not be excessive.
2. The boiling temperature should be low.
3. The critical temperature should be high.
4. The latent heat of vaporization should be high.
5. The specific heat of liquid should be low.
6. The specific volume of vapor should be low.
7. It should be non-corrosive to metals as inert to oils.
8. The refrigerant should be non-inflammable and non-explosive.
9. It should be non-toxic and harmless to human beings or living cells.
10.It should be easily detectable for leaks.
11.It should be easily available and have low cost.
12.It should have satisfactory heat transfer and viscosity coefficients.
Examples:
1. Ammonia (NH3) 3. Carbondioxide ( CO2)
2. Freon-12 4. Freon-22
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