Main Parts Of Vapor Compression Refrigeration Cycles:

1. Evaporator

Its function is to provide a heat transfer surface through which heat can pass from the refrigerated space into the vaporizing refrigerant.

This is generally a Fin & Tube (Hair-Pin type) heat exchanger, similar to Air-Cooled Condensers.

 2. Suction Line

It carries the low-pressure vapor from the evaporator to suction inlet of the compressor.

 3. Compressor

The function of the compressor is to draw refrigerant vapor from the evaporator and to raise Its temperature and pressure to such a print to that it may be easily condensed with normally available condensing media. It also maintains a continuous flow of the refrigerant through the system.

Compression Ratio = Absolute Discharge Pressure / Absolute Suction Pressure

The Capacity of a Compressor is determined by its Mass Flow rate (Lb/Min) and not by Volume Flow(CFM).

The most common compressors used in chillers are reciprocating, rotary screw, centrifugal, and scroll compressors. Each application prefers one or another due to size, noise, efficiency and pressure issues.

 4. Discharge Line

It conveys the high pressure and high-temperature refrigerant from the compressor to the condenser.

 5. Condenser

The function of the condenser is to provide a heat transfer surface through which heat passes from the refrigerant to the condensing medium which is either water or air.

Types of Condensers:
• Air-Cooled
• Water-Cooled

 6. Liquid Receiver

It acts as, a reservoir that stores the liquid refrigerant coming from the condenser and supplies it to the evaporator according to the requirement.

7. Liquid Line

It carries the liquid refrigerant from the receiver and conveys it to the expansion valve.

8. Expansion valve

Function Of This valve is to Supply a proper amount of refrigerant to the evaporator after reducing its pressure considerably so that the refrigerant may take sufficient amount of heat from the refrigerating space during evaporation

The Metering Device converts the High Pressure and High-Temperature Liquid from Condenser to Low Pressure and Low-Temperature Liquid-Vapor mixture, which will be fed to the Evaporator.

An expansion valve is a component in refrigeration and air conditioning systems that controls the amount of refrigerant flow into the evaporator thereby controlling the superheat at the outlet of the evaporator.

Types of Expansion devices

·         Thermostatic EV

·         Capillary tube

·         Hand operated EV

·         Automatic or Constant Pressure EV

·         Float expansion

Types of Vapor Compression Cycles : 

We have already disused that vapor compression cycle essentially consists of compression, condensation, throttling and evaporation. Many scientists have focused their attention to increase the coefficient of performance of the cycle. Through there are many cycles, yet the following are important from the subject point of view:

1. Cycle with dry saturated vapor after compression,
2. Cycle with wet vapor after compression,
3. Cycle with superheated vapor after compression,
4. Cycle with superheated vapor before compression, and
5. Cycle with under cooling or sub cooling of refrigerant,

Advantages of Vapour Compression System : 

·         It has a smaller size for the given capacity of refrigeration.

·         It has less running cost.

·         It can be employed over a large range of temperatures.

·         The coefficient of performance is quite high.

·         Less time required to produce refrigerant effects.

Disadvantages of Vapour Compression System : 

·         The initial cost is high.

·         The prevention of leakage of the refrigerant is the major problem in the vapor compression system.

·         More wear and tear and noise due to Moving Parts 

·         Liquid droplets in suction line may damages.