Flash chamber is an insulated tank. It is always fitted after the metering or throttling device but before the evaporator in a vapour compression refrigeration system.
Need of flash chamber:
It has been observed that the liquid refrigerant coming out from the expansion device contains some vapour refrigerant also. (normally vapour liquid mixture). The vapour refrigerant part while passing through the evaporator coils will not do any heat absorption rather reduce the refrigerating effect. To avoid these problems, flash chamber is provided.
The flash-chamber separates vapour and liquid and allows only liquid refrigerant to pass through the evaporator coils. The vapour refrigerant is collected in the upper portion of the chamber and it is passed to the compressor intake to direct compression. Thus, the flash chamber provides better conditions for heat transfer in evaporator side.
Accumulator is a fluid-storage device used to store the liquid refrigerant. It is fitted just after the evaporator a vapour compression cycle having an accumulator.
Need of an accumulator:
Accumulator is a large cylinder designed to collect the liquid refrigerant coming out from the evaporator due to incomlete evaporation. It prevents the liquid refrigerant entering into the compressor which is designed to compress dry saturated vapour. (prevents the chances of wet compression).
It allows only dry vapour refrigerant to pass into the compressor where the liquid refrigerant collected in the accumulator is returned to the inlet side of the evaporator coils by means of a circulating pump. Thus the accumulator saves the compressor from being damaged by liquid refrigerant.
Advantages of VCRS over air refrigerantion system:
- Low mass flow rate of refrigerant is required.
- High co-efficient of performance (COP).
- Compact in size.
- Relatively inexpensive.
- Low evaporative temperature.
- Ability to transfer large amount of heat (since the working fluid undergoes phase change)
- Very mature technology.