Liquid to Suction Heat Exchanger in Vapour Compression Refrigeration System

A vapour compression refrigeration system is widely used in air conditioning and refrigeration applications. The system works on the principle of removing heat from a low-temperature space and rejecting it to a high-temperature space. The refrigeration cycle of a vapour compression system comprises four main components: compressor, condenser, expansion valve, and evaporator.

The liquid to suction heat exchanger is an important component of a vapour compression refrigeration system. It is used to sub-cool the liquid refrigerant leaving the condenser before entering the expansion valve. This helps to improve the efficiency of the system and increase the cooling capacity. Let's understand the working of a liquid to suction heat exchanger.

Working of Liquid to Suction Heat Exchanger

The liquid to suction heat exchanger is a heat exchanger that is placed in between the liquid line and suction line of the refrigeration system. The liquid refrigerant leaving the condenser is first passed through the heat exchanger, where it is cooled down by the suction gas returning to the compressor. The cooled liquid refrigerant then enters the expansion valve where it is throttled to a low-pressure and low-temperature state.

The suction gas returning to the compressor is heated due to the heat transfer from the liquid refrigerant. This increases the refrigerant's enthalpy and improves the efficiency of the compressor. Additionally, the sub-cooling of the liquid refrigerant ensures that there is no flashing of liquid refrigerant in the evaporator, which can cause a decrease in the cooling capacity and efficiency of the system.

Advantages of Liquid to Suction Heat Exchanger

The liquid to suction heat exchanger offers the following advantages:

1. Improved Efficiency: The sub-cooling of the liquid refrigerant improves the efficiency of the system by reducing the work required by the compressor.

2. Increased Cooling Capacity: The sub-cooling of the liquid refrigerant increases the cooling capacity of the system by ensuring that there is no flashing of liquid refrigerant in the evaporator.

3. Constant COP: The liquid to suction heat exchanger helps to maintain a constant coefficient of performance (COP) of the refrigeration system.

Conclusion

In a vapour compression refrigeration system, the liquid to suction heat exchanger is used to sub-cool the liquid refrigerant leaving the condenser before entering the expansion valve. This helps to improve the efficiency and cooling capacity of the system and maintain a constant COP. Therefore, the correct answer to the question is option C.