Vapour Compression Cycle and Expansion Valve

Vapour Compression Cycle:
The vapour compression cycle is a refrigeration cycle that is widely used in air conditioning and refrigeration systems. It is a closed cycle that involves the circulation of a refrigerant through various components that change its state from a low-pressure gas to a high-pressure liquid and back to a low-pressure gas.

Expansion Valve:
The expansion valve is an important component in the vapour compression cycle. Its primary function is to reduce the pressure of the refrigerant as it leaves the condenser, which results in a drop in temperature and a change in the state of the refrigerant.

State of Refrigerant after Expansion Valve:
The state of the refrigerant immediately after the expansion valve is crucial in determining the efficiency of the cycle. The state of the refrigerant can be determined by analyzing its pressure and temperature.

Wet Vapour:
The correct answer to the given question is option 'C', which states that the refrigerant immediately after the expansion valve is a wet vapour. A wet vapour is a mixture of liquid and vapour refrigerant. The refrigerant at this stage is at a low temperature and low pressure, and some of it has already condensed into a liquid, while the rest remains in a vapour state.

Importance of Wet Vapour:
The wet vapour state is important because it allows the refrigerant to absorb heat from the evaporator and vaporize completely, which results in a more efficient cycle. If the refrigerant were in a saturated liquid state, it would not be able to absorb heat effectively, and the cycle would be less efficient. If the refrigerant were in a dry vapour state, it would not be able to transfer heat effectively, and the cycle would also be less efficient.

Therefore, it is important to maintain the refrigerant in a wet vapour state immediately after the expansion valve to ensure the efficiency of the cycle.