What Affects the Refrigeration Cycles of a Compressor?

The refrigeration cycle removes heat from spaces.K??hlschrank image by Elisabeth Bilewicz from Fotolia.com

A typical refrigeration system--called a vapor compression cycle--circulates a liquid refrigerant or coolant in a closed loop. As the refrigerant is circulated through hot spaces, it removes the heat and transfers it out of the space. All refrigeration systems have four components: the compressor, a condenser, an expansion valve and an evaporator. Each of these components can affect the refrigeration cycle.

Evaporator Operation and Leakage

The evaporator transfers heat from the air to the refrigerant.air conditioner vent image by Tammy Mobley from Fotolia.com

As cool liquid refrigerant is pumped through tightly packed coils in the evaporator, warm air is blown over the coils. The heat in the air is transferred to the liquid refrigerant, which vaporizes the fluid. Often, there is a leak in the evaporator coils and refrigerant leaks out. Over time, all of the refrigerant could be released from the system and the cooling cycle would not be effective. Proper levels of refrigerant must be maintained for adequate operation of the refrigeration cycle.

As the refrigerant leaves the evaporator, it is a saturated vapor containing the heat from the air blown over the coils. The compressor increases the pressure and temperature of the vapor. This high pressure fluid is then cooled in the condenser, utilizing water or air as the cooling medium. The fluid becomes liquid but is still under pressure. If the compressor fails and does not increase the pressure of the refrigerant, downstream operation of the expansion valve will not cool the liquid adequately. Subsequent condenser failure will allow the fluid to remain as a vapor.

As the refrigerant leaves the condenser at high pressure, an expansion valve allows the fluid to rapidly expand, lower the pressure and cooling the liquid significantly. The cooled saturated liquid completes the refrigeration cycle and the coolant is ready to flow back into the evaporator to remove heat and repeat the cycle. If the expansion valve does not decrease the pressure and cool the liquid, hot, high pressure vapor flows into the evaporator and will not pull the heat from the air stream.