The refrigeration cycle is the thermodynamic process by which HVAC and refrigeration systems move heat from one location to another using a refrigerant. The cycle consists of four stages: compression, condensation, expansion, and evaporation.
1. Compression: The compressor pressurizes low-pressure refrigerant gas, raising its temperature significantly above the outdoor ambient temperature.
2. Condensation: Hot, high-pressure refrigerant flows to the condenser coil, where heat is released to the outdoor air and the refrigerant condenses to a liquid.
3. Expansion: Liquid refrigerant passes through an expansion device (metering device), which reduces its pressure and temperature dramatically.
4. Evaporation: Cold, low-pressure refrigerant flows through the evaporator coil, where it absorbs heat from indoor air and evaporates back into a gas, completing the cycle.
This cycle repeats continuously while the system operates. Heat pumps use the same cycle but include a reversing valve to change the direction of refrigerant flow, enabling both heating and cooling.