Refrigeration Cycle & Components
The four components of the refrigeration cycle, compressor types, condensers, evaporators, metering devices, and system pressures.
- Describe the four stages and components of the basic refrigeration cycle
- Compare compressor types including reciprocating, scroll, and screw
- Explain condenser and evaporator function and operating principles
- Identify metering device types including TXV, capillary tube, and AEV
Lesson 1
The Basic Refrigeration Cycle
Four Components, Four Stages
The refrigeration cycle is the foundation of all HVAC cooling and refrigeration systems. It uses four main components to move heat from a cold space to a warm space - the opposite of what heat does naturally.
High Side vs. Low Side
The system is divided into two pressure zones:
- High side (discharge side) - from the compressor outlet through the condenser to the metering device inlet. High pressure and high temperature.
- Low side (suction side) - from the metering device outlet through the evaporator to the compressor inlet. Low pressure and low temperature.
High Side
Compressor discharge to metering device
High pressure
High temperature
Refrigerant changes from gas to liquid
Low Side
Metering device to compressor suction
Low pressure
Low temperature
Refrigerant changes from liquid to gas
State Changes
The refrigerant changes state twice during the cycle:
- Condenser - gas to liquid (condensation) - heat is rejected
- Evaporator - liquid to gas (evaporation) - heat is absorbed
Exam Fundamental
The refrigeration cycle moves heat from a cold space to a warm space. The evaporator absorbs heat (cooling effect). The condenser rejects heat (heating effect). The compressor provides the energy to drive this process.
The refrigeration cycle has four components: compressor, condenser, metering device, and evaporator. The evaporator absorbs heat (cooling), the condenser rejects heat, and the metering device creates the pressure difference between high and low sides.