Key Questions
The following key questions are answered in this module:
How does a refrigerant provide cooling in the vapor-compression refrigeration cycle?
In this cycle, a "refrigerant" alternately absorbs and rejects heat as it circulates through the piping and components of a "refrigeration unit." It absorbs heat as it passes through the space being refrigerated, and then rejects it as it travels through an outside space.
What is a "refrigeration unit"?
A refrigeration unit has four main components - an evaporator, compressor, condenser, and metering device. The refrigerant experiences two different pressures (and temperatures) as it circulates through the piping that connects the components.
When I hear my refrigerator "running," what am I hearing?
The compressor is an electrical component that increases the pressure and temperature of the refrigerant, and it is what you hear when the refrigerator is "running."
What makes a substance a good refrigerant?
Refrigerants are selected based on their boiling point-pressure characteristics, as it is critical that a refrigerant boil below the desired low temperature and condense at a sufficiently high temperature.
Are there other requirements for refrigerants?
Refrigerants must also be environmentally acceptable, chemically stable, and compatible with the materials present, and meet all applicable flammability and toxicity requirements.