working fluid

A working fluid is a substance used in thermal systems, like engines or refrigerators, to transfer heat and perform work. It absorbs heat from a source, such as a combustion process or heat exchanger, and then moves or changes state to release that heat elsewhere, driving mechanical parts or creating cooling effects. Examples include water, refrigerants, and air. Its properties, such as boiling point and heat capacity, are chosen to optimize energy transfer and system efficiency. Essentially, the working fluid is the medium that facilitates energy flow within thermal devices.