Properties of Refrigerants: Entropy

“Entropy” can be a difficult concept to understand. In the context of thermodynamics, entropy can be thought of as a measure of “disorder”. The second law of thermodynamics teaches that entropy always increases over time. 

In the refrigeration cycle, entropy is used to determine the theoretical discharge temperature. The term “theoretical” is applied because we assume the compression process to be isentropic, which means constant entropy.

In reality, entropy always increases, so the theoretical discharge temperature calculation represents an ideal scenario that is never true in the real world.