Refrigeration Fundamentals2 / 17
Pressure-Enthalpy Diagrams & Refrigerant Properties
Reading P-h diagrams, saturation, superheat, subcooling, refrigerant types.
11 min read · Jacob Willis, Net Zero Lead · Last reviewed July 2026
Refrigeration engineers carry one picture in their heads: the pressure-enthalpy diagram, on which the entire vapour-compression cycle draws as a simple four-sided loop. Learn to read it and the cycle stops being a story and becomes arithmetic: every duty, every efficiency and every fault has a shape on the p-h chart. This lesson builds the diagram from scratch and reads a worked cycle off it.
In this lesson
- 01The chart itself
- 02The cycle as a rectangle
- 03Why practitioners bother
- 04Sources and further reading