Glossary
Radial inflow turbines for turbocharging - Basic principles

Isenotropic transformation; isentropic transformation

An isentropic transformation is an “ideal” thermodynamic process—reversible and involving no heat exchange—between a system and its environment. According to the second law of thermodynamics, such a transformation never occurs in reality. It is used as a reference to quantify deviations from the actual transformation.

Polytropic transformation

A polytropic transformation is a thermodynamic process involving a partial exchange of heat between a system and its surroundings. It lies between isothermal and adiabatic transformations.