What does the term "isentropic" refer to in the context of heat engines?

The term "isentropic" specifically refers to processes that occur without any change in entropy. In the context of heat engines, this implies a process that is both adiabatic (no heat transfer) and reversible. Since there is no generation of entropy during these processes, they are considered to be ideal scenarios where the efficiency is maximized.

This understanding is crucial in thermodynamics and helps power engineers design systems that approach these ideal conditions, allowing for improved performance and efficiency. In practice, isentropic processes serve as a benchmark for assessing real-world processes, which typically experience some degree of entropy increase due to irreversibilities and heat losses. Thus, recognizing that isentropic processes maintain constant entropy is fundamental to understanding the principles of heat engines and their performance.