Simple Realization of the Polytropic Process with a Finite-Sized Reservoir

In most thermodynamics textbooks, polytropic processes are introduced by defining the process equation rather than explaining their physical origin. In this paper, we propose a simple model to realize a polytropic process for an ideal gas. The ideal gas is compressed or expanded quasi-statically while in thermal contact with a finite reservoir with constant heat capacity, and the entire system is thermally isolated from the outside environment. We propose an experimental implementation of our model with realistic parameters.

American Journal of Physics