Thermodynamic Theory of the Ideal Stirling Engine

Stirling engines are one of those devices that have fascinated many engineers (including myself) over the years, especially when we’re young and impressionable, before we’ve gotten too cynical about the world. It’s also one of those technologies that hasn’t really been widely adopted, despite YouTubers cries of "free energy," so it obviously isn’t the perfect solution for many problems, but for certain applications they really are neat engines. 

The Midé team has been recently putting in long hours to get a new Stirling project up and running for the US Marines. I chose the Stirling cycle engine for this application because of its naturally high efficiency and because it's an external combustion engine. To support this project I had a significant amount of research to do on the theory that govern Stirling engines – so that we could better design a solution for our military.  In this post I’ll share with you some of the basics I learned and provide a tool to help visualize the Stirling cycle. Hopefully this tool will help you double check some of the basic calculations you might like to do, as well as provide a handy way of plotting some of the properties for an ideal Stirling cycle. You can find the calculator on this page: Ideal Stirling Cycle Calculator