Science Buddies: "Ask an Expert"

Hello all!

This is my first post here, so I am unsure as to any customs in asking questions. So I shall try to make this as clear as possible:

My somewhat recent idea for my next Science Fair project was a question that occurred to me as I was learning about ways to directly convert heat energy to electricity. In the process, I learned of both the Law of Entropy (which answers my original question) and the Stirling Engine. From what I was able to understand, the engine runs on a heat differential, which turns a flywheel and, when attached to a generator, produces electric energy that can be stored in a battery or used in appliances, etc.

So, arriving at my question: Is it possible to use a Stirling engine in conjunction with an internal combustion engine of a car, which produces plenty of heat, in order to produce electricity? And, if so, would it provide any significant or discernible increase in energy efficiency that could be used to power other devices?

Many thanks in advance!

Yes, a Stirling engine could use the waste heat from an internal combustion engine. Many applications of a Stirling engine are in situations where waste heat is available because the Stirling engine works efficiently with relatively small temperature differences. You should be able to find many articles about the Stirling engine with a web search, and there are several books about it.
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I worked for many years in the internal combustion engine business. For decades, innovative people have been trying to apply the Stirling cycle in a manner that is practical for automotive transportation. As Wendell has indicated, you will be able to find much literature about this.

Over the years, with all the interest and hard work to develop an automotive application for the Stirling engine, none have ever been brought to production. That is primarily because of the complexity involved in making a machine that is small and inexpensive enough to meet automotive needs. Typically, Stirling designs require complex mechanical mechanisms and very efficient, complicated heat exchanger systems. Those are the things that have kept it from being practical for automotive applications.

But, the Stirling cycle is theoretically the most efficient thermodynamic cycle there is, and would result in the highest gas mileage vehicles, if a practical design could ever be developed.

To learn more, just Google "automotive stirling engine". You'll learn a LOT!

Have fun!