Stirlingengineforum.com

I am new to this but find the ingenuity in the 'works' of S E's fascinating . All models I have seen so far with usable power seem to run hot has anybody made an SE that runs cold with usable power? if not why not? are there limitations to the power from such there would be greater choice in materials ie,various plastics losing a lot of weight in the process. I can imagine an SE 'fitted' (in) a freezer or even a bank of three or four maybe connected together installed partway in a chest freezer. If you think that would not work fair enough are there any online guidelines for building SE's to specific specs givng predictable performance? Thank You to Boydhouse for his welcome!

There are a several reasons why you only see Strirling engines which are heated. First is that, for an engine capable of producing any substantial power, you need the temperature differential between the hot and cold end to be in hudreds of degrees F. So if the warm end is at, say 70 deg. F ambient and the other end is cooled to 25 degrees F (typical freezer), that's only a 45 degree differential. The second reason is that it is relatively easy to generate heat, but cooling requires much energy input. I would suggest that by most conventional methods, it would take more energy to cool the cold end that the engine would produce.

There is a larger problem with running a Stirling engine in a freezer. In order to keep the freezer cold the freezer must use electrical energy. Much of this energy is wasted in the form of friction and heat dissipated out of the back of the freezer. The user, however, is paying for this lost heat in their electricity bill. If one were to fit a Stirling engine to a freezer and use the freezer to cool down the cold end of the engine, they would be introducing another level of inefficiency.

A better application of Stirling technology is in places where there is wasted energy creating a temperature difference. Solar energy can be used to created high temperatures. Waste heat from factories could be utilized. One could imagine thousands. The key is using temperature reservoirs that happen as a by product of an energy conversion that happens naturally (solar) or one that is currently available (waste heat from factories).