What type of Stirling Engine

[Mac]

I have an application where I would like to use solar to heat oil which in turn could be used to provide power using a sterling engine. The maximium temperature for heated synthetic oil is around 400 degrees C. However I would like to assume an average of around 250 degrees C on the hot side.

My first question is what type of sterling engine would you suggest is going to be the most efficient for this application?

Second question is: Is a large engine significantly more efficient than connecting smaller engines in series?

Look forward to reading your comments

[Ian S C]

I think the ALPHA type STIRLING engine is the most efficient. The TMG ( Thermo Mechanical Generator) Might be suitable. You will waste a lot of energy by heating another medium rather than heating the engine directly. I have used solar heating on a motor that normally is heated with LPG, and got more power from it when heated via a large freznel lens.
Heres a photo of the said motor, it's based on James G. Rizzo's Dyna.

Ian S C

[Mac]

Thank you Ian.

I hear what you are saying regarding the direct heating of the engine. My reasons for wanting to run using the heat from a second medium, is I would like to try and use the medium as a way to store the solar energy for use after dark or on a cloudy day.

The TMG would be a good option, being a hermetically sealed unit, especially in my area due to the corrosive costal environment. However is looses the aesthetic appeal of more traditional designs.

Thanks again for your reply.

[Bumpkin]

Hello Mac. Your concept sounds very much like the solar project at Tamera. Their engine is a large roll-sock type Beta, suitable for mid to low temp differences. They used oil for thermal storage. I don't know if they're still working on the design.
https://www.youtube.com/watch?v=SMMELH7CSNE
Bumpkin

[Trevor]

Hi Mac
I have made an LTD engine 14"Diameter using a large rubber diaphragm. Heating was done by solar hot water from a small homemade thermo heater.
The water was pumped from the reservoir through copper tubing wound inside the displacer.
I do not have the photos any more as the computer failed and I lost them all, however, I can photograph another that I have started to build to show how I placed the inner heating and cooling tubes.
Trev

[Mac]

I like the sound of an LTD as I am a bit worried the the temperature difference I will be working with might not be enough for an Alpha. If you disagree please let me know.

The you tube video clip of the solar project at Tamera is almost certainly responsible for my renewed interest in Stirling engines.

Anyone out there ever tried a 16 cylinder alpha (8 hot, 8 cold)?

[Imperato]

What's the temperature difference you're working with, Mac?

[Ian S C]

The use of solar heat depends a lot on geography, the nearer the equator the better, so it will work in the temperate regions. one important thing with any hot air motor is cooling.

Ian S C