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Ian SC, was saying the advantage of a free piston linear alternator was simplicity of having few moving parts. Wouldn't that also apply to a free piston air compressor or water pump? It would be a really compact unit. And the air compressor could be reversed to act as a frig. I guess the water pump could also be reversed to act as a frig. Might be handy in an off grid cabin.

Just thinking about it, I wonder if you made one end of your free piston engine a conventional motor, and at the other side of the piston another displacer that would work as a cryocooler, all built into one, most ideas that I come up with have all ready been done. A pump, either air or water, no problem. Ian S C

It seems like the free piston engine could be used in perforating ,hammering ,sewing, sawing etc. these niches have been captured by electrical motors, but there might be some application for them.

fullofhotair,
was looking through some of the striling engine magazine articles thread, for links that might apply to what your discussing.

Air conditioning cold from any source of heat
http://books.google.com.au/books?id=uRA ... ce&f=false

Stirling with a fridge on top
http://books.google.com.au/books?id=isq ... 22&f=false

Stirling cycle liquid piston engine, with no moving parts.
http://books.google.com.au/books?id=bAE ... 22&f=false

Harvell's U-tube pump to irrigate Indian arid zone
http://books.google.com.au/books?id=txD ... 22&f=false

And yet it moves
http://books.google.com.au/books?id=5ex ... 22&f=false

And yet it moves again
http://books.google.com.au/books?id=QWV ... 22&f=false

came up.

I think there are also many other applications that a 'Heat Driven' free piston, or 'other type' Stirling engine could be applied to as the 'prime mover', as you have suggested.
It's probably a case that there are more established, conventional, cheaper technologies that already exist that stops the progress of these possible system developments, (economies of scale and technology investment and all that stuff).
Still its nice to think that our much loved Stirling engine, has the possibility for future development in different fields...
vamoose

As a range extending auxiliary power unit in an electric vehicle, and when the vehicle is stopped, a battery charger. Ian S C

Yep i agree Ian,
there is a really good possibility for Stirling engines to be effective in these applications.Especially in Hybrid EV's.
vamoose

When I first saw the fluidyne engine I was amazed at how simple a stirling engine could be, but once you look at working models you realize they are using blow torches to get very small movement. Is it the nature of water to absorb heat that causes this effect? What if you used mercury as a working fluid? That Indian fluidyne water pump with a piston separating the mercury working fluid and the water to be pumped. The pumped water could cool the cold side.

I doubt you would get away with using mercury these days, I think in some places mercury is banned from use in thermometers, and the minute amount in fluorescent lights is frowned on, all the batteries you buy have a little note on them saying No Mercury. I'v got a mercury barometer hanging on the wall about 2 meters away, but if that broke, and I reported it, I'd have to get specialist cleaners in to decontaminate the place, at a cost of thousands$$$$. When we were kids it was fun to play with, used to open up the little mercury button batteries and squeeze the mercury out. Ian S C

Ian SC
Potassium metal might be a good alternative to mercury. It has a melting point of 63.3c. I don't believe it is that toxic. The piston separating the liquid potassium and the cold water should be an insulator so as not to loss heat to the water. A solar trough might be enough to reach a working temperature for a water pump?