Cryo cooling Stirling engines

pcdc2324 · Post by **pcdc2324** » Fri Jul 28, 2006 9:38 am

I recently saw that Coleman is using a Stirling engine in a cooler they produce (price
~$600) that uses a Stirling engine to offer cooling as well as freezing and can run off a
battery for a time. In a question dates on Jan. 9, 2006, a gentleman asked if a Stirling
engine could be used for air conditining. The response was that it couldn't be used as a
compressor, but my question is couldn't the waste heat from a car engine be used to run a
Stirling engine that can cool well enough/is big enough to cool a car and reduce the extra
load off of a car engine?

stan.hornbaker · Post by **stan.hornbaker** » Fri Jul 28, 2006 9:52 am

Strictly speaking the Coleman food cooler uses a Stirling cooler, i.e. a Stirling engine driven by an electric motor. The motor power and the heat removed from the food compartment are rejected to atmosphere.

It would not be practical to use the waste heat from the engine to drive a Stirling engine to drive the Stirling cooler. It could be done but why the expense of the additional engine? Doubling the system cost and not as flexible as the Coleman can also be operated by transformer off the grid.

david_d_rogers · Post by **david_d_rogers** » Thu Apr 16, 2009 9:04 pm

Paul,

I think it's a great idea. It absolutely could work as either a retrofit or an OEM installation. It's lazy, cynical, myopic, and fearful people like hornbaker that have kept truly groundbreaking innovations from coming to the fore.

Good luck to you...and keep thinking outside the box.

bptdude___2569 · Post by **bptdude___2569** » Thu Apr 16, 2009 9:52 pm

David,

That is uncalled for.
Poor form!

The question was if a Stirling engine could be used to drive an air conditioner in a car. And the answer is valid # no.

Could a Stirlingn cooler be used directly off the heat to pump cool air back to take some of the load off the air conditioner for an industrial vehicle in a harse hot environment # should work, but not done yet.

Please keep petty and personal comments off this web site. This is a nice place, where people banter ideas in a safe sandbox. Take the rough play elsewhere.

stan.hornbaker · Post by **stan.hornbaker** » Fri Apr 17, 2009 7:47 am

Having monitored the Stirling scene for some 15 years I have a pretty keen sense of what works and what is an merry-go-round system that sooner rather that later grinds to a stop. Cascading engines works at the expense of additional input driving power. This IS done in order to reach cryogenic low temperatures in the production of liquid gasses.

A Stirling cooler has to have mechanical power input to operate as a cooler, not waste heat. Waste heat is low grade (realatively low temperature) to operate as 'fuel' or heating source for a Stirling engine.

The most recent information on The Stirling Cooled Coleman is that it HASN'T been in production for approximately TWO years and the factory sold the remaining stock on hand for $100 ea. a year ago. This confirmed by a phone call to , the second one recieived today 4/17/09

cchagnot · Post by **cchagnot** » Fri Apr 17, 2009 3:41 pm

I'm with William and Joe on this one.

"I think it's a great idea. It absolutely could work as either a retrofit or an OEM installation.
It's lazy, cynical, myopic, and fearful people like hornbaker that have kept truly
groundbreaking innovations from coming to the fore.

Good luck to you...and keep thinking outside the box."

If one knows anything about the reality of Stirling engine or cooler design and run the
numbers one would immediately see that it doesn't make engineering sense. Stirling
coolers or cryo-coolers are little heat pumps. If one uses the heat from the exhaust, and
had a Stirling engine running a Stirling cooler you're going to take heat, turn it to
mechanical energy, run the cooler using that mechanical energy one has to realize that
both cycles require heat rejection. So, you hope to get rid of the radiator on the car by
adding bigger ones to reject the heat from the Stirling Engines? Not Cool!

Thinking outside of the box is fine but if you don't stay within a realistic engineering box
it's not gonna work. Too many 'outside of the box' people are also outside of the first and
second thermodynamic laws box.

BTW.. The Coleman coolbox was using a Globalcooling FPSC ( see;
http://www.globalcooling.com). They're still produced in Japan by TwinBird in Nigata.
They've got a couple of models with 50 and 100 watt heat lifts. Coleman wouldn't order
enough to really drop the price and in today's "WallMart" world our 'brilliant' US companies
can only think as far as the next quarter's bottom line.

Twinbird still makes the FPSCs but they've switched their target market to a niche one of
deep temperature cooling, providing Cool-boxes for specialized applications down in the
-50C to -70C range I think for vaccine storage and other uses requiring really cold temps.

Cate

bptdude___2569 · Post by **bptdude___2569** » Fri Apr 17, 2009 5:11 pm

Interesting ....

Cate, you are still thinking of using the heat of the engine to run a more or less Stiring engine, to turn a mechanical Stirling cooler.

no no no

It is possible to use a Stirling cooler that uses only heat for an input. I have posted in several places that such devices are a very special variation of Stirling, that intends to only seperate hot from cold, by use of the displacer, and intends to transfer no power.

Such a device is my concept to use as a kind of thermal turbocharger for my daydream solar machine.

So, Paul is also correct, if however forgetful of some manners, that it is possible to relieve the engine of the air conditioner by using exhaust heat, depending on heat available and cooling required.

cchagnot · Post by **cchagnot** » Fri Apr 17, 2009 5:22 pm

Joe,

Send me a sketch. Years ago, at Sunpower I designed & built a gas-fired Free Piston Stirling
cooler. One piston two displacers. It worked great. But it had to have a cooler for the engine
side and one for the cooler side. It would make a great 'gas fired' refrigerator. I can't picture
what you have in mind. Have you run any numbers? Has anyone prototyped even a little one?

Cate

pcdc2324 · Post by **pcdc2324** » Sun Apr 19, 2009 7:11 am

All, thank you for your insights and perspectives. My thoughts from my original post was to
see if the waste heat from a combustion engine could be used for something else. It appears
this is not the case, right now, but that doesn't mean it couldn't happen some day.

bptdude___2569 · Post by **bptdude___2569** » Sun Apr 19, 2009 5:28 pm

hello?
testing?
can anybody hear me?

the answer is:

If you paid me enough, just because you had it, and it was fun for an experiment, I could have built for you a Stirling cooler that runs off the heat of the engine exhaust that produced practical work in the form of cooling.

And no, I won't do the money numbers for you.

I actually know of one design that would have no moving parts, and be compact in size, and long, as would work well with exhaust.

- joe

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