Building a Stirling Engine Heat Pump, Anyone ?

[cristoff]

http://www.apdcryogenics.com/products/

[Juggernault]

Any news about stirling engines? the article is older than 3 years!

[bobo5195]

Stirling engines are over 100yrs old they are old tech.

As a pump they or removing heat from the system there are far far better means. If you want a really efficent water pump use a car turbo or something in a custom casing.

Compressed gas high tolerences are not the words that make a good DIY project.

There is some modern usage of stirling engines though for micro power in places like the UK with ample gas supply to homes. Basically you whack a stirling engine onto a bolier. The high efficentcy of a stirling engine is a good assest if you need to generate electricity cheaply and cleanly. Of course for generating electricity without an ample supply of high grade heat for a stirling engine is pointless and wasteful but still it could lower your electricity bills and its better than the alternative (closed cycle gas turbine aka mini jet engine which is expensive and not good at variable loads).

[Long Haired Git]

Zero moving parts is ideal.
Rotating parts is next best.
Reciprocating parts with gas-tight seals? Never going anywhere methinks. Like peltiers, they're good for showing frosty cold-ends when there isn't 140W of over-volted, overclocked dual core Opteron stuck on one end.

The tech I want to see is the one with that special material you put on a disk and pass through a magnetic field that somehow heats/cools. Rotation not reciprocation, and no seals. By the time it comes along, I wonder what wattage CPUs we'll be dealing with?

[gmat]

LHG actually stirling engines move slowly enough so they can work like 20 years maintenance-free. They are used to power some boats (river freighters) and as cheap, reliable auxiliary power generators.
Their main drawback is poor power-to-weight ratio, which makes them unsuitable for moving vehicles lighter than freighters, as Cadillac found out (iirc it was them who tried a stirling-powered car).
Now about using them as a heat pump... this is a different story.

[billbartuska]

http://www.coleman.com/coleman/Colem...ategoryID=8595

[Joe]

Stirling engines for cooling would be very nice in PC's... Quiet, efficient.

Theres an article on the site already about stirling cooling of PC's done a couple years ago.

[bobo5195]

Everything i heared was that stirling engines are awful as cooling device. A stirling engine vs a heatsink is like comparing a stream to a man with a bucket.

Sitrling engine effeicentcy is at least a linear relation with temprature. 10c is no where near enough temprature gradient for them to work with properly.

[Long Haired Git]

There's a company after my own heart, Coleman.

The esky there shows a delta-T of 70°F which will do me!

Naturally its just keeping something that is cold just as cold when inside an insulated container. How it handles 140W of overclocked, overvolted Opteron is the real question. How it handles full-throttle operation 24x7 is another.

Someone buy one and find out!

[Brians256]

Originally Posted by bobo5195

Everything i heared was that stirling engines are awful as cooling device. A stirling engine vs a heatsink is like comparing a stream to a man with a bucket.

Sitrling engine effeicentcy is at least a linear relation with temprature. 10c is no where near enough temprature gradient for them to work with properly.

Only 10C dT? I would assume that anyone using a stirline heat engine in their PC would be going below ambient. Where have you heard that stirling was a bad cooling technology? The problems I've heard are 1) MTBF and 2) mfg cost. Not efficiency (but I don't know how well it works with different dT's).

[bobo5195]

Thermodynamics professor siad to me. As he put "stirling engines are shit" he was talking in the case of power generation though.

if you want to remove heat from a system use a peltier or refigerant system it's more efficant once costs and things (size etc) are included.

MTBF and mfg costs are key costs excluding them excludes alot of stuff. MFBF is ultimately a small thing as they are basically IC engine pistons which can last for yonks if well designed nut are big stirling engine built to good tolerences is quite expensive and you have to run these things.

I swear that the efficantcy of the system is due to temp differential so at PC kind of tempratures stirling engines of useless. Of the top of my head the only arguement i can support this with is (p2/p1)=(T1/T2)^(gamma -1 / gamma). Where gamma for air is rougly 1.4. So to get a good presure then you are going to need alot of pressure to get things going. I belive their efficantcy is directly linked to pressure by second law of thermodynamics arguments but i need to read a book on this subject. Ultimately a $30 peltier can destory any stirling engine for the purpose you are after. there would be alot of losses trying to convert work to a temprature differential.

[TerraMex]

while we're at stirling engines:
http://www.physics.sfasu.edu/astro/c.../stirling.html
it's ghetto time.

about it's efficiency ... well, since it's being researched to be used in veichles and currently used in low signature submarines , can't be that bad.

[bobo5195]

researched into definitly does not mean that it is a good tech only a possible approach. given it is still at the research stage after decades is probably a bad indictator. As an example car industries adiabatic engines (0 heat transfer) and 2 stroke engines have been under research for years and had billions of $ put into them and have never reached developed product stage.

low signatures submarines is because an external combustor is quiet.

[TerraMex]

but has to be fuel efficient and resonably fast,
if it takes too much space, or too long to reach anywhere,
defeats purpose on such subs.

[bobo5195]

for subs primary consideration is noise.

Engines of this sort can be very fuel efficant if large and expensive. The alternatives like gas turbines are normally cheaper and more eifficant.

if you want range on a sub you go nuclear but that is the kind of place where you would use stirling engines as steam turbine plant is very loud. The energy input for nuclear is enough that it can be done econmically and efficantly by using very high temps.

As cooling and for most normal uses there is no point. It will get comprehensively beaten by normal IC engines and for external combustion (low pollution) there is alot of gas turbine tech that is far far better for the heat input. As a heat pump its too large, too expensive and frankly not very good. refrigerant tech can get you better temps with focues cooling.

[Juggernault]

What about this one:

http://www.globalcooling.com/M100.html

100 Watt heat lift capacity at 0°C / -32°F

Chiller anyone?

[bobo5195]

Thats all very nice but carnot eff is low and COP is not to close to a chiller besides that looks pretty expensive kit.

Also noise everywhere. SPCR will complain about the noise.