Hybrid Car – More Fun with Less Gas

Another approach to solar-powered AC?

register ::  Login Password  :: Lost Password?
Posted by Morris Dovey on September 23, 2006, 2:53 am
 
I've been tinkering with a solar-powered stirling cycle pump (link
below) in my spare time. I'm neither thermodynamics nor stirling cycle
guru - but I've become fascinated by these engines that operate from a
(sometimes quite small) temperature differential.

My interest has been, of course, in using solar energy to power the
engine. In the process of researching the stirling engine, I learned
that if you spin its shaft, it will /produce/ a temperature
differential.

So, imagine that we have a solar-powered stirling cycle engine
putt-putting away - and we couple its shaft to the shaft of a second
(otherwise unpowered) smaller stirling cycle engine.

Does it seem reasonable to use solar energy this way for refrigeration
and cooling?

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/StirlingProject.html



Posted by SJC on September 23, 2006, 3:14 am
 

I've been tinkering with a solar-powered stirling cycle pump (link
below) in my spare time. I'm neither thermodynamics nor stirling cycle
guru - but I've become fascinated by these engines that operate from a
(sometimes quite small) temperature differential.

My interest has been, of course, in using solar energy to power the
engine. In the process of researching the stirling engine, I learned
that if you spin its shaft, it will /produce/ a temperature
differential.

So, imagine that we have a solar-powered stirling cycle engine
putt-putting away - and we couple its shaft to the shaft of a second
(otherwise unpowered) smaller stirling cycle engine.

Does it seem reasonable to use solar energy this way for refrigeration
and cooling?

They use Stirling cryos for chilling and liquifying gases. So they can
really drop the temperature, but I am not sure about bulk BTUs.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/StirlingProject.html




Posted by ghostwriter on September 25, 2006, 7:45 pm
 
Morris Dovey wrote:

Stirling solar has been used for over 100years to produce cold, it was
one of the first large scale uses of the technology other than straight
motive force.  I dont know what modern efficiency numbers are for the
application. For large scale cooling, stirling cryocoolers are very
efficient as I understand it. The problem is likley to be that the RPM
and stroke that works best for generating power at low temp differental
might not be the best for moving heat at a high temp differential. Of
course if all you are looking for is AC you might be fine. But at that
point I would be more likley to use a stirling to power a fan and pull
air though a geothermal heat exchanger, since its a less complex system
in general.

It was orginally used as a way to wow a potential patron, by using
sunlight to produce ice. This was prior to the availablity of modern
refridgeration.


Posted by SJC on September 25, 2006, 8:04 pm
 

  I saw on the NASA site they mentioned 30% efficiency for making
LNG. That would be a COP of .3, which is not so good for AC, but
that is a large temperature differential. There was some talk about using
stirlings for car AC to cool when the engine is off, but I have not seen
any in production.



Posted by Morris Dovey on September 28, 2006, 2:56 pm
 ghostwriter (in 1159213556.802022.299720@i42g2000cwa.googlegroups.com)
said:

| Stirling solar has been used for over 100years to produce cold, it
| was one of the first large scale uses of the technology other than
| straight motive force.  I dont know what modern efficiency numbers
| are for the application. For large scale cooling, stirling
| cryocoolers are very efficient as I understand it. The problem is
| likley to be that the RPM and stroke that works best for generating
| power at low temp differental might not be the best for moving heat
| at a high temp differential. Of course if all you are looking for
| is AC you might be fine. But at that point I would be more likley
| to use a stirling to power a fan and pull air though a geothermal
| heat exchanger, since its a less complex system in general.
|
| It was orginally used as a way to wow a potential patron, by using
| sunlight to produce ice. This was prior to the availablity of modern
| refridgeration.

Hmm - thanks (to SJC, too). We're about to try coupling a pair of the
fluid-piston stirlings together to see if we can develop a "hot side"
and "cold side" in the second engine. If that happens, we can use
another fluid piston stirling pump to circulate the chilled water.

Dunno if it'll work; but it seems worth a try...

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/StirlingProject.html



This Thread
Bookmark this thread:
 
 
 
 
 
 
  •  
  • Subject
  • Author
  • Date
please rate this thread