Low Temperature Differential Stirling

[nick.gilling]

Hi all,

Just thought I'd put some pics up of a stirling that I bought from ebay. There are ones like it on there all the time, I paid about 70 pounds.

I always intended making one but I still haven't got around to setting my workshop up yet so just bought one so I can get an idea of sizes. I could probably then sell a couple I've made and get my money back.

The engine can run from the heat of your hand, even on a hot day. It will run better on the top of a coffee cup or better still on ice cubes. The ice cubes take longer to warm to room temp than the coffee does to cool down to room temp.

Here are some pics anyway. I believe most of the components for this are done on CNC.

Nick

[CJL5585]

I think they are really neat.

How large would one have to be in order to create some useful energy? Could some modifications be made (such as heat generated by the sun, the electrical energy from solar cells, or water from solar collectors) be utilized to generate electrical power?

Would attract a lot of attention.

Jerry

[balsaman]

sweet

[nick.gilling]

I think you'd really struggle to get any useful energy from one of these. People have tried the solar ones before I think, they will run but not provide any useful energy.

On this model scale, it's hard enough just to get the engines to run! It's difficult to produce an engine that overcomes the frictional losses in the mechanisms. That's why this one uses a glass cylinder and graphite piston and gland, aswell as ptfe in some places.

I bet someone has tried larger scale ones somewhere though.

Nick

[pminmo]

There are larger ones and yes capable of producing energy.
http://www.sprol.com/?p=265
http://www.stirlingenergy.com/
http://www.stirlingenergy.com/products.asp?Type=solar
"In 1996, SES acquired the patent, tooling, and equipment rights to the world's most efficient solar dish concentrator system: the Dish Stirling. Initially developed in the 1980s by McDonnell Douglas (now The Boeing Co.) the Dish Stirling system was field-tested by Southern California Edison and Georgia Power for over 175,000 hours between 1982 and 1988. Edison's test data indicated the Dish Stirling out-performed all other solar-to-electric generating systems by a factor of two, yet had comparable start-up costs. SES optimized the McDonnell Douglas dish to operate with a 25kW Stirling power conversion unit (PCU) developed in Sweden by United Stirling, Kockums and Volvo. The resulting system, the "Dish Stirling", has fewer moving parts than comparable diesel engines and operates relatively quietly. The SES Solar Test Site and related tooling and equipment facilities are located at the Boeing facility in Huntington Beach, California. The 25kW SES Dish Stirling system has an operating track record of more than 17 years. Since 1984, it has held the world record for efficiency in converting solar energy into grid-quality electricity."

Since 84 when my old company did the above, think how much energy could have been produced with thousands.................
Since I don't have room for a 37sqft dish in my back yard, and I don't need 25KW my thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.

[CJL5585]

Originally Posted by pminmo Since 84 when my old company did the above, think how much energy could have been produced with thousands................. Since I don't have room for a 37sqft dish in my back yard, and I don't need 25KW my thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.

I really want to thank you for the links.

Only one problem that I can forsee with the above power generation:

It would really cripple the oil companies, the coal companies, and the nuclear power plants if our INCOMPETENT government officials would provide funding for realistic energy production.

I would be interested in seeing the engine plans for this unit.

Jerry

[pminmo]

Originally Posted by CJL5585 Only one problem that I can forsee with the above power generation: It would really cripple the oil companies, the coal companies, and the nuclear power plants if our INCOMPETENT government officials would provide funding for realistic energy production. Jerry

First mistake is relying on the government, more has been acomplished and will be accomplished by private concerns. The government is for politicians, 70% +++ of them are interested in their future as politicans not the well being of citizens. If they have some interest in the citizens, the other percentage trashes them for making them look bad. It's been that way for decades. Our founding fathers when they wrote the constitution realized a large body such as the senate or house couldn't keep their mouths shut. Doesn't make any difference on which party, you tow the party line or be trashed or allowed to be trashed.

Before the net, this stuff was to hard to find, now it's routine research. There is more open source stuff going on than you can shake a stick at, and I mean more than software. sourceforge.net the center of the software universe for open source, is now otherstuff also but no stirlings that I can find

[CJL5585]

Originally Posted by pminmo My thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.

I would like to have a unit capable of about 3500 to 5000 watts.

Any plans, etc.

Jerry

[Geof]

Originally Posted by pminmo ...............Since I don't have room for a 37sqft dish in my back yard, and I don't need 25KW my thinking is doing one or several much smaller to produce 500 watts(hr during peak sun) or so in my back yard.

What efficiency do you expect to get? Full sun at the earth's surface is around 1000 watts per square yard. At 20% conversion efficiency you would need 2-1/2 square yards, i.e. 22-1/2 sq ft.

edit; calculation error, wrong area.

[pminmo]

I've been looking for plans haven't found any suitable. Seems like most plans are models.

5' square is do able. Where did you come up with 20% conversion efficiency?

[Geof]

Originally Posted by pminmo I've been looking for plans haven't found any suitable. Seems like most plans are models. 5' square is do able. Where did you come up with 20% conversion efficiency?

It is more or less in the middle of different efficiency claims I have read. I was wondering if your 37 sq ft and 25000 watts had any relationship; it is close to the efficiency you can get with a passive solar collector heating a fluid.

[pminmo]

Actually I made a goof it was 37' diameter, not 37 sqft. Some claim 30% conversion efficiency these days on solar to motive via stirlings