Has anybody made an engine before that uses a modest heat source but cools with something along the lines of liquid nitrogen?
I'm not sure if it would work out as an energy-efficient exercise (how much energy does it take to liquefy nitrogen?) but it may be useful for compact engines where a high power output is desired.
Actually what got me thinking aobut this is a scooter I saw that I think was invented by dean cayman of Segway fame. It was a hybrid electric scooter that used a stirling engine to drive an alternator to charge a battery. The stirling engine was heated by an LPG bottle.
I remember a couple of years ago a friend of mine made a spa pool heated by a LPG fuelled barbeque - when the gas was running full noise the bottle froze over and got a layer of ice on it - so the gas is actually giving heating AND cooling at the same time - intersting huh?
Anybody have thoughts on this?
Liquid nitrogen cooling
I've run my engine on dry ice before but that's nothing new. A bowl of water ice can run many of the production LTD models. I'm sure it's possible to "fuel" a stirling with liquid nitrogen but as you mention, I doubt it is cost effective or very "green" in terms of total energy consumed. A somewhat large engine could make use of the cooling effect of the propane bottle if it was fired (fueled) by propane I suppose. Could be a problem if it starts heating up the bottle though. The heat transfer ratio potential is over my head on this one. Interesting though.
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spinningmagnets
- Posts: 64
- Joined: Sat Aug 02, 2008 7:34 pm
- Location: NW Kansas, USA
cold from de-compression engine
I hadn't thought of this before, but I think its worth consideration.
I've worked with liquid nitrogen (LN2) and its very expensive. It is transported in a vacuumed double wall thermos container. A small amount of LN2 would make a large volume of cold gas, and coupled with a folding solar dish, it would certainly make powerful and tiny engine.
The Amish are well-known for not using electricity or cars. It is less well-known that thay use a lot of air-tools. The tools are powered from large tanks that store air at medium pressures, and are filled by windmill air-pumps.
This is similar to an air-conditioning cycle. Air is compressed and gets hot. After the tank air-cools a few hours, releasing the pressure then results in cold tools.
Stirlings work, and can generate electricity, but any added power can mean getting a good engine that is smaller.
I think LN2 will have a very tiny possible application, but for a remote engine, adding de-compressing gas (air?) cooling may prove valuable.
For a bench-top toy demonstrator, your idea of using cold propane on its way to the burner is very clever.
I've worked with liquid nitrogen (LN2) and its very expensive. It is transported in a vacuumed double wall thermos container. A small amount of LN2 would make a large volume of cold gas, and coupled with a folding solar dish, it would certainly make powerful and tiny engine.
The Amish are well-known for not using electricity or cars. It is less well-known that thay use a lot of air-tools. The tools are powered from large tanks that store air at medium pressures, and are filled by windmill air-pumps.
This is similar to an air-conditioning cycle. Air is compressed and gets hot. After the tank air-cools a few hours, releasing the pressure then results in cold tools.
Stirlings work, and can generate electricity, but any added power can mean getting a good engine that is smaller.
I think LN2 will have a very tiny possible application, but for a remote engine, adding de-compressing gas (air?) cooling may prove valuable.
For a bench-top toy demonstrator, your idea of using cold propane on its way to the burner is very clever.