Stirling Engine Designs

[rickthorn]

I was just wondering if anyone had ever considered the Stirling Engine concept for marine designs. Something like solar heat collection above deck and some combination of keel and cooling fins down low in the water (drag would be a definite problem though).
Unless very careful attention were used in developing the initial design, benefits probably would not be justified because of many drawbacks, especially amount of power produced and significant drag.

[Boston]

we just went over this is the high torque engines thread
also in the steamless steam engines thread
was a fun study

[marshmat]

Definitely plausible.

Not necessarily efficient, though. The problem with a solar-heated Stirling is the available temperature rise. The Stirling cycle has the same theoretical maximum efficiency as the Carnot (1-Tc/Th) and can, in practice, easily reach about half this value. But it's really, really hard to get much more than 100 C from solar heat unless you have some fairly substantial concentrator arrays. When you run the numbers on that, even a pretty good solar Stirling is only about 12 to 15 % efficient, and ends up being darned heavy to boot. Since solar photovoltaics are lighter, simpler and cheaper than a big Stirling with concentrators and all that jazz, there's been very little economic or technical motivation to pursue solar Stirling power for mobile applications.

The solar Stirling does hold much more promise for land-based applications where large concentrators, and thus substantial temperature differentials, are feasible.

[Boston]

how about a Stirling powered car

http://www.thedailygreen.com/living-green/blogs/cars-transportation/dean-kamen-deka-revolt-electric-car-stirling-461108

came out about 6 months ago with a test model that they claim will be commercially available in about 2 more years

[rickthorn]

The Stirling was something I just wondered about, especially from a "free" energy point of view. Since it's operation is based on temperature difference, it seems like the air conditioning could be worked internally into the system perhaps.
Initially the flying wing was unsuccessful because of it's instability, this was later overcome with the use of flight computer systems. I think there are many, many old designs which should be revisited with todays technologies in greatly advanced propulsion systems, better and lighter engine technologies and the use of composites to reintroduce the ideas in an updated way.
The recent fuel problems in the West will eventually be a blessing in disguise
because of the many new engines and engine advancements that are currently appearing.