Stirling Cycle Machine Analysis
ohioopen.library.ohio.edu
ohioopen.library.ohio.edu
It's so tempting, you think there has to be a way to make it work. But I haven't found one yet and I more or less gave up on it. The most practical ones that I'm aware of are in spacecraft for extreme cooling and in a commercially available generator.
If you've never seen one up close I highly recommend building a model of one and watching it run, it is complete magic compared to internal combustion engines which tend to be noisy and dirty. Stirling engines run so quiet you have to be right up close to realize it is running at all (and even then you probably will subconsciously put your hand on it to verify that it is not just your imagination).
The Philips company, when it still meant something, put together a whole slew of pilots: a boat and a bus, and an endless number of them in the lab. Fortunes have been sunk in these and with preciously little to show for it other than an extreme appreciation for how hard it is to make a really good seal.
Wurm et al's book is the standard in the field, it is very thorough and gives a very good grounding in the theory as well as some appreciation on why this is both a tempting and very hard subject at the same time. Most engines are hard to think of and relatively easy to engineer once you've thought of them. There are two exceptions, Stirling engines and Wankel engines and both have very strongly related problems. Solve the seal issue and the world will pave the way to your door with gold.
IIRC there's a New Zealand company WhisperGen(?) that use them for power from waste heat from water heaters ...
Checking now, they seem to be used as marine power generation these days, I can't find the original site from 15+ years ago.
How It Works
The WhisperGen PPS16 is based on a four-cylinder Stirling-cycle (external combustion) engine that repeatedly heats and cools a mass of pressurised nitrogen gas.
Each time the gas is heated and cooled, the changing gas pressure causes the pistons to move up and down.
This mechanical motion, via a special mechanism called the “wobble yoke”, rotates an alternator to generate DC electricity which can be used to charge a lead-acid battery bank.
The nitrogen gas is heated by a continuous-combustion burner, and cooled by coolant circulating through engine cavities. Heat transferred to the coolant can be used to heat domestic water cylinders and for space heating.
There was a European branch in Spain, seems to have withered, and some stories about expansion plans and pivoting that got trashed by the earthquake fallout.
~ https://www.smh.com.au/business/nzs-whispergen-to-move-to-eu...
Damn shame - I had access to an early model looong ago and was really looking forward to seeing where that went.
That little co-generation unit was a mechanical miracle.
Some more background:
https://www.cruisersforum.com/forums/f14/anyone-know-whats-g...
I'm pretty sure it was the first book in the series, _Weapon_:
https://www.goodreads.com/series/386853-weapon-solo
Didn't know that there was a sequel, so added it to my "Want to Read" list on Goodreads (and the first to my "Read" books).
I’ve been looking for a decent epub of these!
The closer a heat engine/pump gets to maximum theoretical efficiency, the lower its power density.
Odum observed[0] that (for certain linear assumptions) the maximum power density is achieved at half the theoretical Carnot efficiency. He noted that both real engines and biological systems tend to cluster around this optimum.
What's interesting, but not terribly surprising, is that this implies a fundamental and unavoidable tradeoff between machinery cost and operating efficiency.