Zakharra wrote: From what it sounds like, a stirling engine might be an efficient one, but it is not one that delivers a lot of HP which a steam engine can do.
Sōryū-class submarines have four individual 2,000 HP Stirling engines.
Now, aside from noting that submarines are not noted for their expansive and roomy interiors, Kockums -- the Swedish firm whose design those engines are -- has pictures on their website, and it looks like that engine installation, AIP plumbing and all, is a cube roughly 2 metres on a side.
(based on the presence of the scale engineer.
For something designed to run for at least three weeks continuous while making no noise to speak of, that's pretty good, size-wise.
Zakharra wrote:So there is one strike against it. Another strike seems to be its size. To make a stirling capable of delivering a good amount of HP/DP (dragon power) it sounds like the thing would be -huge-. Too big to be viable for manufacturing factories. Steam engines can be made smaller and given OWLs information database, a lot more efficient for its size.
Have you ever seen stationary steam engines from the 1800s? They're immense. They were designed to be as durable and low-maintenance as possible, but they're nothing like compact. You could very easily get a 200 HP engine that was twenty feet high and made out of massive cast iron parts. (It would however run for years.)
The modern expectation of compact engines, derived from automotive applications themselves derived from aircraft where you just never run the thing for days, never mind months or years, doesn't apply to powering factories.
In the factory application, you care more about costs to run than size, and there the Stirling, inherently more thermodynamically efficient and inherently mechanically simpler, wins. It uses less fuel and less mechanic time and breaks less often.
Zakharra wrote:In your opinion, could a stirling deliver the HP needed to run the turbines/flywheel of a good sized factory to power the machines there and be smaller than the building the machines are in?
Sure. Remember, this was actually done in our history; Stirlings were used as stationary engines despite the efficiency problems (sliding seals, not knowing the thermo theory) because they were simple and low maintenance. Given a fix for the seals and some help from Owl with the thermo, it's really quite a no-brainer.
Zakharra wrote:A stirling locomotive? I can't see that being viable at all. A locomotive/train engine needs a LOT of horsepower in a frame small enough that will still fit on a car to pull the engine and cars behind it. In a steam locomotive, its the team that gives the power to move the wheels to pull the train. I cannot see a stirling engine producing that much power.
Why not? We're talking 1880s steam locomotives, here; ~200 psi, 25 tonnes max weight, needs to carry about as much water as coal. Locomotive power is generally given in tractive force, rather than horsepower, since power varies with speed. You don't need a 5000 HP diesel pulling 20,000 tons of unit train to get your railroads started.
Five hundred horsepower is probably too much in that application. That's certainly achievable, and you can use pneumatic or hydraulic drive to turn the wheels and pneumatic brakes. No boilers, no feed water, not fussy about fuel, and cheaper to maintain. A railroad ought to love that.