Stirlingengineforum.com

As ever, watch out for quality with car chargers - converting 12v to 5v leaves plenty of head-room for really crap circuitry that might rob all your power at lower voltages. If you are going down that route (sounds like you aren't) then I would be looking at the kind of "buck-boost convertor&qu...

I read that pressurizing the cylinders adds efficiency, but I don't know how feasible it is with a diaphragm. I don't think it makes much difference whether you use a diaphragm or a traditional piston - pressurisation is a problem for both, as it is primarily the external/atmospheric pressure that ...

what type of engine are you talking about that is easy/simple compared with Stirling/hot air? What I meant was that with IC engines you can quite confidently state that during the combustion stage, the only relevant processes are expansion and heating. In a steam engine or a jet turbine the various...

... there could be more than one factor in play Ah, but that's the thing, isn't it? Some other types of engine it might be easy/relevant to use a simple model, but for Stirling/Hot-air engines there is ALWAYS more factors at play, the difficulty is in working out which ones have a significant effec...

Tom, I don't think you need to be a believer in Kinetic Theory, or any other specific theory, to see that ultimately, the component molecules of your working fluid push on the power piston individually, though it is always easier to think of them "as a whole". All things being equal (which...

The corollary to that point, is that the hot end will tend to be self-regulating (though maybe not always sufficiently!) - heat transfers faster (apparently) between items that have a large temp difference than a small difference, so if the working fluid starts to heat up, presumably the rate of tra...

Les, The trouble with that description of Adiabatic processes, is twofold: 1. In the real world, and especially in hot-air engines, there is ALWAYS some heat transfer in/out of the walls of the engine. 2. Timing. At low speed, or in step-by-step analysis, all of the working-fluid changes temp/pressu...

If the clay won't settle, I guess you'll just have to dry it like salt?

Tom/Vincent, Interesting thoughts. As ever, the real world proves more complex than any 'model/theory' however one thing to bear in mind here is that there are generally considered to be two entirely separate methods of heat transfer: Conduction (which seems to be what you are talking about above) b...

Helium for example can hardly be liquified by any extreme of external cooling and pressure, yet it can be liquified by this method of having it do work expanding in a cylinder to drive an engine to do external "work". Was that a typo? If the expansion of the gas cools it down far enough t...

The specs available on that site, at least at first glance, are essentially non-existent. I wouldn't touch it with a barge pole, and in any case, what is being advertised is little more than a basic kit - you would have to do a lot of work to adapt it to actually cool anything.

I hadn't heard of a "Jake Brake" before - are they really a thing?
My driving instructor taught me how to use engine-braking, then told me never to use the technique unless necessary, as brakes are somewhat cheaper (and easier) to replace than cylinder linings!

I totally agree that the piston would have to remain "in rhythm" with the displacer, but the 'phase angle' would shift. If it shifted far enough, the engine is going to start to "skip a beat" and/or stop completely. I think you might struggle to find a servo that will run fast en...

Tom, I really don't think it is nit-picking to say that gasses NEVER contract on their own, or that the outward pressure of any gas (by definition) is greater than any inter-molecular forces, or gravitational forces, or dark energy. Besides, surely the whole point of this discussion is to try and pi...

One experiment that I have yet to get around to, is de-coupling the displacer from the power piston, and therefore having two flywheels, one driven by the piston, and driving the load; the other driven by an electric motor and driving the displacer. It seems likely to me, that this would automatical...