Stirlingengineforum.com

I think the point that M13Calvin was trying to make is that if you were _able_ to build an engine that was optimised for adiabatic operation, and was 'perfect' in all other regards, it wouldn't be 100% efficient. This is unfortunately true for any engine, of any type - there is a theoretical limit t...

That is going to be a difficult question to answer, and potentially counter-intuitive too! A load of tarmac will certainly heat up a lot in direct sun, but not sure how good the heat conductivity would be - if there is too much insulating effect (as with the compost heap) then you won't get much tra...

That's the strength I see of this - the ∆T comes from two theoretically inexhaustible sources - the mountain stream, and the well tended compost heap. Whoa! The stream is a great source of cooling, but the compost heap not so much, nowhere near to inexhaustible in fact! The point is that you need t...

40 degrees F is kind of mid-range territory for a tea-cup model - some LTD engines can go as low as 4 degrees or so. On the other hand, for a power-producing machine it is tiny - they tend to operate with more like 400 degrees difference, so don't expect to run your house off it! Without knowing how...

I quite agree that that video is surprising, but too much so. The exact nature of heat transfer processes & sequences within the engine are certainly complex, but every motor in existence works by converting one form of energy into another, so any suggestion that running a stirling on top of a c...

A stirling engine with a flywheel beneath the cylinders, for a low centre of gravity. Fire might be placed between the crankshaft and the cylinder. My gut feeling is that you want the cylinder to be horizontal, not vertical. I don't think many engines have a flywheel that is heavy enough for it to ...

the problem is Improper load balancing. Maybe I didn't explain that well - the basic operation of any Stirling involves repeatedly changing the temperature of the working fluid. That cannot happen if the temp of the working fluid reaches the temp of the hot end. Unless the energy removed through wo...

I'm not sure I understand what you are after - fundamentally all engines work in any orientation, its just details like gravity-fed systems that need to be adjusted, so with most simple stirlings, the only thing you need to do is arrange for heat to be applied appropriately.

I think you are getting overly caught up with the theory of work. Yes, doing work converts heat-energy into kinetic-energy, however generally speaking such processes live in the 20% - 50% efficiency range, so the remaining heat-energy must be removed from the system, or it will become impossible for...

"I removed the regenerator and replaced it with a heat exchanger."

I missed that little gem the first time - what does it mean, since the whole point of a regenerator is that it is a specific type of heat exchanger already?

Jess, I think you will find that the loops of piping for a ground-source-heat-pump is measured in hundreds of metres, not a few feet!!

@Tom - I'm not intending to discourage research into Hydrogen (or any research at all!), rather I am trying to encourage research into other options. For me, both methane and methanol are "clean enough" when burned, though methanol also seems to be usable in fuel-cells, where again it appe...

@Tom - I assume from that diagram that each of the pistons is linked together via a crankshaft, so diaphragms wouldn't work, but I may be wrong. Jumping back several steps, I thought that sharkskin worked similarly to the 'step' on a flying boat hull, but sounds like I'm wrong, or at least over-simp...

I'm not 100% sure I understand where you think that this "shark skin" would be beneficial - but if it is for the regenerator, then it seems to me that you will make things worse! The basic design of a regenerator needs to be a compromise - you want to maximise surface area in order to maxi...

Tom - the downsides to Hydrogen include: It has a very low energy density. It is incredibly difficult to store. It is currently very difficult to produce economically - hydrolysis is easy, but not efficient. It is very dangerous when a leak occurs. Leaks always occur, because gaseous hydrogen can pa...