Hybrid Thermoacoustic Stirling Engine

[Tom Booth]

@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 appears to be 'better all-round' than Hydrogen, and many other fuels.

Part of the point of forums like this is to save people the effort of repeating other people's 'mistakes' (I use the term loosely), so I take no offence if your opinion still differs from mine!

As far as the actual relative advantages of one fuel over the other, I have no opinions set in stone.

As much as I might squint and strain to see, however, I can hardly view calling something "junk" encouraging, or anywhere approaching neutral or unbiased.

On a broader front, in terms of the course of history and the future of life on planet earth, I wonder, what is the advantage of a fuel that requires mining coal or cutting down trees over something that can be obtained, literally, from thin air.

Of course, hydrogen can be gotten from coal as well.

And maybe Methanol can be manufactured out of thin air:

https://www.thedrive.com/news/38707/sci ... f-thin-air

I'm involved in an art guild here. Art criticism is something I've participated in on a fairly regular basis. An artists hangs up his work and a group of people pick it apart, say what they like or don't like. Artists, as a whole, being rather sensitive, in general, words of advice are weighed carefully.

I don't think anyone would think of making some blanket assertion in regard to someone's work "modern (or whatever) art is JUNK, you should focus on the classics (or whatever), don't make that mistake".

I suppose it could be argued that such a statement would not be discouraging, but rather encouragement to pursue a different course, though that leaves me to wonder what may be lost , what might have been?

The old butterfly effect. Instead of producing art to inspire future generations, this soul may instead, give up altogether. But it could go either way I suppose.

I'm also a Tesla fan (Nicola that is, not the car). I do believe, mistakenly or not, that at least one of his neglected inventions could have changed the course of history for the better.

[Tom Booth]

It appears, from recent comments posted on YouTube, Tristan Kearney died 23 .08.2021.

[Tom Booth]

...

Now you've got me wondering if that membrane displacer could be actuated by the Ringbom principle
...

Another think that strikes me, is that the membrane displacer type of engine could be easily built in a horizontal configuration as well.
It's suspended with the mechanical linkage between either the crankshaft, or the actuator membrane, and can operate in horizontal position without any additional friction. This would make very compactly built engines possible.

I've looked at the "NASA" free piston engine as well that is able to drive a crankshaft as well (it basically functions as an inverted Ringbom then).
Now I'm wondering if the "NASA" type of displacer could actuate a larger membrane..

Questions, questions. :-P

It is Tristan's many outstandingly successful "proof of concept" engines using membranes instead of a displacer that has led me to applying the idea to Stirling engine design generally.

Here for example:

viewtopic.php?f=1&t=1029&start=135#p17601

And also what I am driving at in this post:

viewtopic.php?f=1&t=5425&start=30#p17570

"that membrane displacer could be actuated by the Ringbom principle"

As Tristan said above: "For sure! It seems to open a whole new window for cheap easy build compact engines that you can actually use".

I tend to agree. Time will tell I guess. I've got a couple of designs drawn up that maybe I can test soon, now that my workshop is just about all set up.

[tenbitcomb]

Maybe displacer is the wrong term here. Someone earlier in the thread said there's a "displacer membrane", but that doesn't seem correct.

Tristan's motor, to me, looks like it could be an alpha configuration. The inner cylinder with the diaphragm is the hot side piston. When the hot side diaphragm depresses, air goes down and then up through the regenerator into the upper cavity where the cold side diaphragm is.

This reinforces a belief growing in my mind that way too much attention has been given to the gamma configuration. Gamma solves problems in alpha designs, but diaphragms alone solve problems in both. Gammas for whatever reason seem more approachable because they don't require as much fine machining as a traditional alpha, and alphas are always described as necessarily using pistons with a tightish fit in their cylinders. But a diaphragm based alpha is even simpler because its bare minimum requires a only a cylinder and two diaphragms, one for hot and one for cold. Maybe a regenerator between. I think Tristan's motor demonstrates this, and I'm guessing it's easier to get working than other engines of competing simplicity (thermal lag, etc.).

The Ringbom principle at work seems to apply to both diaphragms. They are both more or less pushed up at once by the heat pressure at the start, then the air is contracted in the cold section pulling down the cold-side diaphragm first. That allows both diaphragms to find their own place in the cycle. Maybe that's one reason this engine starts so easily. Now if it could just self-start!