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Topic: Tesla's heat engine (split from DDWFTTW) (Read 3046 times) previous topic - next topic - Topic derived from Direct Down Wind Fast...

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Re: Tesla's heat engine (split from DDWFTTW)
Reply #500
This is partly responsible for the apparency that small model Stirling engines are quite feeble and can barely overcome their own friction. This is, I believe, because these engines are for show and are almost never loaded. They are not powering anything, only freewheeling...
This issue with "small" models is likely found in the ratio of frictional area to working volume.  If we assume a fixed stroke and a fixed piston length, the piston frictional area increases in proportion to cylinder diameter, but the volume of working gas (piston stroke times piston area) increases as the square of the cylinder diameter.

More realistically, if we assume piston length and stroke are in direct proportion to the bore, the frictional area of piston against bore is in proportion to the square of the bore and the volume of working gas is in proportion to the cube of the bore.  I believe you can see the implications.

You may be right, though the phenomenon I was talking about, that Stirling engines seem to adjust to a load and run better and cooler when under load and tend to overheat without a load is something I've also seen mentioned in regard to engines. 1kw and up as well.

Anyway, I had to leave school early yesterday (friday), so that afternoon and evening and most of the night I spent going over the Vuilleumier patent.

Having never read it in detail before I found portions of it rather astonishing. Such as how he incorporated gravity to keep his displacers in step by having them simply fall through the cylindar, the whole device being in rotation.

Anyway, I have of course, while fooling around with the idea of marrying a Stirling engine with a heat pump, considered the Vuillemier heat pump, but until now, didn't know much about it and only from second hand sources. Which is why I've had it on my to do list to go over the patent with a fine tooth comb until I understood the cycle enough to know if it would be suitable.

Well, I'm happy to announce, I've worked out the details of a Stirling-Vuilleumier engine .

I'm pretty sure it will run on ice and ambient heat and effect it's own refrigeration to prevent the ice from melting and so act as a Tesla Ambient Heat engine.

The best part is it is quite simple. It looks like everything can run off one crankshaft. It is basically a one piston stirling engine with one ordinary hot /cold type Stirling displacer and a secondary Vuilleumier refrigerating displacer.

Putting the two together was easier than I anticipated.

It also looks like it won't require machining. I think it could be built out of tin cans, pvc pipe, hot glue or some solder, some stainless steel pot scrubbers and a coathanger for a crankshaft. Fishing line to lift the displacers.

Also I'm working on designing a rotary version with the displacers controled by gravity as the contraption rotates.

I really think this could be the breakthrough I've been striving for. The Stirling engine and the Vuilleumier heat pump look like the perfect combination for applying Tesla's Ambient heat engine theory.

The timing I've worked out to try, with the piston at TDC or 0 degrees the stirling displacer should be at 45 degrees and the Vuilleumier refrigerating displacer at 135 degrees (that would be the angles for bending the coat hanger). The two displacer cylinders have their own cans communcating through a pipe between them with the power piston in the middle in a smaller cylindar attached to the pipe between the two displacers.
  • Last Edit: December 02, 2017, 01:38:54 AM by Tom Booth

Re: Tesla's heat engine (split from DDWFTTW)
Reply #501
We need an update on your heat engine.

Re: Tesla's heat engine (split from DDWFTTW)
Reply #502
Sorry, not long after my last post there was a personal family problem which in some ways is still ongoing. It is also nearly time to go back to school.

I worked on several designs for what was described in the last post, a combined Stirling-Vuilleumier engine/heat-pump and have finally arrived at this:

Which is intended as the first frame of a gif animation.

What is illustrated is essentially an ordinary LTD Stirling Engine with a secondary regenerative displacer for fulfilling the function of a Vuilleumier cooler. This is the simplest design and the easiest to build, and in my visualizations at least, should work better than the earlier design I was talking about. If the idea can work at all.

I'm also posting to the Stirling Engine forum:

Re: Tesla's heat engine (split from DDWFTTW)
Reply #503
BTW the movement of the "hot" regenerator is different, or opposite to the timing in the previously described side-by-side arrangement.