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All very interesting Tom.
In the test I just did with my 'LTD' (now a medium T diff) I found the engine was still speeding up as the 'cold' side got hotter, even though the hot side was stable at 148C. Whether this is due to bearings getting freer as they warm, or the wire wool round the edge of the displacer 'bedding in' against the beer can aluminium I've glued around the inside of the displacer cylinder I don't know yet.

Perhaps it's more support for your ideas. :)

Stroller wrote: ↑Sat May 04, 2024 3:59 am All very interesting Tom.
In the test I just did with my 'LTD' (now a medium T diff) I found the engine was still speeding up as the 'cold' side got hotter, even though the hot side was stable at 148C. Whether this is due to bearings getting freer as they warm, or the wire wool round the edge of the displacer 'bedding in' against the beer can aluminium I've glued around the inside of the displacer cylinder I don't know yet.

Perhaps it's more support for your ideas. :)

Not my ideas really. Just observations.

Unexpected observations actually or mostly.

The first time I video taped an experiment that involved putting insulation on the cold side I fully anticipated posting it here on the forum showing how the engine slowed down and stopped due to the heat bottleneck.

Due to blocking the flow of waste heat. Due to the loss of the temperature difference.

The idea was to proudly demonstrate my confirmation of the Carnot principle.

This was that video:

Watch as the engine almost instantly grinds to a halt from overheating once the top of the engine is covered by insulation.

https://youtu.be/fFByKkGr5bE

Watch ... watch... keep watching. Any second now it will overheat and stop...

Twenty minutes later it was still going strong and I was uploading the video to YouTube.

Shocked and puzzled, I watched the video over and over. I thought I could at least show how the engine slowed down, so I got my wife to work a stopwatch while I counted the revolutions.

The engine actually sped up a little after putting the insulation on top.

That's going on four years ago now.

After years of trying to find ways to finally block the "heat flow through the engine" once and for all without success, I've had to seriously consider alternative theories and ideas about how these engines work.

Your observation has a number of plausible explanations, just as with my experiment.

Rather than blocking heat, my insulation is actually conducting MORE heat faster than the surrounding air.

OK. I'll try it with better insulation. I always thought the cold side needed air circulation for cooling by convection, but... cooling by conduction? Could be, I guess.

Aerogel, ceramic fiber, hollow glass microspheres, etc. nothing works. The engine keeps running.

Well, if I can't stop the heat, I can at least MEASURE it as it comes out through the insulation right?

Thermal image camera, thermocouples, I can't find the heat leaving through the insulation either.

What's the explanation?

Heat is being converted into work?

Heat is "disappearing"?

I'm "doing something wrong"

OK, I guess maybe I'm doing something wrong, I'll get some help from the science and physics forum experts in thermodynamics.

Threads locked, banned, labeled a "perpetual motion crank".

The flywheel on your small engine is very light and is as easy to turn as it is to stop. So there's not much work being done for heat to be converted into.

Logically, a well insulated engine is going to equilibriate with and accept very little heat from the heat source. So if there's not much heat going in, and very little energy is required to spin the flywheel, there's not going to be much heat coming out, either as heat or work.

But the flywheel keeps turning, because as you've shown in other vids, the engine can run on tiny differentials of a few degrees. That makes measurement hard.

Stroller wrote: ↑Sat May 04, 2024 8:38 am The flywheel on your small engine is very light and is as easy to turn as it is to stop. So there's not much work being done for heat to be converted into.

Logically, a well insulated engine is going to equilibriate with and accept very little heat from the heat source. So if there's not much heat going in, and very little energy is required to spin the flywheel, there's not going to be much heat coming out, either as heat or work.

But the flywheel keeps turning, because as you've shown in other vids, the engine can run on tiny differentials of a few degrees. That makes measurement hard.

Well you and others perhaps find that explanation satisfying. I think it is unsubstantiated from a physics standpoint though.

A metal flywheel is "light" relative to what?

It is being driven by the kinetic energy of a few thimbles full of rarefied, invisible air molecules colliding with about 1/2 square inch of piston surface.

Anyway, I thought you seemed a bit more open minded than "fool" and some others that have passed through here but regardless of clear evidence to the contrary I see you are going with the same old tired explanations and off hand dismissals I've heard dozens of times already.

For some gas molecules so infinitely small as to be invisible, even to the most powerful microscope, a 4 or 5 inch diameter steel flywheel is, comparatively, "light and easy to turn"?

I don't think so.

On what do you base the opinion that there is "not much heat going in"?

Where do you suppose the heat is going then?

Oh, measurement is so hard. Oh my. Too infinitesimal to measure.

150° temperature difference between boiling water on the hot side and 60° ambient air on the other seems sufficient to see some heat flow across a 3/4 inch displacer chamber, unless something were holding it back or taking the heat away or both.

As I said before, I've got better things to do than trying to reason with a stone.

I only hope maybe you will follow through as you said and hook up some instrumentation to your engine and do your own experiments.

But I won't hold my breath.

For supposedly not doing any work, the heat from friction at the power piston is easily visible, at least 12° ∆T above the "cold side" generally

So that is 12 joules of heat generated from mechanical motion 0 joules of "waste heat" going out through the "sink".

Water in the cup is 170°F

General ambient 65°F

Top of engine 62° to 64°F

Heat generated from work output/friction 75°F (or 12 joules by "fools" normalization, 1° = 1 Joule)

Funny how reflectivity, emissivity, instrument failure etc. etc. doesn't seem to effect the area around the power piston which clearly shows a 12° increase in temperature from work/friction. But heat, supposedly being "rejected", immediately adjacent to that manages to somehow escape detection entirely.

Tom I actually think possible the self cooling aspect of these engines you are exploring.

But these ir guns are finicky, even my expensive one. If you paint everything flat black, then we can start talking.

It still will not be a very accurate overall reading, but at least the general comparison of engine parts will be close.

VincentG wrote: ↑Sat May 04, 2024 10:21 am Tom I actually think possible the self cooling aspect of these engines you are exploring.

But these ir guns are finicky, even my expensive one. If you paint everything flat black, then we can start talking.

It still will not be a very accurate overall reading, but at least the general comparison of engine parts will be close.

So you think this "finickyness" selectively shows power pistons glowing red/white hot with adjacent cold plate readings indicated by dark purple/blue how or why exactly?

Consistently, experiment after experiment?

And my thermocouples I suppose have contracted this same finickyness from the IR camera?

A 12° (or 12 Joule) heat increase is easily observable/detectable.

At about at best a 20% Carnot efficiency there should be about a 12° x 4 = 50°F temperature increase at the cold plate from the "waste heat" generated.

Instead the instrument shows, if anything a negative temperature increase.

How anyone alleging to be objective or scientific can make such nonsensical sweeping dismissals of clear graphic evidence is beyond me. Especially when there is, over the past 200 years zero empirical evidence for the Carnot mumbo jumbo, derived from nonsense, obsolete, heat falling down like a water wheel discredited, disproven caloric theory.

Human nature to cling to the known and familiar I guess.

Tesla at least saw through the Carnot caloric theory nonsense 200 years ago.

Tom Booth wrote: ↑Sat May 04, 2024 11:53 am So you think this "finickyness" selectively shows power pistons glowing red/white hot with adjacent cold plate readings indicated by dark purple/blue how or why exactly?

Because the IR camera uses the full palette of colours for whatever range of temperatures/reflectivities/emissivities are in its field of view. No matter how tiny.

A 12° (or 12 Joule) heat increase is easily observable/detectable.

At about at best a 20% Carnot efficiency there should be about a 12° x 4 = 50°F temperature increase at the cold plate from the "waste heat" generated.

I'm pretty sure Fool was referring to Kelvin, and he was a big dude, nearly twice the size of herr Fahrenheit.

Tesla at least saw through the Carnot caloric theory nonsense 200 years ago.

It seems he failed to share the secret of longevity with anyone before he died in 1943.

Tom Booth wrote: ↑Sat May 04, 2024 9:24 am I thought you seemed a bit more open minded than "fool" and some others that have passed through here but regardless of clear evidence to the contrary I see you are going with the same old tired explanations and off hand dismissals I've heard dozens of times already.

For some gas molecules so infinitely small as to be invisible, even to the most powerful microscope, a 4 or 5 inch diameter steel flywheel is, comparatively, "light and easy to turn"?

I don't think so.

Well it is. As evidenced by videos of LTD engines running for hours on a cup of joe.

On what do you base the opinion that there is "not much heat going in"?
Where do you suppose the heat is going then?

Nowhere, mostly. That's why the engine is still running after several hours.

Oh, measurement is so hard. Oh my. Too infinitesimal to measure.

150° temperature difference between boiling water on the hot side and 60° ambient air on the other seems sufficient to see some heat flow across a 3/4 inch displacer chamber, unless something were holding it back or taking the heat away or both.

In the video you linked, you'd placed a scalpel scalloped piece of insulation foam in the bottom of the displacer cylinder. That'll hold back the heat nicely then. What little does get through is sufficient to keep the engine ticking over.

As I said before, I've got better things to do than trying to reason with a stone.

I only hope maybe you will follow through as you said and hook up some instrumentation to your engine and do your own experiments.

But I won't hold my breath.

I'm not sure the snark level is worth it.
Now I've satisfied myself I can get my LTD engine to spin a stove fan next winter, I've shelved it for now. I have bigger fish to fry with a high temp compressor conversion for sufficient power production to keep a battery topped up while running my fridge and diesel heater. That's around a 60 Watt load. That one will be getting the full measurement suite while I track down the losses.

Stroller wrote: ↑Sat May 04, 2024 12:21 pm

Tom Booth wrote: ↑Sat May 04, 2024 11:53 am Tesla at least saw through the Carnot caloric theory nonsense 200 years ago.

It seems he failed to share the secret of longevity with anyone before he died in 1943.

Oh, you got me. Not 200 years. A mere, what was it around 1900 when he wrote the article?

In the article he said he was contemplating these things around. (Scanning the article) He says 1883 in Paris. A mere 141 years ago.

Stroller wrote: ↑Sat May 04, 2024 12:21 pm

Tom Booth wrote: ↑Sat May 04, 2024 11:53 am So you think this "finickyness" selectively shows power pistons glowing red/white hot with adjacent cold plate readings indicated by dark purple/blue how or why exactly?

Because the IR camera uses the full palette of colours for whatever range of temperatures/reflectivities/emissivities are in its field of view. No matter how tiny.

Apples to oranges.

The colors are just eye candy.

I have half a parts from half a dozen identical engines and have done tests on the accuracy variations due to whatever.

The actual metal plates may show a slight variation next to wood, plastic, vinyl whatever buy perhaps 1°

Some glass and some acrylic will block IR from passing through but that does not effect the surface temperature.

In the above image the "Max" indicator (red square) is directly over the power piston cylinder and the "Max" reading for the point indicated is 75°F

Anyway, like I said, I've got better things to do than try and talk logic and reason on this subject with a brick wall.

Good luck with your projects.

I only hope maybe you will follow through as you said and hook up some instrumentation to your engine and do your own experiments.

But I won't hold my breath.

I'm not sure the snark level is worth it.
Now I've satisfied myself I can get my LTD engine to spin a stove fan next winter, I've shelved it for now. I have bigger fish to fry ...

Why am I not surprised?

I'm a lazy engineer. I don't stuggle to make sense of tiny temperature differences with comparatively big error ranges for unusable power outputs when I can play with bigger projects.

If I were you, I'd be spending this part of the year making parabolic mirrors and stocking up on free tube and rebar wherever I could find it. It's the only way you'll get that 3kW to enjoy for several hours a day. Tracking? Use an old mechanical clock and a few servos to amplify its rotational positioning. Azimuth? A simple profile cut on a sheet of whatever plus a small motor to drive the balanced system. Wind issues? Use steel wires, pulleys, weights and ground spikes to limit movement.

That project's a 'problem' I'd love to have.

Stroller wrote: ↑Sat May 04, 2024 1:55 pm I'm a lazy engineer. I don't stuggle to make sense of tiny temperature differences with comparatively big error ranges for unusable power outputs when I can play with bigger projects.

If I were you, I'd be spending this part of the year making parabolic mirrors and stocking up on free tube and rebar wherever I could find it. It's the only way you'll get that 3kW to enjoy for several hours a day. Tracking? Use an old mechanical clock and a few servos to amplify its rotational positioning. Azimuth? A simple profile cut on a sheet of whatever plus a small motor to drive the balanced system. Wind issues? Use steel wires, pulleys, weights and ground spikes to limit movement.

It's a piece of junk.

I consider my time more profitably spent building something of practical value.

Nobody needs a 3kw generator that requires 10,000 watts heat input with a continuous output of 7,000 watts of hot water 42/7 "waste heat".

If only I could afford the shipping I'd take your junk off your hands for you.

12kW of solar energy costs no more than time and effort, plus some space blankets and ingenuity,

Over at my petite ruine in France I have many 20' lengths of 2" bamboo to lash up a parabolic framework with. And an acre of land to site it on. I have 5 cubic metres of rainwater stored onsite for cooling.