Stupid auto-correct. LOL.
That should be SPOUT area.
Ringbom-Rice conversion?
Re: Ringbom-Rice conversion?
I was able to run another test with a better view of what's going on.
I started out, as before, with the water level just below the top of the support for the aquarium gravel.
As before, after a few minutes of warming the engine on the stove, the water level appears to rise up over the support and up through the gravel.
At this point the water is not yet boiling, or even simmering, but at this point I needed to open the valve to start letting out pressure.
As the pressure dropped the water level visibly rose up through the gravel rapidly, then dropped back down.
As the water heated up enough to begin simmering, the apparent water level continues to rise
As can be seen now, there is some, but not a lot of water vapor bubbles trapped under the support.
As the water reached a simmer, the water vapor bubbles percolating up through the gravel could be seen basically "disappearing" in a flash, or sometimes slowly shrinking and disappearing before reaching the top. At least that's how it looks to me.
Some bubbles do reach to top of the gravel, or the "air" or saturated vapor above the gravel.
https://youtu.be/_DLVKuCr-Z4?si=yikuJsSwfmBRvAqx
I think now it can be very clearly seen that the rise and fall of the water level is due to water vapor bubbles forming and growing, throughout the liquid water causing the water level to rise, then the vapor bubbles shrink and disappear as the pressure is reduced causing the water level to fall.
So, it is not the liquid that is expanding and contracting but the vapor bubbles within the liquid forming, growing and then shrinking and disappearing, displacing the liquid, basically filling the liquid with bubbles causing the water level to rise and fall as the bubbles appear and disappear.
https://youtu.be/f-aJZ2QtWOs?si=e0tsooo25wAEMhFj
Another observation.
I think the characteristic crackling and popping sound that water makes as it begins to boil is basically cavitation bubbles rapidly forming and collapsing.
The vapor bubbles form on the bottom, but because the water higher up is still relatively cool, the vapor bubbles as they detach from the hot bottom, cool and collapse creating the popping and crackling cavitation noise.
I started out, as before, with the water level just below the top of the support for the aquarium gravel.
- Resize_20240329_051915_5673.jpg (170.07 KiB) Viewed 4870 times
As before, after a few minutes of warming the engine on the stove, the water level appears to rise up over the support and up through the gravel.
- Resize_20240329_051916_6654.jpg (189.9 KiB) Viewed 4870 times
At this point the water is not yet boiling, or even simmering, but at this point I needed to open the valve to start letting out pressure.
- Resize_20240329_051916_6983.jpg (123.51 KiB) Viewed 4870 times
As the pressure dropped the water level visibly rose up through the gravel rapidly, then dropped back down.
As the water heated up enough to begin simmering, the apparent water level continues to rise
- Resize_20240329_051917_7857.jpg (193.71 KiB) Viewed 4870 times
As can be seen now, there is some, but not a lot of water vapor bubbles trapped under the support.
- Resize_20240329_051918_8184.jpg (175.68 KiB) Viewed 4870 times
As the water reached a simmer, the water vapor bubbles percolating up through the gravel could be seen basically "disappearing" in a flash, or sometimes slowly shrinking and disappearing before reaching the top. At least that's how it looks to me.
Some bubbles do reach to top of the gravel, or the "air" or saturated vapor above the gravel.
https://youtu.be/_DLVKuCr-Z4?si=yikuJsSwfmBRvAqx
I think now it can be very clearly seen that the rise and fall of the water level is due to water vapor bubbles forming and growing, throughout the liquid water causing the water level to rise, then the vapor bubbles shrink and disappear as the pressure is reduced causing the water level to fall.
So, it is not the liquid that is expanding and contracting but the vapor bubbles within the liquid forming, growing and then shrinking and disappearing, displacing the liquid, basically filling the liquid with bubbles causing the water level to rise and fall as the bubbles appear and disappear.
https://youtu.be/f-aJZ2QtWOs?si=e0tsooo25wAEMhFj
Another observation.
I think the characteristic crackling and popping sound that water makes as it begins to boil is basically cavitation bubbles rapidly forming and collapsing.
The vapor bubbles form on the bottom, but because the water higher up is still relatively cool, the vapor bubbles as they detach from the hot bottom, cool and collapse creating the popping and crackling cavitation noise.
Re: Ringbom-Rice conversion?
I'm pretty sure I know now what conditions are necessary for this engine to run
There probably needs to be just enough water to fill the engine vith a saturated vapor so that the hot bottom of the container can be at least partially dry so it can get extra hot.
When the pressure increases and is at its peak, the water vapor is able to condense out and becomes a liquid on this "extra hot" surface but the moment the pressure begins to fall again this superheated liquid "explodes" back into a vapor, driving the piston out.
The diaphragm needs to be weighted to create enough momentum to expand the vapor enough to cool and condense within the gravel.
As the vapor condenses the piston is pulled down.
Again momentum from the weight causes the pressure to increase enough to allow phase change and more water condenses on the hot plate then "explodes" back into vapor.
If the "dry" hot bottom is TOO hot the water cannot condense upon it easily.
For this to work as described conditions need to be "just right". And with 109% saturated vapor in the bottom of the engine it is impossible for it to not condense on the hot surface as long as the overall ∆T is carefully balanced around the "boiling point" or phase change temperature and pressure.
There probably needs to be just enough water to fill the engine vith a saturated vapor so that the hot bottom of the container can be at least partially dry so it can get extra hot.
When the pressure increases and is at its peak, the water vapor is able to condense out and becomes a liquid on this "extra hot" surface but the moment the pressure begins to fall again this superheated liquid "explodes" back into a vapor, driving the piston out.
The diaphragm needs to be weighted to create enough momentum to expand the vapor enough to cool and condense within the gravel.
As the vapor condenses the piston is pulled down.
Again momentum from the weight causes the pressure to increase enough to allow phase change and more water condenses on the hot plate then "explodes" back into vapor.
If the "dry" hot bottom is TOO hot the water cannot condense upon it easily.
For this to work as described conditions need to be "just right". And with 109% saturated vapor in the bottom of the engine it is impossible for it to not condense on the hot surface as long as the overall ∆T is carefully balanced around the "boiling point" or phase change temperature and pressure.
Re: Ringbom-Rice conversion?
I can report that used 100% as"condensation medium" this stuff DID NOT work.
Using these plastic spacers, it seems that the steam simply rises up through the plastic matrix without condensing so the top chamber of the engine with the power piston/membrane gets hot and filled with steam causing the diaphragm to continually balloon out, again and again, no matter how many times the steam is allowed to escape to relieve the pressure, so there is no chance for the engine to start.
Next I tried layering the plastic spacers with aquarium gravel.
For that I used just enough gravel to cover the bottom screen, then enough plastic spacers to visually cover the gravel (about 1/2 to 3/4 in.) then additional gravel etc. alternating until the condensation chamber was filled to the normal level.
With the layering, the engine started and ran moderately well but tended to become "overheated" and loose power, stop running and not be able to restart, similar to using the plastic spacers alone within a relatively short time (maybe two or three minutes of running time "no-load", that is, with the usual weight but no electric power generation.
The layering however, did not result in better peak performance than using gravel alone. It ran rather steady but never reached a stage of strong power output as generally will occur using just aquarium gravel.
Something else I think might be worth trying, but haven't yet is half gravel and half plastic. That is, one THICK layer of each. One above the other.
- non-thermal-medium.jpg (363.15 KiB) Viewed 4843 times
Using these plastic spacers, it seems that the steam simply rises up through the plastic matrix without condensing so the top chamber of the engine with the power piston/membrane gets hot and filled with steam causing the diaphragm to continually balloon out, again and again, no matter how many times the steam is allowed to escape to relieve the pressure, so there is no chance for the engine to start.
Next I tried layering the plastic spacers with aquarium gravel.
For that I used just enough gravel to cover the bottom screen, then enough plastic spacers to visually cover the gravel (about 1/2 to 3/4 in.) then additional gravel etc. alternating until the condensation chamber was filled to the normal level.
With the layering, the engine started and ran moderately well but tended to become "overheated" and loose power, stop running and not be able to restart, similar to using the plastic spacers alone within a relatively short time (maybe two or three minutes of running time "no-load", that is, with the usual weight but no electric power generation.
The layering however, did not result in better peak performance than using gravel alone. It ran rather steady but never reached a stage of strong power output as generally will occur using just aquarium gravel.
Something else I think might be worth trying, but haven't yet is half gravel and half plastic. That is, one THICK layer of each. One above the other.
Re: Ringbom-Rice conversion?
The transparent engine with the PVC top and radiator valve has been problematic in that it has been difficult to find an adhesive that will anchor the PVC to the glass.
Epoxy of various types SEEMS to work until subject to steam and pressure, then the PVC pops loose from the epoxy. The epoxy seems to adhere rather well to the glass, infact, it is nearly impossible to remove from the glass once fully cured.
So... I tried muffler patch paste, which seemed to adhere to both glass and PVC good enough, but eventually became soft and runny, kind of "melting" like air hardened clay (unfired) or "greenware" apparently it requires dry heat to fully set properly, so that was a mess.
I did, however, get the transparent engine to run using the muffler patch paste, but not for long before the paste softened and, as I found out later, LEAKS had formed where the soft clay-like paste failed to maintain a seal. At first small holes appeared where air was getting sucked through then long cracks at the joint between the glass rim and the PVC. Both of these type of failures were difficult to detect due to the general runny mess.
I got the transparent engine all cleaned up and reassembled, this time using red high temperature RTV silicone. It is not, I found out, the normal RTV silicone formulation, but a kind of gasket material that is advertised as being easier to clean up and remove.
The consistency is like the normal smooth texture silicone that has been mixed with flower or something to give it a thicker somewhat granular consistency.
Not sure how well this "easy to remove" silicone will work for this application.
Epoxy of various types SEEMS to work until subject to steam and pressure, then the PVC pops loose from the epoxy. The epoxy seems to adhere rather well to the glass, infact, it is nearly impossible to remove from the glass once fully cured.
So... I tried muffler patch paste, which seemed to adhere to both glass and PVC good enough, but eventually became soft and runny, kind of "melting" like air hardened clay (unfired) or "greenware" apparently it requires dry heat to fully set properly, so that was a mess.
I did, however, get the transparent engine to run using the muffler patch paste, but not for long before the paste softened and, as I found out later, LEAKS had formed where the soft clay-like paste failed to maintain a seal. At first small holes appeared where air was getting sucked through then long cracks at the joint between the glass rim and the PVC. Both of these type of failures were difficult to detect due to the general runny mess.
I got the transparent engine all cleaned up and reassembled, this time using red high temperature RTV silicone. It is not, I found out, the normal RTV silicone formulation, but a kind of gasket material that is advertised as being easier to clean up and remove.
The consistency is like the normal smooth texture silicone that has been mixed with flower or something to give it a thicker somewhat granular consistency.
Not sure how well this "easy to remove" silicone will work for this application.
Re: Ringbom-Rice conversion?
Actually it appears so far that the RTV gasket stuff is adhering well ho both the glass and the PVC and holds up well under hot water and I even put the engine in the oven to help it cure completely.
The PVC, though, got rather soft in the oven at very low heat. I just read that PVC cannot take the heat of boiling water for long, which seems surprising in that it is for plumbing, where it would be in regular contact with hot water.
The PVC, though, got rather soft in the oven at very low heat. I just read that PVC cannot take the heat of boiling water for long, which seems surprising in that it is for plumbing, where it would be in regular contact with hot water.
- RTV_silicone.jpg (154.62 KiB) Viewed 4837 times
Re: Ringbom-Rice conversion?
I was wrong about a few things.
The engine running does not REQUIRE the bottom boiling dry.
It's nice to be able to see what is going on inside rather than having to guess.
The loud boiling/cavitation-like sound goes away after a while, NOT because the engine runs dry and the steam gets superheated. The water at a full boil is just much quieter.
I had a lot of difficulty getting the glass engine to start. I thought initially, maybe because I wasn't letting it run dry, fearing the high heat without water might crack the glass. But upon examination I found leaks due to the epoxy not adhering to the PVC when steam heated..
I did get it to run after resealing with a different epoxy, but it didn't run for long. I thought this might have been due to the thermal properties of the glass vs. metal.
The metal is more conductive, but was also in two sections. The gap might help reduce heat transfer, but the glass is less heat conductive but seamless.
Anyway, I wanted to test the effect of a temperature gradient. Maybe the glass engine would run longer with a water jacket, so I made one.
After making the water jacket, though, I discovered that the new epoxy had come loose, so the poor performance of the glass engine could have been more pressure leaks rather than a thermal issue.
Anyway, I rebuilt the engine again, but giving up on epoxy, I tried muffler patch paste.. I let it cure over night but apparently it is very water soluble until heated to a high temperature, on a car muffler. Anyway it dissolved when subject to hot steam, but held up long enough to run some tests and make a video.
https://youtu.be/0uFhOOwP5cw?si=3E3Bqqm-k7hcDNkK
That includes some earlier footage showing that there is not "capillary" action drawing water up into the gravel. The apparent rise in the water level is due to phase change (boiling).
So the engine WILL run with water boiling continuously in the bottom. Though I haven't really seen an engine of mine run with as much vigor as I've seen when water is injected into an apparently hot dry engine as in some other videos
So, now I'm leaning towards an alternative theory.
At this point I suspect that the gravel DOES act something like a regenerator.
The gravel near the bottom gets hot first (theoretically, my new theory) while the gravel higher up remains cool.
The percolation from the boiling water causing the air to move up and down, or hitting the diaphragm, causes the air to oscillate up and down through the gravel.
As the air goes down through the gravel it gets hot and expands back upward, and as it goes up it cools and goes down and gets hot again and goes up and cools etc. etc.
In the video I put very cold water from the refrigerator into the water jacket to keep the upper gravel cooler.
The engine ran pretty well for a good long while, and quit running once the cold water got hot.
But, It's difficult to draw any definite conclusions.
First of all the engine ran without the water jacket. I wasn't aware that the epoxy was coming loose, so I don't know if it stopped running due to "overheating" as I thought might be the case, or because of air pressure leaks.
With the muffler patch paste, the sealant was steadily dissolving. After the run, I found there were obvious small air leaks where the goopy paste was sucked through small holes that developed, and the muffler patch did not hold and the glass and PVC pipe were separating.
After the RTV silicone cures fully, I want to re-run some tests to remove any doubts.
It seems clear the silicone is going to hold up much better than anything else I've tried.
Assuming that all or most of the significant phase change action is going on within the gravel, the engine running dry on the stove, as seen in some videos, could allow the gravel near the bottom to get really good and extra hot so that when water is added tbe ∆T in the "regenerator" is more effective.
I imagine the "saturated" cool water vapor going down through the gravel and erupting into steam or hot expanding gasses, pushing the diaphragm up, allowing the hot gas to rise and cool and condense, then shrink back down.
Assuming some "work" is done to convert some heat into work, it might be possible for the gravel higher up to remain cool. However steam DOES carry latent heat and may deposit "heat of condensation" so that the gravel becomes progressively hotter higher and higher up until the ∆T is lost and the engine quits running.
My first tin can "rice" engine seemed to run for a long long time without the upper portion getting hot, but perhaps I did not let it run long enough, or perhaps the heat dissipated through metal better than through glass.
Pretty clearly though, the engine does run with a temperature "gradient" (maintained by the cold water jacket) from the bottom to the top of the gravel. The gravel provides a lot of surface area for heat exchange, like a regenerator.
However, there is the added potential boost in power from phase change, IF the ∆T is great enough to flash the water vapor to steam and then re-condense very rapidly.
I think my video demonstrated that when at the boiling point, phase change, alternating rapidly between vigorous boiling and no boiling and condensation or contraction is possible.
I might try adding a drop of soap. Maybe it would be easier to see the bubbles grow and shrink, but watching, up close, while doing these tests, It is quite obvious to me that the "bubbles" of water vapor do shrink and disappear with just a small increase in pressure when the diaphragm is pushed down, so, why would the same thing not happen when the pressure goes up when the membrane goes down while the engine is running?
Another thing that has become rather obvious is that these engines run more visibly vigorous with more weight.
This is apparently, though, often, nearly all "adiabatic bounce" that could not be sustained if the engine were put under load.
So far I have not exactly isolated the factor that causes these engines to go "crazy", or put out some real power. Though my first tin can engine could run with a finger firmly on the piston magnets, but the glass engine stopped easily with a light touch.
I did have a strange occurrence.
I tried making an engine out of a rather tall narrow asparagus can.
The gravel was quite deep. But in a tall narrow column.
I was using one of those collapsible silicone measuring cups as a power piston.
There was hot water in the bottom starting to boil and I was trying to get the engine started, just waiting for the water to boil and tapping my finger on the diaphragm.
There didn't seem to be much of any build up of pressure, but very suddenly the engine just exploded.
The diaphragm blew off and water and gravel shot out and came down all over the stove top and kitchen counter top and floor.
This was quite a shock.
What caused such an "explosion" I'm not entirely sure, it was quite unexpected.
Maybe because the collapsible accordion-like cup allows a much greater change in volume than a taught diaphragm with very shallow motion. and the tall narrow column of hot gravel possibly combined to generate a much more explosive and sudden phase change. When I pushed down on the collapsible cup.
This might indicate that the further the air or water vapor passes through the gravel, the more powerful the reaction.
Sometimes, even just boiling water in a pot, there can be sudden explosions" where a huge bubble or bubbles appear suddenly and rather erratically.
The engine running does not REQUIRE the bottom boiling dry.
It's nice to be able to see what is going on inside rather than having to guess.
The loud boiling/cavitation-like sound goes away after a while, NOT because the engine runs dry and the steam gets superheated. The water at a full boil is just much quieter.
I had a lot of difficulty getting the glass engine to start. I thought initially, maybe because I wasn't letting it run dry, fearing the high heat without water might crack the glass. But upon examination I found leaks due to the epoxy not adhering to the PVC when steam heated..
I did get it to run after resealing with a different epoxy, but it didn't run for long. I thought this might have been due to the thermal properties of the glass vs. metal.
The metal is more conductive, but was also in two sections. The gap might help reduce heat transfer, but the glass is less heat conductive but seamless.
Anyway, I wanted to test the effect of a temperature gradient. Maybe the glass engine would run longer with a water jacket, so I made one.
After making the water jacket, though, I discovered that the new epoxy had come loose, so the poor performance of the glass engine could have been more pressure leaks rather than a thermal issue.
Anyway, I rebuilt the engine again, but giving up on epoxy, I tried muffler patch paste.. I let it cure over night but apparently it is very water soluble until heated to a high temperature, on a car muffler. Anyway it dissolved when subject to hot steam, but held up long enough to run some tests and make a video.
https://youtu.be/0uFhOOwP5cw?si=3E3Bqqm-k7hcDNkK
That includes some earlier footage showing that there is not "capillary" action drawing water up into the gravel. The apparent rise in the water level is due to phase change (boiling).
So the engine WILL run with water boiling continuously in the bottom. Though I haven't really seen an engine of mine run with as much vigor as I've seen when water is injected into an apparently hot dry engine as in some other videos
So, now I'm leaning towards an alternative theory.
At this point I suspect that the gravel DOES act something like a regenerator.
The gravel near the bottom gets hot first (theoretically, my new theory) while the gravel higher up remains cool.
The percolation from the boiling water causing the air to move up and down, or hitting the diaphragm, causes the air to oscillate up and down through the gravel.
As the air goes down through the gravel it gets hot and expands back upward, and as it goes up it cools and goes down and gets hot again and goes up and cools etc. etc.
In the video I put very cold water from the refrigerator into the water jacket to keep the upper gravel cooler.
The engine ran pretty well for a good long while, and quit running once the cold water got hot.
But, It's difficult to draw any definite conclusions.
First of all the engine ran without the water jacket. I wasn't aware that the epoxy was coming loose, so I don't know if it stopped running due to "overheating" as I thought might be the case, or because of air pressure leaks.
With the muffler patch paste, the sealant was steadily dissolving. After the run, I found there were obvious small air leaks where the goopy paste was sucked through small holes that developed, and the muffler patch did not hold and the glass and PVC pipe were separating.
After the RTV silicone cures fully, I want to re-run some tests to remove any doubts.
It seems clear the silicone is going to hold up much better than anything else I've tried.
Assuming that all or most of the significant phase change action is going on within the gravel, the engine running dry on the stove, as seen in some videos, could allow the gravel near the bottom to get really good and extra hot so that when water is added tbe ∆T in the "regenerator" is more effective.
I imagine the "saturated" cool water vapor going down through the gravel and erupting into steam or hot expanding gasses, pushing the diaphragm up, allowing the hot gas to rise and cool and condense, then shrink back down.
Assuming some "work" is done to convert some heat into work, it might be possible for the gravel higher up to remain cool. However steam DOES carry latent heat and may deposit "heat of condensation" so that the gravel becomes progressively hotter higher and higher up until the ∆T is lost and the engine quits running.
My first tin can "rice" engine seemed to run for a long long time without the upper portion getting hot, but perhaps I did not let it run long enough, or perhaps the heat dissipated through metal better than through glass.
Pretty clearly though, the engine does run with a temperature "gradient" (maintained by the cold water jacket) from the bottom to the top of the gravel. The gravel provides a lot of surface area for heat exchange, like a regenerator.
However, there is the added potential boost in power from phase change, IF the ∆T is great enough to flash the water vapor to steam and then re-condense very rapidly.
I think my video demonstrated that when at the boiling point, phase change, alternating rapidly between vigorous boiling and no boiling and condensation or contraction is possible.
I might try adding a drop of soap. Maybe it would be easier to see the bubbles grow and shrink, but watching, up close, while doing these tests, It is quite obvious to me that the "bubbles" of water vapor do shrink and disappear with just a small increase in pressure when the diaphragm is pushed down, so, why would the same thing not happen when the pressure goes up when the membrane goes down while the engine is running?
Another thing that has become rather obvious is that these engines run more visibly vigorous with more weight.
This is apparently, though, often, nearly all "adiabatic bounce" that could not be sustained if the engine were put under load.
So far I have not exactly isolated the factor that causes these engines to go "crazy", or put out some real power. Though my first tin can engine could run with a finger firmly on the piston magnets, but the glass engine stopped easily with a light touch.
I did have a strange occurrence.
I tried making an engine out of a rather tall narrow asparagus can.
The gravel was quite deep. But in a tall narrow column.
I was using one of those collapsible silicone measuring cups as a power piston.
There was hot water in the bottom starting to boil and I was trying to get the engine started, just waiting for the water to boil and tapping my finger on the diaphragm.
There didn't seem to be much of any build up of pressure, but very suddenly the engine just exploded.
The diaphragm blew off and water and gravel shot out and came down all over the stove top and kitchen counter top and floor.
This was quite a shock.
What caused such an "explosion" I'm not entirely sure, it was quite unexpected.
Maybe because the collapsible accordion-like cup allows a much greater change in volume than a taught diaphragm with very shallow motion. and the tall narrow column of hot gravel possibly combined to generate a much more explosive and sudden phase change. When I pushed down on the collapsible cup.
This might indicate that the further the air or water vapor passes through the gravel, the more powerful the reaction.
Sometimes, even just boiling water in a pot, there can be sudden explosions" where a huge bubble or bubbles appear suddenly and rather erratically.
Re: Ringbom-Rice conversion?
Been working on trying to get the rice engine to turn a flywheel. Mostly just to see if it's possible.
I recall someone mentioning on the other "rice engine" thread that they were going to try it but never reported back.
Anyway, I think I'm done and ready to give it a go as soon as some epoxy dries.
The glass cylinder seems to conduct a lot of heat, so I'm retaining the water jacket as this engine will not run long at all without it.
The flywheel is compact and heavy. I tried to make ithe flywheel weigh about the same as the weights on the diaphragm that have the engine running well and steady, but not necessarily highest power.
The small flywheel diameter is to try to achieve higher RPM since these engines tend to oscillate at a relatively high frequency I figure a flywheel with a minimal diameter will be able to revolve at a higher RPM than one with a larger diameter.
I actually used the same magnets used for the diaphragm to weigh down the flywheel
.
I recall someone mentioning on the other "rice engine" thread that they were going to try it but never reported back.
Anyway, I think I'm done and ready to give it a go as soon as some epoxy dries.
The glass cylinder seems to conduct a lot of heat, so I'm retaining the water jacket as this engine will not run long at all without it.
- rice_engine_with_flywheel.jpg (253.33 KiB) Viewed 4819 times
The small flywheel diameter is to try to achieve higher RPM since these engines tend to oscillate at a relatively high frequency I figure a flywheel with a minimal diameter will be able to revolve at a higher RPM than one with a larger diameter.
I actually used the same magnets used for the diaphragm to weigh down the flywheel
- flywheel_weights.jpg (229.22 KiB) Viewed 4819 times
Re: Ringbom-Rice conversion?
Some late night experimenting, but no great results so far.
https://youtu.be/AaEfauPTqYo?si=0oBcnqy-1X2BbVqA
If the flywheel assembly is removed, which can be accomplished rather quickly by just loosening the big hose clamp, the engine will run, apparently quite strongly.
Put the flywheel back on and you can see the results.
I suspect, in spite of my efforts, there is too much conflict between the rate at which the engine runs naturally "free piston" and the rate at which the flywheel can rotate.
I've had several small thermoacoustic engines that would not run, or ran very poorly, or required enormous blasts of heat to run with a flywheel attached, but ran quite easily and with much less heat required "free piston" without a flywheel.
The engine does, though, make more revolutions with heat applied than when cold, if the piston is just spun by hand.
Getting the diaphragm rate of oscillation and the flywheel RPM synchronized so that they work together rather than hinder each other is a matter of trial and error.
So far I haven't found a combination that results in a running engine. I'll keep tinkering with it though when I can.
https://youtu.be/AaEfauPTqYo?si=0oBcnqy-1X2BbVqA
If the flywheel assembly is removed, which can be accomplished rather quickly by just loosening the big hose clamp, the engine will run, apparently quite strongly.
Put the flywheel back on and you can see the results.
I suspect, in spite of my efforts, there is too much conflict between the rate at which the engine runs naturally "free piston" and the rate at which the flywheel can rotate.
I've had several small thermoacoustic engines that would not run, or ran very poorly, or required enormous blasts of heat to run with a flywheel attached, but ran quite easily and with much less heat required "free piston" without a flywheel.
The engine does, though, make more revolutions with heat applied than when cold, if the piston is just spun by hand.
Getting the diaphragm rate of oscillation and the flywheel RPM synchronized so that they work together rather than hinder each other is a matter of trial and error.
So far I haven't found a combination that results in a running engine. I'll keep tinkering with it though when I can.