Liquid Heating/Cooling of Hot/Cold Alpha Stirling Engine Cylinders?

[JessIAm]

Howdy All!

First off! I'm so glad I found this forum! I have cool dreams for Stirling Engines for electric power production for a house.

The working fluid inside an Alpha Stirling Engine cylinders is gas (typically air). The heat and cold transfer to the cylinders can be through any medium, since the heat (or cold) is absorbed (transferred) from (to) outside the cylinders. Using liquids to heat or cool the appropriate cylinder (and cool the regenerator) should work more efficiently than using gas.

Does anyone know of attempts to do this?

Thanks,

Jess

[JessIAm]

Hm.... Looks like a no.

[JessIAm]

Ok, so here's what I would love to see:

Start with an Alpha Stirling Engine with 2 cylinders - hot and cold.

Have a heat source that heats a liquid heating loop (like burning something or compost pile*). The liquid heating loop is used to heat the hot cylinder.
Make a similar system to cool the cold cylinder. My thought was the cooling loop would have a short section of pipe in a cold stream.

This should work. What issues or concerns can people think of to make this system work?

*Note: A healthy compost heap produces 140 to 150 degrees F.

I got this idea when travelling past a farm on the Oregon coast. The farm was bounded by a cold stream that came from a nearby mountain range.

Looking forward to your feedback :)

[Bumpkin]

You could perhaps look into oil-bath air cleaners as donor technology. They used to be fairly common but are somewhat rare now - (perhaps because of too much pressure drop as the air bubbles through the oil?) Remember 150 f. to 50 f. is only about a 20% absolute temperature difference, so there wouldn't be much pressure to spare.
Edit: OK I just looked at it -it looks like the air doesn't have to 'bubble" through the oil, just pass through the wetted mesh. There still might be a way to use the theory to advantage though.
Bumpkin

[JessIAm]

I was looking at heat pump technology - where a loop of liquid coolant is used to provide heating or cooling to a reversible air conditioner. Some of these systems have loops of piping underground (up to 10 feet), to allow the liquid to dissipate or accumulate heat.

With two of these systems, the temperatures of the cold and hot cylinders of an Alpha Stirling Engine could be kept at constant cold or hot temperatures.

Are Alpha Stirling Engines able to work with a 100 degree temperature difference between hot and cold cylinders?

Thanks,

Jess

[MikeB]

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!!

[JessIAm]

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!!

Doh! The "up to 10 feet" refers to how deeply the piping is buried underground- not it's length. You're correct that the piping can be hundreds of feet. I've seen a setup where someone coiled the piping in loops, so the hundreds of feet didn't require a huge trench.

The point being the ground source heat pump provides a stable temperature for heating or cooling a cylinder of an Alpha Stirling Engine.

[Tom Booth]

I got this idea when travelling past a farm on the Oregon coast. The farm was bounded by a cold stream that came from a nearby mountain range.

Looking forward to your feedback :)

Sorry if you felt ignored. The forum is rather inactive at times.

Probably not related to your idea, but there is a stream running through part of our property I have some plans for, but the stream is about 15 or 20 feet down below an embankment.

I had thought that perhaps the water from the stream could be used for cooling and that pumping energy loss would be minimal or non-existant if the water carrying loop were below water at both ends, particularly if the outlet could be a little below the inlet as it would set up a siphon, once it got going the cold water would flow up and back out without taking any energy out of the system for pumping. Maybe.

My plan also included running the engine cold, below ambient air temperature, and using the cold water to dump the excess ambient heat, but that's a whole different story.

[JessIAm]

Sorry if you felt ignored. The forum is rather inactive at times.

No problem :)

Probably not related to your idea, but there is a stream running through part of our property I have some plans for, but the stream is about 15 or 20 feet down below an embankment.

I had thought that perhaps the water from the stream could be used for cooling and that pumping energy loss would be minimal or non-existant if the water carrying loop were below water at both ends, particularly if the outlet could be a little below the inlet as it would set up a siphon, once it got going the cold water would flow up and back out without taking any energy out of the system for pumping. Maybe.

My plan also included running the engine cold, below ambient air temperature, and using the cold water to dump the excess ambient heat, but that's a whole different story.

Actually, this is very close to my idea! It's half of the system, actually.

Wouldn't it be less power consumption to have a closed loop that traveled from the engine, down to the stream and back to the engine? Since water is incompressible, if the closed loop was full of water you wouldn't need much power to get it flowing. By having the closed loop piping in the stream for a few feet, the cooling water in the loop could shed heat, then travel back to then engine to cool the cold cylinder.

[Tom Booth]

That could certainly work, but I don't know about less power, since a siphon, at least in theory, doesn't use any power whatsoever. In practice, I'm not sure such a siphon would work at all. The water warmed by the engine might tend to create a backflow on the way down. There could also be problems with debris clogging up the system, so a closed system would likely be more practical.

On the other hand, if the water flowed fast enough in the siphon, it would need no power to operate and would probably run cooler than a recirculating system.

[JessIAm]

That could certainly work, but I don't know about less power, since a siphon, ...

We're actually talking about different systems. It sounds like you are using some system to draw water from the stream up to the engine, then return the warmed stream water back to the stream. This constantly uses energy to raise the water. It's the equivalent of using metal fins to cool cold cylinder.

I'm suggesting a closed loop of piping - no inlets or outlets. One end of the loop is up by the engine, the other end of the loop is underwater in the stream itself. Basically, it's a liquid filled radiator that uses the stream water to dissipate heat. This is the equivalent of a cars cooling system, but using the heat absorbing ability of the stream water instead of air flowing over the radiator.

The benefits of the loop bypass the issues with flotsam from the stream getting into the cooling water. The cooling water is enclosed by the closed loop. Since it doesn't have an inlet for stream water, no debris can enter the cooling water.

[Tom Booth]

That could certainly work, but I don't know about less power, since a siphon, ...

We're actually talking about different systems. It sounds like you are using some system to draw water from the stream up to the engine, then return the warmed stream water back to the stream. This constantly uses energy to raise the water. ...

Well, if you count gravity, I guess.

"It's the equivalent of using metal fins to cool cold cylinder."

I'm not sure what you mean by "It's", a siphon or a closed loop?

Metal cooling fins don't use energy either.

Anyway, to maybe make it clearer, though it sounds like you have the idea.

In this video, you could say that my situation is like having my Stirling engine on the bank of this pond, in the video by the "filler cap" which is, of course, higher up than the water level of the pond.

In my situation the pond is not a pond, just a portion of the stream that is higher than the water level further downstream.

Once I had a siphon flowing up the bank and back down the drawing water up, or raising the water, would be powered by gravity pulling the same water down. I can use the water flowing through the pipe at the top of the hill for cooling, so long as it is done in such a way as to not break the suction.

https://youtu.be/yim18B4WW1c

[Tom Booth]

"This constantly uses energy to raise the water. It's the equivalent of using metal fins to cool cold cylinder."

Now I'm wondering if I misunderstood.

By "this" in the above, are you talking about the siphon? I thought so, but now I'm not sure.

Anyway, there are a few other ways to pump water using the energy of the flowing water of the stream itself. Like this contraption, and others, if there is a running stream available:

https://youtu.be/vtHhkAZqC4o

[Tom Booth]

For a long time I've been hoping to find the time to try building one of this type Stirling engine, that might be adapted to your project.

Basically, it runs on hot and cold water.

Maybe it could be scaled up by using 30 and 55 gallon drums or something instead of just tin cans.

Screenshot_20210417-042838.jpg (30.2 KiB) Viewed 14521 times

I don't anticipate that it would produce much power, but should be inexpensive and uncomplicated.

[Tom Booth]

Maybe make a compost next to the creek and do something like:

IMG_20210417_134805858_resize_75.jpg (215.27 KiB) Viewed 14514 times

Sorry, I tend to get carried away with these ideas sometimes.