Stirlingengineforum.com

This is going to take a while:

One down:

https://youtu.be/b8ExVO1WIwc

Sounds a bit scratchy to me. Not sure why.

This doesn't really seem to be a "heat of your hand" engine. At least I couldn't keep it going on just heat of my hand. It's a fairly warm day though, and it hasn't been broken it at all yet.

Runs beautifully on hot water, but a little noisier than I was expecting.

Runs on ice quite nicely also. A lot quieter.

https://youtu.be/VF19ue3XMsQ

When I lifted the engine out of the bowl some of the wet ice cubes adhered to the bottom. Pretty obviously not due to "refreezing". So there goes that theory.

With the long tube to power piston I'd bet it would have a better chance at running from heat of hand if the top side was the hot side.

Seems like a good choice for cold bottom and ambient top side.

VincentG wrote: ↑Fri May 17, 2024 9:56 am With the long tube to power piston I'd bet it would have a better chance at running from heat of hand if the top side was the hot side.

Seems like a good choice for cold bottom and ambient top side.

I think the first thing I'd like to try is running one on ice and the other on heat.

I'm interested in seeing the heat build up, or lack of heat generated at the power piston.

I would assume that even an "ambient" engine running on ice should still generate friction at the power piston.

Would there be any other explanation other than friction if heat is generated at the pp in both hot running and cold running engine?

This is kind of interesting I think.

I took the guts out of that six pack cooler. It didn't really amount to much.

I wondered if the thing could run on 12 volts, maybe it could run on just 9 volts.

So I found a place where I could attach a 9 volt battery on the back of the 12 volt power plug.

Well, it actually ran. The fan ran and the peltier got both hot and cold.

So I rigged up a little stand for the fan and heat sink made from an old 6 volt flashlight lense cover, I wanted to see if it could produce enough cold with just a 9 volt battery to run the Stirling engine.

It actually worked.

I didn't time it, but I'd guess the engine ran for three minutes or more.

Needless to say the 9 volt battery got very hot to the touch and went flat before very long.

I did not make any effort to insulate around the peltier device or heat sink to help retain the cold.
I started making a video, but my phone was out of memory from recording previous videos. I'll have to try again with a fresh battery after I transfer some old videos off the phone onto my laptop.

Anyway, I think this kind of proves a 9 volt battery could run a small refrigerator. A very inefficient peltier refrigerator at that.

An enormous amount of heat going to waste in the process though. From both the hot side of the peltier as well as a lot of heat from the discharging battery.
.

I was thinking of trying this, but looks like somebody beat me to it 3 years ago


https://youtu.be/vsTIWhZ-6HM


The top engine, (hot side of the Peltier), is, well, just watch the video.

The Peltier device may not be that efficient at cooling, but it looks like it's putting out a lot of heat!

I have yet to put that other kit together.

For the butane mini-fridge I'm thinking that perhaps a little peristaltic pump might be more effective than a diaphragm pump

Self priming, can develop higher psi, pumps air or fluid equally well. Leak proof, good efficiency.

Also it appears that the head is detachable, so could potentially be driven mechanically directly by the Stirling engine.


I already received a little diaphragm pump from Amazon but the pump head is not separable from the motor.

Well, it is "separable", but the pump needs the support of the motor and motor shaft to form a seal and to function.

Just thought I would mention, I'm designing a new-ish kind of little butane heat pump to run a Stirling engine.

A conventional heat pump is designed for either heating or cooling, but a Stirling engine can utilize both.

The problem is, to make cold, a heat pump is designed to "reject" heat to the environment. No reason for that since instead, the Stirling engine will be converting the heat into work.

So instead of getting rid of the heat with a fan I'll be using an additional heat exchanger to take the "rejected" heat from the cold side and put it back into the system to be further concentrated by compression on the hot side.

Just in case anyone might be wondering what's going on with this project.

I received several high performance and also some very low voltage peltier chips, but now realize I don't have any thermal paste so had to send for some of that today.

I decided on Grizzly Kryonaut. A liquid metal would be slightly better probably but could corrode aluminium, so seemed like a good idea to avoid that.

I also have, I think, hopefully, everything needed for building the mini-butane vapor compression heat pump.

The kontax models don't come with built in regenerators, so I'm debating if I need to make regenerators for these little KS90v engines. I think so.

For one thing, technically, without a regenerator, is an LTD even a Stirling engine? Secondly, for the extreme nature of the tests I'm planning on doing, Two engines sharing the same cold side "sink" and so forth, I've only ever measured, or apparently or allegedly measured an apparent cooling effect when there was a regenerator involved.

My spare time in the summer months for these projects is also very limited but I am very anxious to proceed with these tests asap.

Even with all the materials on hand though, I still have to manage to somehow set aside the time, so it may still be a little while before I can get back to it.

The kontax displacer almost fits snugly inside a plastic soda or water bottle (but not quite).

I can make the same type of stationary regenerator going up the sides of the displacer chamber, which gave good results in other experiments for keeping the cold side cold

https://youtu.be/NtrYSpYD43w

I'm not going to use the original displacers that came with the engines though. I might want to use them again someday. They would need to be cut down slightly and it's just about as easy to just make new ones.

I meant to include this drawing of the regenerator:
Just fill the cavity between the displacer wall and the plastic ring cut from a soda bottle or whatever with some holes for air flow.

I had to go to the store for some lunch so I took the kontax displacer chamber ring along and went through the coolers looking for a plastic bottle just the right size.

I think I found it:

Perfect!

I just got surprised by some new "toys" at my doorstep:
Some short sample packs of all different size and different activation temperature Nitinol wire.

Not really sure what I might do with it at this point, but I wanted it on hand in case I think of something.

I particularly like the heavy 12 AWG piece. I didn't know you could even get it that thick.

My first impression is it is actually very flexible, moreso than ordinary spring metal but at ordinary ambient temperature it can't be permanently deformed at all.

Feels kind of like relatively soft carbon steel to the touch but springs right back to its original shape after being bent and twisted.

I guess you have to cool it down for it to be temporarily bendable.

I'm kind of anxious to "train" some to do something.

From my research, it is best not to heat it up with a torch and quench it in water as seen in some you tube videos, but rather heat it in a kiln and let it cool down very slowly.