Engine That Uses Ice For "Fuel"

[tsbrownie]

mklotz, Marv suggested this. This Stirling engine will run on ice as "fuel". Stirling engines run on a difference between 2 temperatures. By using ice for the low temp, the Stirling engine operates by moving heat from the air into the cold sink / ice. This is a safe alternative to hot water to demonstrate the engine to children.
The amount of ice in the video allowed it to run for over 2 hours (depends on several factors, like room temp, engine speed, etc.)

OK, the "fuel" for this engine is TECHNICALLY mostly hydrogen being fused in the sun because the electricity to freeze it came from solar, but it's a "fuel" in the sense it is consumed to create motion.

[mklotz]

I used to demonstrate Stirling engines at outdoor exhibitions. Providing a heated surface was problematic so I used those freezable gel packs that are sold for use in picnic coolers. I had considered painting the top plate of the displacement chamber black to absorb sunlight and thus increase the top-to-bottom heat differential and consequent engine speed but I hate painting. Instead, I had some thin black rubber sheeting; I cut a piece to fit on the top plate and that worked well to speed things.

Stirling engines are sold commercially to power fans placed on top of wood stoves used for heating; they help to circulate the heated air...

https://www.stirlingengine.com/produ...ine-stove-fan/

A (possibly apocryphal) story I've heard is that small Stirling engines driving tiny generators were used to power radios dropped to French guerrilla fighters during WWII. Battery technology was weak and the engines could be run in a campfire while the fighters hid out in the woods.

[tsbrownie]

I tried to find something on the French guerrilla radio thing, but came up empty. The Germans had the technology before the war and there were Stirling toys made in 1910. Philips made a home Stirling generator to run their tube radios. So there's circumstantial evidence - it's entirely possible. I like the use of ice, because you can safely show the engine working to small kids without the dangers of hot water or flame. I've got to finish up some videos on other Stirling engines I bought. There's one that's alcohol fired I really like. There's another that's a real hazard because it literally bounces around and the metal fuel can gets so hot the alcohol starts to boil over. I have 2 that have generators, but they only product 0.12-0.2 watts!

[mklotz]

In your engine, a gamma type Stirling, the displacer is driven off the crankshaft which is in turn powered by the power piston.

A later step in the evolution of the Stirling engine was the Ringbom engine. Here the displacer isn't mechanically connected in any way to the power piston; it's completely free-wheeling and activated only by the internal gas flow in the engine.

The video below shows a Ringbom I built. The displacer is housed inside the structure with the brass cylinder on top and the hot end on the bottom being heated by an alcohol lamp. As the engine runs, it bounces up and down on its own.

The brass cylinder is actually a water jacket surrounding the cold end of the displacer chamber. A small pump on the top of the frame circulates water from the reservoir into the jacket to keep the cold end of the displacer chamber cold.

It's a non-trivial engine to scratch build but, with its infernal noise, a real attention getter at exhibitions. I prefer the elegant, noiseless motion of alpha and gamma Stirlings.

[tsbrownie]

I like that! I am going to have to research how it works. Thanks. OK, just went to look. It uses gas pressure as a spring to move the displacer. Clever.

[mklotz]

Stirling engines come in many configurations. One of the most intriguing is the Fluidyne...

https://en.wikipedia.org/wiki/Fluidyne_engine

Liquid pistons and no moving mechanical parts make for a truly ingenious design. I built one of these using glued Plexiglas parts with an embedded ceramic power resistor as the heating element. While it worked, it was hardly exciting to watch. Sadly, it no longer exists. A tragic accident involving a high speed grandchild led to its demise.