What is the name of this Heat Engine?

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Discussion Overview

The discussion revolves around identifying a specific type of heat engine described by a participant, which utilizes bimetallic strips and operates based on temperature differentials. The conversation explores the mechanics of the engine, its construction, and potential names or classifications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes a heat engine made of two different types of metal straps formed into a ring that rotates on rollers when placed in water, suggesting it may be a type of Stirling engine.
  • Another participant suggests searching for "thermodynamic engine bimetallic" but does not find an exact match for the described device.
  • A participant emphasizes the importance of water level and the need for proper adjustment to achieve optimal rotation speed of the bimetal ring.
  • There are suggestions to check the U.S. Patent office for classifications related to bimetal heat engines, with one participant noting it might be named after its inventor.
  • Another participant introduces a different type of engine that uses Nitinol and operates on a temperature differential, drawing a parallel to the bimetal engine.
  • Links to resources discussing bimetal heat engines are provided, but no consensus on the specific name or classification of the engine in question is reached.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific name of the heat engine being discussed. Multiple suggestions and related concepts are presented, but no definitive identification is established.

Contextual Notes

Participants express uncertainty regarding the exact mechanics of the engine, such as its behavior in different water temperatures and the specifics of its construction. There is also ambiguity about the terminology used to describe the device.

Who May Find This Useful

Individuals interested in thermodynamics, heat engines, or bimetallic systems may find this discussion relevant, particularly those looking to identify or understand similar devices.

gary350
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We all know how a thermostat works 2 different type of metal are attach together, when temperature changes 1 metal strap expands more than the other strap causing the straight metal strap to bend.

45 years ago when I was in college the professor brought a desk top heat engine to class. He told us the name of this heat engine and I wrote it down. In the past 45 years I have lost that information. It was not called a sterling engine but it might be a type of sterling engine.

Here is how the engine is build and how it works.

2 different types of thin flat metal straps are made into a donut round circle shape about 3" diameter and connected together. The 3" round double strap is on rollers so it is free to rotate on rollers. I don't remember the details of the rollers, I think there were 3 rollers on the inside and 2 on the outside near the top. The 3" metal ring sets in a cup of cold or hot water when you give the ring a spin it keeps on rotating around the rollers as long as it continues to stay in the water. 1 roller is near the water surface left side of the cup while part of the 3" round ring is in the water. Water temperature makes the strap bend so the metal ring continuously pushes away from the roller and keeps rotating as long as the metal strap stays in the water. As the strap rotates near the top its temperature returns room air temperature the strap returns to its original shape near the top. If water is made colder the strap spins faster. I don't remember if it will rotate the other direction if put in hot water, teacher did not bring hot water, I don't recall he mentioned if the ring rotates the other direction in hot water.

If I knew the name of this device I could do Google search and read about it. I might even be able to find a desk top model for sale.

Does anyone know that this engine is called?

I might be able to draw a picture with paint brush and post if here if anyone would like to see a picture. Is it possible to upload photos here or do they have to be posted some place different then linked here?
 
Science news on Phys.org
gary350 said:
Is it possible to upload photos here or do they have to be posted some place different then linked here?

I think a picture would be very helpful. Use the UPLOAD button, then after the upload click on full image.
slask.png
 

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I don't know a specific name, but googling "thermodynamic engine bimetallic" brings up some interesting hits, although nothing that appears to be what you are describing.
 
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Water level has to be almost to roller 1. The whole assembly might need to be rotated counter clock wise a little bit. Once you get it adjusted correctly in water the bi metal rings spins at a fairly fast speed. It appeared to me like the ring was spinning about 3 turns per second.

Give the bi metal ring a spin the red color ring has to contract more then the green color ring so the bi metal ring develops an inward bow towards the roller this puts pressure on roller 1 forcing the bi metal ring to rotate. Like all sterling engines you need to give the bi metal ring a spin to get it started. Colder the water is the faster the ring spins.
 

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Last edited:
Another place to search is the U. S. Patent office, I think it is classified as a bimetal heat engine...
 
coolul007 said:
Another place to search is the U. S. Patent office, I think it is classified as a bimetal heat engine...

I think it is named after the inventor.
 
gary350 said:
I think it is named after the inventor.
And his name is...?
 
This isn't it, but does work on a temperature differential for the metal loop.
It uses Nitinol, memory shape wire, and one end has to be heated.
the bi-metal engine should work under a similar fashion.
https://www.imagesco.com/articles/nitinol/09.html
 

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