Old stirling with a twist

[Mayhew]

Hi everybody! I am new to the forum although I have viewed it as a guest from time to time. I am glad to be part of the forum and to have access to so many experienced individuals on the topic of Stirling engines. Greetings to all.

I have wanted for a long time to build a Stirling motor with a useful power output, but like most others I have only seen a few examples of engines that are successful.

It seems that the Stirling engine in the modern age has been divided into 4 groups.

• Vintage Stirlings. These are machines dating from the 18-1900's and is mostly seen @ shows
  Hobby and models. Plenty of these around. Mostly for educational purposes and novelty use.
  • Private individuals that are building Stirling motors for their own use, such as generating power.
    • Hi Tech. These are institutions or people that are applying new technology to bring Stirling engines to the modern world.
      
      Stirling Engines during the 18-1900's sold in their thousands. You could go to your local dealer and purchase a working Heat engine, bring it back home and pump water, grind coal or do whatever work the engine was designed for.
      Where they bulky. Yes
      Effiecient by todays standards. No
      Any heat as a fuel source Yes
      Did they do the work they were designed for. Yes!
      
      Why then can the same engine albeit with different materials not be purchased today?
      I do not know the answer but I believe that the Stirling engine still has a role to play as a working engine.
      To this end I have acquired a set of plans for a Heinrici heat engine that dates from the 1800's.
      
      I will endeavour hopefully with the help of the forum to replicate the Heinrici engine, not as a show piece but as a working engine. I will stick to original design,but take advantage of new materials and bearing technology.
      
      I am not a machinist and will be using a local machine shop to manufacture the parts. The forum's help in this will be invaluable.
      I will design and construct a flux generator that will replace 1 or both of the flywheels and test what usable power can be derived from the engine.
      The power generated will be fed into my off-grid solar system for consumption.
      
      The engine will not be pressurized and the only improvements will be that I will be taking advantage of modern materials, both in the mechanical and electrical fields.
      
      The spec of the current Heinricci is as follows. The technical data are:
      Bore: 80 mm
      Power: 1/12 horsepower at 160 rpm
      Flywheel diameter: 332 mm
      Height: 940 mm
      Weight: 68 kg
      
      Please comment.
      Regards
      Mayhew

[MikeB]

Sounds like an interesting project.

I think the general issue with Stirling engines at the moment is three-fold:
1) Bulkier than internal combustion engines.
2) Very little demand for engines driven by solid fuel.
3) Lack of investment, leading to lower relative efficiency than internal combustion engines.

[Yorky]

Hi Mayhew,

The fascination of Stirling engines is different for everyone, I have always wanted to build a steam engine but in my younger years never had the time, money or resources to do anything about it. After one false start I am now fully retired and have the time, but I am still lacking in the other categories so steam is out of the question, but hot air with the option of making an engine out of recycled bits and bobs that can be made with a few blunt handtools is very attractive to me.

I was only ever going to make one engine, which I did and was pleased with the result but people who see it say "It looks great but what does it do?" There are a couple of things that I could make it "do" but it is saddly lacking in the power department.

Being in a state of lockdown with the Coronovirus Pandemic, my wife has suggested that I spend more time in the shed which I have reluctantly agreed to do. Which gives me the oppurtunity of building an engine with usable power. I enjoy building stuff and intend to produce usable power albeit in a smaller range than you are contemplating. My goal is to produce a Stirling Powered, Steam Punk, Mobile Phone Charger. How did people charge their mobiles before electricity was invented?

My comprehension of the Sterling Cycle is negligible and I was suprised that my first attempt to make a stirling engine worked, having got one method working I do not feel brave enough to try a radical departure from that design. Flux Generators, regenerators and other hi-tec bits and pieces sound fascinating but I have not got a clue what you are talking about. That is my problem not yours, do not try and explain them at the moment you are probably fighting a lost cause, I will see yours in the fulness of time.

Good luck with your project, do not give to much of the work away - thats the fun part.

Toodlepip

Yorkie

[exile]

I would probably bet a bit on the more efficient stirling engine.

You can get efficiency without using modern technology.
See: https://orca.cf.ac.uk/54057/1/U585566.pdf
1840 Separated regenerator (s. 46 in pdf, s. 17 in book)
1845 Cycle under pressure (s. 46 in pdf, s. 17 in book)
1880 Air preheater (s. 49 in pdf, s. 20 in book)

I understand that simplicity is appealing, but with a little more complexity you can get a motor better efficiency and power.

And 1/12Hp (~61w) is real low.

Is my 2cent ;)

[Yorky]

In my last reply I confessed my ignorance with regard to flux generators, a term I had not come across before. Out of curiosity I did some basic research and can now see the possibilities and why they are attractive.

I am looking forward to reading more about your thoughts and build.

Toodlepip

[Tom Booth]

As far as I've been able to discover (correct me if I'm wrong) Stirling engines of this type had solid (or sealed hollow) metal displacers. (See image).

I'm inclined to believe, however, that an engine of this general design might benefit by substituting a regenerator material in place of an ordinary displacer.

This might recover heat, or prevent heat loss, increasing efficiency and possibly allow the engine to run cooler.

I'd be most curious to find out if it would make a difference anyway.

[Tom Booth]

This tin can engine seems to be quite powerful for the size and construction. I think it is mentioned in this video that the "displacer" is made of steel wool (technically, I would call that a regenerator, or regenerative displacer).

At any rate, additional videos show the assembly and inner workings and the "displacer" is, infact, a rather large, long roll of loosly wound steel wool.

https://youtu.be/K5EAUBHg_0w

The general construction is also similar, as far as basic design elements.

[Tom Booth]

The steel wool displacer can be seen near to the end of this video:

https://youtu.be/SroPkkqsE8U

[buyengine]

Hi Mayhew,

I would go with a good sterling
I would like you to visit website for further details
Website:- https://usedenginesandtransmission.com/

And good luck with your project

[Tom Booth]

Have you any of these at your used engine shop?

stirlingmotor-macdowell-500x500.jpg (34.21 KiB) Viewed 2752 times

https://youtu.be/KbnGlcQiL1c