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Stirling Engine development

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wotsit02/02/2012 21:01:30
188 forum posts
1 photos
Now this is what I call development of the technology ! - anyone going to have a go?
Sorry about the double post - dog jumped on the computer.

Edited By wotsit on 02/02/2012 21:02:59

Ian S C03/02/2012 07:45:23
7468 forum posts
230 photos
I'd have to have a look around, but I think the stirling engine has headed off into space. Forgotten their name, but two of the probes that did a tour of our solar system, and have now gone into deep space have radio isotope thermocouples generating power for the radio, the radio is still monitored, but time delay is now quite large, and getting longer, but there is no obstruction to radio waves so 5W is ample. I think there is about 100 years left in the fuel system. The stirling engine has more power in a smaller lighter unit. I think there is a stirling engine working in reverse cooling electronics on the space station, and some other statellites. Ian S C
Ian S C03/02/2012 11:05:40
7468 forum posts
230 photos
A wee bit more from NASA, they are propposing a Fission Surface Powr supply of proberbly less than 40kW for lunar or Mars outposts. The fuel is Uranium Dioxide, it would use 1kg in 15 years, although at the moment the life of the machine is only 8 years. Its under test in a vacuum chamber. The fuel section is 10" x 18", it did not say how big the rest of the motor/ generator is, but it can't be too big. Ian S C
Richard Parsons03/02/2012 11:50:41
645 forum posts
33 photos
Using Stirling engines as generators was an idea of Phillips of Eindhoven. In the 30s and 40s they developed the Rhombic drive engine which was intended to replace the Low Tension batteries in Non Mains powered radios. The fuel was any combustible liquid like lamp oil (which would have been used to light the Sahib’s bungalow).
The project was canned because the transistor required a fraction of the power required by the Thermionic valve.
Engine Builder03/02/2012 16:13:12
234 forum posts

Have a look at what this guy is up to. I think this generator is an incredable achivement.
He has a lot of nice engines on youtube.
There are also some videos of the origional philips engines that he owns.


Edited By Engine Builder on 03/02/2012 17:07:37

Billy Mills05/02/2012 15:01:10
377 forum posts
Thanks for the YouTube post David, Cyril has done a great job on the TMG. There is a good article on Wikipedia about Thermomechanical Generators and loads of information in the original patent US 4,345,437.
The use of O rings to seal the "piston" is not what most people would think but a very clever idea. Like a lot of others I have been seduced by Stirling Engines, but the concept of a free displacer oscillating in a sealed volume is very interesting.
Ian S C06/02/2012 10:19:39
7468 forum posts
230 photos
Billy, the TMG is top of my list for my next build, just got to find the materials, ie., two stainless contaners, something suitable for the diaphram. I'v got one 90 mm container, and an old saw blade to carve the planar spring. Ian S C
Richard Parsons06/02/2012 14:33:29
645 forum posts
33 photos
The ‘upper’ engine is I think the Harwell Engine. It is used by Trinity House for powering the lights on Buoys and other sea markers (light houses etc). Well filling the Buoy with Butane is easier than stuffing it with Carbide and lasts a lot longer. Philips great invasions were the Rhombic Drive and the Roll Sock. The Philips engone and later developments are used in Winibago’s to drive the generator and in ‘military equipment’ because of it silence. As a student said of the Beal Free Piston engine “It ain’t the world’s most powerful engine but it sure is the quietest”.
I have a loony neighbours who are very deep into porcelain. I am wondering is could it be used as the ‘Hot End’
Ian S C07/02/2012 00:31:41
7468 forum posts
230 photos
Richard, one of the units that has taken over from the Phillips Bungalow set is the Whispergen, a highly pressurised unit in the form of a 4 cylinder ALPHA motor, designed in Christchurch NZ, and built in Spain for sale in Europe. As for noise, the only way you can tell if the unit is going is to put your hand on it, there is a very slight vibration, thats near enough to silent for me!
My free piston engine is far from silent, but it works,well most times any way.
I think you are on the right track, but would say Ceramics rather than porcelain as in cups and saucers.     Ian S C

Edited By Ian S C on 07/02/2012 00:35:59

Billy Mills07/02/2012 00:55:47
377 forum posts
Well the challenge is to up that 10% efficiency on the TMG Ian, Cyril's variable reluctance generator might be better as a moving coil alternator- i.e. like the motor in a Loudspeaker which happens to have a quite good fixed magnetic path.
I'm still ruminating on the physics inside the displacer, it won't be at a constant temp so perhaps a thin lagging inside around the hot end might help a little. There are a very large number of variables to keep you busy for a long time! Indeed the more you think about it the more you realise how well Cyril has done to make a great working example.
There is another Cooke-Yarborough patent 4,077,216 that is a bit more conventional however the great appeal of the TMG to me is the use of the diaphragm and O rings to seal the gas and avoid the need for pistons and their sliding seals. 90,000 hours is a very impressive running time, when you think that is 90,000 x 3600 x 110 cycles that is some performance. Wonder where we can get some stainless cans? might find some old electrolytic cans but they are aluminium and not usually designed to nest with a small gap.
Ian S C07/02/2012 11:07:17
7468 forum posts
230 photos
At one time some one was producing suitable stainless containers specially for hot air engines, it may have been Andy Ross in the states, or someone connected to him. I'm going looking for stainless containers in Christchurch (NZ) , but its hard these days to find the retail out lets, every things moved from where they used to be.
James G. Rizzo in a Model Engineer artical used stainless soft drink cans, it seems that one brand in the UK uses stainless instead of aluminium, and he used them in his motor. These cans proberbly not rigid enough for a TMG.
Do you think it would be possible to form circular corigations on thin stainless, to make the diaphram.
The TMG I'm thinking of is between the 90 mm of the container I have and 150 mm which would be better. Ian S C
Ian S C07/02/2012 11:46:51
7468 forum posts
230 photos
A week or two ago I looked at the vidio of that TMG, boy does it take a time to load on dial up!! Ian S C

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