water jacket for hot end

Discussion on Stirling or "hot air" engines (all types)
Wellington
Posts: 143
Joined: Mon Apr 18, 2016 4:02 am

water jacket for hot end

Postby Wellington » Tue Jan 16, 2018 9:47 am

Hello

Has anyone any advice to offer regarding the idea of putting a water jacket around a stirlings hot end to heat the hot end with heated water?. Ive seen stirlings running in cups of warm water before and am curious to know how performance will compare to heating the hot end directly with a meth flame. Should i expect more, less, or the same power output? Im using thin 304 stainless for the hot end. Hoping for a reply. Thanks All
Wellington.

Wellington
Posts: 143
Joined: Mon Apr 18, 2016 4:02 am

Re: water jacket for hot end

Postby Wellington » Tue Jan 16, 2018 9:50 am

Wellington wrote:Hello

Has anyone any advice to offer regarding the idea of putting a water jacket around a stirlings hot end to heat the hot end with heated water from meth flame?. Ive seen stirlings running in cups of warm water before and am curious to know how performance will compare to heating the hot end directly with a meth flame. Should i expect more, less, or the same power output? I'm planning to use thin 0.2mm 304 stainless tube for the hot end. Hoping for a reply. Thanks All
Wellington.

Ian S C
Posts: 2045
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: water jacket for hot end

Postby Ian S C » Wed Jan 17, 2018 2:27 am

It would have no comparison with an engine heated by a meths burner, the water jacket would have a maximum temperature of 100*C unless it was a pressure vessel like a boiler, in which case there would be a slight increase in temperature. If you made the water jacket a pressure vessel that would take 100psi, you could get about 198*C, a waste of effort when the heat needed to boil the water would be much better employed directly on an unjacketed hot end.
Ian S C

Wellington
Posts: 143
Joined: Mon Apr 18, 2016 4:02 am

Re: water jacket for hot end

Postby Wellington » Wed Jan 17, 2018 7:54 am

Ian S C wrote:It would have no comparison with an engine heated by a meths burner, the water jacket would have a maximum temperature of 100*C ..........


That's good to know. I was starting to think i would need lots of pricey tubing. I've been looking at the twin syringe engines. They appeal to me because they have two seemingly symmetrical sides which takes the guess work out of dimensions. I have some 2mm wall x 40mm stainless tubing now to start experimenting. do you know of any engines that i can copy that are completely symmetrical with a centered flyweel/generator? Building a linear Stirling seems easy enough but i need to go for a twin design to justify a higher priced engine. Is there a simple experiment i can do with two symmetrical pieces of tubing to get a feel for how stirlings run? Years ago you once kindly provided me with a link to a primer on stirling dimensions but i dont seem to be able to find it. Can you provide that link again?
kind regards
Wellington

Ian S C
Posts: 2045
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: water jacket for hot end

Postby Ian S C » Thu Jan 18, 2018 2:29 am

There is two ways to get the right ratio , (1) if the power piston and the displacer are the same diameter, the stroke of the power piston must be reduced, meaning that either a two throw crank with different crank throws, or a bell crank with different length arms to give the same effect, this way you can make a GAMMA motor with side by side cylinders with a single pin on the crankshaft. These are for GAMMA and BETA motors with a 1 : 1.5 ratio. For an ALPHA motor the ratio is 1 : 1, which as far as maths (mine anyway) is much easier. As far as the Ross Yoke goes, it can be used on GAMMA motors as well as ALPHA, its just made lop sided, with the displacer side 1.5 x the power side.
Your 40 mm SS tube sounds like a good start for a hot cap, unless you can find some cup shaped containers.
Ian S C


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