Low temp stirling engine

[stephen wynnParticipant @stephenwynn40456]

Hi, Is anyone able to answer a few design questions I have on the low temp stirling engines. or point me in the right direction for contacting somebody who knows all about them?

vbw Steve.

[stephen wynnParticipant @stephenwynn40456]

[stephen wynnParticipant @stephenwynn40456]

Hi, its me again, I should have posted my question.

I have just built a low temp stirling engine. I now want to try and improve on it.

If the displacer had holes or slots cut into it. would it increase the speed that the air could pass from one side to the other allowing more time for temperature change to take place. This in theory would increase the pressure differance on every stroke.

Also it should cut down on air resistance from trying to push all the air around the outside of the displacer.

Also on the hot side of the displacer would it be an advantage to have a heat reflecting surface in order to really isolate the hot side of the system.

Im not lazy just don’t want to try things that have already been proven to be inefficient.

very best wishes Steve

 

Edited By stephen wynn on 02/02/2011 16:12:45

[Richard MarksParticipant @richardmarks80868]

Stephen

Look out for a book called “An introduction to low temperature differential stirling engines” by james r senft, ISBN 0-9652455-1-9, this covers everything including regenerator elements,i will build one when i get the time, sorry about the typing but i have one arm out of action at the moment.

dick

[stephen wynnParticipant @stephenwynn40456]

Thank you for your time Dick. And I hope your arm gets better soon.

I will get a copy of James’s book and do some research.

[Ian S CParticipant @iansc]

Hi steve, One method that has been used is with the foam disc displacer, 4 or 6 hole cut through the disc, these are stuffed with steel wool. have’nt tryed it myself, maybe after the motor I,m just getting started with I might try it, I,v got a LTD motor a bit over 6″ dia that runs at 60 to 80 rpm for about 20 minutes on a small bowl of hot water, it goes very well sitting on a pot of veg when I’m cooking dinner, so it would be interesting to see if there was an improvement with the steelwool in the displacer. It’ll be a month or so till I get round to it. Don’t think there would be any advantage using a reflective surface on the hot side, could be more trouble than its worth, and add weight that you don’t need. Ian S C

[stephen wynnParticipant @stephenwynn40456]

Hi, and thanks Ian,

I have some more ideas, but will wait for the book that I have ordered from the library today.

One thing I can say they should have been called ice engines because they seem to go better sat on ice.

Should I ever get a eureka moment I will let you all know.

Mind you if I completely mess it up, I may tell you and we can all have a laugh together.

once again thanks for the information.

vbw Steve

Edited By stephen wynn on 03/02/2011 11:45:51

[Ian S CParticipant @iansc]

Sit the motor on hot water and it goes in one direction, sit it on ice, and it goes the other way. Sit it on hot water, and put ice packs on top, and away it goes much faster, you can have lots of fun trying all the combinations. You’ll have to work hard to make a complete b***s up, although it some times takes quite a while to get the initial run, but once it goes, it’ll start every time. You’v just got to get the basics right, minimum fiction, eliminate air leaks, make sure that the timing is correct, displacer leading the power piston by 90 deg. Ian S C

[Tony MartyrParticipant @tonymartyr14488]

I can’t see that holes in the displacer would help for long since it would tend to allow heat from the hot plate to radiate to the cold plate since air is invisible to radiation. This would reduce the delta t.

The foam diffuser acts as a radiation buffer.

The comments about running in reverse on ice are interesting – I did this on my office windowsill and explained that it was a solar powered engine; which it was: but to my electrical colleagues I explained it was running on ‘coolth’

Tony

[Richard MarksParticipant @richardmarks80868]

Stephen

Any joy with the book? did it help? would appreciate your thoughts on his design as I will build one some day.

Dick

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