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Multiple tube Thermal Acoustic engine

Posted: Fri Jan 20, 2017 5:35 pm
by derwood
This is just a first test of a new Engine I have designed. The heat source is small but it runs quite well with just a small pencil torch.

[youtube][/youtube]

Re: Multiple tube Thermal Acoustic engine

Posted: Fri Jan 20, 2017 10:16 pm
by thanh-cuibap
i like it !! Can you guide me how to make it ??

Re: Multiple tube Thermal Acoustic engine

Posted: Sat Jan 21, 2017 4:47 am
by Trevor
Me to please Derwood - Love the concept you have done on it. That would have to be the best I have seen of late. Well done!
Trev

Re: Multiple tube Thermal Acoustic engine

Posted: Sat Jan 21, 2017 10:44 am
by derwood
I am going to make some changes to the tail end. It uses 29 stainless steel .25 inch tubes welded on each end. The hardest part is to weld the tubes without air leaks. I tried to mig weld the tubes but could not get leak free welds. Tig welding was the key. Thanks for the interest.

Re: Multiple tube Thermal Acoustic engine

Posted: Sat Jan 21, 2017 4:08 pm
by cbstirling2
Clever. Does the heat need to be concentrated at one end of the tubes?
I wonder if a wood fire could be applied along the tube heat exchanger.
What watt output does it have?
How long can it run? (Gives clues how well it dumps heat.) I wonder how much better it would run with cooling fins (with belt driven fan) or a water jacket. Thinking CHP...

Re: Multiple tube Thermal Acoustic engine

Posted: Sat Jan 21, 2017 5:07 pm
by derwood
cbstirling2 wrote:Clever. Does the heat need to be concentrated at one end of the tubes?
I wonder if a wood fire could be applied along the tube heat exchanger.
What watt output does it have?
How long can it run? (Gives clues how well it dumps heat.) I wonder how much better it would run with cooling fins (with belt driven fan) or a water jacket. Thinking CHP...
Yes the heat needs to be at one end. It dumps heat very well. Im still making some changes so power output is unknown. A wood fire would work well.

Re: Multiple tube Thermal Acoustic engine

Posted: Sun Jan 22, 2017 5:45 am
by cbstirling2
What inspired the multitube design?
I thought your tube within a tube design to be very clever. Is there elements here?

I have a flame licker that doesn't run well, thinking of converting it to a thermo acoustic. Is there literature on the tube ratios and such?

Re: Multiple tube Thermal Acoustic engine

Posted: Sun Jan 22, 2017 6:57 am
by derwood
cbstirling2 wrote:What inspired the multitube design?
I thought your tube within a tube design to be very clever. Is there elements here?

I have a flame licker that doesn't run well, thinking of converting it to a thermo acoustic. Is there literature on the tube ratios and such?
The tube within a tube design ran well but once the inner tube heated up it suffered power loss. cooling the inner tube would be very difficult. I have found no literature on the multiple tube design. I just took an educated guess on the number of tubes which still needs to be adjusted. I have noticed a big difference in efficiency with the multiple tube and cooling is easier to achieve.

Re: Multiple tube Thermal Acoustic engine

Posted: Sun Jan 22, 2017 3:02 pm
by cbstirling2
In the far end, is there stainless wool for a regenerator? Seems a little odd that the middle space is heated...

Re: Multiple tube Thermal Acoustic engine

Posted: Mon Jan 23, 2017 1:15 pm
by derwood
Ive made some changes to the engine. It seems that the heating is so much more efficient that I have been able to greatly increase compression. approx. 1 : .75 , lowering compression does not increase stroke length. Currently Piston 3.35inch diameter, stroke 4inches, 3500 strokes per/min free piston mode. Piston and rod weight is 1.9 lbs.

Re: Multiple tube Thermal Acoustic engine

Posted: Mon Jan 23, 2017 1:45 pm
by Aviator168
That's excellent derwood. Like to see a load on it to measure the power output.

Re: Multiple tube Thermal Acoustic engine

Posted: Mon Jan 23, 2017 9:45 pm
by derwood
I noticed an error in my last post. It should read 1500 strokes per/min.