Multiple tube Thermal Acoustic engine

Discussion on Stirling or "hot air" engines (all types)
derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Multiple tube Thermal Acoustic engine

Postby derwood » Fri Jan 20, 2017 5:35 pm

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.

https://youtu.be/5fluS_u13wI

thanh-cuibap
Posts: 147
Joined: Tue Sep 06, 2016 8:09 am
Location: Việt Nam

Re: Multiple tube Thermal Acoustic engine

Postby thanh-cuibap » Fri Jan 20, 2017 10:16 pm

i like it !! Can you guide me how to make it ??

Trevor
Posts: 169
Joined: Sun Nov 06, 2016 4:07 am

Re: Multiple tube Thermal Acoustic engine

Postby Trevor » Sat Jan 21, 2017 4:47 am

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

derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Multiple tube Thermal Acoustic engine

Postby derwood » Sat Jan 21, 2017 10:44 am

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.

cbstirling2
Posts: 113
Joined: Sat Dec 17, 2016 9:35 pm

Re: Multiple tube Thermal Acoustic engine

Postby cbstirling2 » Sat Jan 21, 2017 4:08 pm

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...
CBStirling2

derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Multiple tube Thermal Acoustic engine

Postby derwood » Sat Jan 21, 2017 5:07 pm

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.

cbstirling2
Posts: 113
Joined: Sat Dec 17, 2016 9:35 pm

Re: Multiple tube Thermal Acoustic engine

Postby cbstirling2 » Sun Jan 22, 2017 5:45 am

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?
CBStirling2

derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Multiple tube Thermal Acoustic engine

Postby derwood » Sun Jan 22, 2017 6:57 am

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.

cbstirling2
Posts: 113
Joined: Sat Dec 17, 2016 9:35 pm

Re: Multiple tube Thermal Acoustic engine

Postby cbstirling2 » Sun Jan 22, 2017 3:02 pm

In the far end, is there stainless wool for a regenerator? Seems a little odd that the middle space is heated...
CBStirling2

derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Multiple tube Thermal Acoustic engine

Postby derwood » Mon Jan 23, 2017 1:15 pm

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.

Aviator168
Posts: 308
Joined: Tue Feb 08, 2011 2:29 pm
Location: Brokeville, NY. USA

Re: Multiple tube Thermal Acoustic engine

Postby Aviator168 » Mon Jan 23, 2017 1:45 pm

That's excellent derwood. Like to see a load on it to measure the power output.

derwood
Posts: 113
Joined: Sat Dec 11, 2010 10:15 pm

Re: Multiple tube Thermal Acoustic engine

Postby derwood » Mon Jan 23, 2017 9:45 pm

I noticed an error in my last post. It should read 1500 strokes per/min.


Return to “Stirling and "Hot Air" Engine Forum”

Who is online

Users browsing this forum: Baidu [Spider], Bing [Bot] and 67 guests