Heater & Regenerator Design

Discussion on Stirling or "hot air" engines (all types)
cbstirling2
Posts: 107
Joined: Sat Dec 17, 2016 9:35 pm

Re: Heater & Regenerator Design

Postby cbstirling2 » Sat Mar 11, 2017 10:10 am

Looks cool! Excited to see it run. Please post a YouTube video.

Is there enough distance for the displacer pushrod?

Bumpkin, good question. Do people bring the crank back to center for uniformity or is it a balance concern?
I think there is too much metal in that arm. I'd drill holes it in and remove metal.
CBStirling2

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Mon Mar 27, 2017 4:54 pm

Couple of recent pics.

Almost ready for a run!!!!

Image

Image

Image

Trevor
Posts: 164
Joined: Sun Nov 06, 2016 4:07 am

Re: Heater & Regenerator Design

Postby Trevor » Tue Mar 28, 2017 3:55 am

Really looking good Richi - It will be nice to see that one running.
Trevor

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Tue Mar 28, 2017 7:54 am


richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Tue Mar 28, 2017 7:55 am

Quick little test run this morning. No water connected so only a short burst as didn't want to get it too hot.

James
Posts: 12
Joined: Sun Nov 13, 2016 10:44 pm

Re: Heater & Regenerator Design

Postby James » Tue Mar 28, 2017 4:57 pm

Hi richi,

That's one nice Stirling engine model you have there. Just curious though if have further information like its power output and the estimated cost for making it.

cbstirling2
Posts: 107
Joined: Sat Dec 17, 2016 9:35 pm

Re: Heater & Regenerator Design

Postby cbstirling2 » Tue Mar 28, 2017 8:45 pm

Awesome! It would be interesting to try a few different phase angles to see differences in output.
CBStirling2

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Wed Mar 29, 2017 5:28 am

I was happy it ran so well. It was my first build so was a little nervous.

It's cost me around £300 in parts and materials.

I designed it to be fairly modular so I could change various components to try different things later on.

I plan to enclose the crank case and pressurise it for the next step. I'm hoping for 10 Watts at atmospheric air and hope to push it towards 100W with pressure and perhaps alternative gasses.

Ian S C
Posts: 1954
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Heater & Regenerator Design

Postby Ian S C » Fri Mar 31, 2017 2:31 am

My feeling is that the main problem with pressurising a motor is designing a good seal for the crankshaft bearing,. You will find as pressure rises, it will use more heat, and require better cooling.
Ian S C

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Fri Mar 31, 2017 11:37 am

I've done away with the need for a crank shaft seal all together. The motor / generator in inside the pressurised volume. I use it to start the engine, then flick a switch over to connect it to my load.

Yes i expect the returns from increased pressure to be a lot less than theory. I can see it will show the limitations in heat exchanger surfaces. Im pretty happy the water cooled parts will be fine and stay cool. I have done some work to increase the surface area on the inside of the cylinder, ive doubled it over a smooth bore, but more would be better.

I've also allowed forma small ring between heater and cooler. At the minute its aluminium with graphite gaskets either side. But the plan is to machine this from a ceramic. I will add this at some point, the material is fairly expensive.

Ian S C
Posts: 1954
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Heater & Regenerator Design

Postby Ian S C » Sat Apr 01, 2017 1:31 am

Good work there, that is the ideal answer. I thought perhaps you were just going to box in the current motor, with the crankshaft sticking out to take a pulley. Under ideal conditions the start motor should not need more than about one rev under power to start the motor.
Ian S C

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Sat Apr 01, 2017 10:55 am

The plan is to box in the base. At the end of the crank is a gear. The motor / generator will be in a solid housing and the shaft will pass into the main housing to engage the gear. I will seal it with an o ring in the motor housing, so i can still adjust the gear ratio via different pinion gear sizes as the housing will have a degree of adjustment.

The current mounting posistion is just for now running at atmospheric. Time is fast running out on my project deadline so the results will all from atmospheric runs.

I wired it up today and sussed out the temperature data logger hardware / software. Water cooling plumbed in. So it was time to give it more of a run.

Was outside this afternoon and was a bit windy so was blowing the gas burner round a bit.

But managed 7.7 Watts at 500 rpm. Quite happy with that.

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Sat Apr 01, 2017 11:40 am

Excuse the mess.

Short clip as it cooled down.

https://youtu.be/VvL3IXLPNS4

richjbarnett
Posts: 21
Joined: Fri Dec 02, 2016 9:57 am

Re: Heater & Regenerator Design

Postby richjbarnett » Mon Apr 03, 2017 1:45 pm

Little update.

Got a little more organised tonight. Data loggger recording etc.

Managed a peak output of 15.3 Watts.

Happy with that.

Ian S C
Posts: 1954
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Heater & Regenerator Design

Postby Ian S C » Tue Apr 04, 2017 3:08 am

It will get better as the motor gets run in, at the rate your going you might end up with nearer 20 Watts.
Ian S C


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