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Pressure and temperature measurements
Posted: Thu Sep 30, 2010 1:01 pm
by HeavyChevy
Hello to all. I have built my first tin can stirling engine by following Mr. Boyd's directions (thank you) and after some adjustments, I was able to get it to run.
Next I plan to add some instrumentation to do some analysis (it's for a school project). Has anyone measured the hot and cold air temps and the pressure in the cylinders? I'm trying to determine if I can use a manometer or if I'll need a psi pressure gauge.
Thanks in advance for your input.
Re: Pressure and temperature measurements
Posted: Fri Oct 01, 2010 9:52 pm
by jimlarsen
I use a non-contact infrared thermometer to measure surface temperatures on the engine. I have not measured pressures. You might be able to glean a little info by reading about this engine:
http://stirlingengine.com/product/29
You can see my non-scientific temperature reading at the end of this short video:
http://www.youtube.com/16strings#p/u/20/VaNingzXkvI
Jim Larsen
http://StirlingBuilder.com
Re: Pressure and temperature measurements
Posted: Wed Oct 13, 2010 11:32 am
by HeavyChevy
In case anyone is interested, I measured my tin can engine.
Air temperature inside displacer:
Hot air temp = 275 deg C
Cold air temp = 102 deg C
Gauge pressure in power cylinder:
Contraction stroke = -4 inches of water
Expansion stroke = +3 inches of water
Re: Pressure and temperature measurements
Posted: Sun Oct 17, 2010 11:43 am
by speedless
Hi
Im very interested.
How did you measure? In practical I mean,instruments,pressure connections ....
The indication of more Contraction force than Expansion force
confirms the subjective "feeling",I have from experiments.
Jan
Re: Pressure and temperature measurements
Posted: Mon Oct 18, 2010 3:35 pm
by HeavyChevy
For the temperatures, I used type K thermocouples. I drilled a small hole in the top and bottom of the displacer cylinder and inserted the tip of the thermocouple into the dead air space between the displacer piston and the displacer cylinder.
For the pressure, I drilled a small hole at the base of the power cylinder and inserted a small (probably <2mm OD) metal tube. It’s in the dead air space between the power piston and the displacer cylinder. I then attached a plastic tube, shaped it into a “U” shape, filled it with water to make a manometer.
Re: Pressure and temperature measurements
Posted: Thu Oct 21, 2010 6:50 pm
by HeavyChevy
Good point Ian. My speed was 130 rpm. Is that about normal? Can I ask how you measured the torque? I need to do that with mine but haven't thought of a good method.
Thanks
Re: Pressure and temperature measurements
Posted: Sat Oct 23, 2010 9:08 am
by HeavyChevy
I don't have a copy of Rizzo's book. Would it be possible for someone who has it to scan and post the picture? does anyone have a photo of their own torque measurement device? What values of torque are you all getting from your tin can engine?
Re: Pressure and temperature measurements
Posted: Sat Oct 30, 2010 9:31 am
by speedless
Hi HeavyChevy
Thanks for your answer.
If you just want to show the poweroutput you can attach a little dc-motor to the flyweel and a multimeter to show the poweroutput.
Voltage/revs or with a load (LED) amps/rev.
Check this for a cheap and easy rev.counter:
http://stirlingengineforum.com/viewtopic.php?f=1&t=580
Best of luck with your project.
Jan