Power

Discussion on Stirling or "hot air" engines (all types)
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selina50
Posts: 2
Joined: Sun May 09, 2010 7:38 am

Power

Post by selina50 »

Hi,

Have recently built a engine. The power was measured which was higher then its kinetic energy of the flwheel at maximum rpm. Any idea why this is? My theory is that the flywheel is merely storing kinetic energy and does no work.

Thank you
Last edited by selina50 on Thu May 13, 2010 4:48 pm, edited 4 times in total.
robertvi
Posts: 7
Joined: Tue Apr 13, 2010 4:03 am

Re: Power of the Stirling engine

Post by robertvi »

Hi, hopefully a real expert will answer your question properly soon :D

I think the kinetic energy is telling you how much energy is stored in the flywheel when it reaches max RPMs (like how much energy you could get out of it if you did some work like lifting a weight by slowing the wheel down to a stop), where as the power tells you how fast the engine is producing measurable (work) energy under load. So you seem to be comparing a fixed amount of energy with an energy production rate.

The power output you calculated should be telling you how much useful work is being generated per second by the engine while its running under your test load. It seems to make sense to me that a good engine should be able to power up its own flywheel quite easily (unless the engine was built by me, in which case it doesn't even run :D haha). So sure, it could be that the rate of energy output under load seems large compared to the total amount of energy stored in the moving flywheel.

Without any external load, the engine is still moving the piston and displacer up and down, overcoming some small air resistance on the moving parts and friction etc, so this must count as work done when their is no intentional load added by you.

That's my 2 cents.
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