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updated on 09/17/08 |
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Page
created in September 2002 |
version 1.1
Improvements over version 1.0
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1
- slight increase in capacity obtained by replacing the bottom
(end) of the original unit with a flat aluminum disc ep 0.5
500 t/min
2
- replace styrofoam displacer a displacer-regenerator
in Scotch Brite thick and 11 mm using a slide in stainless steel
piano wire
This mover, like its predecessor, is simply stuck to the glue heat, which in this case, good resistance to repeated operation of the engine on a cup of boiling water - disadvantages: the tendency of the Scotch Brite to unravel slightly after a few hours of operation at "high speed" - to remedy this, we take the precaution of coating the periphery of a thin layer of transparent adhesive neoprene (the few fibers that were created from the upper and lower surfaces do not appear very annoying - maybe they play the role of springs?)
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3
- increase the diameter of the piston rings which increases
to 20 mm, and use of a membrane packs (available
in stores, see FAQ) - (optionally interposing
an O-ring seal between the two washers)
4
- adoption of a system of adjustment on the length of
the piston rod: this coupling by two nuts welded to the tin can to
balance the travel of the rod relative to the deflection of the diaphragm (the
deflection of the membrane must be> 2 mm than the pushrod engine)
5 - results: gain in performance quite sensitive, since
the operating time from 35 minutes to 2 hours over a cup of boiling water
and more than 14 hours in a thermos bottle of 0.85 liters (at
right) - the
maximum speed from 170 rpm to 540 rpm - the minimum temperature gradient down
to 22 ° C to 10 ° C - mechanical power developed jumped "dramatically" since
jumps from 1 mW to about 7 mW!
Skinned
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Note: the model
is fitted by the zigzag rod appeared a little later on the 1.2 engine
and 3.2 |
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Measures
Below are some curves
showing the speed of rotation depending on the temperature difference, the
torque and power available
(missing statements for the last two, the area between 0 and 200 rpm is uncertain
and could have a significantly different look ...)
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speed |
couple |
power |
having heard that
the TGV had recently reached the 575, I met the challenge with the Stirling
1.1
posed on a cup of
boiling water and two ice cubes on the top shelf, it has easily surpassed
the 620 rpm: new record!
To achieve this level of
performance  ,
he took first place the lower plate of 0.5 mm, a little too soft, a
hard aluminum 2 mm thick. Then you will notice on the video a little
hard red side of the piston engine: it is a relief valve (1).
Its role is to prevent the internal pressure exceeds
atmospheric pressure. Indeed, when the engine is placed on a heat source,
resulting in an increase of pressure in this configuration, is detrimental
to performance. The relief valve pressure stabilizes the average engine
in a few gf/cm2 below atmospheric pressure and allows a more balanced
functioning of the membrane. Installing this valve saves about 50 rpm. |
This video is running at 15 fps, the frame
analysis shows that the speed is around 600 rpm at the beginning
of the sequence, 590 rpm for close-ups, and 575 rpm / min at the
end of traveling - clockwise direction when the ice is at the forefront |
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(1) relief valve consists of a tubular rivet hole which is bonded a rubber disc cut from a balloon - the disc is glued on half of its periphery to allow it to rise as a result of the pressure and allow air to escape - see models 1.2 , 3.5 , 3.6, 3.7, Otona no Kagaku, and FAQ
Good
DIY ... |