This engine design is not perfectly new in principle. A similar design was
demonstrated at the 8th ISEC in Ancona 1997 by Prof. Rallis (University
of
Witwatersrand; SouthAfrica), which originally is from Mr.Silberbauer (University
of Witwatersrand;South Africa). I modified it by mounting a
diaphragm Ringboom piston to the side of the cylinder and turning the
displacer around an axis instead of lifting it directly. In this
first-draft-design
I built the cold side from 1mm aluminum sheet, instead of using a water cooled
aluminum foil to build a pumping chamber above a fixed plate.
As well you can tell by the photos, that I took used parts....as I said ....this
is a frist draft engine, although my other engines are very diletantic
built and lag accuracy.
The advantage in relation to the original horizontal design of Silberbauer
simply is, that it's simpler to build (for a beginner or a diletantic builder),
because no spring is used here and a stroke of almost 20mm of the
displacer could be reached, while the Ringboom piston's stroke is only
2mm.If I would have built it like Silberbauer, for the same displaced
volume, I would have to build a Ringboom piston with a 10mm stroke
which would have had more friction in a diaphragm design.Of course the
original Silberbauer design is better for vertical sunlight and this design
you see here, has no thermodynamical advantages.
The photos shows the displacers axis, made from brass. The side walls are
from a plastic drainage tube (180mm in diameter). The cold side is just a
1mm aluminum sheet, fixed in its center by a 4mm screw to the front
acrylic 4mm glass for being a better pressure vessel. The 13mm isolation
tube
(tubing for isolation electrical wire) is just taken from my workshop. Perhaps
some other dimensions for a water column will do better ? The diaphragm
rubber is a piece of childrens ballon. While mounting this diaphragm, you
have to be carefull to place the rubber that way, that it as little in tension
as
possible for its intire 2mm stroke. The cylinder is sealed with silicon paste.
The brass axis is a 2mm tube with an 1mm piano wire inside. The displacer
is made of polyurethan foam and wedge shaped, covered on its hot side with
black silk (which was just at hand in my workshop, but black paint will
do even better). The engine has no stand. I liked to publish it here on my
webside, because of its simplicity.
To give some numbers:
Cylinder diameter 180mm
Speed
120 strokes a minute
Delta T
40 degrees C
Ringboom piston 15mm diameter
Ringboom diaphragm 24mm diameter
Front
acrylic glass
Water column tube 13mm diameter
