Page 11 – The Gas Circuit and Fins
The schematic of the engine shown
previously, represents the patented design of 1816.
I
call that design the “simple beta” or “tin can”
design.
The air flows around the plunger/displacer.
In
the diagram opposite, the base of the displacer has a piston ring.
This makes it possible for the displacer to pump air around a gas
circuit. I call it the “pumped beta”.
The
advantage is that gas can be routed through a larger number of
narrow channels.
This increases the contact area between hot
metal and the gas – better gas heating.
In the
diagram the green displacer is at mid stroke moving downwards.
Air
beneath the displacer is being pumped through ports located around
the cylinder
into slots within
the water cooler.
The gas then passes upward through the
orange
regenerator section.
Then through slots inside the hot cap
(red).
Finally, gas exits the
slotting, passing through ports, into the space above the
displacer.
The whole of the inside of the hot cap and
cooler cylinder is slotted with very narrow slots.
This
dramatically increases the heat transfer surface area. Gas
molecules are only heated/cooled when they touch the metal
surface.
The gas is kept in the slots by a liner which fits
inside, against the fins. This liner also
acts as the
cylinder for the piston and the piston ring at the base of the
displacer.
There is a gap in the slotting, between the
hot cap and the cold end.
This void is where the
regenerator wire is packed.
So, in summary, in the
pumped beta, the gas is circulated, with every stroke,
through
a very much increased area
of contact with the hot fins, the regenerator wire
and the
cold fins.
This larger heat transfer area allows far
larger heat transfer and more power.
