I was excited about this configuration, because on the web I can't found too much information from this type of engine.
Some people said it is failed, and this configuration is not possible to work, but why?
I needed one! :)
OK! I found some pdf documents about some experiments without any usable information for a simple DIY engine.
So, I started to think as a modeller, how can I create a simple design from something what I can buy in the market.
So the air pump was the solution.
This is a long life, low maintenance solution with a good price and long life time period.
I choosen the RESUN's ACO-003 electromagnetic air pump for it.
It has a 45mm diameter piston with dry sealing in a graphite-steel cylinder.
Some modification on the engine:
- took off the air filter and the nozzle cup
- took off the valves
- closed the holes all around the engine
- fixed the spring's end, took off the ball valve from there and closed
- insulated the piston's head with polystyrene
The piston's maximum stroke is approximately 15mm.
After I created a custom passive hot side heat exchanger from aluminium flat heat pipes.
The pipes dimensions: L: 200mm W: 1,2mm H: 5mm
I collected 30 pcs of them with 0,35mm gap between neighboring parts.
Molded the whole HX with two components polyurethane.
That was the biggest pain in the ars...
The engine's free piston is a 100 mm of a simple motocycle's rubber boots.
This is a simple solution for this stroke limit.
The self resonance frequency was near by 30-40 Hz,
so should compress a bit with an adjustable end for the best phase shift.
The regenerator is fine stainless steel mesh.
I used 45˙ different layer by layer for the lower heat conduction.
The length was 30 mm
Added some bolts, threaded rod, PVC tubes
and the chiller was ready to use.
Yes it hasn't got cold side HX!
But no insulated around the cold side, so it is loaded from the outside.
The cold heat exchanger will be the next step. I'll update it as soon as possible!
