I started recently a new Rotary Displacer [RD-LTD] stirling project. Idea, as usual, is to make use of regenerative cycles and utilize cheap and abundant low quality heat. I will not (yet) tell you my life story, so going to keep it short :)
Idea Summary:
1. Old pressure vessel (300+bar design pressure) of ~30l volume is cut open, with the cut being perpendicular to the cylinder axis.
2. A unit is build, consisting of hot circuit (HC), regenerator (R) and cooling circuit (CC), each taking 120 degrees of the cylinder.
3. The heat and injected and exported using high pressure seamless pipes of 16mm outside diameter, with a 2mm wall, for which openings are made in the pressure vessel, and the pipes are welded in these openings, so that hermetic conditions are held.
4. A displacer, taking up 120 degrees is build. The displacer initial position is midway between HC and CC, whereas in action is oscillating 60 degrees from this midpoint in both directions, so as to displace the large fraction of mass of the working fluid from HC into R and consequently from R into CC.
5. The total woring volume is ~ 12 to 15l.
6. The design mean operating pressure is ~60bar, which depending on the results of hydrostatic testing of the unit will be adjusted appropriatly within reasonable safety margins (0.3-0.5 the pressure of the test).
7. Design working temperature is: HC(290K to 390K); CC(280K to 300K);
8. Power output will be through a second hydraulic circuit, connected in series with the first, but with a fluid of much higher viscosity (oil for hydraulic machinery). Hence, a quasy liquid piston setup will be made. The liquid piston (oil) will then be displacing a regular 'solid' piston.
Main aims of the work are:
Increase heat exchange area, working space volume and pressure as much as possible, so as to achieve as high power density with as low temperature difference as possible. Other design strategies include system simplification, so that fabrication in 'garage' conditions is possible.
Currently, we have cut the cylinder, mounted the flange and tested the unit up until 60 bars. Tests with higher pressures will follow. The design of the heart of the engine, namely the heat-exchange-regenerator, as well as all the rest is under development.
Here are some pics and graphs:
- complete.png (89.61 KiB) Viewed 3423 times
- mech2.png (87.84 KiB) Viewed 3423 times
- complete.png (89.61 KiB) Viewed 3423 times