Cooler on Displacer Cylinder

[Osama]

Hey!

I have seen some designs of Gamma Type Stirling engine and I found a cooler/heat sink on the displacer cylinder. Why would we need a cooler on the Displacer Cylinder when we have the power piston cylinder (cold cylinder) to maintain the temperature difference?

[Ian S C]

Osama, displacer cylinder; 1/3 hot, middle third, then bottom 1/3 cold, better to start cooling the air here before it enters the power cylinder, and on a BETTA motor that is the power cylinder. It's usually the easiest place to fit a water jacket, or cooling fins. Ian S C

[Osama]

Hey Ian,

So if I am using a regenerator in the pipe connecting the two cylinders, would I need to place the cooler then?

Thanks

[Ian S C]

The cooling system would be at the cold end of the regenerator, ie., in a GAMA motor, on the power cylinder.
Ian S C

[Osama]

Okay thanks!

I am using a piston rod to connect thee displacer piston to the flywheel. Can you recommend what seal to use for the piston rod?

PS: My engine is GAMMA type, with hot end temperature of 400 degree centigrade and the cylinders will be pressurized at 1 atm pressure

[Ian S C]

I have used a number of different materials to make bushings for displacer rods: Graphite impregnated Teflon, Brass, Bronze, and Cast Iron, all with success, mostly I use stainless steel for the displacer rod, often it is tubing. Ian S C