mounting distances for heat/cooling tanks?

[jumpers]

I am building a walking beam type stirling, and would like to know the "proper distance" for the heating/cooling tanks. I am useing the plans provided here at the best site around for Stirling information!!
Right on Mr. Boyd!

[SScandizzo]

Jumpers,

While I haven't built this particular engine, I can confidently make some suggestions. The purpose of the fire box and the water tank is to provide a temperature gradient across the displacer cylinder. The greater the differential, the more efficient the engine will be. As a general rule, I'd suggest dividing the displacer cylinder into thirds: top third for the cooling tank, bottom third for the fire box, and middle third exposed.

-Stefan

[jumpers]

Thanks for your reply, now I can solder my unit complete.I should have realized the rationality! Dam, lol.(just kidding). So then; if we further that equation to the effect, to gain more action on the power piston; would it be recommended to increase the heat/cold to higher/lower temperatures,and provide a larger expantion/contraction space to act on the power piston?

[SScandizzo]

I think its safe to say that increased heat and cold will generate more power per stroke. HOWEVER, there is a practical limit. Take a LTD (low temperature differential) engine as an example: I wouldn't recommend putting a propane torch on the hot side of one of those as the tolerances and materials were not designed for such usage.

While applying more heat is the probably the easiest method for increasing power output, it is not the only one nor does it improve the engine's efficiency. Decreasing friction, reducing dead space, improving temperature separation, and ensuring a closed (sealed) system all make the engine more efficient (more power per unit heat energy).

-Stefan

[stanhbaker]

Decreasing friction, reducing dead space, improving temperature separation, and ensuring a closed (sealed) system all make the engine more efficient (more power per unit heat energy). -Stefan

Stefan, Jumpers:
DO NOT SEAL an LTD Stirling Asolutely Leak Tight. It will bind up as the overall/average internal temperature rises, increases the internal pressure, and prevents return stroke of piston.

The leakage at the displacer rod gland is usuallly sufficient to allow the mean/average(?) internal pressure to remain at or close to atmospheric.

Larger machines frequently incorporate closed pressurized crankcases in which case the overall internal pressure may be several bars.