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Has been experimenting the said subject and found the results fascinating. Both ionizing and adding a little mercury to the working gas can increase the thermal conductivity a lot. However, I do not have measurements.

ionize what, and how?
Have you at least quantized "of-thumb" the influence of ionization, and the use of mercury?

Mercury is present in vapor form only at temperatures above 629-800 ° K, in an engine "normal " cycle (from 300 to 1000 ° K), almost all of the mercury is liquid, it seems a mess.

However, to my knowledge the mercury, but overall its vapors are highly toxic, and harmful to the human genome (MINAMATA teaches !!!: SEE "MINAMATA DISEASE") ).

Minamata: please see:
http://en.wikipedia.org/wiki/Minamata_disease

Ionizing could be easily done, I can find small car / house ionizers in the dollar stores - install in the regenerator, add power; done like dinner.

I think the only practical way is to change the gas to some thing like Helium, I see that one of the local shopping chains here in NZ have small cylinders of Helium for filling party balloons. You could try Argon, it's readilly available. You only need enough to displace the air in the sealed side of the motor, unless it is pressurised, which it really should be if you are worrying about power, and efficiency. ian S C

which it really should be if you are worrying about power, and efficiency.

Isn't this why we are working on stirlings. The bottom line is. We need to get a lot of heat in to/out of the working gas very quickly. Stirlings are already in a disadvantage as the temperature is much lower than ICEs. However, we can make it up by pressurizing.

hephaestus wrote:Ionizing could be easily done, I can find small car / house ionizers in the dollar stores - install in the regenerator, add power; done like dinner.

OK, but we're all over again, if you buy an ionizer (for air) as you do it go? ....with external source of power I suppose, and it is possible that the energy produced is not sufficient to maintain the ionization, ....is a closed way.

The right way is what is indicated by Jan, use of fluids of good performances, in adequate pressure (and an affordable cost, because the fluid is contained and not lost).
This means a serious construction, with passages in thin tubes to maximize the minimum viscosity of the gas. and especially in a closed body; a so important construction needs or recommends high temperatures and relevant materials, efficient cooling system...
Good, a thousand miles from cans and wire, ...

I think you would have difficulty getting an Ionizer to work inside a hot displacer cylinder, and definitely not a cheap dollar store one. Ian S C

It would be a nice thing for a low temp engine. For a high temp engine, using a internal heater (heat sink) is much more effective. I personally do not like to use many small heating tubes. It is just too many parts and more likely to have a leak. Now, we just have to figure out how to get the heat into the internal heat sink.

It is true that the best solutions are simple, and you are sorry to use so many tubes because it is complex; despite that sometimes you fall into cumbersome and unlikely solutions.
The criteria of simplicity must be also in the principles of operation.
The heat transfer without tubes is only with small engines. With engines larger, the surface to volume ratio becomes increasingly difficult and tubes are the solution considered necessary.
It 'also true that much progress has been achieved thanks to those who sought easy shortcuts.

Ah. You sounded like tubes are the only way to increase contact surface. Tell you the truth. The regenerator heats up the gas much better than those tubes ever can.

Internal, and external finning is another way of increasing heating area. I believe that the method used for brazing tubes is a vacuum system, I think this is some thing to do with the manufacturing of refrigerators. Ian S C

Aviator,
Only way? Not, of course.
But how to regenerate a heat that has not entered the engine, ...and is gone?
Ian said true, fin is a good solution, ... for small engine.
The passage of heat is proportional to the surface (the heat passes through the surfaces), the heat content is proportional to the volume (to fill), magnifying a motor areas increase with the exponential 2 (square), but the volumes in the exponential 3 (cube).
An engine of the same shape but three times large has an area 9 times larger, but has a volume 27 times larger.
Magnifying an engine input and output of heat have become more complex, of course if someone consider that the performance has some ...importance.

That depends on design. For example. If you keep the stroke the same, the increase in bore size does not compromise area to volume ratio.

Aviator is not question of bore.
Tripling the size of an engine. How do you bore for an heat exchange surface 27 times greater? How do you build an engine under pressure like that?