Will water or ATF absorb helium?

[spinningmagnets]

I am contemplating the problems with using helium as the medium in a Stirling to see if its worth the trouble.

I believe the displacer can be moved with external magnets, so there will be no possible shaft seal leakage from the displacer cylinder. This leaves the power-piston rings and the power piston rod seal.

If I put the expanding/retracting helium into the top of a "U" pipe with fluid in it, a piston on the other side would be raised and lowered by the cycling fluid.

Even the first version should have two side by side "U"-tubes, with the two piston rod ends attached by a rocking beam to each other. This would prevent the lifting piston from trying to draw a cavity void from the liquid.

Hydraulic actuator pistons and rods are easily available off-the-shelf. The piston seals are well-designed to seal while sliding in a cylinder with high-pressure hydraulic oil.

I know from reading about ram water-pumps, that a snifter valve must be included to keep some air bubbles in the accumulator (an upside down cup) so it can act as an air-spring.

Without this snifter valve, the air pocket will be absorbed over time by the water. Also, carbonated beverages are another example of a pressurized gas (CO2) being absorbed into a liquid.

I can envision this working on a high-pressure/low-RPM engine. Helium is non-flammable, cheap, and easy to get from baloon suppliers, but leakage past seals on most conventional Stirlings can be a major roadblock to making an easy-to-build high-power Stirling.

The magnetic seal-less displacer and liquid U-tube seal might fix this problem,...IF the gas is not absorbed by the liquid.

I am leaning towards synthetic Automatic Transmission Fluid (ATF)

Any thoughts on this? Thanks in advance...

[supertankerm60a3]

I only know these bits of info. Helium is used in DEEP scuba diving because it is NOT absorbed by the blood (mostly water) under pressure. During the Apollo program they tested the fuel and oxidizers used in the hypergolic engines (Service and Lunar Excusion Modules) because they were afraid of the fuel becoming "fizzy". It was not absorbed there either. So I would guess you would be safe.