Could someone tell me how easy is the following process or if it is possible at all ?

Question

Turn Helium from a liquid into a gas and back again ?
I also want to know if the process can be made portable ?

I would appreciate anyone who answers this question if they would leave an email or IM contact to come back to with any further questions I may have please ?

Answer 1

Turning helium from liquid to gas is extremely easy. Its boiling point is 4.2 degrees Kelvin. Liquefying it is not as easy. But it is routinely done, and liquid helium is the primary cooling method for cryogenic work and experiments. Its cost in 2002 was around $5/liter US. By comparison, liquid nitrogen is only $0.25/liter. It is produced most efficiently on a large scale. It's certainly possible to make the process portable, but you'd need a really good reason to justify the expense. Even if you can't practically liquefy it locally, it's almost certainly worth recovering the helium gas and returning it to a central site for purification and liquefaction.

Answer 2

It is certainly not true that you can convert any gas to a liquid by applying pressure - you can only do this below the critical point, and this is low for Helium (5.2K).

Liquifying gases is done by aidabatic expansion, otherwise know as the Joule Thomson effect. This means allowing the gas to expand without allowing it to exchange any energy at all with its surroundings. It is achieved by passing the gas under pressure through a well insulated throttle. As the gas expands it cools. The cooled gas is then allowed to futher cool the gas that is being pressurised for expansion.

There is a catch - which is that cooling only occurs below the inversion point. Above this temperature expanding the gas actually heats it, and for helium the inverstion temperature is a chilly -222 C. So you have to get it there first before using expansion.

Onnes won the Nobel prize for liquifying helium, because it is such a tricky feat.

Answer 3

Any gas can be condensed into liquid form by applying enough pressure to it, or lowering the temperature or both. When propane is stored in a tank it's under so much pressure that it's in liquid form. When a leak develops in the tank, or the valuve is open, the propane leaks out in gaseous form.

You would just need a way to compress the helium and/or cool it enough so it goes into liquid form. This may be difficult to do as it would require ALOT of pressure and a strong enough tank to withstand the pressure.