It's gonna depend. For example, CO₂ doesn't condense at normal pressures. That's why you see solid and gas CO₂ but not liquid.

I read all the time articles on "non-condensing gases".

I even find a US Patent regarding those gases.

Why dont you read the following.

http://www.freepatentonline.com/20040194311.pdf

H.L.

In the "real world" - No, there is no such thing as a non-condensing gas - if you lower the temperature enough you will liquefy ALL gases (with helium being the leader @ -268.93; close to the unobtainable Absolute Zeros):

http://en.wikipedia.org/wiki/List_of_elements_by_boiling_point

At specific temperatures and pressures - Yes, there will be gases that will not condense.

So to get a better answer - you need to specify a particular temperature and pressure.

Thank you GUEST.

But I still do not understand why in technical litterature we are still talking about "non-condensing gases".

http://www.freepatentonline.com/20040194311.pdf

Regards

H. L.

In general, substances can be described by a phase diagram, also called pressure-enthalpy or Mollier chart. This will show the combinations of temperature and pressure at which the substance can be a solid, liquid, or gas.

Thank you Tornado,

Why dont you read my reply to Guest.

I appreciated your effort.

Regards,

H. L.

Your link is broken. Please provide one that works.

Sorry TVP45,

Try this one, and go to the bottom of the first page.

http://www.freepatentsonline.com/y2004/0194311.html

Regards,

H. L.

A gas might be noncondensing under certain combinations of temperature and pressure, as in the link to the patent, but under colder temperatures and/or higher pressure it would condense. I am not a chemist, and thus might be corrected on this, but I know of no nondensing gases generally.

OK, I get your question now. It's not that there is any particular gas that is non-condensing by its nature. You're looking at heat pipes where a portion of the gas doesn't condense, i.e. is non-condensing.

Are you familiar with heat pipes?

TVP45

No I am not familiar with heat pipes, but I read all the descriptions of the patent and now I have a good idea of what it is.

Thank you,

H. L.

This "non-condensing" gas is in reference to a refrigerant system.

All refrigerant systems, be they a central air conditioner, or a walk in freezer, need to be evacuated of "non-condensing" gases, ESPECIALLY water vapor.

Apparently, someone is trying to use a process via heat conduction to purge a heat pipe of gases that will not condense at certain temperatures, and/or pressures.

You can perform a similar task in a sealed system with a vaccuum pump.

What makes anything the state it is, is temperature, and pressure. A "non-condensing" gas, could be almost any of them, depending on temperature, and pressure.

The most common place for this described apparatus in the "real world" would be a specific type of CPU heat sink. You will often see them with copper pipes attached. The AMD Phenom II series stock supplied heat sink is an example of a heat-piped style sink.

Does that answer your question?