Behaviour of Cryogenic Liquid Nitrogen

[leongw]

What will happen to liquid nitrogen in a storage vessel if the pressure is increased beyond its critical point pressure (33.99 bar abs)? Will it remain as liquid?

 

[Compositepro]

Yes. You can place as much pressure as you like on a liquid. Above the critical temperature there is no difference between liquid and vapor phase so, basically, the phases do not exist.

 

[leongw]

Hi Compositepro,

Thanks for your reply. Does this means above the critical temperature, will it remain as liquid?

 

[IRstuff]

It's sort of both:

http://en.wikipedia.org/wiki/Critical_temperature#Pure_substances:_vapor-liquid_critical_point

http://www.britannica.com/EBchecked/topic/143409/critical-point

It might be considered to be a gas whose density is that of the liquid at the critical point.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[IRstuff]

If you're asking what will happen if you decide to pour out some of the nitrogen, I would think that it would immediately vaporize upon hitting normal pressure, since it's well above its boiling point.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[Chemeng100]

Leongw,


Assuming the initial temperature is -320F and pressure is atmospheric (14.69 psia), it will just remain a liquid until the critical temperature is reached due to heat transfer in the vessel. Then once you reach the critical temperature and stay above the critical pressure, it will be a supercritical fluid.

 

[BigInch]

Then things get wierd. Pipe transport will probably deliver a volume equivalent to what you would get if it was a liguid, but at the pressure drop you would expect for a gas.