The Naked Scientists

The Naked Scientists Forum

Author Topic: One of those Liquid Nitrogen questions  (Read 8729 times)

Offline BlueSun

  • First timers
  • *
  • Posts: 1
    • View Profile
One of those Liquid Nitrogen questions
« on: 30/12/2011 21:41:10 »
I was thinking ....

how much pressure can I create by placing liquid nitrogen in a container with a small opening at the top?
lets just say the container is unbreakable and the outside temperature is 100f heating the container to the same heat as well.

there is a critical pressure point of LIN to consider of 492.3 psia, what happens to it above such pressure?

thanks for your wisdom
 :) ;) :D ;D 8D 8 :o) O8)


 

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
Re: One of those Liquid Nitrogen questions
« Reply #1 on: 30/12/2011 22:27:04 »
The property you are interested in is Vapor Pressure.

http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=5


Unfortunately, I'm only seeing vapor pressure charts for low temperatures.

Nitrogen filled welding cylinders are distributed as pressurized gas, so the vapor pressure at "Room Temperature" is exceeding 2000 psi or so.
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Re: One of those Liquid Nitrogen questions
« Reply #2 on: 31/12/2011 01:16:04 »
According to my handy-dandy thermo calculator, if you heat LN2 at atmospheric pressure to 100f (37.8C) and don't allow it to expand or escape, it will reach a pressure of 308,425kPa (that's about 44,732 psi) and it will form a supercritical fluid.

Don't know much about supercritical fluids, but I think they are neither a gas or a liquid.

To stay below the critical pressure (3390kPa), you'd have to let it expand to about 22 times its original volume.

BTW, it's not all that easy to heat the stuff. If you put it in a non-insulated container, water from the atmosphere will freeze on the container and slow down the heat transfer. People have made vehicles that run on liquid nitrogen, but one of the major problems is ice forming on the heat exchanger.

(Standard atmospheric pressure is 100kPa)

 

The Naked Scientists Forum

Re: One of those Liquid Nitrogen questions
« Reply #2 on: 31/12/2011 01:16:04 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums