When compressed nitrogen enters a room

[Coolman8]

Can anyone please advice the impact when compressed nitrogen at an absolute pressure of 3 bar, -50deg C dew point entering a room (atmospheric pressure, 20 deg C 45% RH) at a volume flow rate of 72CMH.

Is this consider a polytropic expansion process?

Any help would be greatly appreciated.

 

[stanlsimon]

Assuming there is a throttling valve that does not allow much heat transfer or produce any useful work you approximately have an isenthalpic process. At three bar this would be like letting the air out of a tire. A cooling of the gas stream should be expected.

Use of the polytropic equations should be limited to quasistatic processes where Pv**n=constant.

 

[mbeychok]

Is this not essentially the same question which you asked in the "Chemical Engineering Other Topics" forum, which thread now has 18 responses.

Nitrogen gas is a dangerous asphyxiant and filling a room with nitrogen is very unsafe. Would you tell us why you are asking your question?

In any event, as mentioned in the previous response:

(1) if the nitrogen gas is initially below its Joule-Thomson inversion temperature (348 deg C at atmospheric pressure and somewhat different at 3 bar of pressure) and

(2) the gas enters through a throttling valve that does not allow much heat transfer and does no mechanical work

then you have a constant enthalpy expansion (called a Joule-Thomson expansion) and the gas will be cooled.

Looking up the Joule-Thomson coefficient at the pressure and temperature of your nitrogen gas (and you haven't told us the gas temperature), and then calculating the temperature change is a tedious job. Ask a consulting chemical engineer to do it for you.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

[stanlsimon]

If you are proposing to use a system like this to put out a fire then you should look at Halon systems, or the newer versions which use the method of injecting non lethal quantities of gas into the space which are concentrated enough to interfere with the combustion process on the molecular level. Look at the FIKE website and follow NFPA requirements for this kind of system so that you don't kill some people and maybe yourself.

 

[Coolman8]

It is not my call but thanks for the information. We will be seeking help from the experts to analysis the effectiveness of the mixing process

Thanks again for the help. Appreciate it.