Ideal gas approach valid for this situation?

jpina · March 16, 2016, 08:11

Dear all,

I’m studying a heating at V=ct of a recipient with a geometry like the following:

The heating is from 298K to 363K with an initial pressure of 1 atm.

Using the ideal gas equation I obtain P2=T2/T1*P1

My big question is:

Can I consider the situation using the ideal gas approach?

My doubt is the low heigth of the geometry, only 0.8mm.

Thanks a lot!

FMDenaro · March 16, 2016, 09:18

and what physical phenomenon should occur for which the ideal gas law would not be valid?? in any case you are much greater than the f.m.p.

jpina · March 16, 2016, 10:30

I have read that for little molar volumes the ideal gas approach is not valid.

But it is not my molar volume what is little, but only my volume! As far as I know, ideal gas approach is not valid for low temperatures or high pressures.

agd · March 16, 2016, 12:46

As FMDenaro pointed out, your geometry is much larger than the molecular mean free path, which will be on the order of 70 nm for your problem. Your pressure and temperature are also neither too low or high.

March 16, 2016, 08:11	Ideal gas approach valid for this situation?	#1
jpina Senior Member Jordi Pina Join Date: Mar 2015 Posts: 157 Rep Power: 11	Dear all, I’m studying a heating at V=ct of a recipient with a geometry like the following: The heating is from 298K to 363K with an initial pressure of 1 atm. Using the ideal gas equation I obtain P2=T2/T1P1 My big question is: Can I consider the situation using the ideal gas approach? My doubt is the low heigth of the geometry, only 0.8mm*. Thanks a lot!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
difference between ideal gas & boussinesq approach	meda	Main CFD Forum	3	September 15, 2020 14:53
Convergence issues with Mixture model, when gas treatment changed to ideal gas	DVS	Fluent Multiphase	1	September 23, 2013 11:59
Two-Phase Buoyant Flow Issue	Miguel Baritto	CFX	4	August 31, 2006 12:02
question about ideal gas thermal flow	yong	Main CFD Forum	0	January 6, 2006 23:58
Gas pressure question	Dan Moskal	Main CFD Forum	0	October 24, 2002 22:02

March 16, 2016, 09:18		#2
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,776 Rep Power: 71	and what physical phenomenon should occur for which the ideal gas law would not be valid?? in any case you are much greater than the f.m.p.

March 16, 2016, 10:30		#3
jpina Senior Member Jordi Pina Join Date: Mar 2015 Posts: 157 Rep Power: 11	I have read that for little molar volumes the ideal gas approach is not valid. But it is not my molar volume what is little, but only my volume! As far as I know, ideal gas approach is not valid for low temperatures or high pressures.

March 16, 2016, 12:46		#4
agd Senior Member Join Date: Jul 2009 Posts: 357 Rep Power: 18	As FMDenaro pointed out, your geometry is much larger than the molecular mean free path, which will be on the order of 70 nm for your problem. Your pressure and temperature are also neither too low or high.