do permeability and inertia loss coefficients values depend on working fluid?

sh.a.ghafour · October 7, 2016, 10:56

Dear colleagues,
i work on the simulation of Stirling regenerator as a porous media.
i have correlations for Cf vs. Re and Nu vs. Re for a specific regenerator with Hydrogen as a working fluid and with these correlations i can calculate permeability and inertia loss coefficient (the inputs for porous media model).

can i use these coefficients for the same regenerator but with Helium as the working fluid and under different Temperatures ?????
Also can i use the same correlation for Nu into heat transfer coefficients calculation for the second case?

LuckyTran · October 7, 2016, 23:23

The loss coefficients are properties of the flow and the shape and structure of the porous media.

An analogue would be friction factor, which we take as only depending on Re and shape factors (roughness, etc).

sh.a.ghafour · October 8, 2016, 00:23

OK
If i has a correlation in the form of "Cf =a1/Re+a2" for a specific regenrator but with H2 as a working fluid. Can i use the same correlation for He as the working fluid????

Goenitz · April 15, 2019, 14:05

Quote:

Originally Posted by sh.a.ghafour

OK
If i has a correlation in the form of "Cf =a1/Re+a2" for a specific regenrator but with H2 as a working fluid. Can i use the same correlation for He as the working fluid????

Hi

Do you know how can we calculate resistance loss coefficient (for CFX input) from inertia loss coefficient?

Dronzer · July 5, 2020, 23:38

Quote:

Originally Posted by LuckyTran

The loss coefficients are properties of the flow and the shape and structure of the porous media.

An analogue would be friction factor, which we take as only depending on Re and shape factors (roughness, etc).

Hi LuckyTran,

I have a tubular, U-shaped heat exchanger geometry where the working fluid is air.
This model has been tested (experiments) in detail earlier, and its porous media coefficients have been estimated.
Now I need to use the same heat exchanger geometry (for CFD), but the working fluid is replaced with water.
Can I use the above porous coefficients for water?
Kindly make your replies.
Thanks in advance.

October 7, 2016, 10:56	do permeability and inertia loss coefficients values depend on working fluid?	#1
sh.a.ghafour New Member shreehan Abd El-Ghafour Join Date: Apr 2015 Posts: 12 Rep Power: 11	Dear colleagues, i work on the simulation of Stirling regenerator as a porous media. i have correlations for Cf vs. Re and Nu vs. Re for a specific regenerator with Hydrogen as a working fluid and with these correlations i can calculate permeability and inertia loss coefficient (the inputs for porous media model). can i use these coefficients for the same regenerator but with Helium as the working fluid and under different Temperatures ????? Also can i use the same correlation for Nu into heat transfer coefficients calculation for the second case?

October 7, 2016, 23:23		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,752 Rep Power: 66	The loss coefficients are properties of the flow and the shape and structure of the porous media. An analogue would be friction factor, which we take as only depending on Re and shape factors (roughness, etc).

October 8, 2016, 00:23		#3
sh.a.ghafour New Member shreehan Abd El-Ghafour Join Date: Apr 2015 Posts: 12 Rep Power: 11	OK If i has a correlation in the form of "Cf =a1/Re+a2" for a specific regenrator but with H2 as a working fluid. Can i use the same correlation for He as the working fluid????