Ansys CFX condensing flows

maheshchamarti · August 27, 2019, 12:16

I am trying to model a condensing flow in Ansys CFX for a Radial inflow turbine with inlet guide vane and impeller. The expansion causes a 15% by wt liquid at the outlet. Iam having convergence issues by modelling the gas as a fictitious ideal gas by specifying CP,viscosity, molecular weight, conductivity and ref pressure and temperature.
The gas parameters are as follows
cpfld 11721.66 lbf*ft/slug*R
cvfld 8914.53 lbf*ft/slug*R
visc 2.735E-07 lbf*s/ft^2
conduct 5.355E-03 lbf/s*R
tinlet 436.98 R
pinlet 158414.40 psf
pstatic 86027.01 psf
mdot per vane 0.48317 slug/s

Can someone suggest the best way to model this gas ? Thank you.

Regards,
Mahesh

Gert-Jan · August 28, 2019, 02:20

Look for IAPWS or H2ORKvl materials

maheshchamarti · August 28, 2019, 10:54

Hi Gert-Jan,
Thank you for your reply. Can you be more specific? The gas contains methane 94% and 6% ethane by wt. Thank you.

Gert-Jan · August 28, 2019, 11:22

Sorry. I was preoccupied and thought you were talking about Steam.
In your case..........

The Ethane and part of the methane condensates? You should look for:
Materials -> Import Library Data -> import Wet Soave Relich Kwong
Then select CH4vl and C2H6vl

If you select these materials, you will model the gas and liquid as equilibrium. Then the interphase mass transfer is instantaneous. If you want to model non-equilibrium materials, you need to select the v and l materials separate and setup the mass transfer rates yourself, using Ranz Marshall or similar.

Good luck. You might need this.

August 27, 2019, 12:16	Ansys CFX condensing flows	#1
maheshchamarti New Member Mahesh Chamarti Join Date: Feb 2017 Posts: 17 Rep Power: 9	I am trying to model a condensing flow in Ansys CFX for a Radial inflow turbine with inlet guide vane and impeller. The expansion causes a 15% by wt liquid at the outlet. Iam having convergence issues by modelling the gas as a fictitious ideal gas by specifying CP,viscosity, molecular weight, conductivity and ref pressure and temperature. The gas parameters are as follows cpfld 11721.66 lbfft/slugR cvfld 8914.53 lbfft/slugR visc 2.735E-07 lbfs/ft^2 conduct 5.355E-03 lbf/sR tinlet 436.98 R pinlet 158414.40 psf pstatic 86027.01 psf mdot per vane 0.48317 slug/s Can someone suggest the best way to model this gas ? Thank you. Regards, Mahesh

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August 28, 2019, 02:20		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	Look for IAPWS or H2ORKvl materials

August 28, 2019, 10:54		#3
maheshchamarti New Member Mahesh Chamarti Join Date: Feb 2017 Posts: 17 Rep Power: 9	Hi Gert-Jan, Thank you for your reply. Can you be more specific? The gas contains methane 94% and 6% ethane by wt. Thank you.

August 28, 2019, 11:22		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	Sorry. I was preoccupied and thought you were talking about Steam. In your case.......... The Ethane and part of the methane condensates? You should look for: Materials -> Import Library Data -> import Wet Soave Relich Kwong Then select CH4vl and C2H6vl If you select these materials, you will model the gas and liquid as equilibrium. Then the interphase mass transfer is instantaneous. If you want to model non-equilibrium materials, you need to select the v and l materials separate and setup the mass transfer rates yourself, using Ranz Marshall or similar. Good luck. You might need this.