How to import CO2?

mzggzm · February 26, 2019, 10:55

Hi,

I am looking to simulate CO2 flow. I am using CFX. I have found academic papers describing simulations with CO2 but I am unsure how to import CO2 to make it an available fluid to select. I am using workbench 17.1. I was hoping someone could help me out. Thanks

evcelica · February 26, 2019, 13:43

There are so many options I don't know where to begin. It depends on what type of simulation you will be running, and at what conditions. You don't just, "Import CO2".

You have to decide if constant properties and incompressible are suitable, or if ideal gas is more appropriate, with or without temperature dependent properties. Or do you need real gas equation of state, or an RGP file with liquid and gas properties.

mzggzm · February 27, 2019, 00:10

Quote:

Originally Posted by evcelica

There are so many options I don't know where to begin. It depends on what type of simulation you will be running, and at what conditions. You don't just, "Import CO2".

You have to decide if constant properties and incompressible are suitable, or if ideal gas is more appropriate, with or without temperature dependent properties. Or do you need real gas equation of state, or an RGP file with liquid and gas properties.

Thanks for the response, I am a novice user, only have set up 4 or 5 simulations in the past. I need to simulate it as compressible, density and viscosity changing with pressure. Temperature will be constant. Looking to simulate supercritical CO2. Since posting I have found how to bring CO2 into the available materials (via import from library). Do you have a suggestion on which CO2 from this library to bring in if I am looking for the non-constant properties I have described above? Looking at the phase diagram for CO2, the pressures and temperatures I am looking to run at are within the supercritical range but closer to the liquid side so I was going to choose one of the CO2l options.

evcelica · February 27, 2019, 14:10

If it is supercritical, don't use liquid properties. Import that and take a look at what the properties are, they are constant properties.

The gas phase combustion "CO2" is a gas and would be more appropriate, but still this is not a perfect material model. It is ideal gas, variable specific heat, and uses constant viscosity and thermal conductivity which may or may not be applicable to your simulation conditions.

I would suggest you learn about the different methods for defining material properties, and define the material yourself. A Program such as RefProp can be used to determine what the material properties are at different temperature and pressures. Then you can decide if you need to make viscosity or some other property a function of temperature/pressure, and how you should define you material for your specific conditions.

February 26, 2019, 10:55	How to import CO2?	#1
mzggzm New Member mike Join Date: Feb 2019 Posts: 2 Rep Power: 0	Hi, I am looking to simulate CO2 flow. I am using CFX. I have found academic papers describing simulations with CO2 but I am unsure how to import CO2 to make it an available fluid to select. I am using workbench 17.1. I was hoping someone could help me out. Thanks

February 26, 2019, 13:43		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,173 Rep Power: 23	There are so many options I don't know where to begin. It depends on what type of simulation you will be running, and at what conditions. You don't just, "Import CO2". You have to decide if constant properties and incompressible are suitable, or if ideal gas is more appropriate, with or without temperature dependent properties. Or do you need real gas equation of state, or an RGP file with liquid and gas properties. Opaque likes this.

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February 27, 2019, 14:10		#4
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,173 Rep Power: 23	If it is supercritical, don't use liquid properties. Import that and take a look at what the properties are, they are constant properties. The gas phase combustion "CO2" is a gas and would be more appropriate, but still this is not a perfect material model. It is ideal gas, variable specific heat, and uses constant viscosity and thermal conductivity which may or may not be applicable to your simulation conditions. I would suggest you learn about the different methods for defining material properties, and define the material yourself. A Program such as RefProp can be used to determine what the material properties are at different temperature and pressures. Then you can decide if you need to make viscosity or some other property a function of temperature/pressure, and how you should define you material for your specific conditions.