What are you trying to do? I don't believe that Design-Space is capable of modeling gases. Clarify what you're trying to do, as one shouldn't generally need "material properties" for gases in a linear program.
Brad
i am trying to see the heat distubution in a quartz tube, one end flange will see Helium, so i need to apply convection to that area etc ie film cofficient
Then you do not need helium material properties; you instead need to model the convection coefficient. I don't believe that helium properties are going to give you that.
I would recommend posting the following question in the Heat Transfer and Thermodynamics Engineering forum:
"Where can I find information on convection coefficients between various gases and solids (specifically between helium and quartz)?"
That is question you need answered. You may not get that question answered, but somebody could instead provide you some ballpark values.
I'm sorry that I can't answer it myself, but hopefully I have pointed you down a better path.
I don't know of on-line links, but refer to Spiers Technical Data on Fuels or McAdams Heat Transmission. These will refer you to the formulas for the Nusselt Prandtl numbers, etc you'll need to derive the heat transfer coefficient using the material properties of helium. With gases the prandthl number doesn't vary much so you may be able to use values of htcs to air.
