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I have a lot of gas properties in a model but I discovered that he volumetric thermal expansion coefficient is not among them. I've found little about how the constant relates to other properties - I only know of how it's used, and there's abundant tables of them.

Can the constant be derived from any combination of the following (some parameters vary with temperature, etc)?

  • Temperature
  • Pressure
  • Density
  • Average molecular weight
  • Specific heat
  • Entropy
  • Enthalpy
  • Internal energy
  • Sutherlands constant (viscosity)
  • Lambda constant (viscosity)
  • Static and kinematic viscosity
  • Speed of sound
  • Bulk modulus
  • For each molecular component:
    • Molar/volumetric percentage
    • Mass percentage
    • Molecular weight
    • Partial pressure
    • Density

I'd rather derive the thermal expansion coefficient from other existing values if possible. If not, I guess a lookup table will be in order.

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  • $\begingroup$ It is derived from the equation of state. That, is, the relationship between P, V, and T. $\endgroup$
    – Chet Miller
    Commented Aug 23, 2016 at 19:02
  • $\begingroup$ Hmm. I actually don't have that. Both my temperatures and pressures (from which density is derived) are empirical and don't represent the result of instantaneous fluctuations, but rather different environments equalized over long periods of time. The partial pressures and such come from the gas percentages (also empirical) in the differing environments. Is there no other way to get it? I don't have any data on instantaneous pressure-volume-temperature relations - anything on the subject would be nothing more than an added lookup table. $\endgroup$
    – KarenRei
    Commented Aug 24, 2016 at 7:52
  • $\begingroup$ If you have a multicomponent mixture, then there are ways of deriving the equation of state, but it isn't simple (unless the mixture behaves as an ideal solution). Also, there are empirical mixing rules that can be applied. See Moran et al Fundamentals of Engineering Thermodynamics $\endgroup$
    – Chet Miller
    Commented Aug 24, 2016 at 13:18

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