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    Chris Neal

    Hello. I saw the following quoted suggestion put forward on the Cantera forums in regards to non-ideal equations of state.

    "I also have some suggestion about the implementation of non-ideal gas EoS in Cantera. According to some literature I read about Refprop of NIST and other real gas, they think the future of EoS implementation is Helmholtz form A=A(T,v,X_i). Because of thermodynamic completeness, if we have a explicit expression of Helmholtz energy, we can get Gibbs, Internal Energy, Enthalpy, Entropy, Chemical potential, etc. in explicit form through derivatives of Helmholtz energy. And Helmholtz energy is also very useful in phase equilibrium calculation (aka. flash, dew, bubbling point). Helmholtz energy is also very useful in CFD because the specific volume v in its formula is related to inverse of density, which is usually used as solution variable in compressible solver. It is more convenient than pressure in compressible solver. Further, all cubic form EoS (Peng-Robinson, VdW, Redlich-Kwong, etc. ) can be converted to Helmholtz form directly. So we can use auto-differentiation to implement all other thermodynamic quantities with accuracy and easiness."

    Is it true that Helmholtz is where things are going(I honestly have no idea about any developments that happen in the EoS space)?