A reference multiparameter thermal conductivity equation for carbon dioxide with an optimized functional form.

A new thermal conductivity equation λ = λ(T,ρ) in a multiparameter format was developed for carbon dioxide through the application of an optimization technique of the functional form. The proposed equation is valid for temperatures from the triple point (Tt = 216.592 K; Pt = 0.51795 MPa) to 1000 K and pressures up to 200 MPa. The calculation of density, which is an independent variable of the equation, from the experimental (T,P) conditions is performed with a high accuracy equation of state for the fluid. The thermal conductivity equation shows an average absolute deviation of 1.19% on the selected 1407 primary data points. Its performances are slightly better than those of the corresponding conventional model by Vesovic et al. [J. Phys. Chem. Ref. Data 19, 763 (1990)] available from the literature; moreover the new equation is simpler to use in particular for the near-critical region. Tables of generated values of carbon dioxide thermal conductivity are provided for check of the code implementations and for quick evaluations.