Modeling the thermal conductivity of hydrofluorocarbons, hydrofluoroolefins and their binary mixtures using residual entropy scaling and cubic-plus-association equation of state

Entropy Scaling of Thermal Conductivity: Application to Refrigerants and Their Mixtures

“…An interesting case to discuss here is the R125 + R32 mixture, which has 520 data points from nine sources but has an average relative deviation of −3.0%. Liu et al who used another RES approach observed similar results and showed that data of this mixture fall below the points of pure R32 and R125 at the same RES. Both works concluded that in order to have better prediction of the experimental data, the R32 + R125 mixture should have a larger scaling factor ζ mix than both pure components, which cannot be obtained from typical arithmetic or geometric average mixing rules.…”

“…34 The relative deviations of the experimental values from both models are illustrated in Figure 11. We could potentially compare with the other RES approaches such as those proposed by Fouad 13 or Liu et al; 31 however, these models use either the PC-SAFT EoS or CPA EoS to calculate residual entropy, the implementations of which are not available to us. Sample thermal conductivity calculations using both RES and ECS models for each mixture are listed in Table S2 in the Supporting Information, and the Python code for one sample calculation is provided in the Supporting Information as well.…”

“…1,32 The enhancement is significant and even relatively far from the critical point. 33 None of the previously published RES approaches [13][14][15][16]31 for thermal conductivity take the critical enhancement into account, while this research will be the first one to do so.…”

“…The RES approach was originally developed by Rosenfeld in the 1970s. It is a hypothesis based on the analysis of hard spheres and inverse-power-law potentials in the liquid phase and was investigated by isomorph theory in recent years. − This approach has been verified for the viscosity of the Lennard-Jones fluid and hundreds of real fluids (hydrocarbons, − refrigerants, − and other commonly used fluids , ) but only verified for thermal conductivity of a few real fluids. − , Compared to viscosity, the major challenge in modeling thermal conductivity is that the critical enhancement, which arises from the long-range density fluctuations that occur in a fluid near its critical point, is significant in a much wider window in temperature and density. , The enhancement is significant and even relatively far from the critical point . None of the previously published RES approaches − , for thermal conductivity take the critical enhancement into account, while this research will be the first one to do so.…”

“…18−22 This approach has been verified for the viscosity of the Lennard-Jones fluid 12 and hundreds of real fluids (hydrocarbons, 23−25 refrigerants, 26−28 and other commonly used fluids 29,30 ) but only verified for thermal conductivity of a few real fluids. [13][14][15][16]31 Compared to viscosity, the major challenge in modeling thermal conductivity is that the critical enhancement, which arises from the long-range density fluctuations that occur in a fluid near its critical point, is significant in a much wider window in temperature and density. 1,32 The enhancement is significant and even relatively far from the critical point.…”