Thermodynamic properties of 1,1,1,2-tetrafluoroethane (R134a) in the critical region

A multiparameter thermal conductivity equation for R134a with an optimized functional form

“…In order to take advantage also of these data sets, part of which is available in the vicinity of the critical point making them particularly interesting, the thermal diffusivity values have been converted into thermal conductivity using Eq. (1), with the required thermodynamic properties calculated either from the Tillner-Roth and Baehr EoS [1] or from the crossover model [2,26] according to the (T, ρ) conditions, as explained in Section 4.1.…”

“…In particular, the crossover model from Tang et al [2] with the parameter values given by Krauss et al [26] was considered. The boundary for the switching between the two thermodynamic models was established searching for small jumps in the density and isobaric heat capacity values calculated from the two equations of state.…”

“…For R134a both a highly accurate fundamental equation of state (EoS) [1] valid in wide (T, P) ranges and a crossover model for the critical region [2] are available; from these all the thermodynamic properties can be accurately calculated. Moreover, the viscosity has been studied in a previous paper [3], whereas the present work is addressed to the modeling of the thermal conductivity.…”

Critical and Crossover Phenomena in Fluids and Fluid Mixtures

“…An extension of the crossover theory by retaining 6 terms in the Landau expansion has been developed [4,13,60], referred to as six-term crossover Landau model. The six-term crossover Landau model (with some minor variations) has been used to represent the thermodynamic properties of a variety of fluids in an appreciable range of temperatures and densities around the critical point including steam [4,67], carbon dioxide [4,68], ethane [4,68,69], methane [69,70], argon [71], sulfur hexafluoride [72], and a number of refrigerants like RI34a [73], R152a [74], and ammonia [75].…”

The Extended Crossover Peng–Robinson Equation of State for Describing the Thermodynamic Properties of Pure Fluids

“…In the original application of the crossover transformation performed by Chen et al [4] and also by Tang et al [15,23,24], κ 2 was approximated so that the higher-order terms in expansion of Eq. (36) were ignored.…”