制冷剂六氟丙烯(R1216)Helmholtz状态方程研究OA

A Helmholtz energy equation of state(EoS)for hexafluoropropene(R1216)was developed based on the experimental data of vapor pressure,saturated liquid and vapor densities,pρT properties,vaporphase speed of sound,and ideal gas heat capacity at constant pressure.The model parameters were optimized using a hybrid solution algorithm.The applicable range of this EoS spans from the triplepoint temperature of 117.65 K to 370 K and the pressures up to 10 MPa.Within this range,the average absolute relative deviation(AARD)of gas-liquid phase density,gas-phase sound velocity,ideal gas isobaric heat capacity,and saturated vapor pressure is less than 1.62%;the AARDs for saturated gas-liquid phase density are 3.60%and 0.62%,respectively.The extrapolation behavior of the EoS was evaluated using derived thermodynamic properties,including Virial coefficients,the compressibility factor,capacities,pVT relationships,the speed of sound,and the phase identification parameter.The Helmholtz EoS was evaluated by experimental data and the trends of derived thermodynamic properties.The results proved that the Helmholtz EoS can calculate thermodynamic properties accurately and satisfy thermodynamic constraints within the experimental data range,it also exhibits reliable thermodynamic extrapolation behavior under extreme conditions such as high temperature,high pressure,and the state far from the triple point.