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Thermodynamic Properties of Trifluoroethylene (HFO1123): (p, rho, T) Behavior and FundamentalEquation of State



Ryo Akasaka, Yukihiru Higashi, Naoya Sakoda, Sho Fukuda, Eric W. Lemmon


The (p, rho, T) behavior of trifluoroethylene (HFO1123) was investigated with the isochoric method. A total of 87 (p, ρ, T) data were obtained along nine isochores (42, 98, 151, 197, 296, 493, 691, 790, and 888 kg · m−3) at temperatures from 300 K to 430 K and pressures up to 6.9 MPa. The uncertainties in temperature measurements are estimated to be within ±10 mK below 380 K and ±20 mK at higher temperatures, and the uncertainties in pressure measurements are estimated to be within ±1 kPa below 380 K and ±2 kPa at higher temperatures. The estimated overall relative uncertainty in density measurements is within ±0.15 %. A new Helmholtz energy equation of state was formulated based on the (p, ρ, T) data and recently published experimental data for the vapor pressure, liquid and vapor densities including those at saturation, vapor-phase sound speed, and idealgas isobaric heat capacity. The equation is valid at temperatures from 200 K to 480 K and pressures up to 20 MPa. Typical uncertainties in calculated properties within the range are 0.1 % for vapor pressures, 0.1 % for liquid densities, and 0.2 % for vapor densities, except in the critical region where larger deviations up to about 1.5 % are sometimes observed in densities. The uncertainties in calculated vapor-phase sound speeds and ideal-gas isobaric heat capacities are 0.03 % and 1 %, respectively. The equation shows reasonable extrapolation behavior at extremely low and high temperatures, and at high pressures.
International Journal of Thermophysics


Density, Equation of state, Heat capacity, Sound speed, Trifluoroethylene, Vapor pressure


Akasaka, R. , Higashi, Y. , Sakoda, N. , Fukuda, S. and Lemmon, E. (2020), Thermodynamic Properties of Trifluoroethylene (HFO1123): (p, rho, T) Behavior and FundamentalEquation of State, International Journal of Thermophysics, [online], (Accessed July 22, 2024)


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Created July 16, 2020, Updated January 21, 2023