Direct measurements of the enthalpy of vaporization for R290 + R1216 and R1234ze(E) binary mixtures by differential scanning calorimetry

Abstract

In this work, the enthalpy of vaporization (ΔvapH) of refrigerants and mixtures has been investigated experimentally and theoretically, and an accurate and simple method for directly measuring ΔvapH has been developed. First of all, the ΔvapH of R290, R1216, R1234ze(E) and their mixtures were measured at temperatures from 260 to 290 K using a modified high-pressure differential scanning calorimeter combined with a pressure balance unit and a sample injection system. Seven temperature points were measured for each component. After that, compared the experimental results with commonly used estimation methods, such as Clausius-Clapeyron equation and Helmholtz-energy equation of state. The experimental results were in good agreement with Helmholtz equation, with the maximum deviation within 1.89%. In the end, the empirical formula was used to fit the experimental results. The average absolute deviations between the experimental values and the fitting values were between 0.07% and 0.40%, and the maximum absolute deviations were between 0.11% and 1.05%.