Enthalpy of Vaporization Measurements of Liquid Methane, Ethane, and Methane + Ethane by Differential Scanning Calorimetry at Low Temperatures and High Pressures

Abstract

This paper presents measurements of the enthalpy of vaporization of pure and binary hydrocarbon fluid mixtures using a commercial differential scanning calorimeter (DSC). The DSC was modified to allow the direct measurement of enthalpies of vaporization, ΔvapH, at temperatures as low as 80 K and pressures as high as 10 MPa and was tested by measuring enthalpies of vaporization, both under vaporization and under condensation, for pure methane at T = (118, 123, 128, and 133) K and pure ethane at T = (208 and 213) K. The measured values had relative deviations of less than 3% from recommended literature values. Then ΔvapH was measured for mixtures of methane + ethane, methane + propane, and ethane + propane at various temperatures by both condensing and vaporizing samples. In contrast to the pure fluid measurements, the measurement pathway affected the value of ΔvapH obtained because the condensation occurred along a constant composition pathway whereas the composition varied during vaporization as a result ...