“…The thermodynamic relations that relate the excess molal enthalpy, h: , the heat of mixing, h;, and the activity coefficient, y r can be found in the literature (see, for example, Walas, 1985) and are summarized by Albright et al (1962): and Since the total pressure is low (much lower than the critical pressure), the effect of pressure in Eq. A3 is very small (about an order of magnitude less than the effect of temperature) and can be neglected.…”