Phase Equilibria in the Two-Component Diphenyl Oxide–n-Nonadecane System

Abstract—The melting diagram of the diphenyl oxide–n-nonadecane system is calculated by the Schroeder, UNIFAC, and UNIFAC Dortmund methods and is shown to belong to the eutectic type. Individual substances and their mixtures are studied experimentally using a differential scanning microcalorimeter. Two endoeffects corresponding to the polymorphic transition of n-nonadecane and eutectic melting are observed on the DTA curve of eutectic alloy heating. The eutectic coordinates calculated by these methods are compared with the experimental data. The specific enthalpy of melting, molar entropy and enthalpy of melting, volume specific enthalpy of melting, and density are calculated for the eutectic alloy under standard conditions. The eutectic mixture can be recommended for using as a heat carrier and a working fluid of a heat accumulator.