Phase Diagrams of the Diphenyl Oxide–n-Hexadecane System

A theoretical and experimental study is performed for liquid–solid phase equilibria in the two-component diphenyl oxide– n- hexadecane system. The results show that this system is eutectic. Two means are chosen for the theoretical study of the system: the Schröder–Le Chatelier equations and the original UNIFAC system. Experimental studies are made via differential thermal analysis on a DSC unit. Results from the theoretical and experimental studies are presented in the form T – x diagrams of the system. The theoretical and experimental data are compared to one another. Each way of calculating is assessed, and recommendations are made for their application. The eutectic coordinates (melting point and composition) are determined experimentally. The following values are determined experimentally for a eutectic melt: the enthalpy of melting; density at 25°C; kinematic viscosity in the temperature range of 25 to 50°C; flash point in an open cup; boiling point, and refractive index in the temperature range of 25 to 40°C. The composition of the eutectic melt can be used in industry as a heat transfer fluid.