Measurement of the Density of Biphenyl / Diphenyl Oxide Mixtures at Isobaric Conditions

Abstract

The density of the eutectic mixture of biphenyl and diphenyl oxide was measured at 12 to 40 bar and up to 400 °C for the first time. An unused quality as delivered and a used quality from a parabolic trough plant were tested. Significant compressibility was observed for both qualities giving rise to density increases of 3% for the unused fluid at 40 bar and 4.8% for the used fluid compared to the technical data sheet of Dowtherm A.