Measurements of Thermophysical Properties of Ethanol plus Hexamethyldisiloxane and Ethanol plus Octamethyltrisiloxane Mixtures in the Temperature Range of 293-343 K at 100 kPa

Due to its advantageous combination of individual properties, the utilization of zeotropic mixtures as working fluids can improve the overall efficiency in various thermodynamic cycle processes, such as organic Rankine cycle processes or Kalina processes. Therefore, the properties such as density, viscosity, and surface tension are measured for ethanol, hexamethyldisiloxane (MM), octamethyltrisiloxane (MDM), and their mixtures ethanol/MM and ethanol/MDM at 100 kPa and at different temperatures (293-343 K) and compositions. The measured fluid properties are investigated with different experimental systems: an IMETER measuring system is used for all three mentioned properties. Additionally, the density is determined by a density meter with an oscillating U-tube and the surface tension by a drop shape analyzer system. For the mixtures of ethanol/MM and ethanol/MDM, neither literature data exist nor distinct mixture parameters in REFPROP v.10.0 are available, but the present experimental results are compared with different mixing rules. Furthermore, specific parameters are developed with the Jouyban-Acree model in order to enable a calculation of the presented thermophysical properties for the given mixtures.