Measurement of electrical properties of refrigerants and refrigerant–oil mixtures

The paper deals with the description of a new pressure proof device developed at ILK Dresden for measuring electrical properties of refrigerants, oils and refrigerant–oil mixtures under pressure. The determination can be performed based on DIN EN 60247. This standard is valid for the determination of the relative permittivity, the dielectric dissipation factor and the direct current (DC) resistivity of isolating fluids at atmospheric pressure. The measurements can be made in a temperature range from −30 °C to 90 °C at pressures up to 80 bar under dry atmospheric conditions. The sensitivity of the method as well as its considerable flexibility meets the requirements of the industrial and commercial refrigeration. Challenges regarding the development and performance of the measuring cell as well as some preliminary experimental results are presented. The focus of the experiments is on environmentally friendly refrigerants (GWP < 150) such as R744, R1234yf and R152a, and their mixtures with lubricants.