An ultrasonic device for measuring the oil concentration in flowing liquid refrigerant

摘要

Liquid refrigerant/oil concentrations in a flowing system were monitored using speed ofsound and temperature measurements. Data were taken for R12 with 3GS and 5GS oilsand an R-134a/Ester mixture with concentrations ranging from 0.0 to 10.64 and 0.0 to9.11 percent by mass, respectively. Temperatures for the tests ranged from -22??C (-7.6OF) to 40 ??C (104 OF). Analysis of the data showed the predicted oil concentration dependslinearly on both acoustic velocity and temperature. The technique was very reliable, withuncertainties ofless than 0.23 weight percent for the R-12 mixtures and 0.26 weightpercent for the R-134a mixtures at typical system concentrations. A slight dependence ofacoustic velocity on pressure was found.