An Ultrasonic Device for Measuring the Oil Concentration in Flowing Liquid Refrigerant

Liquid refrigerant/oil concentrations in a flowing system were monitored using speed of sound and temperature measurements. Data were taken for R12 with 3GS and 5GS oils and an R-134a/Ester mixture with concentrations ranging from 0.0 to 10.64 and 0.0 to 9.11 percent by mass, respectively. Temperatures for the tests ranged from -22??C (-7.6 OF) to 40 ??C (104 OF). Analysis of the data showed the predicted oil concentration depends linearly on both acoustic velocity and temperature. The technique was very reliable, with uncertainties ofless than 0.23 weight percent for the R-12 mixtures and 0.26 weight percent for the R-134a mixtures at typical system concentrations. A slight dependence of acoustic velocity on pressure was found.Air Conditioning and Refrigeration Center Project 0