Abstract
Measurement of an oil circulation ratio (OCR) in refrigerating cycles is important for evaluating the reliability of a compressor and the performance of heat exchangers. The OCR is typically measured by a sampling method, but the method consumes time and can not measures the transient change of the OCR. On the other hand, the OCR measurement by the sound speed of refrigerant/oil mixture is easily done in real-time. In this study, the ultrasonic sound speed sensor was developed, and the sound speed of the refrigerant/oil mixture was measured. Moreover, the correlation between the sound speed and the oil concentration is clarified.
