Real Time Oil Concentration Measurement in Automotive Air Conditioning by Ultraviolet Light Absorption

• Published in: SAE transactions 1991-01, Vol.100 (6), p.315-322
• Main Authors: Kutsuna, Kiyoharu, Inoue, Yoshimitsu, Mizutani, Takehito, Sudo, Eiichi, Araga, Toshimi
• Format: Article
• Language: English
• Subjects: Air compressors; Air conditioning. Ventilation; Applied sciences; Calibration; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Flow velocity; Ground, air and sea transportation, marine construction; Heating, air conditioning and ventilation; Liquids; Lubricants; Refrigerants; Refrigeration; Road transportation and traffic; Techniques, equipment. Control. Metering; Ultraviolet radiation; Water temperature; Wavelengths
• ISSN: 0096-736X; 2577-1531

A method of r e a l time oil concentration measurment has been developed utilizing the effect of ultraviolet light absorption by lubricating oil in the liquid refrigerant line of an automotive air conditioning system. The light wavelengths from 200nm to 370nm are selected based on the ultraviolet light absorption sensitivity of the oils and refrigerants (CFC12,HFC134a). The effects of temperature, pressure and contaminantion on the absorbance of light are investigated in order to determine how these parameters affect the concentration measurement. The density changes of refrigerants are then compensated in the calculation for the oil concentration. The uncertainties of the overall concentration measurement are less than ± 0.1 weight percent at 1 weight percent concentration. A transient oil circulation of the automotive air conditioner is measured by using this method.