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Understanding lubrication failures at the shoe/swashplate contact of automotive swashplate compressors will greatly enhance the reliability of the air conditioning system. Maintaining proper lubrication is not always possible during transient conditions. Therefore, a method for detection of lubricant loss is of great interest to the automotive industry. Three methods for detecting lubrication loss were examined: contact resistance, acoustic emission, and dynamic pressure oscillations. A mobile air conditioning test stand capable of recording many system parameters was used. Oil return to the compressor was monitored using an oil separator and a refrigerant/oil concentration sensor. Data were taken during steady oil return rates and after oil shut off. The electrical contact resistance between the shoe and swashplate was used to indicate changes in the lubrication conditions at this critical interface. Measurements were taken at two oil return rates during steady oil return tests.

This paper presents experimental results concerning the distribution of the refrigerant R134a in the inlet header of plate evaporators in automotive air-conditioning systems, as a function of operating conditions. Typical conditions in such air-conditioning systems cover the: mass flow rates of 20-60 g/s, and inlet vapor quality at the inlet header of up to 30%. The distribution of the refrigerant is expressed as the fraction of the liquid available at the inlet. The distribution results are given with flow images (shown in the paper) followed by analysis and discussions of the results.