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Adiabatic two-phase flow experiments have been carried out in an evaporator plate assembly which has entry and exit header vestibules on one side and a U pattern flow passage with round or cross ribbed protuberance in the channel. Over the practical flow range in common installation orientations, non-uniform distributions were found in both surface wetting on the internal walls of a single channel and the flow rates in a number of parallel channels. The poor performances of the plate surface wetting in single channel and the flow distribution in the multiple channels would severely limit the heat transfer capability of the current designs.

Systematic design of mobile air-conditioning system components in R134a systems has been hampered by inaccurate knowledge of the flow quality, especially the amount of liquid returned to the compressor. The thermodynamic quality is typically used, but it is somewhat unreliable due to the large percentage of miscible compressor oil circulating with the refrigerant. A technique for measuring the flow quality in the refrigeration loop based on phase segregation and recombination has been developed and verified. The refrigerant quality has been deduced with the aid of standard sampling methods for measuring the percentage of oil in circulation. Hence, the relative contributions of all three components of the flow have been measured. The method is suitable for relative evaluation of component performance on a test stand. The method has been applied to measuring evaporator discharge quality at standard conditions and to quantifying accumulator liquid carryover.