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Flash Gas?

With the increase in flash gas, the evaporator loses capacity, and oil return to the system is no longer reliable. Electronic expansion valves would open wider to compensate for flash gas which provides no refrigeration effect. Additional steps of compressor loading would be required to re-compress this vapour which has been compressed once before. The life of the equipment may be greatly shortened.

Consider a R404a system, with an eight psi drop in the liquid line. At 90F (32°C) condensing, flash gas is only 2% by weight. At these higher pressures the bubbles are compressed and present little problem. But if we lower the condensing temperature to 60F (15°C), the flash gas will occupy 34% of the liquid line volume.

flash gas

flash gas