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Burrah Boy
24-07-2009, 01:35 PM
Hi guys, this is a quote from a document I am reading on a cascade system using co2 as the low temp refrigerant. " The evaporator in the R404 system is a plate heat exchanger, which acts as the condenser for the R744 cycle. It condenses the discharge gas from the R744 compressor serving the Low temp system and the flash gas from the WET SUCTION on the high temp R744 evaporator"
Could someone please explain what they mean by wet suction. Is it liquid that hasnt boiled off????
Thanks!

US Iceman
24-07-2009, 02:45 PM
A wet suction line is; a suction line which intentionally has liquid refrigerant present, in addition to the vapor.

In some industrial refrigeration systems this is done on purpose as excess liquid is fed to the evaporator. The heat picked up by the evaporator will only boil off so much liquid refrigerant. The remaining liquid which is not boiled off exits the evaporator with the vapor. Subsequently, the vapor and liquid both flow down the suction line. Since liquid is present, the suciotn line is called wet. This liquid/vapor mixture flows back to the inlet of an accumulator which is a liquid/vapor separator.

Conversely, the suction vapor flowing out of the liquid/vapor separator is considered dry, if the accumulator/separator has done its job of removing the liquid.

Burrah Boy
24-07-2009, 07:50 PM
Thanks a lot, NOW it obviously makes sense!