How is plate heat exchangers used in an ammonia refrigeration system?

How is plate heat exchangers used in an ammonia refrigeration system?
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Answer :

Plate heat exchangers are widely used in ammonia refrigeration systems, and they can be much smaller  than the equivalent tubular exchanger can. They work best flooded. A flooded exchanger system needs  a way to separate the liquid from the vapor. A typical system has a vessel, which acts as knockout drum,  accumulator, and header tank in one, along with the heat exchanger. Liquid ammonia flows from the  vessel to the exchanger, and liquid/vapor is returned to the middle of the drum. Vapor is removed from  the top of the drum. The liquid/vapor mixture from the exchanger has a lower density than the liquid  entering the exchanger, so gravity provides the driving force to circulate the refrigerant.
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