Heat transfer plate, plate pack and plate heat exchanger

A method of using a plate heat exchanger comprising a number of heat transfer plates, each having an essentially rectangular outer periphery, and being symmetric about its longitudinal axis, and having, within said outer periphery,

• a first port portion which is disposed in one edge portion of the heat transfer plate,
• a second port portion which is disposed in a second edge portion of the heat transfer plate, and
• a heat transfer portion which is disposed between said port portions and extends between side outer peripheral edges of the heat transfer plate and which has a heat transfer surface across its entire width and length wherein
• the first port portion comprises a circular first vapor inlet port which extends over essentially the whole width of the plate,
• the second port portion comprises at least one first condensed vapor outlet port which is relatively smaller than the first vapor inlet port,
• the first port portion comprises a second outlet port for a second fluid which second outlet port is disposed between said first vapor inlet port and the second port portion,
• the second port portion comprises a second inlet port for said second fluid, which second inlet port is arranged between said at least one first condensed vapor outlet port and the first port portion, and
• the second inlet port has a port area that is 10-50% of the corresponding port area of said first vapor inlet port
• wherein said first vapor inlet ports of the heat transfer plates form a first inlet channel through the heat transfer plates of the heat exchanger, said first condensed vapor outlet ports of the heat transfer plates form a first outlet channel through the heat transfer plates, said second inlet ports of the heat transfer plates form a second inlet channel through the heat transfer plates and said second outlet ports of the heat transfer plates form a second outlet channel through the heat transfer plates, the first inlet channel and the first outlet channel being in fluid communication with each other via a first set of plate interspaces and the second inlet channel and the second outlet channel communicating with each other via a second set of plate interspaces, and each of the plate interspaces in the first set having a channel height that is greater than each of the plate interspaces in the second set, said first and said second sets of plate interspaces being in heat transfer communication with one another, the method comprising
• cooling a vapor to form a condensed vapor by passing said vapor into said first inlet channel and through said first set of plate interspaces and removing said condensed vapor from the heat exchanger by passing it through said first outlet channel, and simultaneously
• warming the second fluid by passing the second fluid into said second inlet channel and though said second set of plate interspaces and removing said warmed second fluid from the heat exchanger by passing it through said second outlet channel.