Plate heat exchanger
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A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two liquids. This has a major advantage over a conventional heat exchanger in that the liquids are exposed to a much larger surface area, as the liquids spread out over the plate. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. It is not as common to see plate heat exchangers due to the fact that they need well-sealed gaskets, to prevent the liquids from escaping, although modern manufacturing processes have made them feasible.
The concept behind a heat exchanger is the use of pipes or other containment vessels to heat or cool one liquid by transferring heat to another. In most cases, the exchanger consists of a coiled pipe containing one liquid that passes through a chamber containing the other. The walls of the pipe are usually made of metal, or another substance with a high thermal conductivity]], to facilitate the interchange, whereas the outer casing of the larger chamber are made of a plastic or substance with low conductivity, to discourage heat from escaping the exchanger.
The plate heat exchanger is an improvement on this basic design that allows a more rapid transfer of heat. In place of a pipe passing through a chamber, there are instead two chambers, usually thin in depth, separated at their largest surface by a metal plate. The plate produces an extremely large surface area, which allows for the fastest possible transfer. Making each chamber thin ensures that the majority of the volume of the liquid contacts the plate, again aiding exchange.
In Plate Heat Exchanager (PHE) generally plates are arranged in such a way that it forms channels of hot and cold liquid alternately. Due to corrugations in the plate high turbulent flow increases the heat transfer rate. As compared to Shell & Tube Heat Exchanger, PHE can give approach of 1°C whereas Shell & Tube Heat Exchanger gives approach upto 5°C. For the same amount of heat exchange the area requirement for the PHE is very less. Expansion of the heat transfer area is possible in PHE. Due to the above reasons PHE are used for the better and controlled heat transfer. Some of the big player in the PHE business are Alfa Laval, GEA, APV and Sondex. [NIXXON]
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