A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat. Fluids are a subset of the phases of matter and include liquidsgasesplasmas andto some extentplastic solids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids spread out over the plates.This facilitates the transfer of heatand greatly increases the speed of the temperature change. Plate heat exchangers are now common and very small brazed versions are used in the hot-water sections of millions of combination boilers.
The plates produce an extremely large surface areawhich allows for the fastest possible transfer. Making each chamber thin ensures that the majority of the volume of the liquid contacts the plateagain aiding exchange. The troughs also create and maintain a turbulent flow in the liquid to maximize heat transfer in the exchanger. A high degree of turbulence can be obtained at low flow rates and high heat transfer coefficient can then be achieved.