1. Plate type selection: The plate type or corrugated type should be determined according to the actual needs of the heat exchange occasion. For a large flow rate and a small allowable pressure drop, a plate with a small resistance should be selected, and a plate with a large resistance should be used. According to the fluid pressure and temperature, confirm whether to choose the detachable type or the brazed type. When confirming the plate type, it is not appropriate to choose a plate with a small plate area, so as to avoid too many plates, the flow velocity between the plates is too small, and the heat transfer coefficient is too low. Pay attention to this problem for larger heat exchangers.
2. Process and flow channel selection: Process refers to a group of parallel flow channels in the same direction of the medium in a half-welded plate heat exchanger, while flow channels refer to the flow of medium in adjacent plate plates in a plate heat exchanger aisle. In general, several flow channels are connected in parallel or in series to form different combinations of cold and hot medium channels. The process combination form should be calculated based on heat exchange and fluid resistance, and confirmed in accordance with the requirements of the process conditions. Try to make the convective heat transfer coefficients in the cold and hot water channels equal or close to each other, so as to obtain a good heat transfer effect. Because the convective heat transfer coefficients on both sides of the heat transfer surface are equal or close, the heat transfer coefficient gets a larger value. Although the flow velocity between the plates of the plate heat exchanger varies, the average flow velocity is still used in the calculation of heat exchange and fluid resistance. Since the "U" shaped single-pass nozzles are fixed on the pressure plate, it is easy to disassemble.
3. Pressure drop check: The design and selection of the half-welded plate heat exchanger
generally requires pressure drop, so it should be checked. If the pressure drop is too high to allow the pressure drop to be checked, the design selection calculation needs to be performed again until it meets the process requirements.