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The plates are the core components of plate heat exchangers; the heat exchange between the cold and hot fluids takes place on these plates. They serve as the heat transfer elements of the heat exchanger, and in addition, they must withstand the pressure difference on both sides. Therefore, choosing the appropriate plate type and flow channels for the plate heat exchanger has a significant impact on the operation of the heat exchange equipment, its heat transfer efficiency, and fluid resistance. 1 Plate type selection: The plate type and corrugation pattern of the plate heat exchanger should be determined based on the requirements of the actual heat exchange conditions. For applications with high flow rates and low allowable pressure drops, a plate type with low resistance should be selected. Based on the pressure and temperature of the heat exchange medium, it is determined whether to choose a detachable type or a brazed type. For equipment with a large heat exchange area, it is not advisable to use plates with too small a surface area, as this may result in an excessive number of plates, lower flow velocities between them, and consequently a low heat transfer coefficient. 2 Selection of flow processes and flow channels: A flow process refers to a set of parallel flow channels within a heat exchanger in which a fluid moves in the same direction, while a flow channel denotes the path through which the fluid flows between two adjacent plates in a plate heat exchanger. Generally, several flow channels are connected in parallel or series to form various combinations of cold and hot medium channels. To enable the fluid to flow between the plate bundles in accordance with specific requirements, the corners of the plates are perforated as needed, gaskets are applied as required, and they are arranged in an orderly manner to form flow channels; this is known as a flow arrangement. The process combination form should be determined based on heat transfer and fluid resistance calculations, while meeting the requirements of the process conditions. When the convective heat transfer coefficients of the media on both sides of the heat transfer surface are equal or similar, a higher heat transfer coefficient can be achieved. Therefore, to obtain better heat transfer performance, it is advisable to make the convective heat transfer coefficients in the cold and hot fluid channels equal or similar. 3 Pressure drop verification: When designing and selecting plate heat exchangers, certain requirements are generally placed on the pressure drop, and it should be verified. If the verified pressure drop exceeds the allowable value, redesign and selection calculations must be carried out again until the process requirements are met.