Issues to consider when selecting plate heat exchangers

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1. Plate type selection The plate format or corrugated type should be determined based on the actual requirements of the heat exchange application. For situations with high flow rates and a low allowable pressure drop, a plate type with low resistance should be selected; conversely, a plate type with high resistance should be chosen. Based on the fluid pressure and temperature conditions, determine whether to choose a detachable or brazed type. When determining the plate configuration, it is not advisable to choose plates with too small a surface area, as this can lead to an excessive number of plates, resulting in low flow velocities between them and consequently a low heat transfer coefficient. This issue is particularly important to consider in larger heat exchangers. 　　2. Selection of flow paths and channels A flow path refers to a set of parallel channels within a plate heat exchanger in which a fluid flows in the same direction, while a channel refers to the flow path for the fluid formed by two adjacent plates within a plate heat exchanger. Generally, several flow channels are connected in parallel or series to form various combinations of cold and hot medium pathways. 　　The process combination form should be determined based on heat transfer and fluid resistance calculations, while meeting the requirements of the process conditions. Strive to make the convective heat transfer coefficients in the cold and hot water channels equal or similar, thereby achieving the best heat transfer performance. Because the heat transfer coefficient attains a higher value when the convective heat transfer coefficients on both sides of the heat transfer surface are equal or similar. Although the flow velocities between the plates of a plate heat exchanger vary, the average flow velocity is still used in heat transfer and fluid resistance calculations. Since the nozzles of the single \"U\"-shaped process are all fixed on the pressing plate, they are easy to install and remove. 　　3. Pressure drop verification: During the design and selection of plate heat exchangers, certain requirements are generally imposed on the pressure drop, so it is necessary to conduct a verification. If the verified pressure drop exceeds the allowable value, redesign and selection calculations must be carried out again until the process requirements are met.