Process Selection in The Selection And Design Of Plate Heat Exchangers

Under normal operating conditions, plate heat exchangers with symmetrical flow channels are more commonly chosen because when the volume flow rates of the two media fluids are roughly the same, choosing an equal path arrangement is more reasonable; When there is a significant difference in fluid flow rate between the two sides of the plate heat exchanger, the fluid on the side with lower flow rate should be arranged in multiple processes as much as possible. The side of the plate heat exchanger that undergoes phase change is generally a single process. Multi process plate heat exchangers generally adopt the same number of channels for the same liquid in the plate heat exchanger unless there is a special need.
Under a certain pressure drop, a multi process arrangement will result in a decrease in the corresponding pressure drop on each side, leading to a decrease in flow rate and a corresponding decrease in heat transfer efficiency. In addition, the arrangement of multiple processes with unequal flow is also an important factor in reducing the average heat transfer temperature difference, which should be avoided or reduced as much as possible.
In recent years, with the diversification of application conditions of plate heat exchangers, asymmetric channel forms have emerged in domestic plate heat exchangers. More and more foreign plate heat exchangers adopt a "thermal mixing" plate combination form, which allows for the mismatch between heat, flow rate, and pressure drop, thus saving heat exchange area.