Plate heat exchangers are divided-wall heat transfer heat exchangers. Cold fluid transfers heat through the heat exchanger plates. The fluid and the plates are in direct contact. The heat transfer methods are heat conduction and convective heat transfer. The key to improving the heat transfer efficiency of plate heat exchangers is to increase the heat transfer coefficient and logarithmic average temperature difference. 1. To improve the heat transfer coefficient of the heat exchanger, only by simultaneously increasing the surface thermal coefficients on both sides of the plate and reducing the thermal resistance of the scale layer, selecting plates with high thermal conductivity, and reducing the thickness of the plate, can we effectively improve the heat transfer coefficient of the heat exchanger. (1) Increase the surface heat transfer coefficient of the plate Because the corrugations of the plate heat exchanger can cause the fluid to generate turbulence at a small flow rate, a high surface heat transfer coefficient can be obtained. The surface heat transfer coefficient is related to the geometric structure of the plate corrugations and the flow state of the medium. The waveform of the plate includes herringbone, straight, spherical, etc. After years of research and experiments, it has been found that chevron plates with triangular corrugated cross-sections have higher surface heat transfer coefficients, and the larger the included angle of the corrugations, the higher the media flow velocity in the flow channel between the plates, and the greater the surface heat transfer coefficient. (2) Reduce the thermal resistance of the dirt layer The key to reducing the thermal resistance of the dirt layer of a heat exchanger is to prevent the plate structure. When the plate structure thickness is 1mm, the heat transfer coefficient is reduced by about 10%. Therefore, pay attention to monitoring the water quality at the hot and cold ends of the heat exchanger to prevent plate structure and prevent debris in the water from adhering to the plates. Some heating units add chemicals to the heating medium to prevent water theft and corrosion of steel parts. Therefore, pay attention to water quality and viscous chemicals causing debris to stain the heat exchanger plates. If there are sticky debris in the water, a special filter should be used for treatment. When selecting pharmaceuticals, you should choose non-sticky pharmaceuticals. Select plates with high thermal conductivity Plate materials can be selected from austenitic stainless steel, titanium alloy, steel alloy, etc. Stainless steel has good thermal conductivity, with a thermal conductivity of about 14.4W/(mk), high strength, good stamping properties, and is not easy to be oxidized. The price is lower than that of titanium alloys and copper alloys, but its resistance to chloride ion corrosion is poor. (3) Reduce the thickness of the plate The design thickness of the plate has nothing to do with its corrosion resistance, but is related to the pressure bearing capacity of the heat exchanger. Thickening of the plates can improve the pressure bearing capacity of the heat exchanger. When the combination of chevron plates is adopted, adjacent plates are inverted with each other, and the ripples contact each other, forming a point with high density and uniform distribution. The sealing structure of the corners and edges of the plates has been gradually improved, giving the heat exchanger a good pressure bearing capacity. On the premise of meeting the pressure bearing capacity of the heat exchanger, a smaller plate thickness should be selected as much as possible. 2. Increase the logarithmic mean temperature difference Plate heat exchanger flow patterns include countercurrent, downstream and mixed flow patterns. Under the same working conditions, the logarithmic mean temperature difference is large in countercurrent and small in countercurrent, and the mixed flow pattern is between the two. The method to increase the logarithmic average temperature difference of the heat exchanger is to use a mixed flow pattern with countercurrent or close to countercurrent as much as possible, increase the temperature of the hot side fluid as much as possible, and reduce the temperature of the cold side fluid.