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How to improve the surface heat transfer coefficient of plate heat exchanger

1. Reduce the thermal resistance of the dirt layer

The key to reducing the thermal resistance of the fouling layer of the plate heat exchanger is to prevent the plate from fouling. When the plate fouling thickness is 1 mm, the heat transfer coefficient is reduced by about 10%. Therefore, care must be taken to monitor the water quality on both sides of the heat exchanger to prevent fouling of the plates and prevent debris in the water from adhering to the plates. In order to prevent water theft and corrosion of steel parts, some heating units add chemicals to the heating medium. Therefore, attention must be paid to the water quality and viscosity caused by sundries to contaminate the heat exchanger plates. If there are viscous debris in the water, special filters should be used for treatment. When choosing medicines, it is advisable to choose non-stick medicines.

2. Use plates with high thermal conductivity

The plate material can choose austenitic stainless steel, titanium alloy, copper alloy, etc. Stainless steel has good thermal conductivity, with a thermal conductivity of about 14.4 W/(m•K), high strength, good stamping performance, and is not easy to be oxidized. The price is lower than that of titanium alloy and copper alloy. It is used most in heating engineering, but its Poor resistance to chloride ion corrosion.

3. Reduce plate thickness

The design thickness of the plate has nothing to do with its corrosion resistance, but is related to the pressure bearing capacity of the plate heat exchanger. Thicker plates can improve the pressure-bearing capacity of the heat exchanger. When the herringbone plate combination is adopted, the adjacent plates are turned upside down, and the corrugations are in contact with each other, forming a fulcrum with high density and uniform distribution. The corners of the plates and the edge sealing structure have been gradually improved, so that the heat exchanger has a good performance. Pressure endurance. The maximum pressure-bearing capacity of the domestic detachable plate heat exchanger has reached 2.5 MPa. The thickness of the plate has a great influence on the heat transfer coefficient, the thickness is reduced by 0.1mm, the total heat transfer coefficient of the symmetrical plate heat exchanger is increased by about 600W/(m •K), and the asymmetrical type is increased by about 500 W/(m •K) ). On the premise of meeting the pressure-bearing capacity of the heat exchanger, the thickness of the plate should be as small as possible.