To improve the heat transfer coefficient of the heat exchanger, the heat transfer coefficient of both sides of the plate can be effectively improved only by improving the surface heat transfer coefficient of both sides of the plate, reducing the thermal resistance of the fouling layer, selecting the plate with high thermal conductivity and reducing the thickness of the plate.
1. Because the ripple of plate heat exchanger can make the fluid produce turbulence at a small flow rate, it can obtain a higher surface heat transfer coefficient. The surface heat transfer coefficient is related to the geometric structure of plate ripple and the flow state of medium. The waveforms of the plates include herringbone, straight, spherical, etc. After years of research and experiments, it is found that the herringbone plate with triangular corrugated cross-section has a high surface heat transfer coefficient, and the larger the included angle of the corrugated plate, the higher the flow velocity of the medium in the channel between the plates, the greater the surface heat transfer coefficient.
2. The key to reduce the thermal resistance of the fouling layer of the heat exchanger is to prevent the fouling of the plates. When the scale thickness of the plate is 1mm, the heat transfer coefficient decreases about 10%. Therefore, it is necessary to monitor the water quality on both sides of the heat exchanger to prevent the plate from scaling and the water debris from adhering to the plate. In order to prevent water theft and steel corrosion, some heating units add chemicals to the heating medium. Therefore, it is necessary to pay attention to the contamination of heat exchanger plates caused by water quality and viscosity. If there are sticky impurities in the water, special filter shall be used for treatment. When choosing the medicament, it is better to choose the medicament without viscosity.
3. The plate material can be stainless steel, titanium alloy, copper alloy, etc. Stainless steel has good thermal conductivity, thermal conductivity of about 14.4w / (m · K), high strength, good stamping performance, and is not easy to be oxidized. Its price is lower than that of titanium alloy and copper alloy. It is used most in heating engineering, but its ability to resist chloride ion corrosion is poor.