The plate heat exchanger is a high-efficiency heat exchange device composed of a plurality of corrugated heat transfer plates at a certain interval by welding or pressing by a rubber gasket. According to the processing technology, it is divided into a detachable heat exchanger and a fully welded non-removable heat exchanger. The welded heat exchanger is a structure between the two, that is, the two fluids are assembled as relatively independent structures.What are the methods to increase the heat transfer coefficient of plate heat exchangers?
(1) Improve the phe plates surface heat transfer coefficient
Since the corrugation of the plate heat exchanger enables the fluid to generate turbulence at a small flow rate, a high surface heat transfer coefficient can be obtained, and the surface heat transfer coefficient is related to the geometry of the plate corrugation and the flow state of the medium. The waveform of the plate includes herringbone shape, straight shape and spherical shape. After years of research and experiments, it is found that the herringbone plate with triangular shape of corrugation has a high surface heat transfer coefficient, and the larger the angle of the corrugation, the higher the medium flow velocity in the flow channel between the plates, the greater the surface heat transfer coefficient.
(2) Reduce the thermal resistance of the fouling layer
The key to reducing the thermal resistance of the fouling layer of the heat exchanger is to prevent plate fouling. When the thickness of the plate scaring is 1 mm, the heat transfer coefficient is reduced by about 10%. Therefore, it is necessary to pay attention to monitoring the water quality at both ends of the heat exchanger to prevent scaling of the plates and to prevent the inclusion of impurities in the water on the plates. Some heating units add chemicals to the heating medium in order to prevent water theft and corrosion of steel parts. Therefore, it is necessary to pay attention to the water and viscous agents causing debris to contaminate the heat exchanger plates. If there is viscous debris in the water, it should be treated with a special filter. When using a drug, it is advisable to choose a non-stick agent
(3) Select heat exchanger plate with high thermal conductivity
The plate material can be selected from austenitic stainless steel, titanium alloy, steel alloy. Stainless steel has good thermal conductivity, thermal conductivity 14.4W/(mk), high strength, good stamping performance, not easily oxidized. The price is lower than that of titanium alloy and copper alloy, but it’s poort resistance to chloride ion corrosion.