The plate heat exchanger is a heat transfer type heat exchanger. The hot and cold fluid transfers heat through the heat exchanger plate, and the fluid is in direct contact with the plate. The heat transfer mode is heat conduction and convection heat transfer. The key to improving the heat transfer efficiency of plate heat exchangers is to increase the heat transfer coefficient and the logarithmic mean temperature difference.
(1) Improve the surface heat transfer coefficient of the sheet
Since the corrugation of the plate heat exchanger enables the fluid to generate turbulence at a small flow rate (Reynolds number - 150 Å), a higher surface heat transfer coefficient can be obtained. The surface heat transfer coefficient is related to the geometry of the sheet corrugations and the flow state of the medium. The waveform of the plate includes a herringbone shape, a straight shape, and a spherical shape.
(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 sheet scale is 1 mm thick, the heat transfer coefficient is reduced by about 10%. Therefore, it is necessary to pay attention to monitoring the water quality on both sides of the heat exchanger to prevent scaling of the plates and to prevent the inclusion of impurities in the water on the plates.
(3) reduce the thickness of the plate
The design thickness of the plate is independent of its corrosion resistance and is related to the pressure bearing capacity of the heat exchanger. The plate is thickened to improve the pressure bearing capacity of the heat exchanger. When the herringbone plate is used, the adjacent plates are inverted and the corrugations are in contact with each other, forming a fulcrum with large density and uniform distribution. The corner hole and edge sealing structure of the plate have been gradually improved, so that the heat exchanger has a good bearing pressure capacity.