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Selection of plate type and flow channel of plate heat exchanger
Release time:
2022-08-12
Process refers to a group of parallel flow channels in the heat exchanger along the same flow direction, and this channel refers to the medium flow channel composed of two adjacent plates in the plate heat exchanger.
Selection of plate type and flow channel of plate heat exchanger
Plate heat exchanger plate is an efficient heat exchanger composed of a series of corrugated metal plates. A thin rectangular channel is formed between different plates to exchange heat. Plate heat exchanger plate is an ideal equipment for liquid-liquid and liquid-vapor heat exchange. It is characterized by high heat exchange efficiency, small heat loss, compact and lightweight structure, small floor area, wide application range and long service life. Under the same pressure loss, its heat exchange coefficient is 3-5 times higher than that of the tubular heat exchanger, its floor area is 1/3 of that of the tubular heat exchanger, and its heat recovery rate can be as high as 90%. The plate is the core element of the plate heat exchanger. The cold and hot fluids exchange heat on the plate, which is the heat exchange element of the heat exchanger. In addition, it also bears the pressure difference on both sides. Therefore, the selection of appropriate plate type and flow channel of plate heat exchanger has a great impact on the operation of heat exchange equipment, heat exchange efficiency and fluid resistance.
The plate shape and ripple of plate heat exchanger shall be determined according to the actual heat exchange conditions. For large flow and small allowable pressure drop, the plate with small resistance should be selected. According to the pressure and temperature of the heat exchange medium, the removable type or brazed type shall be selected. For equipment with large heat exchange area, do not select plates with small plate area. Otherwise, the number of plates is too large, the flow rate between plates is too small, and the heat transfer coefficient is too low. Removable plate heat exchanger is composed of multiple corrugated plates for stamping in a certain interval, sealed by gaskets around, compressed by overlapping framework and compression screw, and the four corner holes of the plates and gaskets form fluid distribution and gathering pipes. At the same time, the hot and cold fluids are reasonably separated again to make them flow in the flow channels on both sides of each panel and pass through the plate heat exchanger.
Process refers to a group of parallel flow channels in the heat exchanger along the same flow direction, and this channel refers to the medium flow channel composed of two adjacent plates in the plate heat exchanger. Generally, several flow channels are connected in parallel or in series to form different combinations of hot and cold media channels. In order to make the fluid flow between the plate bundles according to certain requirements, the four corners of the plate bundles are punched as required, and the gaskets are pasted as required, and arranged regularly to form a flow channel, which is called flow combination. The flow combination form shall be determined according to the calculation of heat transfer and fluid resistance, and meet the requirements of process conditions. When the convective heat transfer coefficient of the medium on both sides of the heat exchange surface is equal or close, the heat transfer coefficient can get a larger value. Therefore, in order to obtain better heat transfer effect, we should try to make the convective heat transfer coefficient in the cold and hot water channels equal or close. In the design and selection of plate heat exchanger, there are certain requirements for pressure drop, which should be checked. If the check pressure drop exceeds the allowable pressure drop, it is necessary to redesign and type selection calculation until the process requirements are met.
