First, the establishment of Plate heat exchanger bypass Pipe When the flow of hot and cold media is relatively large, can be in the large flow side Plate Heat Exchanger import and export of the question to set up a bypass tube, reduce the flow into the plate Heat Exchanger, reduce resistance. For ease of adjustment, a regulating valve should be installed on the bypass tube. This method should adopt the Countercurrent arrangement, make the cold medium out plate heat exchanger temperature is higher, ensure that the plate heat exchanger outlet confluence after the cold medium temperature can meet the design requirements.
The plate heat exchanger bypass tube can ensure that the plate heat exchanger has a high heat transfer coefficient and reduce the resistance of the plate heat exchanger, but the adjustment is slightly more complex.
Second, the choice of plate heat exchanger form The average flow rate of medium in the channel between plate heat exchanger is 0. 3~ 0. 6M/S is appropriate, resistance to not greater than KPA is appropriate. According to the flow ratio of different hot and cold media, different forms of plate heat exchanger can be selected by reference to table 1, and the cross-sectional area ratio of non-symmetrical plate heat exchanger in the table is 2.
Using symmetrical or asymmetric type, single process or multi-process plate heat exchanger, the plate heat exchanger bypass tube can be set up, but should be calculated by detailed heat. When the flow rate of hot and cold media is relatively large, the use of hot mixing plate than the use of symmetrical single-process plate heat exchanger can reduce the plate area. The diameter of the corner hole on both sides of the hot mixing plate is usually equal, and when the flow ratio of the cold and hot medium is too large, the angle lone L pressure loss on one side of the cooling medium In addition, thermal mixing plate design technology is difficult to achieve accurate matching, often resulting in a limited amount of plate space savings.
Therefore, hot mixing plate should not be used when the flow rate of hot and cold medium is too large.
Third, the use of asymmetric type plate heat exchanger The symmetrical plate heat exchanger is composed of plate with the same corrugated geometrical structure on both sides of the plate, forming a plate heat exchanger with equal cross-sectional area of hot and cold runner circulation. According to the heat transfer characteristics and pressure drop requirements of the hot and cold fluid, the asymmetric (unequal cross-sectional area type) plate heat exchanger changes the geometric structure of the two sides of the plate, forming the plate heat exchanger with different cross-sectional area of the hot and cold runner, and the angle lone l diameter on the side of the wide runner is larger. The heat transfer coefficient of asymmetric plate heat exchanger decreases slightly, and the pressure drop decreases greatly. When the flow rate of hot and cold media is relatively large, the use of asymmetric single process than the use of symmetrical single-process plate heat exchanger can reduce the plate area of 15% 3o%.
