Performance Optimization Of The Plate Of PHE And Entransy Theoretical

As thermal power mechanical apparatus, plate heat exchangers (PHE) have been widely used inalmost all the industrial fields due to their advantages such as excellent heat transfer performance andcompact structure. Much heat energy was economized by employing the PHE. With the developmentof Computation Fluid Dynamics technology, the distribution of pressure, temperature and velocityvectors can be obtained.In this thesis, commercial CFD software was used to optimize the chevron corrugated plate heatexchangers on the basis of two old plates with different angle β.Three different models have beenestablished in Gambit, and then calculated by CFD and HTFS respectively. Both numerical andexperimental research results showed that the Nu of the H-type plate is the highest, the resistance ofcompound of the V-type plate is the lowest and the complex performance of Mix-type plate is thehighest.The angle of the plate was firstly optimized based on zigzag corrugated plate. Models withinclination angle β from20°to60°have been constructed and simulated in the same boundaryconditions. Results showed that the value of Nu and the pressure loss of the fluid in the plate went upwith the increase of β. While the comprehensive performance parameters of the fluid decreased as βrised and sharply reduced When the value of β reached to40°. Therefore, it can be concluded that thevalue of inclination angle β should be controlled in less than40°.For ordinary corrugated plate, the longitudinal wave height is consistent. On the basis ofchoosing tortuous wave plate, an optimize design of corrugated longitudinal has been carried out.Models have been established under different longitudinal wave height ratio, the value of which is0、0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9and1. Results from the numerical simulation by Fluentindicated that the increasing longitudinal wave height ratio resulted in the decrease of Nu but increaseof the pressure loss. Take the comprehensive performance parameters of the plate into account, theoptimize property appeared at a=0.4. From the above results, a new plate can be designed at theripple angle of40°and longitudinal wave height ratio of0.4. Models of both new and old plate fornumerical calculation were then established at the same size of350mm×200mm.After the first optimization of the angle and longitudinal wave height for the corrugated plate,the second optimization was carried out in order to enhance the heat transfer efficiency. Therefore,dimple with the size of0.6mm in diameter and5.5mm in ripple depth was added on the twists and turns corrugated plate. From the simulation result, the plate added with dimple showed betterperformance than before.The minimum thermal resistance theory was developed based on the Entransy theory putforward by professor Guo Zengyuan and has been applied to the design of plate heat exchanger. Inthis thesis, the minimum thermal resistance theory was used to obtain the thermal resistance value ofthe plate models above. The new plate model with the highest heat transfer efficiency got smallerthermal resistance value than the old plate model.