Study On Heat Transfer Characteristics Of Multi-unit Parallel Flow Type Evaporator

Parallel flow heat exchanger with a louver fin is widely used in the fields of automobile, chemical, aerospace and power machinery because of its many advantages. Through the louvered fins increase fluid disturbance to break the flow of the boundary layer near wall, in order to enhance the effect of heat exchanger. Louver fin has been a hot topic in the field of academic research because of its good heat transfer performance and compactness.This paper mainly for the numerical study on heat transfer and flow performance of multiple parallel flow evaporator on the air side, analyze the influence on the performance of multiple parallel flow evaporator on the air side of different structural parameters. In this paper, three dimensional simulations on the air side heat transfer and flow performance of louvered fins were carried out with the CFD software FLUENT. The factors of influencing heat transfer and flow characteristics of louvered fins are fin pitch, louver angle, louver height louver pitch, louver arrangement structure and so on. Three dimensional simulations on the air side heat transfer and flow performance of louvered fins were carried out. Colburn factor and friction factor of louvered fins were calculated in the Re number of80~800. The calculation results and experimental correlations results of literature are identical with each other, and thus it proves the exactness of simulation. Fins temperature field distribution, air velocity distribution and pressure field distribution were analyzed when different Re number. At the same time, It was emphasized that the heat transfer coefficient and pressure drop of louvered fins was influenced by some main structural parameters of louvered fins, such as fin pitch, louver angle, louver height louver pitch, louver arrangement structure. The results would provide a basis and guidance for similar engineering design and further research.The results show that:Temperature gradient of fins with louvers is larger than fins without louvers, it shows the shutters structure is helpful for enhancing the heat transfer effect of louvered fins. The temperature distribution on symmetry plane of louvered fin model is not even, it proves that the calculation results of a three dimensional model is exacter than the calculation results of a two dimensional model. In this paper simulation range, along with the increase of fin pitch, the heat transfer coefficient and pressure drop showed a trend of decrease; along with the increase of louver pitch, the heat transfer coefficient and pressure drop showed a trend of decrease; along with the increase of louver height, the heat transfer coefficient and pressure drop showed a trend of increase; Low Re, the heat transfer coefficient is obviously influenced by louver angle, high Re, the heat transfer coefficient is not obviously influenced by louver angle; Louver arrangement structure can influence the heat transfer and flow performance of louvered fins, heat transfer effect is enhanced when louver arrangement structure is irregular.