Research Of Influence On Heat Exchange Efficiency In Direct Air-cooling Unit With The Installment Of Deflector

As the fact of the shortage and uneven distribution of water resources, air-cooling technology of the thermal power plant with remarkable water-saving effect developed rapidly in China’s northwest water-deficient area. Air-cooling unit uses air as a cooling medium, whose operation is no longer dependent on excessive consumption of water resources.After years of development, air-cooling technology is during the period of gradually matured and widely used. As one of the air-cooling technology, direct air-cooling system uses ambient air as the cooling medium to cool down the exhaust steam directly, which eliminates the cooling water and other intermediate medium. As the core device of direct air-cooling system, Air Cooling Condenser has a critical influence on stability and efficiency of the system. As heat exchange resistance of the air-cooling condenser is mainly at the air side, the key factors affecting the characteristic of air-cooling condenser operating performance is the characteristic of its airflow field.This paper aims to improve the internal flow field of air-cooled units. Through analysis on theory, then using numerical simulation with engineering practice, this paper study the impact on heat exchange efficiency of direct air-cooling unit with the installation of deflector.Based on computational fluid dynamics knowledge, this paper builds a physical and mathematical model of air cooling unit, then uses the FLUENT software to simulate the model. Using the SIMPLE algorithm and the standard k-ε model, the paper constructs a series of equations, considers the coupling of static and dynamic, establishes the boundary conditions of the porous medium model combined with the heat sink model. By building numerical analysis model of air-cooling units assembled deflector at different locations, the paper analyzes the improved situation for internal air flow field of air-cooling unit with different deflector’s positions. After calculating and comparison,the paper get the conclusion that the improvement on the efficiency of air-cooled unit by installing deflector with the 1.25meters distance to air-cooled heat transfer is better than the installment with the distance of 2.25meters. On this basis, the paper changed the deflector mounting angle, and finally proposes optimized deflector’s installing position.