Structure Optimization And Numerical Simulation Of Evaporative Condenser For Small Scaled Air Condition

With the development of society, refrigeration has become a necessary aspect of people's daily life and industrial production and has been used more and more widely and frequently. As the environment issue is put on the agenda, water scarcity is also concerned a lot. Especially in recent years, the shortage of power resources becomes so serious that high demands for energy conservation of the refrigeration system and application are required. Compared to the other forms of condensers, evaporative condenser draws more attention by its advantages of water-saving, energy conservation, and compact structure, which is been used more and more in refrigeration system.The heat and mass transfer process in evaporative condenser is quite complex, and there is no specific formula for the calculation of many thermodynamic parameters, but some empirical formula. After analyzed and summarized the heat and mass transfer process, appropriate formulas are chosen for calculation. Structure calculation of evaporative condenser is taken according to the condition of small scaled air condition, which includes heat flux, choice and calculation of relative parameters for the tube, initial structure design, option for the amount of water spray and wind, calculation of heat transfer coefficient inside the tubes and for water film outside the tube, calculation of convection heat transfer coefficient and mass transfer coefficient of air outside the tube, calculation of equivalent heat transfer coefficient outside the tube, and calculation of air flow resistance outside.For the purpose of optimum design, a steady local turbulent mathematical model of evaporative condenser is established based on numerical simulation by using Fluent software. Heat transfer boundary condition of fin is determined by means of liquid-solid coupled method for outside heat transfer calculation. Under analysis of heat transfer properties of evaporative condense with fins and without, a conclusion that evaporative condense with fins can improve the performance of heat exchanging is reached. Through the simulation of performance of heat exchange under different amount of wind, it is been proved that appropriate increase of air flow can improve the heat transfer performance and there exists a best air flow. In addition, different mathematical models are established under different fin pitches for simulation analysis, which shows that system has a better heat exchange performance when the fin pitch is between 1.8mm and 2.0mm.