Study On Heat Transfer Enhancement And Performance Of Evaporation Condenser With Convex Concave Plate

Small energy consumption,water saving and energy saving,low operating cost, less investment are the characteristics of the evaporative condenser,and the heat exchange efficiency of it is higher than other types.Three respects of theoretical research,experimental research and numerical simulation research of plate-type evaporative condenser were researched in this paper. The method of combining three researches was effective,it was better to study the fluid flowing characteristic and the heat and mass transfer performance on the air-water side. The mainly research content was divided into the following aspects in this paper:(1)Theoretical analysis on the heat and mass transfer mechanism of the plate-type evaporative condenser,and the important influencing factors on evaporation and the composition and structure characteristics of the plate-type evaporative condenser weremainly analyzed.Inaddition, the heat and mass transfer mechanism and the influence factors on the evaporative condenser heat and mass transfer performance were analyzed.(2)Calculation correlations on heat and mass transfer of plate-type evaporative condenser were build,and they have been verified by the experimental data. In addition, for the purpose to improve the heat and mass transfer performance of evaporative condenser, calculation correlations could be used to guide the design of evaporative condenser and to analyze the heat resistance.(3)Parameters such as air flow rate,spraying water flow rate,temperature and so on have been measured in order to research the affect on the heat and mass transfer performance of the plate-type evaporative condenser. And the effect on energy efficiency ratio of the refrigerating capacity, dry-bulb temperature, heat flux of plate, temperature of cooling water and enthalpy difference between the outlet and inlet air were investigated.The energy efficiency ratio increases with the increase of the refrigerating capacity, and the EER is 4.90 at the capacity of 170 k W; The energy efficiency ratio decreases first and then increases with the increase of the dry-bulb temperature, and the energy efficiency ratio can be up to 4.82 at the best operating condition of the dry-bulb temperature of 29.50℃; The energy efficiency ratio increases with the increase of the heat flux, and the EER is 4.90 at the plate heat flux density of 4200W/m2; The energy efficiency ratio increases with the increase of the temperature of cooling water, but the impact is not obvious, and the EER is 4.87 at the temperature of cooling water of 33.15℃; The energy efficiency ratio increases with the increase of the enthalpy difference between the outlet and inlet air, and the EER is up to 4.92 at the enthalpy difference between the outlet and inlet air of 30.0k J/kg.(4)The fluid flow characteristics and the performance of heat and mass transfer were analyzed by using the method of numerical simulation. In addition, the parameters of plate spacing,air velocity,spraying water flow rate,heat flux,height of plate slab bulge,angle and height of PVC packing on the influence of heat and mass transfer performance of the plate-type evaporative condenser. For the purpose to realize the best heat and mass transfer performance, the plate and PVC packing structure and the operation parameters were optimized through the method of numerical simulation.Results show that for the the best heat and mass transfer performance of the plate evaporative condenser, the best operation condition of the plate unit, the spraying water flow rate was kept at 0.05kg/s, the plate heat flux was kept at 3700W/m2, plate spacing was kept at 24 mm, the height of plate slab bulge was kept at 6mm, the height of PVC packing was kept at 7mm.