Study On Heat Transfer And Flow Resistance Characteristics And Structure Optimization Of The Plate-Tube Type Evaporative Condenser

Energy conservation and emissions reduction has become the consensus of the whole society because of energy shortage and environmental degradation. As a kind of efficient heat exchange equipment which is water-saving and energy-saving, the application and promotion of evaporative condenser play an important role in promoting energy conservation and emissions reduction. Therefore, the study of evaporative condenser is very valuable for engineering application.In order to rearch the change rule of the performance when chilled water outlet temperature is from 7℃ rise to 11℃, the vortex type water chiller which used plate-tube type evaporative condenser was analysised by theory and measured by experiment. The result show that: With the increase of chilled water outlet temperature, the total electric power consumption increased by 3.62%, system refrigerating capacity increased by 7.45% and energy efficiency ratio increased by 4.26%. Meanwhile, total heat transfer coefficient of evaporative condenser increased from 150.23W/(m2·K) to 168.15W/(m2·K), sensible heat quantity increased from 12.49 kW to 19.53 kW, latent heat exchange capacity increased from 165.98 kW to 172.02 kW, the ratio of latent heat exchange capacity in total heat transfer quantity decreased from 93.00% to 89.80%. With the increase of chilled water outlet temperature, the temperature of spray water in the circle increased. In the condition of same chilled water outlet temperature, the temperature of spray water was increased first and then decreased in the flow process from spraying to falling into sink. The temperature of spraying and falling into sink was almost the same.Three-dimensional model of flow unit of spray water and the air between plate tube was established according to the plate-tube structure of evaporative condenser. The gas-liquid two phase flow between the plates was simulated by discrete phase model of Fluent software. The result of comparing simulation with the test data shows that the error of dry bulb temperature, wet bulb temperature and moisture content of outlet air is less than 5%. In order to research the effect of spray water, inlet wet air, space of plate, parameters of plate structure on the heat and mass transfer process between air and water in the plates, the simulation was conducted by Fluent software. The following conclusions were made. With the rise of spray water flow, the heat transfer performance is improved, but the power consumption of water pump increases greatly, so the actual spray water flow is 0.035 kg/s. The drop of dry bulb temperature of inlet wet air is beneficial to improving heat transfer performance, but the effect is not obvious. The drop of moisture content of inlet wet air is beneficial to improving heat transfer performance. With the rise of inlet air flow rate, the heat transfer performance improved, but the power consumption of fan increased, so the actual inlet air flow rate should be considered. The decrease of plate space is helpful for improving heat transfer performance, but fluid-resistance increases greatly, so the actual space of plate is 25 mm. When the height of concave structure is 5mm, the major diameter of concave structure is 29 mm, the minor diameter of concave structure is 12 mm, the heat transfer performance improved.