Transfer Characteristic Of The Wet-bulb Temperature And Optimization For The Plate Wet Air Cooler

The plate wet air cooler combines the technical advantages of plate heat exchangers with dry cooling and evaporative cooling. When hot climates in summer, water spraying runs and outlet temperature of hot fluids plays down because heat transfer is enhanced by evaporative cooling. The plate wet air coolers are new type of cooling equipments and have a great market foreground. By theoretical and experimental methods, some key problems were lucubrated, such as heat and mass transfer, transfer characteristic of the wet bulb temperature, optimization for the frame and running for the plate wet air cooler. The research results can be used to popularize the plate wet air cooler.Transfer models were developed with overall wetting condition and part overall wetting and some water droplets larding in air condition. The relative errors of efficiency prediction are small than 2 percent because Lewis factor is equal to 1.The method to determine the mean saturated line slope of moist air was presented, which can apply to hot water and air. The wall wetting rate has remarkable effect on cooling efficiency. But water droplets in air effects are small and can be ignored in engineering calculations.Introducing the wet bulb specific heat capacity and the wet bulb heat transfer coefficient, a new mathematical model for the plate wet air cooler was developed based on the wet bulb temperature transfer characteristic. Analytical solutions for the parallel-flow and approximate analytical solutions for the cross-flow were presented. The solutions were found to be good agrees with experimental results. The transfer characteristic of air dry/wet bulb temperature and spraying water temperature were discussed. The LMTD method based on this mathematical model is applicable to design and verify for the plate wet air cooler. The ratio of the wet bulb heat transfer coefficient to the heat transfer coefficient under air-cooled conditions was investigated theoretically and experimentally. The relative errors of the ratio between theoretical and experimental valves are small than 7 percent. The method to determine the limited temperature for dry/wet running conditions was presented. Multi-object frame optimization model were developed. Combined with the thermal and hydraulic correlations for dry/wet conditions of plate wet air cooler, the optimization model can be used to optimize the dry/wet limited temperature and frame parameters.