Design And Research Of An Open Heat And Mass Transfer Coupled Evaporation System

An open heat and mass transfer coupled evaporation system was designed with introducing the humidification and dehumidification technology and the heat pump technology into the field of evaporation and concentration,in order to solve the problems of low energy efficiency,high evaporation temperature,overinvestment in equipment and high operating costs in this field.This new system realized the recycling of energy inside the system and the in vitro ammonium chloride solution cooling crystallization.The influence law of the temperature of the inlet humidifier humid air,the relative humidity of the inlet humidifier humid air,and the volume of the packing on the new system was studied.A humidifier device which was suitable for the new system was built,and the influence law of the mass flow rate of the humid air and the relative humidity of the humid air on the unit were experimentally studied.Specific tasks accomplished including the followings:(1)The temperature of the outlet humidifier concentrate is limited by the thermodynamic wet-bulb temperature of the inlet humidifier humid air and the size of packing.(2)The energy consumption decreases with increasing the temperature of the inlet humidifier humid air in the range of simulated working conditions.The energy consumption of the temperature of the humid air amount of 32.5℃is 1.25 times than that of 42.5℃.The energy consumption increases with the increase of the relative humidity of the inlet humidifier humid air.When the relative humidity of the humid air is 50.0%,the energy consumption is 1.84 times than that of30.0%.The energy consumption reduces with decreasing the volume of the packing,but the law is opposite on the highest outlet concentrate temperature.The energy consumption of volume of the packing amount of 20 m~3 is 2.29 times than that of 50 m~3.(3)Compared with the calculation,the maximum error of the relative humidity and the evaporation of the humid air are 21%,and the liquid to gas ratio and the temperature of the outlet humidifier humid air change the same trend.These can explain the accuracy of the simulation.(4)The evaporation of the device first increases,and then decreases with reducing the relative humidity of the humid air,in the range of experimental working conditions.The evaporation of the device reduces with decreasing the mass flow rate of the humid air.When the mass flow rate of the humid air is 57.2 kg/h,the evaporation is 1.15 times than that of 48.1 kg/h.