Experimental And Numerical Simulation Investigation Of Characteristics Of Rotary Heating Distillation Of Brine Solution At Low Pressure

Environmental control and life support system (ECLSS) is an essential prerequisite for the long-term operation of the station, among which the urine wastewater recycle processing is the crucial part and difficult to tackle. Nowadays, there are two international technologies for urine separation technology:membrane separation technology and the vapor compression distillation technology (VCD). This article selects vapor compression distillation unit as the research object and applies the experiment and numerical simulation method in order to study the characteristics of the steam separation.The fluid flow and the film formation in a rotary evaporator were analyzed through a serious of visualization experiments, as well as the effects of different speed conditions, liquid height and the tilt angle on the solution spreading situation. The results show that the higher the liquid level the greater the range of spread and the more dramatic fluctuations in fluid turbulence at high speed; the greater the angle, the larger the liquid film spreading. An optimum tilt angle of70°was chose as the experimental condition by comprehensive comparison. Then the vapor compression distillation experiment with the brine solution as the working fluid was conducted. The results indicated the centrifugal separation properties depend on heating temperature, rotational speed and concentration. Among them, heating temperature is the dominant factor, for example, when the temperature is between35degree Celsius (35℃)and60degree Celsius (60℃), the water production rate will reach94.54%-95.89%. Compared to heating temperature, the rotational speed has less influence. The max fluctuates is less than0.2%with different rotational speed. In addition, the concentration increases with decreased water production rate.A CFD simulation has performed to study the characteristics of the solution flow and heat and mass transfer phenomenon by coupling two-phase flow model and phase-change model. The influence of the wall heating temperature, rotation speed, liquid level and angle of flask on the evaporative distillation process has been investigated. It can be concluded that the wall heating temperature has a main affect. As the temperature increases, the efficiency increases due to the intensive heat transfer coefficient. The rotate speed and angle have an effect on flow patterns. The changing of solution disturbance and heated area will change the heat and evaporation distillation. Increasing the level of the solution can reduce the rate of heat transfer, which leads to a lower efficiency of the distillation. The angle change not only affects the areas of the free surface, may also have an effect on the flow pattern. As the angle adds, the perturbation solution increases, the heat transfer phenomenon strengthen, at last the distillation efficiency increases.The results were used to develop a comprehensive description of phenomenon of vapor compression distillation which is used in Chinese space station ECLSS technology.