| It has become a hot issue of development about the shortage of freshwater resources. In coastal areas, develop seawater desalination project is an effective way to solve the problem about shortage of freshwater resources. Using the natural evaporation and concentration technology on desalinated seawater, and can solve the problem of comprehensive utilization of desalinated seawater effectively. It can avoid the discharge of desalinated seawater which can impact the Marine ecological environmental effectively. Through the natural evaporation and concentration of desalinated seawater for the salt, it enlarged the chain of desalination industry, which can use the seawater resources fully and efficiently. It also reduces the cost of desalination industry, which had a great significance on researching.Building a natural evaporation simulation system of desalinated seawater indoor, the simulation system was an independent space with the square of 5X8 m2. It can simulate the meteorological factors and operation conditions which influence the desalinated seawater natural evaporation were well. Using the simulation system we can study the relationship between the natural evaporation rate and meteorological factors & operating conditions. The meteorological factors include irradiation intensity, environmental temperature, air relative humidity, speed of wind and the operating conditions include brine temperature, concentration of brine and depth of brine. The signal of the experimental data can be automatic monitored and collected in the simulation system.The experimental material is the desalinated seawater from the Bay of Bohai. According to the local meteorological condition of Binhai New Area of Tianjin, simulated the natural evaporation process of desalinated seawater under different meteorological factors and operating conditions for the whole year. The experimental results show that if it has the same or similar conditions in others, with the higher irradiation intensity, environmental temperature, brine temperature and speed of wind, the natural evaporation rate of desalinated seawater were higher; but with the higher air relative humidity and concentration of brine, the natural evaporation rate of desalinated seawater were lower. According the typical weather conditions in Tianjin, which means the irradiation intensity was 600±50W/m2, the environmental temperature was 25±1℃, the air relative humidity was 40%±5%, the brine temperature was 25±1℃, the speed of wind was 4.0±1m/s, the concentration of brine was 6±1℃ Be’and the depth of brine was about 20cm, then the evaporation rate of desalinated seawater was between 0.29mm/h and 0.43mm/h.Building the natural evaporation neural network model of desalinated seawater based on the Matlab software. From the network training on the experimental data, we get the model. The result of the network training which the average relative error of the predicted values and the true value was 27.9% shows a good model had obtained. Using the model to predict the evaporation rate of non-training samples, the result shows the average relative error of the predicted values and the experimental data was 16.7%, which proved the model of natural evaporation was accurate and reliable, also had a high predictive ability.We studied the single factor and multiple factors analysis on the natural evaporation process of desalinated seawater by using the natural evaporation model. The single factor analysis results show that the laws of single factor from the model predicts had a good match on the laws from experimental analysis, which checked the natural evaporation model accuracy again. The multi-factor analysis results indicate that the effect of primary and secondary order which shows by R value was:irradiation intensity (0.224)> brine temperature (0.157)-speed of wind (0.148)> air relative humidity (0.109)> the environment temperature (0.056). |
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