Study On The Heating Process By Solar Energy With Brine Of Seawater Desalination As Feed

Shortage of freshwater resources has become a bottleneck problem restricting the development of the coastal economic. Seawater Desalination is one of an effective methods to solve the crisis of freshwater resources in coastal area. Membrane Distillation (MD) desalination and seawater desalination utilized solar energy are the availability methods to reduce the cost of seawater desalination industrialization.The heating performance of seawater desalination brine by evacuated tube collector solar energy system was studied in this work. Using a concentrated brine automatic acquisition and monitoring systems, the effects of solar radiation intensity, temperature, relative humidity, wind speed and flow rate and temperature of the brine on the heating performance of6°Be brine were carried out.10m2vacuum tube solar collector was used and the volume flow rate of the brine was controlled at0.12m3/h-0.14m3/h.The experiments were carried out in Tianjin Economic-Technological Development Area from May2007to May2008. The results showed that among the six factors, solar radiation intensity had strongly influence to the heating performance of seawater desalination brine, followed by air temperature. Relative humidity, wind speed, feed temperature and flow rate of seawater desalination brine had little effect on seawater desalination brine heating performance.Outlet temperature of seawater desalination brine raised10℃to40℃from room temperature, it was from35℃to65℃. The heat collection efficiency of seawater desalination brine was different from30%to80%. Accordingly,20%to40%energy saving was reached if seawater desalination brine was heated by solar energy and the feed temperature was70℃in MD process. The average heat collection rate of the seawater desalination brine was about5.182kJ/(kg·m2) basing on the unit mass of seawater desalination brine. At the weather conditions of high solar radiation intensity and high temperature, significant solar energy heating performance of seawater desalination was got until4:00pm to5:00pm erverday.Using Matlab, an ANN model of seawater desalination brine heating performance by solar energy was found. The forecast value was basically consistent with the experimental results through using the hour average data to train. The predict results have showed a good accordance with the experimental, the error was less than5%. Under typical climate condition cities including Yongxing island, Dalian, Shanghai, Haikou, Shantou and Fuzhou, ANN model was used to predict seawater desalination brine MD preheating process by solar energy. The result showed that the heating collecting rate of seawater desalination brine was all above7.941kJ/(kg.m2). Seawater desalination brine was heated from20℃by solar energy under the climate condition of Yongxing island, the outlet temperature of brine was from45℃to75℃, and the outlet temperature of brine was from45℃to65℃under the other five cities climate condition. The heating efficiency of seawater desalination brine was from30%to75%,20%to40%energy was saved accordingly.