Study on Negative Pressure Multi-Stage Falling Film Evaporation in Solar Energy Seawater Desalt
Wang Qiang,Zhang Xiaoyan,Zheng Hongfei,Zhang Lianying,Zhang Jing,Jiang Hua
（School of Energy and Power Engineering,Xi'an Jiaotong University, Xi'an 710049,China)

Abstract: A thorough analysis is conducted on seawater evaporation outside of the horizontal tube and saturated vapor condensation inside the horizontal tube.Negative pressure multi-stage falling film evaporation enhances heat and mass exchange greatly when the temperature of hot water is given, and the quantity of the seawater evaporation is increased. At the same time, the condensation of saturated steam is strengthened when the pressure inside the horizontal tube increased. The efficiency of the solar energy seawater desalt device designed according to this theory is much higher than that of the traditional plate one.It can operate with lower solar energy heating water temperature and the desalt efficiency is above 70%.
Keywords: multi-stage falling film evaporation;seawater desalt;solar energy