Analysis of the characteristics of heat and mass transfer of a three-effect tubular solar still and experimental research

A self-made solar-powered or residual heat-powered three-effect tubular solar still is used to analyze the characteristics of heat and mass transfer and study on normal-pressure and fixed-temperature heating in and fixed-power heating, attempting to figure out the principles of heat and mass transfer as well as the parameters of water production by desalination. The interior heat and mass transfer of still is consistent with three-effect energy equilibrium formula, the process of which mainly includes natural convection mass transfer and radiation heat exchange. The experimental results show that there exists a direct-proportion linear relationship between the temperature and water production by desalination at normal pressure, that at negative pressure, the water production is several times as large as that at normal pressure, increasing with the decrease of interior pressure, and reaching as high as 1.12 kg/h when the temperature is at 80 degrees C and the interior pressure is close to the saturation vapor pressure of 50 kPa at the first level, and that the water yield by desalination increases as the heating power (<300 W) increases, the optimal heating power is 300 W and its corresponding performance ratio reaches the highest value of 1.3. (C) 2013 Elsevier B.V. All rights reserved.