Integrated solar still with an underground heat exchanger for clean water production

摘要

A simplified model of heat and mass transfer of integrated solar still with an underground heat exchanger (GHEX) is presented. The solar still has 70?m length and 0.5?m2inlet area. Moreover, the underground heat exchanger was 70?m length and 0.2?m diameter. The model includes a theoretical analysis in the transient mode for both the solar still and underground heat exchanger under warm climate region throughout the year. This system uses solar energy to saturate the air in the solar still, which is conducted into a buried pipe. Fresh water will be formed by condensation as long as the surface temperature of the pipe wall is less or equal to the dew point temperature of the humid air. A numerical method has been employed to solve the governing equations of heat and mass transfer characteristics in both the solar still and the underground heat exchanger. The soil temperature was taken as a function of soil depth and time along the year. The amount of fresh water produced was found strongly depends on solar intensity. It was respectively 4.7 (kg/m?day) and 0.32 (kg/m?day) for the highest and lowest values of solar radiation during the year. A good agreement has been shown when the results were compared with previous work.