A floating vapor condensation structure in a heat-localized solar evaporation system for facile solar desalination

Solar evaporation by heat localization has drawn great interests for efficient and facile solar desalination since 2014. However, most of efforts have been put into improving the vapor generation performance in the last few years, with facile and efficient vapor condensation remaining a challenge. In this work, we propose a feasible method to condense vapor, featured with simple structure, cost effective, easy to mass scale and flexible operation. The energy efficiency in the solar-vapor-water process is theoretically analyzed based on the heat and mass transfer in our solar desalination system, to provide guidance especially for improving the vapor condensation process. The structure influence of the grid-trough condenser on the energy utilization in the vapor-water process is further investigated by experimental methods. Combining the optimal grid-trough condenser with a reverselydesigned heat-localized evaporator, the new-designed system shows a great potential in facile solar desalination. It could achieve a freshwater production rate of 0.393 kg m-2 h- 1 and a vapor collection efficiency of 38.8% under one sun illumination by the relatively optimal condenser which strikes a balance between efficiency, cost and system complexity. The seawater tests and outdoor experiments confirm that this system still could perform well and float spontaneously on a lake to produce freshwater continuously. Additionally, the energy efficiency of this system has ample room for improvements through optimizing the system structure and employing new materials.

Automated summary

Efficient and easy-to-operate vapor condensation method is proposed for solar desalination, with a balance between optimization based on theory and experimentation. The system shows great potential for sustainable freshwater production.