Research On Solar Seawater Desalination Based On Interfacial Evaporation Of Porous Materials

In recent decades,with the rapid population growth and water pollution caused by industrial development,the scarcity of freshwater resources has posed a threat to the sustainable development of human society.As a sustainable energy source,solar energy has attracted wide attention due to its green environmental protection and low cost advantages.In this thesis,two new types of photothermal conversion materials are developed,which can ensure that the evaporator has high light absorption capacity and photothermal conversion efficiency in the solar radiation spectrum.In addition,the structure of the solar double-layer interface evaporator is optimized to improve the evaporation rate and efficiency,and avoid the deposition of salt particles on the evaporation interface.The main research contents are as follows:In this thesis,TiNO photothermal conversion materials were prepared by magnetron sputtering technology and physical vapor deposition.The surface morphology,porosity and light absorption properties of the materials were analyzed.The photothermal layer has extremely high light selective absorption in the ultraviolet-visible light region,and the absorption rate in the visible light wavelength range of 390-780nm is as high as 92.6%.Under the light intensity of 1 k W·m^-2,the evaporation efficiency reached 84.05%.In order to explore the actual evaporation and condensation performance of the Ti NO evaporator,experiments were carried out on the amount of fresh water produced in the condensing device,and the average evaporation and condensation efficiency reached 46%.In order to further enhance the light absorption properties of solar photothermal conversion materials,a self-desalting porous reduced graphene oxide（rGO）foam was prepared by a hydrothermal method.Through performance characterization and experimental tests,it is found that the porous rGO photothermal conversion material has excellent light absorption capacity and photothermal conversion performance,and the absorption rate is as high as 95%in the full solar spectrum range of 250-2500 nm.Under the light intensity of 1 k W·m^-2,the evaporation efficiency reached 89.6%.Tested in a condensing device,its evaporative condensation efficiency reached 56.4%,and the salinity of the desalinated water was reduced by 4 orders of magnitude,fully meeting the WHO drinking water standards.The analysis and comparison of the two kinds of evaporators showed that the light absorption performance and evaporation performance of the porous rGO evaporator were more prominent.COMSOL was used to simulate the temperature and vapor concentration distribution of the porous rGO evaporator,and the conduction,convection and radiation losses of the evaporation system were calculated by thermodynamic analysis.The temperature and evaporation rate are in good agreement with the experimental results.This thesis is devoted to designing and fabricating an efficient interfacial evaporation system from the perspective of mechanism,fabricating light-to-heat conversion materials with high light absorption properties,and designing an adiabatic water supply structure for thermal localization and reducing energy loss,which will provide a basis for the development of solar interfacial evaporation technology in the future.new research ideas.