Experimental Study On Seawater Desalination Of Solar Steam Generation Based On Photothermal Conversion Of Carbon Composites

With the development of human society and the increasing demand of fresh water for daily life,the shortage of fresh water has become one of the most critical problems facing human society.Solar steam generation,as a novel technology,has attracted received extensive attention in recent years.It can not only can produce fresh water for water scarce areas,but also efficiently use solar energy without harming the environment.Despite these successful advances has been achieved in improving evaporation performance,the large-scale application of solar steam generation system is still limited by the complexity and high cost of material preparation process.Therefore,it is urgent to develop a solar steam generation system with low cost,easy processing,high optical absorption,sufficient water supply capacity and high evaporation efficiency.In this paper,a new 3D inverted cone structure of blue brick-graphene for solar steam generation was designed.Blue brick has unique heat management and light absorption properties.A bi-layer inverted cone structure was prepared by daubing graphene on blue bricks.It is found that the blue brick-graphene evaporator has the characteristics of low thermal conductivity,sufficient water supply capacity and high optical absorption performance.The results showed that the photothermal conversion layer with 9.6mg/m L graphene concentration was the most suitable high-efficiency optical absorber.The optical absorption efficiency of a 3D inverted cone evaporator can reach about 97.3%.At the same time,the design of 3D inverted cone evaporator reduces the contact area between light absorption layer and water,which prevented the heat loss and further improved the temperature of the light absorption layer,and it also can improve the steam performance.The results show that the steam rate and efficiency of the new 3D inverted cone evaporator can be as high as 1.21 kg·m^-2·h^-1 and 84%respectively under one sun(one sun=1k W·m^-2),and the blue brick-graphene evaporator also has good durability and efficient desalination capacity.When scientists always focused on finding high-quality materials and efficient structures,they often neglect to use the residual heat of the sea water.In this paper,a solar steam generation system was developed based on a new p DA-r GO-PTFE photothermal membrane,and the membrane distillation system using residual heat was applied to the new solar steam generation system.In the experiment,a new p DA-r GO-PTFE photothermal membrane was prepared by physical deposition and chemical reaction.The photothermal membrane has good hydrophilicity and high spectral absorption.The results show that the optimal concentration of photothermal layer is20mg/ml,and the evaporation rate and efficiency of p DA-r GO-PTFE membrane can reach up 1.45 kg·m^-2·h^-1 and 93.8%respectively under one sun.In addition,a new solar house device of solar steam generation and membrane distillation coupling system was designed,and membrane distillation system was added to the side wall of the seawater pool to utilize the residual heat,and additional gains are obtained.Under 0.66 solar irradiation,the average evaporation rate of a new solar house could reach about 1.10kg·m^-2·h^-1,and there is an additional 0.71 kg·m^-2·h^-1membrane permeation flux by the residual heat.At the same time,it also provides much domestic water and other additional products.And a new solar house device has good durability and desalination capacity,and the ion retention rate of condensate collected is close to 99.8%.Therefore,a new design idea of solar house will provide a new reference for solving the shortage of water resources,domestic water and the application of solar steam generation in the future.