Design Of An Integrated Interface Evaporation System And Its Research Applications

With the increase of population and environmental pollution,the shortage of fresh water resources has become an important constraint to human development.Seawater reserves are huge,and desalination of seawater is an effective way to solve freshwater shortage.The current mature desalination methods such as forward and reverse osmosis,membrane distillation,multi-stage flash distillation,etc.all consume large amounts of fossil energy and are unsustainable.Solar energy is clean and non-polluting,with huge reserves,desalination of seawater using solar energy is undoubtedly an ideal way to solve the lack of fresh water.Research on solar desalination of seawater is progressing rapidly,but it has not yet been commercialized on a large scale and is still at the experimental stage,mainly because of the low rate of freshwater production and the high cost of freshwater production.In this paper,we design an integrated interfacial water evaporation and collection system that can effectively increase the freshwater production rate.The research work in this paper has two main aspects.The coal pitch carbon point is used as the photothermal conversion material and the sponge is used as the substrate to design a solar evaporator,which is coupled by four individual evaporators to form a four-stage cycle integrated interfacial water evaporation and collection system.The integrated system can effectively reduce the heat loss from the evaporator to the free water at the lower end and make effective use of the latent heat of condensation to increase the water temperature at the evaporative interface and improve the rate of evaporative interface vapor generation.The integrated system can effectively reduce the humidity inside the chamber and at the evaporation interface to promote the overflow of steam and improve the steam production rate and condensate collection rate.Compared with the traditional single-slope solar evaporator,the condensate collection rate of the integrated system increased by 130% to 620 g m-2 h-1.The integrated system operated in different concentrations of salt water（0-10 wt%）,and the fresh water collection rate did not decrease significantly,and the salt resistance and cycle stability performance were good.Accounting for the condensate cost of the integrated system,the cost of condensate was 0.029 ￥/L,which was much lower than the market price of deionized water,and the economy was good.The integrated interfacial evaporation and collection system shows great potential for practical application in solar water desalination.Based on the integrated interfacial water evaporation and collection system,the evaporation structure was studied and analyzed,and a three-dimensional stepped evaporation structure was designed.The three-dimensional stepped structure enables the water supply and evaporation volume to be matched effectively,and effectively reduces the heat loss of the system.Without increasing the condensation chamber,the freshwater collection rate of the system was increased by 31% to 825 g m-2 h-1,which significantly increased the freshwater production rate.The three-dimensional ladder structure still maintained good structural strength and evaporation performance after 10 evaporation tests.After two weeks of operation in combination with the integrated interfacial water evaporation and collection system,the threedimensional ladder-like structure still maintained good evaporation performance and the threedimensional ladder structure had good cyclic stability.The research work of this subject designed an integrated interface water evaporation and collection system to achieve a substantial increase of fresh water production rate through the management and utilization of heat,which provides possible ideas for the practical application of solar desalination seawater.