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Research subject: Solar energy is a renewable resource that is abundant and can solve many problems of energy shortage. In order to use solar energy to desalinate water and produce high quality steam, one of the cheap and commercially proposed structures is floating solar steam generation system. In this system, water is transferred to the surface of the system in a controlled manner and is converted to steam using the heat generated in the photothermal layer. There are generally four main challenges in solar steam generation systems. These challenges include managing and preventing heat loss, structural strength, managing and transferring water within the structure, absorbing light and converting light into heat.
Research approach: In this paper, floating multilayer solar steam generation systems were fabricated in which porous polyurethane foam was used as the substrate and thermal insulation layer. Moreover, felt was used as the water-transfer layer. Photothermal materials including graphite, gold, and mixtures of graphite and gold were used as the light-absorbing layers to produce high-quality steam. Also, in order to determine the water evaporation rate and the efficiency of the systems, the amount of changes in water mass and system temperature has been measured.
Main results: Among the different solar steam generation systems studied, the system made of graphite-gold mixture absorber is able to produce steam at a rate of 1.257 kg.m^-2.h^-1. This rate is equivalent to an efficiency of about 82%. To evaluate the performance of the systems in more real situation, they were tested using seawater. As resulted, the rate of evaporation of seawater by the graphite-gold mixture system is 1.201 Kg.m^-2.h^-1 and its efficiency is 78.4%.

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The use of interfacial solar evaporation systems can be a suitable method to deal with the problem of fresh water shortage in the world. Interfacial solar evaporation systems can be widely used in the production of fresh water due to the use of solar energy as a without any costs energy and no environmental effects and also free from high pressure operations and no need for moving parts. But in order to use interfacial solar evaporation system for practical application, evaporation rate with high efficiency is required. In this research, the performance of a hollow cylindrical interfacial solar evaporation system with nature inspired water distribution to steam generation has been evaluated by numerical simulation. This system can absorb solar radiation more effectively. In this study, in order to accurately investigate the performance of the interfacial solar evaporation systems, steam generation and system efficiency were evaluated by changing environmental factors. Also, in order to investigate the performance of the interfacial solar evaporation systems under different angles of solar radiation in real world conditions, the rate of steam generation in two days of summer solstice and winter solstice in Tehran city has been evaluated. The results of this research show that the cylindrical interfacial solar evaporation system can have a steam generation rate of 3.09 kg/m².h and 9.09 kg/m².h in winter solstice and summer solstice respectively in Tehran city with wind flow