Concentrated solar technologies that primarily use mirrors or lenses to concentrate sunlight on a receiver are becoming ever more popular not just for generating electricity but also for desalination. My research focuses on improving efficiency of desalination via steam generation using carbon foam to localize heat by studying how the thickness and treatment of carbon foam affect efficiency of evaporating water when exposed to sunlight.
I obtained carbon foam of thicknesses ranging from 0.3 cm to 1.3 cm and treated it with a warm dilute acid solution to make it hydrophilic. The foam layer was placed on the surface of water and illuminated by a light source overhead. The change in mass of water and the temperature of the water and foam layer were measured over time. With the light source on, heat was localized due to the high absorption spectrum of the foam. I found that the thickest foam succeeded in evaporating 84% more water in an hour than the control with no carbon foam. The thinnest foam evaporated 48% more water than the control. Untreated, hydrophobic carbon foam localizes heat but generates less steam than the control. This suggests that efficiency of solar steam generation is increased with a thick layer of carbon foam that can transport water through the heated layer. The efficiency was similarly high when generating steam from salt water. I designed a portable and efficient solar desalination device that takes advantage of localized heating by the treated carbon foam.