Professor Zhu Jia, a professor at the School of Modern Engineering and Applied Science at Nanjing University who is in charge of the research, introduced that they use a technology of solar seawater desalination using the principle of photodistillation, which can produce fresh water without other energy. Therefore, it is an ideal seawater desalination solution. Energy conversion efficiency is low and has not been able to be applied on a large scale.
To this end, Zhu Jia's group proposed a new idea, which has two major innovations: one is to use graphene to make a foldable and lightweight film to absorb solar distilled seawater, which greatly increases portability; the second is Separate the graphene absorber from seawater to reduce thermal conductivity losses.
In addition, in most of the past work, the absorber was in direct contact with water, causing energy to be dissipated through the heat conduction of the water itself, so optical focusing, heat insulation and other means were needed to maintain thermal balance. They designed a special two-dimensional water channel that does not allow the absorber to directly contact the seawater, so it can achieve efficient conversion without external assistance.
According to reports, Zhu Jia's group designed a cylindrical thermal insulator made of styrofoam. The outer layer of the thermal insulation is coated with a weaverin coating to form a special water channel. The top of the cylinder is covered with a graphene film. During work, weaverin absorbs water from the lower pool through capillary action, supplies the upper film to heat into steam, and then collects fresh water.
According to Zhu Jia, the energy conversion efficiency of light to steam was generally about 60% under the same conditions, and their devices could reach 80%. After the preliminary conversion, the water quality exceeded the international universal standards such as the World Health Organization. In addition, the film is foldable and lightweight, and the manufacturing cost is low, so "the application range is greatly improved". Of course, the long-term stability of this device requires time and testing in different application scenarios.