Preparation of biomass-based yam solar absorber for enhanced solar evaporation application

The solar evaporation system has become a research hotspot in the field of photothermal conversion technology in recent years because of its high photothermal conversion efficiency and practicality of promotion. Biomass solar absorbers have excellent solar absorption properties and high solar-water vapor conversion, but they have the limitations of long feedstock production cycle and high carbonization temperature. As a kind of biomass materials, yam is not only inexpensive, but also has a short production cycle and rich pore structures. Therefore, in this paper, a yam based solar absorber with rich pore structure was prepared, and the photothermal conversion efficiency of the absorber was further investigated. The yam was treated with freeze-dried method and carbonized at different temperatures to obtain yam solar absorbers. Then the thermal stability and porosity of solar absorber was found to gradually rise as the treatment temperature increased. The solar absorption rate of the carbonized yam was close to 90% in the near UV-visible region. Solar-water vapor control experiments with different treatments of the solar absorber of the yam were carried out in simulated solar-driven interface steam generation system (SISGS). An absorber treated at 200 °C in the sun was found to have the best performance with a solar-water vapor conversion of about 90% and a water evaporation rate of 1.3164 kg m−2 h−1.