A photothermal reservoir for highly efficient solar steam generation without bulk water

Xuan Wu; Ting Gao; Chenhui Han; Jingsan Xu; Gary Owens; Haolan Xu

doi:10.1016/j.scib.2019.08.022

A photothermal reservoir for highly efficient solar steam generation without bulk water

Sci Bull (Beijing). 2019 Nov 15;64(21):1625-1633. doi: 10.1016/j.scib.2019.08.022. Epub 2019 Aug 22.

Authors

Xuan Wu¹, Ting Gao¹, Chenhui Han², Jingsan Xu², Gary Owens¹, Haolan Xu³

Affiliations

¹ Future Industries Institute, University of South Australia, Mawson Lakes Campus, SA 5095, Australia.
² School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4001, Australia.
³ Future Industries Institute, University of South Australia, Mawson Lakes Campus, SA 5095, Australia. Electronic address: haolan.xu@unisa.edu.au.

PMID: 36659575
DOI: 10.1016/j.scib.2019.08.022

Abstract

A solid photothermal reservoir is designed to implement solar-steam generation in the absence of bulk water. The photothermal reservoir is composed of a water absorbing core encapsulated by a photothermal reduced graphene oxide based aerogel sheet which absorbs light and converts it into heat thus evaporating the stored water. The photothermal reservoir is able to store 6.5 times its own weight in water, which is sufficient for one day solar evaporation, thus no external water supplement is required. During solar-steam generation, since no bulk water is involved, the photothermal reservoir minimizes heat conduction loss, and maximizes both of the exposed evaporation surface area and net energy gain from the environment, leading to an energy efficiency beyond the theoretical limit. An extremely high water evaporation rate of 4.0 kg m^-2 h^-1 (normalized to projection area) is achieved in laboratory studies over a cylinder photothermal reservoir with a diameter of 5.2 cm and a height of 15 cm under 1.0 sun irradiation. Practical evaluation of the photothermal reservoir outdoors as part of a desalination device demonstrates a similar evaporation rate where the salinity of the clean water produced is lower than 24 ppb. Thus the photothermal reservoir shows great potential for real world applications in portable solar-thermal desalination.

Keywords: Aerogel; Photothermal; Solar-steam generation; Solar-thermal energy.