The Energy Efficiency of Interfacial Solar Desalination: Insights from Detailed Theoretical Analysis

TL;DR

This paper provides a detailed thermal analysis of interfacial solar desalination, clarifying its energy efficiency mechanisms, advantages over traditional methods, and factors influencing performance, offering insights for future system improvements.

Contribution

It introduces a comprehensive thermal model that explains the energy efficiency of interfacial evaporation and evaluates environmental and design factors affecting performance.

Findings

Interfacial evaporation has advantages over traditional evaporation.

Environmental conditions cannot be fully mitigated by subtracting dark evaporation.

System design improvements can enhance overall desalination efficiency.

Abstract

Solar-thermal evaporation, a traditional steam generation method for solar desalination, has received numerous attentions in recent years due to the significant increase in efficiency by adopting interfacial evaporation. While most of the previous studies focus on improving the evaporation efficiency by materials innovation and system design, the underlying mechanisms of its energy efficiency are less explored, leading to many confusions and misunderstandings. Herein, we clarify these mechanisms with a detailed thermal analysis model. Using this model, we elucidate the advantages of interfacial evaporation over the traditional evaporation method. Furthermore, we clarify the role of tuning the solar flux and surface area on the evaporation efficiency. Moreover, we quantitatively prove that the influence of environmental conditions on evaporation efficiency could not be eliminated by subtracting the dark evaporation rate from evaporation rate under solar. We also find that interfacial evaporation in a solar still does not have the high overall solar desalination efficiency as expected, but further improvement is possible from the system design part. Our analysis gains insights to the thermal processes involved in interfacial solar evaporation and offers perspectives to the further development of interfacial solar desalination technology.