Session: K13-02: EVAPORATION AND POOL BOILING FROM ENHANCED SURFACES

Paper Number: 138554

138554 - Solar-Driven High Performance Evaporator Enabled by Natural Convection With Salt Rejecting Capability 

Abstract: 

Thermally localized solar evaporation provides a sustainable solution to address the water-energy nexus, which is promising for the applications in vapor generation, seawater desalination, wastewater treatment, and medical sterilization. However, salt accumulation has been identified as one of main practical challenges, which induces undesired fouling and reduces device lifetime. Here, we develop a novel confined water layer structure enabling a simultaneously highly efficient and salt rejecting solar evaporation. With high-fidelity modeling and experimental characterization of conjugated heat transfer, fluid mechanics and mass transport, we optimize the solar evaporator design to enable salt transport without sacrificing energy efficiency. The fundamental understanding of salt transport shown in this work paves a new avenue toward the high-performance and reliable solar evaporation with low-cost and high material flexibility. 

Additionally, we investigate the detailed mechanisms of natural convection, which is driven by the density difference due to the solar heating and water evaporation. Experimentally, we observe a significant enhancement of fluidic flow and salt rejection continuously to the bottom of the container. This promises further application for accelerated particle settling and long-term and passive operation, especially with realistic water source and even contaminated waste water. On the evaporating surface, we investigate the size effects of natural convection and mass diffusion, and a small-size evaporator may present overestimated performance due to the edge effect. This is critical when scaling the bench-scale experimental results to potential large-scale applications. 

Presenting Author: Xiangyu Li University of Tennessee Knoxville

Presenting Author Biography: Dr. Xiangyu Li is an assistant professor at the Department of Mechanical, Aerospace, and Biomedical Engineering at the University of Tennessee Knoxville. His research focuses on using thermal sciences and materials innovation to enable high performance thermal systems.
Previously he received his Ph.D. degree from Purdue University, focusing on composite materials for building radiative cooling paints and electronics thermal management. He later worked as a postdoctoral associate at MIT, on various projects involving atmospheric water harvesting, thermal energy storage, high temperature heat exchanger design and solar desalination.

Authors:

Xiangyu Li University of Tennessee Knoxville
Haochen Li University of Tennessee Knoxville
Lenan Zhang MIT
Shadman Hridoy University of Tennessee Knoxville