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

Paper Number: 138524

138524 - High-Performance Atmospheric Water Harvester Design Driven by Waste Heat 

Abstract: 

Water scarcity remains a grand challenge in both developed and developing regions of the globe. Sorption-based atmospheric water harvesting (SAWH) is an emerging and promising solution for water scarcity, especially in arid and non-coastal regions. Traditional approaches to atmospheric water harvesting such as fog harvesting and dewing system are often not applicable in low humidity, whereas SAWH has demonstrated great potential to provide fresh water under a wide range of conditions. Despite of the recent materials development, most demonstrated devices still lack sufficient water production while maintaining a compact form factor. Most of the existing SAWH prototypes in literature are solar-driven water harvesting devices incorporating the development of novel adsorbent materials, including zeolites, metal-organic framework materials (MOFs), and hygroscopic composite. Further optimization of such devices and the adoption of dual stages helped recycle the latent heat of condensation to increase the performance of SAWH devices. However, due to the low solar energy density and inconsistent weather conditions, the amount of water harvested from existing prototypes is still inadequate to meet daily human need. Comparably, existing waste heat from various sources can offer the low-cost high-density energy.

In this work, we focus on the adsorption bed design for water harvesters to achieve high water production, multicyclic operation and compact form factor. Driven by high-density waste heat, the design enables fast cycling kinetics and maximizes the daily water production. We identify and optimize several key design parameters associated with air channels between adsorbent fins to maximize water uptake. Specifically, there is a tradeoff between water vapor supply and diffusion resistance for multi-cycle operation. A thermofluidic numerical model has been developed to optimize the novel adsorption bed. With enhanced adsorption kinetics and high-density desorption energy, the proposed design promises high water production within a compact form factor. The modeling efforts and experimental validation illustrate an optimized design space with fin-array adsorption bed for water harvesting enabled by high-density waste heat. 

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. 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
Bachir El Fil MIT
Buxuan Li MIT
Gustav Graeber Humboldt-Universität zu Berlin