Design, Modeling and Testing of Optimized Metallic Porous Structures for Passive Pumping in Dual-Use Solar-Thermal Desalination Systems
Date of Award
12-12-2024
Degree Name
Ph.D. in Mechanical Engineering
Department
Department of Mechanical and Aerospace Engineering
Advisor/Chair
Andrew Schrader
Abstract
Water scarcity is a growing challenge worldwide, resulting from increased population growth, industrial practices, and shifting climates. Researchers have been studying reliable, efficient, and cost effective, ways and techniques to obtain high quality fresh water using both a renewable and clean energy source such as power from solar energy or solar thermal concentration. Independent, self-operated, and low maintenance systems are highly desired for desalination systems. Deployable, solar-thermal desalination systems are promising technologies for promoting water security and sustainable community development in remote or storm-damaged coastal regions. However, these systems produce less distillate per unit energy input compared to industrial- scale desalination systems. The introduction of novel, metallic wicks in these systems increases distillate efficiency by generating an evaporation interface. It is proposed that metallic wicks with optimized micro-structure porous properties, i.e. porosity, permeability, capillary pressure, etc., will further increase distillate yields in capillary-driven desalination modules. Recent studies have demonstrated the potential of metallic wicks for increased distillate production at low-temperature (< 60 °C) operation. Many other studies assessed the quality of the distilled water, but they did not evaluate the salt accumulated at the water- vapor interface within the wick resulted from the evaporation. Another important issue that impacts the passive flow resulted from the wicking action is the dry-out that might occur within the metallic wick in the porous medium due to the evaporation process. A two-dimensional, steady-state heat and mass transfer study was performed to investigate the impact of various microstructure properties such as porosity and permeability, and environmental conditions such as solar irradiation on the distillate yield, wick dry-out, and salt diffusion/precipitation within candidate porous media structures. In this work, a two- dimensional, steady-state heat and mass transfer analysis was performed to investigate the thermohydraulic performance of metallic porous wick desalination modules attached to the underside of a floatovoltaic panel for passive thermal management and dual-use freshwater production. This includes investigation of the impact of various microstructure properties such as porosity and permeability, and environmental conditions such as solar irradiation on the distillate yield, wick dry-out, and salt diffusion/precipitation within candidate porous media structures. A parametric study is performed to identify the limiting bulk properties and operating conditions of flat Ni-based porous wicks that maximize passive cooling of photovoltaic cells and distillate production while mitigating salt concentration gradients (pressure drop limitation and salt limitation) to avoid wick clogging. A sensitivity study is performed on more complex wick geometries (e.g. biporous and L-shaped structures) to identify possible improvements to salt diffusion performance relative to thermal management and evaporative performance. The optimized wick properties were used in the design and modeling of a laboratory scale solar-thermal desalination system. Results show wicks with porosity of 0.5 or more can be used in the proposed solar desalination system.
Keywords
Electrical Engineering, Engineering
Rights Statement
Copyright © 2024, author.
Recommended Citation
Alfarhan, Abdullah, "Design, Modeling and Testing of Optimized Metallic Porous Structures for Passive Pumping in Dual-Use Solar-Thermal Desalination Systems" (2024). Graduate Theses and Dissertations. 7460.
https://ecommons.udayton.edu/graduate_theses/7460
