Solar Engineering Of Thermal Processes

Transition metal carbides and nitrides (MXenes), a family of two-dimensional (2D) inorganic compounds, are materials composed of a few atomic layers of transition metal carbides, nitrides, or carbonitrides. Ti3C2, the first 2D layered MXene, was isolated in 2011. This material, which is a layered bulk material analogous to graphite, was derived from its 3D phase, Ti3AlC2 MAX. Since then, material scientists have either determined or predicted the stable phases of >200 different MXenes based on combinations of various transition metals such as Ti, Mo, V, Cr, and their alloys with C and N. Extensive experimental and theoretical studies have shown their exciting potential for energy conversion and electrochemical storage. To this end, we comprehensively summarize the current advances in MXene research. We begin by reviewing the structure types and morphologies and their fabrication routes. The review then discusses the mechanical, electrical, optical, and electrochemical properties of MXenes. The focus then turns to their exciting potential in energy storage and conversion. Energy storage applications include electrodes in rechargeable lithium- and sodium-ion batteries, lithium-sulfur batteries, and supercapacitors. In terms of energy conversion, photocatalytic fuel production, such as hydrogen evolution from water splitting, and carbon dioxide reduction are presented. The potential of MXenes for the photocatalytic degradation of organic pollutants in water, such as dye waste, is also addressed, along with their promise as catalysts for ammonium synthesis from nitrogen. Finally, their application potential is summarized.

Applications of 2D MXenes in energy conversion and storage systems

MXene, a new series of 2D material, has been steadily advancing its applications to a variety of fields, such as catalysis, supercapacitor, molecular separation, electromagnetic wave interference shielding. This work reports a carefully designed aqueous droplet light heating system along with a thorough mathematical procedure, which combined leads to a precise determination of internal light-to-heat conversion efficiency of a variety of nanomaterials. The internal light-to-heat conversion efficiency of MXene, more specifically Ti3C2, was measured to be 100%, indicating a perfect energy conversion. Furthermore, a self-floating MXene thin membrane was prepared by simple vacuum filtration and the membrane, in the presence of a rationally chosen heat barrier, produced a light-to-water-evaporation efficiency of 84% under one sun irradiation, which is among the state of art energy efficiency for similar photothermal evaporation system. The outstanding internal light-to-heat conversion efficiency and great light...

MXene Ti3C2: An Effective 2D Light-to-Heat Conversion Material

Solar energy can be used to evaporate water and generate steam, however this usually requires expensive optical concentrators. Ni et al. demonstrate a low-cost solar receiver based on thermal concentration that generates steam at 100 ∘C without the need for optical concentration.

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Steam generation under one sun enabled by a floating structure with thermal concentration

Self-healing hydrophobic light-to-heat conversion membranes for interfacial solar heating are fabricated by deposition of light-to-heat conversion material of polypyrrole onto a porous stainless-steel mesh, followed by hydrophobic fluoroalkylsilane modification. The mesh-based membranes spontaneously stay at the water-air interface, collect and convert solar light into heat, and locally heat only the water surface for enhanced evaporation.

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Hydrophobic Light‐to‐Heat Conversion Membranes with Self‐Healing Ability for Interfacial Solar Heating

Single basin solar still with fin for enhancing productivity

Performance study on basin type double slope solar still with different wick materials and minimum mass of water

Single basin double slope solar still with minimum basin depth and energy storing materials

Desalination of effluent using fin type solar still

Although, more than two-thirds of the Earth is covered by water, shortage of potable water is a serious issue that many countries suffer from. Furthermore, the worldwide rapid growth of industry and population has resulted in a large boom in demand for fresh water. The solar still, in many respects, is an ideal source of fresh water for both drinking and agriculture; it is one of the most important and technically viable applications of solar energy. There are many types of solar still; the simplest and most proven is the basin type. Investigations showed that the basin-type solar still has been found to be of limited performance. Numerous experimental and numerical investigations on basic types of solar still have been reported in various literatures. An extensive review for solar desalination systems has been carried out in this paper.

K. Srithar

Papers

Single basin solar still with fin for enhancing productivity

Performance study on basin type double slope solar still with different wick materials and minimum mass of water

Single basin double slope solar still with minimum basin depth and energy storing materials

Desalination of effluent using fin type solar still

Performance analysis of solar stills based on various factors affecting the productivity—A review