Author: Nan Sun
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Atmospheric water is a vast freshwater resource and it could potentially relieve billions of people worldwide from water shortage. A number of nature-inspired surfaces have been developed to enhance water harvesting, specifically, through modification to the surface chemistry or physical structures. However, conflicting results were reported regarding the effects of these surfaces, showing that a fundamental understanding of water collection mechanisms on the complex natural and synthetic surfaces is still lacking.In this research effort, the atmospheric water harvesting is studied at the two ends of the possible conditions, i.e., diffusion controlled dew harvesting and convective fog harvesting. For dew harvesting, we theoretically and experimentally show that the total water condensation rate is independent of surface wettability and physical roughness when the thickness of the water vapor concentration boundary layer is significantly larger than that of the physical roughness. The finding defines the lower limit of water harvesting rate from air through condensation. On the other end, a new model based on particle deposition is proposed to describe the fog harvesting process. Droplet deposits are treated as dynamic particle collectors and a droplet roughness parameter is derived to quantify their effect on fog harvesting rate. The model explains why the fog harvesting rate on rough, chemically patterned surfaces can be significantly enhanced compared with flat chemically homogeneous surfaces. The model can also predict the optimal pattern size for fog harvesting, which explains why pattern size of specific length scale is required for Namib Desert beetles to efficiently capture water from air. Furthermore, two novel nature-inspired materials with high surface roughness and efficient water removal mechanisms are developed, which have shown enhanced water harvesting capability.
Author: Alina Dale LaPotin
Publisher:
ISBN:
Category :
Languages : en
Pages : 72
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Book Description
Atmospheric water harvesting (AWH) is the capture and collection of water that is present in the air either as vapor or small water droplets. Adsorption-based AWH uses adsorbent materials to collect water vapor from the air, the advantage being that the adsorbents can be regenerated by low-grade thermal sources, and condensation can occur at ambient temperatures. It has the potential to be more widely applicable to areas which are facing water scarcity because it can operate in areas with consistently low relative humidity (RH), where traditional approaches such as dewing and fog harvesting aren't feasible. Previous work in this area has demonstrated AWH driven by direct solar heating in low RH conditions (10 - 40%). However, water harvesting productivity, LMD (liters of water harvested per square meter solar receiver area per day), of these devices is limited by vapor transport in packed adsorbent layers, which severely limits adsorbent layer thickness. Additionally, the heat flux which must be rejected at the condenser is significant and consists of both heat conducted through the device and the latent heat of condensation. In this thesis, we present a new configuration for a solar-thermal adsorption-based AWH device which uses two stages (TS-AWH) to increase the LMD over single-stage devices. The TS-AWH device uses the latent heat of condensation from the top stage as well as a temperature gradient between the stages to drive desorption of the bottom stage. This configuration provides greater utilization of the solar energy received at the absorber, recycling of the latent heat, and takes full advantage of the temperature difference between the solar absorber and the condenser. We present our framework for modeling heat and mass transport in adsorbent layers and use this model to design layers which can be incorporated in AWH systems for passive operation on a daily cycle. We developed a model of the TS-AWH system which predicts that both layers can be desorbed under unconcentrated sunlight. We used AQSOA zeolites ZO1 and Z02 for the adsorbents and our characterizations showed that they exhibit favorable properties for AWH, including fast intracrystalline kinetics. Based on insight gained from parametric studies of the effect of geometric parameters on LMD, we built and tested a prototype using ZO1 in outdoor water harvesting experiments on the MIT roof, where we showed solar-driven regeneration using unconcentrated sunlight. We demonstrated the validity of the TS-AWH concept by achieving a higher LMD than the maximum performance of a single-stage device, showing the promise of using TS-AWH to increase the performance of solar-thermal adsorption-based AWH systems. Our device demonstrates progress towards scaling up solar-thermal AWHs, as we harvested 80x more water than our previous device under similar, unconcentrated solar flux conditions.
Author: Hyunho Kim (Ph. D.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 146
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Book Description
Sorption-based energy technologies can be used to efficiently harvest fresh water from the atmosphere and to store thermal energy for climate control. Recent advances in porous adsorbents such as metal-organic frameworks (MOFs), with high sorption capacity and low regeneration temperature requirements, allow us to efficiently utilize them for these applications. However, detailed experimental and theoretical frameworks for the use of advanced sorbents have not considered several important aspects (e.g., inter/intracrystalline diffusion kinetics). This thesis provides a generalized framework to select the materials, design, and develop sorption-based energy and water systems. First, this thesis presents the design and demonstration of a device based on porous MOF-801 [Zr 6O4(OH) 4(fumarate)6] powered by natural sunlight (solar-thermal) that captures water from the atmosphere at ambient conditions, down to 20% RH. Under these conditions, operation of competing technologies, such as dew-based atmospheric water generators (AWGs), is infeasible. Laboratory experiments and computational simulations were used to optimize the device based on this MOF to maximize water delivery capacity in arid climates. We subsequently tested an optimized device in an exceptionally arid climate with 10-40% RH and sub-zero dew points. With a solar flux with 1.8x concentration for desorption, we demonstrated the operation of our device with a thermal efficiency ~14%. Finally, we quantitatively analyzed the water quality and showed that the MOF compound was stable to water, and the metal ions and organic linkers did not leach from the framework into the harvested water. Our demonstration indicates that passive operation of sorption-based AWGs with high efficiencies (> 20%) is possible and can be operated with abundant low-grade heat sources (~100°C) under exceptionally dry climates of RH
Author: Banh Tien Long
Publisher: Springer Nature
ISBN: 3030996662
Category : Technology & Engineering
Languages : en
Pages : 982
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Book Description
This book presents selected, peer-reviewed proceedings of the International Conference on Advanced Mechanical Engineering, Automation and Sustainable Development 2021 (AMAS2021), held in the city of Ha Long, Vietnam, from November 4 to 7, 2021. AMAS2021 is a special meeting of the International Conference on Material, Machines and Methods for Sustainable Development (MMMS), with a strong focus on automation and fostering an overall approach to assist policy makers, industries, and researchers at various levels to position local technological development toward sustainable development. The contributions published in this book stem from a wide spectrum of research, ranging from micro- and nanomaterial design and processing, to special applications in mechanical technology, environmental protection, green development, and climate change mitigation. A large group of contributions selected for these proceedings also focus on modeling and manufacturing of ecomaterials.
Author: Anil Kumar
Publisher: Springer Nature
ISBN: 9811596786
Category : Science
Languages : en
Pages : 1134
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Book Description
This book presents the select proceedings of the second International Conference on Recent Advances in Mechanical Engineering (RAME 2020). The topics covered include aerodynamics and fluid mechanics, automation, automotive engineering, composites, ceramics and polymers processing, computational mechanics, failure and fracture mechanics, friction, tribology and surface engineering, heating and ventilation, air conditioning system, industrial engineering, IC engines, turbomachinery and alternative fuels, machinability and formability of materials, mechanisms and machines, metrology and computer-aided inspection, micro- and nano-mechanics, modelling, simulation and optimization, product design and development, rapid manufacturing technologies and prototyping, solid mechanics and structural mechanics, thermodynamics and heat transfer, traditional and non-traditional machining processes, vibration and acoustics. The book also discusses various energy-efficient renewable and non-renewable resources and technologies, strategies and technologies for sustainable development and energy & environmental interaction. The book is a valuable reference for beginners, researchers, and professionals interested in sustainable construction and allied fields.
Author: C N Shankar Rao
Publisher: S. Chand Publishing
ISBN: 9355018940
Category :
Languages : en
Pages : 360
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Book Description
This book has been written as per the syllabus prescribed by Council for Technical Education and Vocational, Nepal for all Engineering students. The book has been developed in view of the recent development of the subject. The book covers important topics such as Introduction and Three Phase of Soil, Index Properties of Soil, Soil Classification, Soil Water and Effective Stress, Compaction, Consolidation. Shear Strength of Soils, Earth Pressure Theory, Bearing Capacity etc. have been explained in lucid manner. The book will prove to be a boon to the students preparing for engineering or diploma examinations.
Author: Amrik Singh Phuman Singh
Publisher: UTeM Press
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 305
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Book Description
This open access e-proceeding is a compilation of 134 articles presented at the 8th Mechanical Engineering Research Day (MERD'22) - Kampus Teknologi UTeM, Melaka, Malaysia on 13 July 2022.
Author: Daniel Beysens
Publisher: CRC Press
ISBN: 1000793915
Category : Technology & Engineering
Languages : en
Pages : 370
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Book Description
The world’s ever-increasing need for fresh water has led to the use of non-conventional sources such as rain and fog water collection. Although rain water collection is relatively simple, the supply is often erratic. Passive fog water collection has been used in several parts of the world but is only relevant to certain geographical locations. Dew occurrence, however, is far more widespread, can form in most climates and geographic settings, show high frequency and prevalence throughout the year. During the past 20 years, dew collection has therefore been investigated as a serious supplemental source of fresh water. Dew Water offers a thorough review of dew, its formation characteristics and potential for dew collection, for audiences that include policy-makers, non-governmental organizations involved in development aid and sustainable development, engineers, urban planners, researchers and students.After providing a background on atmospheric water, humid air, and sky and materials emissivity, the book deals with dew formation and its estimation with a focus on the use of meteorological data. Dew measurement techniques are reviewed and discussed as well as dew collection by passive means. Computational fluid dynamics technique is described for better design of dew collectors. Dew quality (chemistry, biology) is assessed in view of potable water quality. Costs and economic aspects are also considered.
Author: Rohit Sharma
Publisher: Springer Nature
ISBN: 9819930332
Category :
Languages : en
Pages : 816
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Book Description
Author: Science Museum (Great Britain)
Publisher:
ISBN:
Category : Science museums
Languages : en
Pages : 472
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