Thermal Transport In Nanoporous Materials For Energy Applications
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Thermal Transport In Nanoporous Materials For Energy Applications
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Author : Jin Fang
language : en
Publisher:
Release Date : 2012
Thermal Transport In Nanoporous Materials For Energy Applications written by Jin Fang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
The present study investigates the complex relationship between nanostructures and microscale thermal transport in nanoporous thin films for energy applications. It experimentally and numerically demonstrates that the effective thermal conductivity of nanoporous materials can be tuned by controlling their nanoscale architectures including porosity, pore diameter, wall thickness, nanocrystal size, and crystallinity as well as surface passivation. This study reports measurements of the cross-plane thermal conductivity of nanoporous thin films with various architectures between 25 and 315 K. Physics-based models combining phonon transport theory and effective medium approximations were developed to interpret the experimental data. Ordered mesoporous titania and silicon thin films were prepared based on evaporation-induced self-assembly method. Pure silica zeolite films were produced by either in-situ growth or by spin coating a zeolite nanoparticle suspension followed by crystal growth upon heating. These synthesized thin films were systematically and fully characterized. They featured ordered nanopores with porosity, pore diameter, and film thickness ranging from 30% to 59%, 0.5 to 25 nm, and 120 to 370 nm, respectively. Their dense matrix was amorphous, polycrystalline, or consisted of an aggregate of nanocrystals. The thermal conductivity of all synthesized nanoporous films increased monotonically with temperature within the temperature range considered. At low temperatures, the nanoporous films behaved like amorphous or strongly disordered materials and their thermal conductivity was proportional to T^n with n varied between 1 and 2.3. At high temperatures, the thermal conductivity increased slowly with temperature or reached a plateau due to strong phonon Umklapp scattering and the saturation of phonon modes. The presence of pores in amorphous mesoporous thin films had a purely geometrical effect by reducing the cross-sectional area through which heat can diffuse. By contrast, in crystalline mesoporous thin films the presence of pores also increased phonon scattering. In addition, the film thickness generally did not affect the measured thermal conductivity. Indeed, phonon scattering by pores and by nanocrystal grain boundary dominated over boundary scattering and were identified as the dominant scattering mechanisms for nanoscale energy transport in the synthesized nanoporous films. This study further establishes that the effective thermal conductivity keff of crystalline nanoporous silicon was strongly affected not only by the porosity fv and the system's length Lz but also by the pore interfacial area concentration Ai. A modified effective medium approximation combining kinetic theory and the coherent potential approximation suggested that keff was proportional to (1-1.5fv) and inversely proportional to the sum (Ai/4+1/Lz). This scaling law was in excellent agreement with the thermal conductivity of nanoporous silicon predicted by molecular dynamics simulations for spherical pores as well as for cylindrical pores and vacancy defects. Finally, this study demonstrated, using equilibrium molecular dynamics simulations, that surface passivation added another parameter for reducing the thermal conductivity of nanostructured materials. To do so, there should be strong acoustic vibrational modes coupling between surface and passivation atoms. For example, oxygen passivation reduced the thermal conductivity of nanoporous crystalline silicon. In addition, the effect of passivation reduced with temperature because of increasing contribution of Umklapp scattering. These results could help establish new strategies to control the thermal conductivity of nanoporous materials for a wide range of applications including thermoelectric devices, supercapacitors, dye-sensitized solar cells, and hydrogen storage devices.
Adsorption And Diffusion In Nanoporous Materials
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Author : Rolando M.A. Roque-Malherbe
language : en
Publisher: CRC Press
Release Date : 2007-03-05
Adsorption And Diffusion In Nanoporous Materials written by Rolando M.A. Roque-Malherbe and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-03-05 with Science categories.
As nanomaterials get smaller, their properties increasingly diverge from their bulk material counterparts. Written from a materials science perspective, Adsorption and Diffusion in Nanoporous Materials describes the methodology for using single-component gas adsorption and diffusion measurements to characterize nanoporous solids. Concise, yet comprehensive, the book covers both equilibrium adsorption and adsorption kinetics in dynamic systems in a single source. It presents the theoretical and mathematical tools for analyzing microporosity, kinetics, thermodynamics, and transport processes of the adsorbent surface. Then it examines how these measurements elucidate structural and morphological characteristics of the materials. Detailed descriptions of the phenomena include diagrams, essential equations, and fully derived, concrete examples based on the author's own research experiences and insight. The book contains chapters on statistical physics, dynamic adsorption in plug flow bed reactors, and the synthesis and modification of important nanoporous materials. The final chapter covers the principles and applications of adsorption for multicomponent systems in the liquid phase. Connecting recent advances in adsorption characterization with developments in the transport and diffusion of nanoporous materials, this book is ideal for scientists involved in the research, development, and applications of new nanoporous materials.
Nanoporous Materials For Molecule Separation And Conversion
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Author : Jian Liu
language : en
Publisher: Elsevier
Release Date : 2020-07-21
Nanoporous Materials For Molecule Separation And Conversion written by Jian Liu and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-07-21 with Technology & Engineering categories.
Nanoporous Materials for Molecule Separation and Conversion cover the topic with sections on nanoporous material synthesis and characterization, nanoporous materials for molecule separation, and nanoporous materials for energy storage and renewable energy. Typical nanoporous materials including carbon, zeolite, silica and metal-organic frameworks and their applications in molecule separation and energy related applications are covered. In addition, the fundamentals of molecule adsorption and molecule transport in nanoporous materials are also included, providing readers with a stronger understanding of the principles and topics covered. This is an important reference for anyone exploring nanoporous materials, including researchers and postgraduate students in materials science and chemical engineering. In addition, it is ideal for industry professionals working on a wide range of applications for nanoporous materials. Outlines the fundamental principles of nanoporous materials design Explores the application of nanoporous materials in important areas such as molecule separation and energy storage Gives real-life examples of how nanoporous materials are used in a variety of industry sector
Diffusion And Thermal Transport In Bulk And Nano Materials
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Author : Helmut Mehrer
language : en
Publisher: Trans Tech Publications Ltd
Release Date : 2018-11-01
Diffusion And Thermal Transport In Bulk And Nano Materials written by Helmut Mehrer and has been published by Trans Tech Publications Ltd this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-11-01 with Technology & Engineering categories.
This volume is dedicated to the memory of Professor Dr. Nicolaas Augustinus Stolwijk whose works were related with study of a wide spectrum of diffusion processes in metals, intermetallic compounds, semiconductors, solar grade silicon, polymer electrolytes and in minerals.
Thermal Transport In Tin Capped Vertically Aligned Carbon Nanotube Composites For Thermal Energy Management
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Author : Pankaj B. Kaul
language : en
Publisher:
Release Date : 2014
Thermal Transport In Tin Capped Vertically Aligned Carbon Nanotube Composites For Thermal Energy Management written by Pankaj B. Kaul and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Carbon nanotubes categories.
The total thermal resistance of a thermal interface material (TIM) depends on its thermal conductivity, bond line thickness (BLT) and the contact resistances of the TIM with the two bounding surfaces. This work reports development and thermal characterization of tin-capped vertically aligned multi-walled carbon nanotube (VA-MWCNT) array-epoxy composites for thermal energy management in load-bearing structural applications. The epoxy matrix is expected to impart mechanical strength to these systems while the VA-MWCNTs provide avenues for high thru-thickness thermal conductivity across the material interface. A transition zone (capping layer) comprising of a Sn thin film is introduced at the interface between the MWCNTs and the bounding surfaces to minimize the total interface thermal resistance of the TIM. Three-omega measurement method is utilized to characterize thermal conductivity in the tin-capped VA-MWCNT-epoxy composites as well as in its individual constituents, i.e. bulk EPON-862 (matrix) from 40K-320K, tin thin films in the temperature range 240K-300K and in individual MWCNTs at room temperature, taken from the same VA-MWCNT batch as the one used to fabricate the CNT-epoxy composites. Multilayer thermal model that includes effects of thermal interface resistance is developed to interpret the experimental results. The thermal conductivity of the carbon nanotube-epoxy composite is estimated to be ~ 5.8 W/m-K, and exhibits a slight increase in the temperature range of 240 K to 300 K. The results of the study suggests that the morphological structure/quality of the individual MWCNTs as well as the tin thin layer on the VA-MWCNT array are dominating factors that control the overall thermal conductivity of the TIM. These results are encouraging in light of the fact that the thermal conductivity of a VA-MWCNT array can be increased by an order of magnitude by using a standard high temperature post-annealing step. In this way, multifunctional (load bearing) TIMs with effective through thickness thermal conductivities as high as 25 W/m-K, can potentially be fabricated. Recently, tin has been identified as an attractive electrode material for energy storage/conversion technologies. Tin thin films have also been utilized as an important constituent of thermal interface materials in thermal management applications in the first part of this thesis. In this regards, in the present work, we also investigate thermal conductivity of two nanoscale tin films, (i) with thickness 500 ± 50nm and 0.45% porosity, and (ii) with thickness 100 ± 20nm and 12.21% porosity. Thermal transport in these films is characterized over the temperature range from 40K-310K, using a three-omega method for multilayer configurations. The experimental results are compared with analytical-numerical predictions obtained by considering both phonon and electron contributions to heat conduction as described by frequency-dependent phenomenological models and Born-von-Karman (BvK) dispersion for phonons. The thermal conductivity of the thicker tin film (500nm) is measured to be 46.2W/m-K at 300K and is observed to increase with reduced temperatures; the mechanisms for thermal transport are understood to be governed by strong phonon-electron interactions in addition to the normal phonon-phonon interactions within the temperature range 160K-300K. In the case of the tin thin film with 100nm thickness, porosity and electron-boundary scattering supersede carrier interactions, and a reversal in the thermal conductivity trend with reduced temperatures is observed; the thermal conductivity falls to 1.83 W/m-K at 40K from its room temperature value of 36.1 W/m-K, which is still more than an order of magnitude higher than predicted by the minimum thermal conductivity model. In order to interpret the experimental results, we utilize analytical models that account for contributions of electron-boundary scattering using the Mayadas-Shatzkes (MS) and Fuchs-Sondheimer (FS) models for the thin and thick films, respectively. Moreover, the effects of porosity on carrier transport are included using a treatment based on phonon radiative transport involving frequency-dependent mean free paths and the morphology of the nanoporous channels. The systematic modeling approach presented in here can, in general, also be utilized to understand thermal transport in semi-metals and semiconductor nano-porous thin films and/or phononic nanocrystals.
Thermal Transport For Applications In Micro Nanomachining
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Author : Basil T. Wong
language : en
Publisher: Springer Science & Business Media
Release Date : 2008-07-19
Thermal Transport For Applications In Micro Nanomachining written by Basil T. Wong and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-07-19 with Science categories.
Beginning with an overview of nanomachining, this monograph introduces the relevant concepts from solid-state physics, thermodynamics, and lattice structures. It then covers modeling of thermal transport at the nanoscale and details simulations of different processes relevant to nanomachining. The final chapter summarizes the important points and discusses directions for future work to improve the modeling of nanomachining.
Nano Scale Heat Transfer In Nanostructures
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Author : Jihong Al-Ghalith
language : en
Publisher: Springer
Release Date : 2018-03-06
Nano Scale Heat Transfer In Nanostructures written by Jihong Al-Ghalith and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-03-06 with Science categories.
The book introduces modern atomistic techniques for predicting heat transfer in nanostructures, and discusses the applications of these techniques on three modern topics. The study of heat transport in screw-dislocated nanowires with low thermal conductivity in their bulk form represents the knowledge base needed for engineering thermal transport in advanced thermoelectric and electronic materials, and suggests a new route to lower thermal conductivity that could promote thermoelectricity. The study of high-temperature coating composite materials facilitates the understanding of the role played by composition and structural characterization, which is difficult to approach via experiments. And the understanding of the impact of deformations, such as bending and collapsing on thermal transport along carbon nanotubes, is important as carbon nanotubes, due to their exceptional thermal and mechanical properties, are excellent material candidates in a variety of applications, including thermal interface materials, thermal switches and composite materials.
Access In Nanoporous Materials
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Author : T.J. Pinnavaia
language : en
Publisher: Springer Science & Business Media
Release Date : 2006-04-11
Access In Nanoporous Materials written by T.J. Pinnavaia and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006-04-11 with Science categories.
This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, and engineering, with length scales ranging from Ångstromsup to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area ofcurrent interest and brings together leading experts to give an up-to-date discussion of their work and the work ofothers. Each article contains enough references that the interested reader can accesstherelevant literature. Thanks aregiven to the Center forFundamental Materials Research atMichigan State University forsupportingthis series. M.F. Thorpe, Series Editor E-mail: [email protected] EastLansing,Michigan, September, 1995 PREFACE This book records selected papers given at an interdisciplinary Symposium on Access in Nanoporous Materials held in Lansing, Michigan, on June 7-9, 1995. Broad interest in the synthesis of ordered materials with pore sizes in the 1.0-10 nm range was clearly manifested in the 64 invited and contributed papers presented by workers in the formal fields of chemistry, physics, and engineering. The intent of the symposium was to bring together a small number ofleading researchers within complementary disciplines to share in the diversity of approaches to nanoporous materials synthesis and characterization.
Transport Of Fluids In Nanoporous Materials
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Author : Suresh K. Bhatia
language : en
Publisher: MDPI
Release Date : 2019-01-25
Transport Of Fluids In Nanoporous Materials written by Suresh K. Bhatia and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-01-25 with Chemical engineering categories.
This book is a printed edition of the Special Issue "Transport of Fluids in Nanoporous Materials" that was published in Processes
Nanoscale Thermoelectrics
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Author : Xiaodong Wang
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-11-18
Nanoscale Thermoelectrics written by Xiaodong Wang and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-18 with Technology & Engineering categories.
For the efficient utilization of energy resources and the minimization of environmental damage, thermoelectric materials can play an important role by converting waste heat into electricity directly. Nanostructured thermoelectric materials have received much attention recently due to the potential for enhanced properties associated with size effects and quantum confinement. Nanoscale Thermoelectrics describes the theory underlying these phenomena, as well as various thermoelectric materials and nanostructures such as carbon nanotubes, SiGe nanowires, and graphene nanoribbons. Chapters written by leading scientists throughout the world are intended to create a fundamental bridge between thermoelectrics and nanotechnology, and to stimulate readers' interest in developing new types of thermoelectric materials and devices for power generation and other applications. Nanoscale Thermoelectrics is both a comprehensive introduction to the field and a guide to further research, and can be recommended for Physics, Electrical Engineering, and Materials Science departments.