Download or read book Thermal Energy Transport and Conversion in Disordered Materials written by Jianlin Zheng and published by . This book was released on 2018 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal properties (thermal conductivity and specific heat) of the disordered materials, such as amorphous silicon (a-Si), polymer, and nano-crystalline semiconductors, are of significant interests for fundamental understanding of thermal transport process and for technical applications in thermal energy management and conversion. Due to the random distribution of atoms or molecules in disordered materials, the study of thermal transport is more challenging than that in crystalline materials. Understanding of the heat carrier transport behavior can be utilized to engineer the thermal properties in disordered materials, which can be applied for better devices thermal design and improving thermal energy conversion efficiency. We have studied the size dependent thermal conductivity of a-Si thin films and nanotubes, and observed unusually high and anisotropic thermal conductivity in the isotropic a-Si nanostructure. This manifests surprisingly broad mean free path distribution of the propagating modes (propagons), which is found to range from 10 nm to 10 [mu]m, in the disordered and isotropic structure. Constraining the long MFP propagons by boundary scattering in thin film and nanotubes explains the appreciable size effect in a-Si. Additionally, we developed a novel platform to measure the specific heat of low-dimensional disordered materials. By measuring the frequency dependent temperature rise data along the Nylon nanofibers (NFs), we are able to extract the specific heat and thermal conductivity simultaneously. While the thermal conductivity is increased by 50% over the bulk value in the 600 nm NFs, the specific heat exhibits bulk-like behavior. Finally we engineered the thermal conductivity in nano-crystalline bismuth-antimony-telluride (BST) by embedding SiO2 or diamond nanoparticles (NPs) at temperature below 300K, which has important application in thermoelectric cooling. We have shown that the embedded NPs work as additional scattering centers for lattice vibration (or called phonons), and can efficiently scatter the long MFP phonons in BST. We have observed 23% reduction of thermal conductivity, and 15% improvement of thermoelectric figure of merit (ZT) in the 0.5 vol. % Diamond NPs mixing sample, compared to the non-NPs nano-crystalline BST.

Download or read book Nanoscale Thermal and Thermoelectric Energy Transport in Crystalline and Disordered Materials written by Jiawei Zhou and published by . This book was released on 2019 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy transport provides the fundamental basis for operation of devices from transistors to solar cells. Despite past theories that successfully illustrate the principles behind the energy transport based on solid state physics, the microscopic details of the energy transport are not always clear due to the lack of tool to quantify the contribution from different degrees of freedom. Recent progress in first principles computations and development in optical characterization has offered us new ways to understand the energy transport at the nanoscale in a quantitative way. In this thesis, by leveraging these techniques, we aim to providing a detailed understanding of thermal and thermoelectric energy transport in crystalline and disordered materials, especially about how the energy transport depends on atomistic level details such as chemical bondings. Specifically, we will discuss three examples. 1) Electron transport in semiconductors: how electrons propagate as they interact with lattice and impurities. 2) Interaction between charge and heat: how the free carriers have an impact on the heat dissipation in semiconductors 3) Heat conduction in polymers: how the heat transfer in an amorphous system depends on its molecular structures. In the case of electron transport, we developed and applied first principles simulation to show that a large electron mobility can benefit from symmetry-protected non-bonding orbitals. Such orbitals result in weak electron-lattice coupling that explains the unusually large power factors in half-Heusler materials - a good thermoelectric material system. By devising an optical experiment to probe the ultrafast thermal decay, we quantified the effect of electron-phonon interaction on the thermal transport. Our results show that the thermal conductivity can be significantly affected by the free carriers. Lastly, we built a theoretical model to understand the heat conduction in amorphous polymers, and used this knowledge to design materials that are heat-conducting yet soft. These understandings will potentially facilitate discovery of new material systems with beneficial charge and heat transport characteristic.

Download or read book Frontiers in Thermal Transport and Energy Conversion written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2020-03-13 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal transport and energy conversion has remained an active field for at least 200 years, with numerous opportunities for discoveries and new applications. Recently, experiments have advanced researchers' understanding of basic physics, and how new discoveries might translate into applications in energy, materials, quantum technologies, and other areas. The National Academies convened a workshop on April 11, 2019 to identify and assess the frontier of current research in the field of thermal transport and energy conversion. Discussions involved topics related to thermal transport and quasi-particle hydrodynamics, thermal transport beyond the quasiparticle paradigm, the thermal hall effect from neutral spin excitations in frustrated quantum magnets, quantization of the thermal hall conductivity at small hall angles, and thermal spin transport, including spin-seebeck and magnon drag effects. These topics were strategically selected with the goal of uncovering key challenges, opportunities, and issues in order to guide future efforts and investments to advance the field. This publication offers a condensed summary of the discussions and presentations from the workshop, which was unclassified and open to the public.

Download or read book Nanoscale Energy Transport and Conversion written by Gang Chen (PhD) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gang Chen provides an overview of microscale heat transfer, focusing on thermal energy storage and transport. He also presents related topics on the transport of electrons, phonons, photons and molecules and is part of the 'MIT-Pappalardo' series in mechanical engineering.

Download or read book Frontiers in Thermal Transport and Energy Conversion written by Engineering National Academies of Sciences (and Medicine) and published by . This book was released on 2020 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Heat Transfer in Porous Media written by M. Kaviany and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the empirical treatment of fluid flow and heat transfer in porous media is over a century old, only in the last three decades has the transport in these heterogeneous systems been addressed in detail. So far, single-phase flows in porous media have been treated or at least formulated satisfactorily, while the subject of two-phase flow and the related heat-transfer in porous media is still in its infancy. This book identifies the principles of transport in porous media and compares the avalaible predictions based on theoretical treatments of various transport mechanisms with the existing experimental results. The theoretical treatment is based on the volume-averaging of the momentum and energy equations with the closure conditions necessary for obtaining solutions. While emphasizing a basic understanding of heat transfer in porous media, this book does not ignore the need for predictive tools; whenever a rigorous theoretical treatment of a phenomena is not avaliable, semi-empirical and empirical treatments are given.

Download or read book Thermodynamics of Energy Conversion and Transport written by Stanislaw Sieniutycz and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists and engineers are nowadays faced with the problem of optimizing complex systems subject to constraints from, ecology, economics, and thermodynamics. It is chiefly to the last of these that this volume is addressed. Intended for physicists, chemists, and engineers, the book uses examples from solar, thermal, mechanical, chemical, and environmental engineering to focus on the use of thermodynamic criteria for optimizing energy conversion and transmission. The early chapters centre on solar energy conversion, the second section discusses the transfer and conversion of chemical energy, while the concluding chapters deal with geometric methods in thermodynamics.

Download or read book Thermoelectric Energy Conversion written by Ryoji Funahashi and published by Woodhead Publishing. This book was released on 2021-01-19 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric Energy Conversion: Theories and Mechanisms, Materials, Devices, and Applications provides readers with foundational knowledge on key aspects of thermoelectric conversion and reviews future prospects. Sections cover the basic theories and mechanisms of thermoelectric physics, the chemical and physical aspects of classical to brand-new materials, measurement techniques of thermoelectric conversion properties from the materials to modules and current research, including the physics, crystallography and chemistry aspects of processing to produce thermoelectric devices. Finally, the book discusses thermoelectric conversion applications, including cooling, generation, energy harvesting, space, sensor and other emerging areas of applications. Reviews key applications of thermoelectric energy conversion, including cooling, power generation, energy harvesting, and applications for space and sensing Discusses a wide range of materials, including skutterudites, heusler materials, chalcogenides, oxides, low dimensional materials, and organic materials Provides the fundamentals of thermoelectric energy conversion, including the physics, phonon conduction, electronic correlation, magneto-seebeck theories, topological insulators and thermionics

Download or read book Thermal Transport Properties in Polymers and Hybrid Materials written by Hao Ma and published by . This book was released on 2020 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding thermal transport processes can guide the rational design of devices and systems for thermal energy conversion and management. Despite the significant progress in thermal transport of inorganic crystals, thermal transport in complicated materials, such as polymers and hybrid materials, remains largely unexplored. This thesis first presents our discovery of the large thermal rectification effects in the novel tapered bottlebrush polymers using nonequilibrium molecular dynamic simulations. In sharp contrast to all other reported asymmetric nanostructures, we observed that the heat current from the wide end to the narrow end in tapered bottlebrush polymers is smaller than that in the opposite direction. It was demonstrated that a more disordered to less disordered structural transition within tapered bottlebrush polymers is essential for generating non-linearity in heat conduction for thermal rectification. Moreover, the thermal rectification factor increases with device length, reaching as high as ~70% with a device length of 28.5nm. This large thermal rectification with strong length dependence uncovers an unprecedented phenomenon - diffusive thermal transport in the forward direction and ballistic thermal transport in the backward direction. This thesis then focuses on thermal transport properties in hybrid materials: graphene-C60 heterostructures and hybrid organic-inorganic (CH3NH3)3Bi2I9 crystals. Graphene-C60 heterostructures assembled by van der Waals interactions between graphene and C60 have shown exciting potential for multifunctional devices. Understanding thermal transport in graphene-C60 heterostructures is the key to guiding the design of vdW heterostructures with desired thermal transport properties. Our equilibrium molecular dynamics simulations found that the in-plane thermal conductivity of the graphene-C60 heterostructure is as high as about 234 W/(mK) at room temperature, exceeding those of most pure metals. On the other hand, vdW interactions enhance the interfacial thermal conductance between graphene and C60 by strengthening out-of-plane phonon couplings between graphene and C60 and increasing in-plane and out-of-plane phonon couplings of the graphene layer. Our study demonstrates that the interfacial thermal conductance of graphene-C60 heterostructure is comparable to that of graphene-hexagonal boron-nitride (hBN) heterostructure. Hybrid perovskite analogues, such as methylammonium bismuth iodide (CH3NH3)3Bi2I9, have emerged as candidate photovoltaic and thermoelectric materials due to their low toxicity and high stability. Thermal transport and phonon properties of (CH3NH3)3Bi2I9 were studied neither experimentally nor theoretically, which hinders the optimal selection and design of stable, non-toxic hybrid perovskite material for photovoltaic and thermoelectric applications. We mapped out the phonon dispersion of (CH3NH3)3Bi2I9 single crystals at 300 K using inelastic x-ray scattering. The frequencies of acoustic phonons are among the lowest of crystals. Nanoindentation measurements verified that these crystals are very compliant and considerably soft. The frequency overlap between acoustic and optical phonons results in strong acoustic-optical scattering. All these features lead to an ultralow thermal conductivity.

Download or read book Materials and Technologies for Direct Thermal to electric Energy Conversion written by Jihui Yang and published by . This book was released on 2006 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermal Energy written by Yatish T. Shah and published by CRC Press. This book was released on 2018-01-12 with total page 1112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book details sources of thermal energy, methods of capture, and applications. It describes the basics of thermal energy, including measuring thermal energy, laws of thermodynamics that govern its use and transformation, modes of thermal energy, conventional processes, devices and materials, and the methods by which it is transferred. It covers 8 sources of thermal energy: combustion, fusion (solar) fission (nuclear), geothermal, microwave, plasma, waste heat, and thermal energy storage. In each case, the methods of production and capture and its uses are described in detail. It also discusses novel processes and devices used to improve transfer and transformation processes.

Download or read book Thermal Energy Conversion Utilizing Magnetization Dynamics and Two carrier Effects written by Sarah J. Watzman and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The majority of the world’s energy comes from nonrenewable sources, with over 60% rejected as waste-heat. If waste-heat could be recovered, the effect on humanity would be equivalent to that of adding a renewable energy source, majorly increasing society’s energy conversion efficiency. This can be accomplished through the use of thermoelectric materials, which convert a temperature gradient (like that from waste-heat) into a usable voltage output. Conventional thermoelectric materials have not increased in commercial efficiency in recent years, therefore a different approach is taken in this dissertation. Here, metals are explored as thermoelectric materials despite having a low thermoelectric efficiency. Magnon drag, an advective process utilizing magnetization dynamics in a temperature gradient to pull charge carriers through a crystal lattice, is shown to dominate thermoelectric transport in ferromagnetic transition metals. Experimental comparison with theory offers a pathway for increasing the thermoelectric efficiency in metals by increasing their magnon-drag thermopower. Additionally, novel transport is explored in the recently experimentally-realized class of materials called Weyl semimetals, where tuning the electronic band structure gives unique topological transport signatures. Predicted to have large transverse transport coefficients, NbP is experimentally proven to effectively convert a temperature gradient into a perpendicular output voltage via the Nernst effect. Transverse thermoelectric devices have technological advantages over conventional Peltier or Seebeck longitudinal modules (in which the applied temperature gradient is parallel to the output voltage), but they require an externally applied magnetic field. Further control over the band structure in Weyl semimetals offers a solution, where YbMnBi2 is experimentally predicted to effectively utilize a transverse geometry without the need for an external magnetic field. This effect is predicted to arise from the Berry curvature of the electronic band structure, which functions like an internal magnetic field. The novel and unique signatures of Weyl semimetals indicate their strong potential as candidate materials for thermoelectric energy generation and cooling.

Download or read book Semiconductor Nanowires written by J Arbiol and published by Elsevier. This book was released on 2015-03-31 with total page 573 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanowires promise to provide the building blocks for a new generation of nanoscale electronic and optoelectronic devices. Semiconductor Nanowires: Materials, Synthesis, Characterization and Applications covers advanced materials for nanowires, the growth and synthesis of semiconductor nanowires—including methods such as solution growth, MOVPE, MBE, and self-organization. Characterizing the properties of semiconductor nanowires is covered in chapters describing studies using TEM, SPM, and Raman scattering. Applications of semiconductor nanowires are discussed in chapters focusing on solar cells, battery electrodes, sensors, optoelectronics and biology. Explores a selection of advanced materials for semiconductor nanowires Outlines key techniques for the property assessment and characterization of semiconductor nanowires Covers a broad range of applications across a number of fields

Download or read book Thermal Energy Transport in Micro nanostructures written by Alexis Ryan Abramson and published by . This book was released on 2002 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book From Energy Storage to Photofunctional Materials written by Rainer Pöttgen and published by Walter de Gruyter GmbH & Co KG. This book was released on 2022-12-05 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many elements and inorganic compounds play an extraordinary role in daily life for numerous applications, e. g., construction materials, inorganic pigments, inorganic coatings, steel, glass, technical gases, energy storage and conversion materials, fertilizers, homogeneous and heterogeneous catalysts, photofunctional materials, semiconductors, superconductors, soft- and hard magnets, technical ceramics, hard materials, or biomedical and bioactive materials. The present book is written by experienced authors who give a comprehensive overview on the many chemical and physico-chemical aspects related to application of inorganic compounds and materials in order to introduce senior undergraduate and postgraduate students (chemists, physicists, materials scientists, engineers) into this broad field.

Download or read book 108 1 Hearings Energy and Water Development Appropriations For 2004 Part 4 2003 written by and published by . This book was released on 2003 with total page 3122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy and Water Development Appropriations for 2004 written by United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development and published by . This book was released on 2003 with total page 1570 pages. Available in PDF, EPUB and Kindle. Book excerpt: