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Author: Pedro Andrés Galione Klot
Publisher:
ISBN:
Category :
Languages : en
Pages : 188
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Book Description
The present thesis aims at studying the use of phase change materials (PCM) in thermal energy storage (TES) applications and to develop and implement numerical tools for their evaluation. Numerical analysis is nowadays an indispensable tool for the design, evaluation and optimization of thermal equipment, complementing the experimental techniques. Two levels of analysis are carried out, one in the field of Computational Fluid Dynamics, allowing the accurate simulation of the complex heat transfer and fluid dynamics phenomena present in solid-liquid phase change problems; and another one in which the governing equations are treated assuming several suitable simplifications and integrating empirical correlations, intended for the study of whole thermal storage systems throughout several charge/discharge cycles. Furthermore, the specific application of thermal storage in concentrated solar power (CSP) stations is studied. Different single-tank systems, making use of both sensible and latent energy capacities of the materials, are evaluated and compared against the two-tank molten-salt systems used in current CSP plants. Moreover, a new single-tank TES concept which combines the use of solid and PCM filler materials is proposed, with promising results for its utilization in CSP. In chapters 2 and 3, a numerical fixed-grid enthalpy model for the simulation of the solid-liquid phase change is developed. This technique is implemented using the Finite Volume Method in a collocated unstructured domain discretization and using explicit time integration schemes. Issues regarding the form of the energy equation, the treatment of the pressure equation as well as the momentum source-term coefficient introduced by the enthalpy-porosity method, are described in detail in the first chapter. In the second, the possibility of taking into account the variation of the different thermo-physical properties with the temperature is dealt with. Thermal expansion and contraction associated to the phase change are taken into account in the conservation equations and different strategies for the numerical treatment of the energy equation are discussed in detail. Furthermore, simulations of an interesting case of melting of an encapsulated PCM are carried out using two and three-dimensional meshes, and the results are compared against experimental results from the literature. In the next two chapters, the issue of numerically simulating whole single-tank TES systems is developed. These systems are composed of a single tank filled with solid and/or PCM materials, forming a packed bed through which a heat transfer fluid flows. Thermal stratification separates the fluid layers at different temperatures. The zone in which a steep temperature gradient is produced is called "thermocline", and it is desirable to maintain it as narrow as possible in order to keep a high stored exergy. Different designs of single-tank TES systems ¿classified according to the filler material/s used¿ are evaluated for CSP plants. The analysis is performed evaluating different aspects, as the energy effectively stored/released and the efficiency in the use of the theoretical capacity after several charge/discharge cycles, obtaining results independent of the initial thermal state. The operating time is not fixed, but depends on the temperature of the fluid coming out of the tank, limited by the restrictions of the receiving equipment (solar field and power block). Degradation of the stratification is observed to occur after several cycles, due to the temperature restrictions. In this context, a new concept of single-tank TES is presented, which consists of the combination of different layers of solid and PCM filler materials in a suitable manner, resulting in a lower degradation of the thermocline and increasing the use of the theoretical capacity. This concept, called Multi-Layered Solid PCM (MLSPCM), is demonstrated as a promising alternative for its use in CSP plants.
Author: Pedro Andrés Galione Klot
Publisher:
ISBN:
Category :
Languages : en
Pages : 188
Get Book Here
Book Description
The present thesis aims at studying the use of phase change materials (PCM) in thermal energy storage (TES) applications and to develop and implement numerical tools for their evaluation. Numerical analysis is nowadays an indispensable tool for the design, evaluation and optimization of thermal equipment, complementing the experimental techniques. Two levels of analysis are carried out, one in the field of Computational Fluid Dynamics, allowing the accurate simulation of the complex heat transfer and fluid dynamics phenomena present in solid-liquid phase change problems; and another one in which the governing equations are treated assuming several suitable simplifications and integrating empirical correlations, intended for the study of whole thermal storage systems throughout several charge/discharge cycles. Furthermore, the specific application of thermal storage in concentrated solar power (CSP) stations is studied. Different single-tank systems, making use of both sensible and latent energy capacities of the materials, are evaluated and compared against the two-tank molten-salt systems used in current CSP plants. Moreover, a new single-tank TES concept which combines the use of solid and PCM filler materials is proposed, with promising results for its utilization in CSP. In chapters 2 and 3, a numerical fixed-grid enthalpy model for the simulation of the solid-liquid phase change is developed. This technique is implemented using the Finite Volume Method in a collocated unstructured domain discretization and using explicit time integration schemes. Issues regarding the form of the energy equation, the treatment of the pressure equation as well as the momentum source-term coefficient introduced by the enthalpy-porosity method, are described in detail in the first chapter. In the second, the possibility of taking into account the variation of the different thermo-physical properties with the temperature is dealt with. Thermal expansion and contraction associated to the phase change are taken into account in the conservation equations and different strategies for the numerical treatment of the energy equation are discussed in detail. Furthermore, simulations of an interesting case of melting of an encapsulated PCM are carried out using two and three-dimensional meshes, and the results are compared against experimental results from the literature. In the next two chapters, the issue of numerically simulating whole single-tank TES systems is developed. These systems are composed of a single tank filled with solid and/or PCM materials, forming a packed bed through which a heat transfer fluid flows. Thermal stratification separates the fluid layers at different temperatures. The zone in which a steep temperature gradient is produced is called "thermocline", and it is desirable to maintain it as narrow as possible in order to keep a high stored exergy. Different designs of single-tank TES systems ¿classified according to the filler material/s used¿ are evaluated for CSP plants. The analysis is performed evaluating different aspects, as the energy effectively stored/released and the efficiency in the use of the theoretical capacity after several charge/discharge cycles, obtaining results independent of the initial thermal state. The operating time is not fixed, but depends on the temperature of the fluid coming out of the tank, limited by the restrictions of the receiving equipment (solar field and power block). Degradation of the stratification is observed to occur after several cycles, due to the temperature restrictions. In this context, a new concept of single-tank TES is presented, which consists of the combination of different layers of solid and PCM filler materials in a suitable manner, resulting in a lower degradation of the thermocline and increasing the use of the theoretical capacity. This concept, called Multi-Layered Solid PCM (MLSPCM), is demonstrated as a promising alternative for its use in CSP plants.
Author: Ibrahim Dinçer
Publisher: John Wiley & Sons
ISBN: 1119956625
Category : Science
Languages : en
Pages : 585
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Book Description
The ability of thermal energy storage (TES) systems to facilitate energy savings, renewable energy use and reduce environmental impact has led to a recent resurgence in their interest. The second edition of this book offers up-to-date coverage of recent energy efficient and sustainable technological methods and solutions, covering analysis, design and performance improvement as well as life-cycle costing and assessment. As well as having significantly revised the book for use as a graduate text, the authors address real-life technical and operational problems, enabling the reader to gain an understanding of the fundamental principles and practical applications of thermal energy storage technology. Beginning with a general summary of thermodynamics, fluid mechanics and heat transfer, this book goes on to discuss practical applications with chapters that include TES systems, environmental impact, energy savings, energy and exergy analyses, numerical modeling and simulation, case studies and new techniques and performance assessment methods.
Author: Santiago Torras Ortiz
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
El objetivo principal de esta tesis es la resolución numérica de problemas de transferencia de calor y dinámica de fluidos y su aplicación para el estudio del comportamiento transitorio de sistemas térmicos de acumulación de energía (TES). Tres diferentes sistemas han sido considerados, cubriendo un amplio rango de condiciones de trabajo (desde muy baja de temperatura criogenica hasta muy alta temperatura en plantas CSP) y aplicaciones (desde domestica/residencial hasta energía renovables o de la industria aeroespacial). En este sentido, i) sistemas recuperadores de energía térmica para residencias en el rango de bajo a media temperatura; ii) un acumulador térmico usado un sistema de propulsión criogenica en el espacio en el rango de baja temperatura y; iii) sistema de acumulación térmica del tipo dos tanque para plantas solares de alta concentración en el rango de alta temperatura. La tesis esta dividida en cinco capítulos. El capitulo 2, esta dedicado en presentar la metodología empleada para la resolución computacional de la dinámica de fluidos y problemas de transferencia de calor en un dispositivo con almacenamiento para la recuperación de energía térmica de agua que se vierte al drenaje para viviendas residenciales. El estudio de las características del dispositivo fue realizado usando herramientas numéricas y experimentales. La simulación numérica fue realizada usando la plataforma NEST. La discretización de la ecuaciones de gobierno basadas en técnicas de volúmenes finitos. Correlaciones empíricas especiales han sido implementadas para ser usadas en la resolución numérica del flujo de fluido dentro de una tubería en espiral. Una infraestructura experimental ha sido desarrollada para el análisis del sistema. Diferentes flujos másicos y temperaturas de operación han sido estudiados. Los resultados numéricos han sidos comparados con resultados experimentales. La simulación numéricas realizadas predicen razonablemente bien el comportamiento transitorio de estos dispositivos. El capitulo 3, enfoca su atención en un prototipo de acumulador para baja temperatura usado para sistemas de propulsión criogenica en el espacio. Las simulaciones numéricas fueron realizadas usando la plataforma NEST. En este capitulo, dos modelos numéricos son adaptados, uno para resolver el flujo bifásico a través de tuberías bajo condiciones criogenicas, y otra para solucionar el material de cambio de fase usando un modelo entalpico de malla fija. El análisis numérico se basa en: i) la resolución unidimensional y transitoria de las ecuaciones gobernantes del fluido propulsor; ii) resolución multidimensional y transitoria de las ecuaciones gobernantes en la región ocupada por el material de cambio de fase, incorporando modelo de turbulencia para solucionar el fenómeno de convección que se produce; iii) los elementos solidos son modelados considerando un tratamiento multidimensional y transitorio de la ecuación de la energía. Los resultados numéricos son comparados con resultados experimentales de la literatura. La validación experimental bajo diferentes condiciones de trabajo de fluido criogenico y/o del material de cambio de fase muestra las posibilidades de este modelo para fines de optimización del diseño y de predicción. El capitulo 4, esta enfocado en el desarrollo de modelos numéricos para la simulación de sistemas de acumulación de energía térmica de dos tanques en centrales solares de alta concentración. La simulación numérica fue desarrollada dentro de la plataforma NEST, donde los diferentes elementos que componen el sistema son asociados para solucionar todo el sistema. Algunos elementos del sistema han sido especialmente desarrollados. Los modelos matemáticos consideran el comportamiento transitorio de la sal fundida, el gas de la cavidad, las paredes del tanque y sus aislantes, diferentes configuraciones de cimientos, la radiación entre la sal y las paredes del tanque en la zona de la cavidad del gas.
Author: Luisa F. Cabeza
Publisher: Elsevier
ISBN: 1782420967
Category : Technology & Engineering
Languages : en
Pages : 623
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Book Description
Thermal energy storage (TES) technologies store thermal energy (both heat and cold) for later use as required, rather than at the time of production. They are therefore important counterparts to various intermittent renewable energy generation methods and also provide a way of valorising waste process heat and reducing the energy demand of buildings. This book provides an authoritative overview of this key area. Part one reviews sensible heat storage technologies. Part two covers latent and thermochemical heat storage respectively. The final section addresses applications in heating and energy systems. - Reviews sensible heat storage technologies, including the use of water, molten salts, concrete and boreholes - Describes latent heat storage systems and thermochemical heat storage - Includes information on the monitoring and control of thermal energy storage systems, and considers their applications in residential buildings, power plants and industry
Author: S. Kalaiselvam
Publisher: Elsevier
ISBN: 0124173055
Category : Technology & Engineering
Languages : en
Pages : 445
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Book Description
Thermal Energy Storage Technologies for Sustainability is a broad-based overview describing the state-of-the-art in latent, sensible, and thermo-chemical energy storage systems and their applications across industries. Beginning with a discussion of the efficiency and conservation advantages of balancing energy demand with production, the book goes on to describe current state-of-the art technologies. Not stopping with description, the authors also discuss design, modeling, and simulation of representative systems, and end with several case studies of systems in use. - Describes how thermal energy storage helps bridge the gap between energy demand and supply, particularly for intermittent power sources like solar, wind, and tidal systems - Provides tables, illustrations, and comparative case studies that show applications of TES systems across industries - Includes a chapter on the rapidly developing field of viable nanotechnology-based thermal energy storage systems
Author: Ibrahim Dincer
Publisher: John Wiley & Sons
ISBN: 9780471495734
Category : Science
Languages : en
Pages : 602
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Book Description
During the last two decades many research and development activities related to energy have concentrated on efficient energy use and energy savings and conservation. In this regard, Thermal Energy Storage (TES) systems can play an important role, as they provide great potential for facilitating energy savings and reducing environmental impact. Thermal storage has received increasing interest in recent years in terms of its applications, and the enormous potential it offers both for more effective use of thermal equipment and for economic, large-scale energy substitutions. Indeed, TES appears to provide one of the most advantageous solutions for correcting the mismatch that often occurs between the supply and demand of energy. Despite this increase in attention, no book is currently available which comprehensively covers TES. Presenting contributions from prominent researchers and scientists, this book is primarily concerned with TES systems and their applications. It begins with a brief summary of general aspects of thermodynamics, fluid mechanics and heat transfer, and then goes on to discuss energy storage technologies, environmental aspects of TES, energy and exergy analyses, and practical applications. Furthermore, this book provides coverage of the theoretical, experimental and numerical techniques employed in the field of thermal storage. Numerous case studies and illustrative examples are included throughout. Some of the unique features of this book include: * State-of-the art descriptions of many facets of TES systems and applications * In-depth coverage of exergy analysis and thermodynamic optimization of TES systems * Extensive new material on TES technologies, including advances due to innovations in sensible- and latent-energy storage * Key chapters on environmental issues, sustainable development and energy savings * Extensive coverage of practical aspects of the design, evaluation, selection and implementation of TES systems * Wide coverage of TES-system modelling, ranging in level from elementary to advanced * Abundant design examples, case studies and references In short, this book forms a valuable reference resource for practicing engineers and researchers, and a research-oriented text book for advanced undergraduate and graduate students of various engineering disciplines. Instructors will find that its breadth and structure make it an ideal core text for TES and related courses.
Author: Robert John Gross
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 34
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Book Description
Author: Amritanshu Shukla
Publisher: CRC Press
ISBN: 1000586936
Category : Science
Languages : en
Pages : 313
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Book Description
In light of increasing human-induced global climate change, there is a greater need for clean energy resources and zero carbon projects. This new volume offers up-to-date coverage of the fundamentals as well as recent advancements in energy efficient thermal energy storage materials, their characterization, and technological applications. Thermal energy storage (TES) systems offer very high-energy savings for many of our day-to-day applications and could be a strong component for enhancing the usage of renewable/clean energy-based devices. Because of its beneficial environmental impact, this technology has received wide attention in the recent past, and dedicated research efforts have led to the development of novel materials, as well to innovative applications in very many fields, ranging from buildings to textile, healthcare to agriculture, space to automobiles. This book offers a valuable and informed systematic treatment of latent heat-based thermal energy storage systems, covering current energy research and important developmental work.
Author: Raghavendra Rohith Kasibhatla
Publisher:
ISBN: 9783832548933
Category :
Languages : en
Pages : 0
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Book Description
Natural energy sources like sun and wind as well as waste heat from industrial processes are characterized by a fluctuating energy supply. To balance supply and demand in renewable energy systems, thermal energy storage (TES) is an important concept. This can be realized by storages containing numerous capsules filled with an appropriate phase change material (PCM). For applications it is essential to optimize the heat flow during the charging and discharging processes. The author presents a method for numerical simulation of these processes. He has developed a multi-scale approach combining detailed modelling of single capsules and a coarser simulation of a whole storage system. Numerical results from simulation are compared to measured data from experiments.
Author: Wolf Dieter Steinmann
Publisher: Springer Vieweg
ISBN: 9783658020033
Category : Technology & Engineering
Languages : en
Pages : 350
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Book Description
Storage systems for medium and high temperatures are an emerging option to improve the energy efficiency of power plants and industrial facilities. Reflecting the wide area of applications in the temperature range from 100 °C to 1200 °C, a large number of storage oncepts has been developed. This book provides a descriptive classification of the various concepts, giving characteristic performance data and design fundamentals. Systems based on sensible heat storage, latent heat storage and thermo-chemical processes are presented, including the state of maturity and innovative solutions. Essential for the effective integration of thermal storage systems is the optimal adaption to the specific requirements of an application. This is shown in the second part, where storage solutions for conventional and solar thermal power plants are described. Further examples show the integration into batch processes, mobile applications or options to support the utilization of waste heat. Systems using thermal energy storage for facility scale storage of electricity are also described.
