Fundamentals Of Heat And Fluid Flow In High Temperature Fuel Cells

Download Fundamentals Of Heat And Fluid Flow In High Temperature Fuel Cells full books in PDF, epub, and Kindle. Read online Fundamentals Of Heat And Fluid Flow In High Temperature Fuel Cells ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!

Fundamentals of Heat and Fluid Flow in High Temperature Fuel Cells

Author : Majid Ghassemi
Publisher : Academic Press
ISBN 13 : 0128157542
Total Pages : 197 pages
Book Rating : 4.1/5 (281 download)

DOWNLOAD NOW!

Book Synopsis Fundamentals of Heat and Fluid Flow in High Temperature Fuel Cells by : Majid Ghassemi

Download or read book Fundamentals of Heat and Fluid Flow in High Temperature Fuel Cells written by Majid Ghassemi and published by Academic Press. This book was released on 2020-08-18 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Heat and Fluid Flow in High Temperature Fuel Cells introduces key-concepts relating to heat, fluid and mass transfer as applied to high temperature fuel cells. The book briefly covers different type of fuel cells and discusses solid oxide fuel cells in detail, presenting related mass, momentum, energy and species equation. It then examines real case studies of hydrogen- and methane-fed SOFC, as well as combined heat and power and hybrid energy systems. This comprehensive reference is a useful resource for those working in high temperature fuel cell modeling and development, including energy researchers, engineers and graduate students. - Provides broad coverage of key concepts relating to heat transfer and fluid flow in high temperature fuel cells - Presents in-depth knowledge of solid oxide fuel cells and their application in different kinds of heat and power systems - Examines real-life case studies, covering different types of fuels and combined systems, including CHP

Fuel Cell Fundamentals

Author : Ryan O'Hayre
Publisher : John Wiley & Sons
ISBN 13 : 1119113806
Total Pages : 612 pages
Book Rating : 4.1/5 (191 download)

DOWNLOAD NOW!

Book Synopsis Fuel Cell Fundamentals by : Ryan O'Hayre

Download or read book Fuel Cell Fundamentals written by Ryan O'Hayre and published by John Wiley & Sons. This book was released on 2016-05-02 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete, up-to-date, introductory guide to fuel cell technology and application Fuel Cell Fundamentals provides a thorough introduction to the principles and practicalities behind fuel cell technology. Beginning with the underlying concepts, the discussion explores fuel cell thermodynamics, kinetics, transport, and modeling before moving into the application side with guidance on system types and design, performance, costs, and environmental impact. This new third edition has been updated with the latest technological advances and relevant calculations, and enhanced chapters on advanced fuel cell design and electrochemical and hydrogen energy systems. Worked problems, illustrations, and application examples throughout lend a real-world perspective, and end-of chapter review questions and mathematical problems reinforce the material learned. Fuel cells produce more electricity than batteries or combustion engines, with far fewer emissions. This book is the essential introduction to the technology that makes this possible, and the physical processes behind this cost-saving and environmentally friendly energy source. Understand the basic principles of fuel cell physics Compare the applications, performance, and costs of different systems Master the calculations associated with the latest fuel cell technology Learn the considerations involved in system selection and design As more and more nations turn to fuel cell commercialization amidst advancing technology and dropping deployment costs, global stationary fuel cell revenue is expected to grow from $1.4 billion to $40.0 billion by 2022. The sector is forecasted to explode, and there will be a tremendous demand for high-level qualified workers with advanced skills and knowledge of fuel cell technology. Fuel Cell Fundamentals is the essential first step toward joining the new energy revolution.

Dynamic Modeling and Predictive Control in Solid Oxide Fuel Cells

Author : Biao Huang
Publisher : John Wiley & Sons
ISBN 13 : 1118501039
Total Pages : 345 pages
Book Rating : 4.1/5 (185 download)

DOWNLOAD NOW!

Book Synopsis Dynamic Modeling and Predictive Control in Solid Oxide Fuel Cells by : Biao Huang

Download or read book Dynamic Modeling and Predictive Control in Solid Oxide Fuel Cells written by Biao Huang and published by John Wiley & Sons. This book was released on 2013-01-25 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high temperature solid oxide fuel cell (SOFC) is identified as one of the leading fuel cell technology contenders to capture the energy market in years to come. However, in order to operate as an efficient energy generating system, the SOFC requires an appropriate control system which in turn requires a detailed modelling of process dynamics. Introducting state-of-the-art dynamic modelling, estimation, and control of SOFC systems, this book presents original modelling methods and brand new results as developed by the authors. With comprehensive coverage and bringing together many aspects of SOFC technology, it considers dynamic modelling through first-principles and data-based approaches, and considers all aspects of control, including modelling, system identification, state estimation, conventional and advanced control. Key features: Discusses both planar and tubular SOFC, and detailed and simplified dynamic modelling for SOFC Systematically describes single model and distributed models from cell level to system level Provides parameters for all models developed for easy reference and reproducing of the results All theories are illustrated through vivid fuel cell application examples, such as state-of-the-art unscented Kalman filter, model predictive control, and system identification techniques to SOFC systems The tutorial approach makes it perfect for learning the fundamentals of chemical engineering, system identification, state estimation and process control. It is suitable for graduate students in chemical, mechanical, power, and electrical engineering, especially those in process control, process systems engineering, control systems, or fuel cells. It will also aid researchers who need a reminder of the basics as well as an overview of current techniques in the dynamic modelling and control of SOFC.

Fundamentals of the Finite Element Method for Heat and Mass Transfer

Author : Perumal Nithiarasu
Publisher : John Wiley & Sons
ISBN 13 : 047075625X
Total Pages : 467 pages
Book Rating : 4.4/5 (77 download)

DOWNLOAD NOW!

Book Synopsis Fundamentals of the Finite Element Method for Heat and Mass Transfer by : Perumal Nithiarasu

Download or read book Fundamentals of the Finite Element Method for Heat and Mass Transfer written by Perumal Nithiarasu and published by John Wiley & Sons. This book was released on 2016-03-07 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of the Finite Element Method for Heat and Mass Transfer, Second Edition is a comprehensively updated new edition and is a unique book on the application of the finite element method to heat and mass transfer. • Addresses fundamentals, applications and computer implementation • Educational computer codes are freely available to download, modify and use • Includes a large number of worked examples and exercises • Fills the gap between learning and research

Advances in Synthesis Gas: Methods, Technologies and Applications

Author : Mohammad Reza Rahimpour
Publisher : Elsevier
ISBN 13 : 0323985211
Total Pages : 560 pages
Book Rating : 4.3/5 (239 download)

DOWNLOAD NOW!

Book Synopsis Advances in Synthesis Gas: Methods, Technologies and Applications by : Mohammad Reza Rahimpour

Download or read book Advances in Synthesis Gas: Methods, Technologies and Applications written by Mohammad Reza Rahimpour and published by Elsevier. This book was released on 2022-10-18 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Synthesis Gas: Methods, Technologies and Applications: Syngas Process Modelling and Apparatus Simulation consists of numerical modeling and simulation of different processes and apparatus for producing syngas, purifying it as well as synthesizing different chemical materials or generating heat and energy from syngas. These apparatus and processes include, but are not limited to, reforming, gasification, partial oxidation, swing technologies and membranes. - Introduces numerical modeling and the simulation of syngas production processes and apparatus - Describes numerical models and simulation procedures utilized for syngas purification processes and equipment - Discusses modelling and simulation of processes using syngas as a source for producing chemicals and power

Handbook of Thermal Management Systems

Author : Fethi Aloui
Publisher : Elsevier
ISBN 13 : 0443190186
Total Pages : 862 pages
Book Rating : 4.4/5 (431 download)

DOWNLOAD NOW!

Book Synopsis Handbook of Thermal Management Systems by : Fethi Aloui

Download or read book Handbook of Thermal Management Systems written by Fethi Aloui and published by Elsevier. This book was released on 2023-08-24 with total page 862 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Thermal Management Systems: e-Mobility and Other Energy Applications is a comprehensive reference on the thermal management of key renewable energy sources and other electronic components. With an emphasis on practical applications, the book addresses thermal management systems of batteries, fuel cells, solar panels, electric motors, as well as a range of other electronic devices that are crucial for the development of sustainable transport systems. Chapters provide a basic understanding of the thermodynamics behind the development of a thermal management system, update on Batteries, Fuel Cells, Solar Panels, and Other Electronics, provide a detailed description of components, and discuss fundamentals. Dedicated chapters then systematically examine the heating, cooling, and phase changes of each system, supported by numerical analyses, simulations and experimental data. These chapters include discussion of the latest technologies and methods and practical guidance on their application in real-world system-level projects, as well as case studies from engineering systems that are currently in operation. Finally, next-generation technologies and methods are discussed and considered. Presents a comprehensive overview of thermal management systems for modern electronic technologies related to energy production, storage and sustainable transportation Addresses the main bottlenecks in the technology development for future green and sustainable transportation systems Focuses on the practical aspects and implementation of thermal management systems through industrial case studies, real-world examples, and solutions to key problems

Fundamentals of Heat and Mass Transfer

Author : T. L. Bergman
Publisher : John Wiley & Sons
ISBN 13 : 0470501979
Total Pages : 2249 pages
Book Rating : 4.4/5 (75 download)

DOWNLOAD NOW!

Book Synopsis Fundamentals of Heat and Mass Transfer by : T. L. Bergman

Download or read book Fundamentals of Heat and Mass Transfer written by T. L. Bergman and published by John Wiley & Sons. This book was released on 2011-04-12 with total page 2249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Heat and Mass Transfer, 7th Edition is the gold standard of heat transfer pedagogy for more than 30 years, with a commitment to continuous improvement by four authors having more than 150 years of combined experience in heat transfer education, research and practice. Using a rigorous and systematic problem-solving methodology pioneered by this text, it is abundantly filled with examples and problems that reveal the richness and beauty of the discipline. This edition maintains its foundation in the four central learning objectives for students and also makes heat and mass transfer more approachable with an additional emphasis on the fundamental concepts, as well as highlighting the relevance of those ideas with exciting applications to the most critical issues of today and the coming decades: energy and the environment. An updated version of Interactive Heat Transfer (IHT) software makes it even easier to efficiently and accurately solve problems.

High-temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications

Author : S.C. Singhal
Publisher : Elsevier
ISBN 13 : 0080508081
Total Pages : 423 pages
Book Rating : 4.0/5 (85 download)

DOWNLOAD NOW!

Book Synopsis High-temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications by : S.C. Singhal

Download or read book High-temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications written by S.C. Singhal and published by Elsevier. This book was released on 2003-12-08 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications provides a comprehensive discussion of solid oxide fuel cells (SOFCs). SOFCs are the most efficient devices for the electrochemical conversion of chemical energy of hydrocarbon fuels into electricity, and have been gaining increasing attention for clean and efficient distributed power generation. The book explains the operating principle, cell component materials, cell and stack designs and fabrication processes, cell and stack performance, and applications of SOFCs. Individual chapters are written by internationally renowned authors in their respective fields, and the text is supplemented by a large number of references for further information. The book is primarily intended for use by researchers, engineers, and other technical people working in the field of SOFCs. Even though the technology is advancing at a very rapid pace, the information contained in most of the chapters is fundamental enough for the book to be useful even as a text for SOFC technology at the graduate level.

PEM Fuel Cells

Author : Gurbinder Kaur
Publisher : Elsevier
ISBN 13 : 0128237090
Total Pages : 584 pages
Book Rating : 4.1/5 (282 download)

DOWNLOAD NOW!

Book Synopsis PEM Fuel Cells by : Gurbinder Kaur

Download or read book PEM Fuel Cells written by Gurbinder Kaur and published by Elsevier. This book was released on 2021-11-16 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: PEM Fuel Cells: Fundamentals, Advanced Technologies, and Practical Application provides a comprehensive introduction to the principles of PEM fuel cell, their working condition and application, and the latest breakthroughs and challenges for fuel cell technology. Each chapter follows a systematic and consistent structure with clear illustrations and diagrams for easy understanding. The opening chapters address the basics of PEM technology; stacking and membrane electrode assembly for PEM, degradation mechanisms of electrocatalysts, platinum dissolution and redeposition, carbon-support corrosion, bipolar plates and carbon nanotubes for the PEM, and gas diffusion layers. Thermodynamics, operating conditions, and electrochemistry address fuel cell efficiency and the fundamental workings of the PEM. Instruments and techniques for testing and diagnosis are then presented alongside practical tests. Dedicated chapters explain how to use MATLAB and COMSOL to conduct simulation and modeling of catalysts, gas diffusion layers, assembly, and membrane. Degradation and failure modes are discussed in detail, providing strategies and protocols for mitigation. High-temperature PEMs are also examined, as are the fundamentals of EIS. Critically, the environmental impact and life cycle of the production and storage of hydrogen are addressed, as are the risk and durability issues of PEMFC technology. Dedicated chapters are presented on the economics and commercialization of PEMFCs, including discussion of installation costs, initial capital costs, and the regulatory frameworks; apart from this, there is a separate chapter on their application to the automotive industry. Finally, future challenges and applications are considered. PEM Fuel Cells: Fundamentals, Advanced Technologies, and Practical Application provides an in-depth and comprehensive reference on every aspect of PEM fuel cells fundamentals, ideal for researchers, graduates, and students. - Presents the fundamentals of PEM fuel cell technology, electrolytes, membranes, modeling, conductivity, recent trends, and future applications - Addresses commercialization, public policy, and the environmental impacts of PEMFC in dedicated chapters - Presents state-of-the-art PEMFC research alongside the underlying concepts

Modeling Solid Oxide Fuel Cells

Author : Roberto Bove
Publisher : Springer Science & Business Media
ISBN 13 : 1402069952
Total Pages : 405 pages
Book Rating : 4.4/5 (2 download)

DOWNLOAD NOW!

Book Synopsis Modeling Solid Oxide Fuel Cells by : Roberto Bove

Download or read book Modeling Solid Oxide Fuel Cells written by Roberto Bove and published by Springer Science & Business Media. This book was released on 2008-04-20 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book fills the need for a practical reference for all scientists and graduate students who are seeking to define a mathematical model for Solid Oxide Fuel Cell (SOFC) simulation. Structured in two parts, part one presents the basic theory, and the general equations describing SOFC operation phenomena. Part two deals with the application of the theory to practical examples, where different SOFC geometries, configurations, and different phenomena are analyzed in detail.

Water and Thermal Management of Proton Exchange Membrane Fuel Cells

Author : Kui Jiao
Publisher : Elsevier
ISBN 13 : 032391117X
Total Pages : 402 pages
Book Rating : 4.3/5 (239 download)

DOWNLOAD NOW!

Book Synopsis Water and Thermal Management of Proton Exchange Membrane Fuel Cells by : Kui Jiao

Download or read book Water and Thermal Management of Proton Exchange Membrane Fuel Cells written by Kui Jiao and published by Elsevier. This book was released on 2021-06-05 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water and Thermal Management of Proton Exchange Membrane Fuel Cells introduces the main research methods and latest advances in the water and thermal management of PEMFCs. The book introduces the transport mechanism of each component, including modeling methods at different scales, along with practical exercises. Topics include PEMFC fundamentals, working principles and transport mechanisms, characterization tests and diagnostic analysis, the simulation of multiphase transport and electrode kinetics, cell-scale modeling, stack-scale modeling, and system-scale modeling. This volume offers a practical handbook for researchers, students and engineers in the fields of proton exchange membrane fuel cells. Proton exchange membrane fuel cells (PEMFCs) are high-efficiency and low-emission electrochemical energy conversion devices. Inside the PEMFC complex, physical and chemical processes take place, such as electrochemical reaction, multiphase flow and heat transfer. This book explores these topics, and more. - Introduces the transport mechanism for each component of PEMFCs - Presents modeling methods at different scales, including component, cell, stack and system scales - Provides exercises in PEMFC modeling, along with examples of necessary codes - Covers the latest advances in PEMFCs in a convenient and structured manner - Offers a solution to researchers, students and engineers working on proton exchange membrane fuel cells

High-Temperature Solid Oxide Fuel Cells for the 21st Century

Author : Kevin Kendall
Publisher : Elsevier
ISBN 13 : 0124104835
Total Pages : 522 pages
Book Rating : 4.1/5 (241 download)

DOWNLOAD NOW!

Book Synopsis High-Temperature Solid Oxide Fuel Cells for the 21st Century by : Kevin Kendall

Download or read book High-Temperature Solid Oxide Fuel Cells for the 21st Century written by Kevin Kendall and published by Elsevier. This book was released on 2015-11-21 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-temperature Solid Oxide Fuel Cells, Second Edition, explores the growing interest in fuel cells as a sustainable source of energy. The text brings the topic of green energy front and center, illustrating the need for new books that provide comprehensive and practical information on specific types of fuel cells and their applications. This landmark volume on solid oxide fuel cells contains contributions from experts of international repute, and provides a single source of the latest knowledge on this topic. - A single source for all the latest information on solid oxide fuel cells and their applications - Illustrates the need for new, more comprehensive books and study on the topic - Explores the growing interest in fuel cells as viable, sustainable sources of energy

Fuel Cells and Hydrogen

Author : Viktor Hacker
Publisher : Elsevier
ISBN 13 : 0128115378
Total Pages : 298 pages
Book Rating : 4.1/5 (281 download)

DOWNLOAD NOW!

Book Synopsis Fuel Cells and Hydrogen by : Viktor Hacker

Download or read book Fuel Cells and Hydrogen written by Viktor Hacker and published by Elsevier. This book was released on 2018-07-20 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel Cells and Hydrogen: From Fundamentals to Applied Research provides an overview of the basic principles of fuel cell and hydrogen technology, which subsequently allows the reader to delve more deeply into applied research. In addition to covering the basic principles of fuel cells and hydrogen technologies, the book examines the principles and methods to develop and test fuel cells, the evaluation of the performance and lifetime of fuel cells and the concepts of hydrogen production. Fuel Cells and Hydrogen: From Fundamentals to Applied Research acts as an invaluable reference book for fuel cell developers and students, researchers in industry entering the area of fuel cells and lecturers teaching fuel cells and hydrogen technology. - Includes laboratory methods for fuel cell characterization and manufacture - Outlines approaches in modelling components, cells and stacks - Covers practical and theoretical methods for hydrogen production and storage

Fuel Cell Engineering

Author :
Publisher : Academic Press
ISBN 13 : 0123868750
Total Pages : 481 pages
Book Rating : 4.1/5 (238 download)

DOWNLOAD NOW!

Book Synopsis Fuel Cell Engineering by :

Download or read book Fuel Cell Engineering written by and published by Academic Press. This book was released on 2012-08-14 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel cells are attractive electrochemical energy converters featuring potentially very high thermodynamic efficiency factors. The focus of this volume of Advances in Chemical Engineering is on quantitative approaches, particularly based on chemical engineering principles, to analyze, control and optimize the steady state and dynamic behavior of low and high temperature fuel cells (PEMFC, DMFC, SOFC) to be applied in mobile and stationary systems. - Updates and informs the reader on the latest research findings using original reviews - Written by leading industry experts and scholars - Reviews and analyzes developments in the field

Fundamentals of Convective Heat Transfer

Author : Gautam Biswas
Publisher : CRC Press
ISBN 13 : 0429583796
Total Pages : 331 pages
Book Rating : 4.4/5 (295 download)

DOWNLOAD NOW!

Book Synopsis Fundamentals of Convective Heat Transfer by : Gautam Biswas

Download or read book Fundamentals of Convective Heat Transfer written by Gautam Biswas and published by CRC Press. This book was released on 2019-07-15 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal convection is often encountered by scientists and engineers while designing or analyzing flows involving exchange of energy. Fundamentals of Convective Heat Transfer is a unified text that captures the physical insight into convective heat transfer and thorough, analytical, and numerical treatments. It also focuses on the latest developments in the theory of convective energy and mass transport. Aimed at graduates, senior undergraduates, and engineers involved in research and development activities, the book provides new material on boiling, including nuances of physical processes. In all the derivations, step-by-step and systematic approaches have been followed.

Fundamentals Of Heat Transfer

Author : Dr. D Sendil Kumar
Publisher : Academic Guru Publishing House
ISBN 13 : 8197261563
Total Pages : 211 pages
Book Rating : 4.1/5 (972 download)

DOWNLOAD NOW!

Book Synopsis Fundamentals Of Heat Transfer by : Dr. D Sendil Kumar

Download or read book Fundamentals Of Heat Transfer written by Dr. D Sendil Kumar and published by Academic Guru Publishing House. This book was released on 2024-04-13 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this comprehensive "Fundamentals of Heat Transfer," readers explore the intriguing world of thermal energy transformation. The book guides readers through heat exchange's difficulties from fundamentals to applications. Our voyage focuses on the complex dance of molecules and energy that transfers heat from high to low temperatures. Readers learn about conduction, convection, and radiation—the three pillars of heat transfer—through clear explanations and illustrations. From heat conduction through solids to fluid convection currents, each idea is explained to reveal its fundamentals. As the voyage proceeds, readers are provided with the tools they need to traverse the landscape of heat transfer analysis and design. Mathematical models elucidate heat conduction routes, while practical insights help optimize heat exchangers and thermal systems. With each page flip, readers get a better grasp of how to analyses, forecast, and manage thermal processes with accuracy and efficiency. However, the exploration does not occur in isolation. Recognizing the multidisciplinary character of heat transfer, the book broadens its scope to include fields such as fluid mechanics, thermodynamics, and materials science. By making links between these disciplines, readers get a comprehensive grasp of how heat transfer interacts with and impacts many domains of engineering and science.

Foundations of Heat Transfer

Author : Dorin Vasilescu
Publisher :
ISBN 13 : 9781681171203
Total Pages : 0 pages
Book Rating : 4.1/5 (712 download)

DOWNLOAD NOW!

Book Synopsis Foundations of Heat Transfer by : Dorin Vasilescu

Download or read book Foundations of Heat Transfer written by Dorin Vasilescu and published by . This book was released on 2015-08 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat may be defined as the transfer of thermal energy across a well-defined boundary around a thermodynamic system. The thermodynamic free energy is the amount of work that a thermodynamic system can perform. Enthalpy is a thermodynamic potential that is the sum of the internal energy of the system plus the product of pressure and volume. Heat transfer is the exchange of thermal energy between physical systems, depending on the temperature and pressure, by dissipating heat. The fundamental modes of heat transfer are conduction or diffusion, convection and radiation. Heat transfer always occurs from a region of high temperature to another region of lower temperature. In the simplest of terms, the discipline of heat transfer is concerned with only two things: temperature, and the flow of heat. Temperature represents the amount of thermal energy available, whereas heat flow represents the movement of thermal energy from place to place. Heat transfer is a process function, as opposed to functions of state; therefore, the amount of heat transferred in a thermodynamic process that changes the state of a system depends on how that process occurs, not only the net difference between the initial and final states of the process. Several material properties serve to modulate the heat transferred between two regions at differing temperatures. Examples include thermal conductivities, specific heats, material densities, fluid velocities, fluid viscosities, surface emissivities, and more. Taken together, these properties serve to make the solution of many heat transfer problems an involved process. Foundations of Heat Transfer focuses on the basic modes of heat transfer.