Theodore L. Bergman, Adrienne S. Lavine, Frank P. Incropera, David P. DeWitt Fundamentals of Heat and Mass Transfer 2011

Theodore L. Bergman, Adrienne S. Lavine, Frank P. Incropera, David P. DeWitt...

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Fundamentals of Heat and Mass Transfer

Department of Mechanical Engineering University of Connecticut

Mechanical and Aerospace Engineering Department University of California, Los Angeles

College of Engineering University of Notre Dame

School of Mechanical Engineering Purdue University

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Preface

In the Preface to the previous edition, we posed questions regarding trends in engineering education and practice, and whether the discipline of heat transfer would remain relevant. After weighing various arguments, we concluded that the future of engineering was bright and that heat transfer would remain a vital and enabling discipline across a range of emerging technologies including but not limited to information technology, biotechnology, pharmacology, and alternative energy generation.

Since we drew these conclusions, many changes have occurred in both engineering education and engineering practice. Driving factors have been a contracting global economy, coupled with technological and environmental challenges associated with energy production and energy conversion. The impact of a weak global economy on higher education has been sobering. Colleges and universities around the world are being forced to set priorities and answer tough questions as to which educational programs are crucial, and which are not. Was our previous assessment of the future of engineering, including the relevance of heat transfer, too optimistic?

Faced with economic realities, many colleges and universities have set clear priorities.

In recognition of its value and relevance to society, investment in engineering education has, in many cases, increased.Pedagogically, there is renewed emphasis on the fundamental principles that are the foundation for lifelong learning. The important and sometimes dominant role of heat transfer in many applications, particularly in conventional as well as in alternative energy generation and concomitant environmental effects, has reaffirmed its relevance. We believe our previous conclusions were correct: The future of engineering is bright, and heat transfer is a topic that is crucial to address a broad array of technological and environmental challenges.

In preparing this edition, we have sought to incorporate recent heat transfer research at a level that is appropriate for an undergraduate student. We have strived to include new examples and problems that motivate students with interesting applications, but whose solutions are based firmly on fundamental principles. We have remained true to the pedagogical approach of previous editions by retaining a rigorous and systematic methodology for problem solving. We have attempted to continue the tradition of providing a text that will serve as a valuable, everyday resource for students and practicing engineers throughout their careers.

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Approach and Organization

Previous editions of the text have adhered to four learning objectives:

1.The student should internalize the meaning of the terminology and physical principles associated with heat transfer.

2.The student should be able to delineate pertinent transport phenomena for any process or system involving heat transfer.

3.The student should be able to use requisite inputs for computing heat transfer rates and/or material temperatures.

4.The student should be able to develop representative models of real processes and systems and draw conclusions concerning process/system design or performance from the attendant analysis.

Moreover, as in previous editions, specific learning objectives for each chapter are clarified, as are means by which achievement of the objectives may be assessed. The summary of each chapter highlights key terminology and concepts developed in the chapter and poses questions designed to test and enhance student comprehension.

It is recommended that problems involving complex models and/or exploratory, whatif, and parameter sensitivity considerations be addressed using a computational equationsolving package. To this end, the Interactive Heat Transfer(IHT) package available in previous editions has been updated. Specifically, a simplified user interface now delineates between the basic and advanced features of the software. It has been our experience that most students and instructors will use primarily the basic features of IHT. By clearly identifying which features are advanced, we believe students will be motivated to use IHTon a daily basis. A second software package, Finite Element Heat Transfer(FEHT), developed by F-Chart Software (Madison, Wisconsin), provides enhanced capabilities for solving two-dimensional conduction heat transfer problems.

To encourage use of IHT, a Quickstart User s Guidehas been installed in the software. Students and instructors can become familiar with the basic features of IHTin approximately one hour. It has been our experience that once students have read the Quickstart guide, they will use IHTheavily, even in courses other than heat transfer. Students report that IHTsignificantly reduces the time spent on the mechanics of lengthy problem solutions, reduces errors, and allows more attention to be paid to substantive aspects of the solution. Graphical output can be generated for homework solutions, reports, and papers.

As in previous editions, some homework problems require a computer-based solution.

Other problems include both a hand calculation and an extension that is computer based. The latter approach is time-tested and promotes the habit of checking a computer-generated solution with a hand calculation. Once validated in this manner, the computer solution can be utilized to conduct parametric calculations. Problems involving both hand- and computer-generated solutions are identified by enclosing the exploratory part in a red rectangle, as, for example,(b), (c), or(d).This feature also allows instructors who wish to limit their assignments of computer-based problems to benefit from the richness of these problems without assigning their computer-based parts. Solutions to problems for which the number is highlighted (for example,1.26) are entirely computer based.

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What’s New in the 7th Edition

Chapter-by-Chapter Content ChangesIn the previous edition, Chapter 1 Introduction was modified to emphasize the relevance of heat transfer in various contemporary applications. Responding to today’s challenges involving energy production and its environmental impact, an expanded discussion of the efficiency of energy conversion and the production of greenhouse gases has been added. Chapter 1 has also been modified to embellish the complementary nature of heat transfer and thermodynamics. The existing treatment of the first law of thermodynamics is augmented with a new section on the relationship between heat transfer and the second law of thermodynamics as well as the efficiency of heat engines. Indeed, the influence of heat transfer on the efficiency of energy conversion is a recurring theme throughout this edition.

The coverage of micro- and nanoscale effects in Chapter 2 Introduction to Conductionhas been updated, reflecting recent advances. For example, the description of the thermophysical properties of composite materials is enhanced, with a new discussion of nanofluids. Chapter 3 One-Dimensional, Steady-State Conduction has undergone extensive revision and includes new material on conduction in porous media, thermoelectric power generation, and micro- as well as nanoscale systems. Inclusion of these new topics follows recent fundamental discoveries and is presented through the use of the thermal resistance network concept. Hence the power and utility of the resistance network approach is further emphasized in this edition.

Chapter 4Two-Dimensional, Steady-State Conductionhas been reduced in length.

Today, systems of linear, algebraic equations are readily solved using standard computer software or even handheld calculators. Hence the focus of the shortened chapter is on the application of heat transfer principles to derive the systems of algebraic equations to be solved and on the discussion and interpretation of results. The discussion of Gauss–Seidel iteration has been moved to an appendix for instructors wishing to cover that material.

Chapter 5 Transient Conductionwas substantially modified in the previous edition and has been augmented in this edition with a streamlined presentation of the lumpedcapacitance method.

Chapter 6 Introduction to Convectionincludes clarification of how temperature-dependent properties should be evaluated when calculating the convection heat transfer coefficient. The fundamental aspects of compressible flow are introduced to provide the reader with guidelines regarding the limits of applicability of the treatment of convection in the text.

Chapter 7 External Flow has been updated and reduced in length. Specifically, presentation of the similarity solution for flow over a flat plate has been simplified. New results for flow over noncircular cylinders have been added, replacing the correlations of previous editions. The discussion of flow across banks of tubes has been shortened, eliminating redundancy without sacrificing content.

Chapter 8 Internal Flowentry length correlations have been updated, and the discussion of micro- and nanoscale convection has been modified and linked to the content of Chapter 3.

Changes toChapter 9 Free Convectioninclude a new correlation for free convection from flat plates, replacing a correlation from previous editions. The discussion of boundary layer effects has been modified.

Aspects of condensation included in Chapter 10 Boiling and Condensation havebeen updated to incorporate recent advances in, for example, external condensation on finned tubes. The effects of surface tension and the presence of noncondensable gases in modifying

Preface v FMPreface.qxd 2/21/1 6:1 PM Page v condensation phenomena and heat transfer rates are elucidated. The coverage of forced convection condensation and related enhancement techniques has been expanded, again reflecting advances reported in the recent literature.

The content of Chapter 1 Heat Exchangers is experiencing a resurgence in interest due to the critical role such devices play in conventional and alternative energy generation technologies. A new section illustrates the applicability of heat exchanger analysis to heat sink design and materials processing. Much of the coverage of compact heat exchangers included in the previous edition was limited to a specific heat exchanger. Although general coverage of compact heat exchangers has been retained, the discussion that is limited to the specific heat exchanger has been relegated to supplemental material, where it is available to instructors who wish to cover this topic in greater depth.

The concepts of emissive power, irradiation, radiosity, and net radiative flux are now introduced early in Chapter 12 Radiation: Processes and Properties, allowing early assignment of end-of-chapter problems dealing with surface energy balances and properties, as well as radiation detection. The coverage of environmental radiation has undergone substantial revision, with the inclusion of separate discussions of solar radiation, the atmospheric radiation balance, and terrestrial solar irradiation. Concern for the potential impact of anthropogenic activity on the temperature of the earth is addressed and related to the concepts of the chapter.

Much of the modification to Chapter 13 Radiation Exchange Between Surfacesemphasizes the difference between geometrical surfaces and radiative surfaces, a key concept that is often difficult for students to appreciate. Increased coverage of radiation exchange between multiple blackbody surfaces, included in older editions of the text, has been returned to Chapter 13. In doing so, radiation exchange between differentially small surfaces is briefly introduced and used to illustrate the limitations of the analysis techniques included in Chapter 13.

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