Janna - Engineering Heat Transfer

ENGINEERING
HEAT TRANSFER

Third Edition

HEAT TRANSFER

A Series of Reference Books and Textbooks

SERIES EDITOR

Afshin J. Ghajar

Regents Professor

School of Mechanical and Aerospace Engineering

Oklahoma State University

Engineering Heat Transfer: Third Edition, William S. Janna

Upcoming titles include:

Conjugate Problems in Convective Heat Transfer, Abram S. Dorfman

Introduction to Thermal and Fluid Engineering, Allan D. Kraus, James R. Welty, Abdul Aziz

ENGINEERING HEAT TRANSFER

Third Edition

WILLIAM S. JANNA

CRC Press

Taylor & Francis Group

6000 Broken Sound Parkway NW, Suite 300

Boca Raton, FL 33487-2742

2009 by Taylor & Francis Group, LLC

CRC Press is an imprint of Taylor & Francis Group, an Informa business

No claim to original U.S. Government works

International Standard Book Number-13: 978-1-4200-7202-0 (Hardcover)

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Library of Congress Cataloging-in-Publication Data

Janna, William S.

Engineering heat transfer/ William S. Janna. -- 3rd ed.

p. cm. -- (Heat transfer)

Includes bibliographical references and index.

ISBN 978-1-4200-7202-0 (alk. paper)

1. Heat--Transmission. 2. Heat exchangers. I. Title. II. Series.

TJ260.J36 2008

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Dedication

To Him who is our source of love and knowledge

To Marla who transforms His love into strength

And to the reader for whom knowledge becomes wisdom

Contents

The philosophy of Engineering Heat Transfer is the same as it was when the book was first writtento write a readable, user-friendly book that provides many practical examples, without overwhelming the student. Many students think in concrete terms using pictures to envision what is being discussed. Thus drawings, sketches, graphs, etc., are used extensively in this book to enhance the learning process. Thinking in concrete terms is especially helpful in an area, such as heat transfer, which is highly abstract.

Every effort was made to provide many examples and a large number of confidence-building problems. The examples amplify the theory and show how the derived equations are used to model physical problems. Confidence-building problems are relatively simple and to some extent follow the examples. When a few of these types of problems are solved, the student will hopefully feel comfortable with the information and can then apply it with confidence to situations that are not obvious, and that increase in complexity. Problem solving is a skill that must be developed slowly, methodically, and thoroughly. The emphasis is on problems that are practical in nature. Applications of the material make this book interesting.

The new direction in engineering education is the implementation of design throughout the curriculum. In addition, the design experience is meant to culminate in capstone courses, such as design of fluid thermal systems or mechanical design. Such necessary courses are taught at the senior leveleither first or second semester. Moreover, these capstone design courses require knowledge of certain prerequisites such as fluid mechanics and heat transfer. In many curricula, heat transfer is taught at the junior or first semester-senior level. Rather than being a course in itself, it is now a backbone course for a senior design experience that is supposed to put it all together. So the emphasis in this book is on problem-solving skills with real world examples. The niche that this book fills is that of a book written with practical applications in mind that can fit into the overall design experience. The time is right to move forward and keep pace with what is occurring in engineering education.

Text Modifications

The previous editions of this book had derivations of the NavierStokes equations in three coordinate systems. They also contained the derivations of the boundary layer equations, integral methods of solution, etc. As such, they were aimed originally at the senior mechanical engineering student who wanted to go to graduate school. The integral method for solution of the boundary layer equations, although interesting and clever, does not help a senior-level student learn how to design anything. Therefore, the current edition has been modified to make it better suited for an emerging place in the mechanical engineering curriculum. The objective here is to produce a revised book for a new market.

discusses one-dimensional conduction. Heat flow through walls, cylinders, and fins are all considered.

discusses steady-state conduction in multiple dimensions. The analytical method of solution applied to a simple problem is presented to illustrate the mathematical complexity of such problems. Next, alternative solution methods, including graphical and numerical methods, are presented. Much of the material in the first three chapters has been reorganized.

discusses unsteady-state heat conduction, and it contains the lumped capacitance method as well as Heisler charts for more complex problems. Heisler charts have been modified to make them easier to read in the regions where the Fourier number is very small.

provides an introduction to convection. A discussion of basic fluid mechanics is given, which serves as an overview of the convection chapters that follow. The NavierStokes equations are presented but not derived. The thermal energy equation is derived; however, the equations are used to solve problems in laminar flow for which there are exact solutions.