Process Heat Transfer

Dedication

This book is dedicated to C.C.S.

Process Heat TransferPrinciples and Applications

R.W. Serth

Department of Chemical and Natural Gas Engineering,Texas A&M University-Kingsville,Kingsville, Texas, USA

AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD

PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO

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British Library Cataloguing in Publication Data

Serth, R. W.Process heat transfer : principles and applications1. Heat - Transmission 2. Heat exchangers 3. Heat exchangers - Design4. Heat - Transmission - Computer programsI. Title621.4022

Library of Congress Catalog number: 2006940583

ISBN: 978-0-12-373588-1

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Typeset by Charon Tec Ltd (A Macmillan Company), Chennai, Indiawww.charontec.comPrinted and bound in USA

06 07 08 09 10 11 10 9 8 7 6 5 4 3 2 1

Contents

Preface viiiConversion Factors xPhysical Constants xiAcknowledgements xii

1 Heat Conduction 11.1 Introduction 21.2 Fouriers Law of Heat Conduction 21.3 The Heat Conduction Equation 61.4 Thermal Resistance 151.5 The Conduction Shape Factor 191.6 Unsteady-State Conduction 241.7 Mechanisms of Heat Conduction 31

2 Convective Heat Transfer 432.1 Introduction 442.2 Combined Conduction and Convection 442.3 Extended Surfaces 472.4 Forced Convection in Pipes and Ducts 532.5 Forced Convection in External Flow 622.6 Free Convection 65

3 Heat Exchangers 853.1 Introduction 863.2 Double-Pipe Equipment 863.3 Shell-and-Tube Equipment 873.4 The Overall Heat-Transfer Coefficient 933.5 The LMTD Correction Factor 983.6 Analysis of Double-Pipe Exchangers 1023.7 Preliminary Design of Shell-and-Tube Exchangers 1063.8 Rating a Shell-and-Tube Exchanger 1093.9 Heat-Exchanger Effectiveness 114

4 Design of Double-Pipe Heat Exchangers 1274.1 Introduction 1284.2 Heat-Transfer Coefficients for Exchangers without Fins 1284.3 Hydraulic Calculations for Exchangers without Fins 1284.4 Series/Parallel Configurations of Hairpins 1314.5 Multi-tube Exchangers 1324.6 Over-Surface and Over-Design 1334.7 Finned-Pipe Exchangers 1414.8 Heat-Transfer Coefficients and Friction Factors for Finned Annuli 1434.9 Wall Temperature for Finned Pipes 1454.10 Computer Software 152

vi C O NT E NT S

5 Design of Shell-and-Tube Heat Exchangers 1875.1 Introduction 1885.2 Heat-Transfer Coefficients 1885.3 Hydraulic Calculations 1895.4 Finned Tubing 1925.5 Tube-Count Tables 1945.6 Factors Affecting Pressure Drop 1955.7 Design Guidelines 1975.8 Design Strategy 2015.9 Computer software 218

6 The Delaware Method 2456.1 Introduction 2466.2 Ideal Tube Bank Correlations 2466.3 Shell-Side Heat-Transfer Coefficient 2486.4 Shell-Side Pressure Drop 2506.5 The Flow Areas 2546.6 Correlations for the Correction Factors 2596.7 Estimation of Clearances 260

7 The Stream Analysis Method 2777.1 Introduction 2787.2 The Equivalent Hydraulic Network 2787.3 The Hydraulic Equations 2797.4 Shell-Side Pressure Drop 2817.5 Shell-Side Heat-Transfer Coefficient 2817.6 Temperature Profile Distortion 2827.7 The WillsJohnston Method 2847.8 Computer Software 295

8 Heat-Exchanger Networks 3278.1 Introduction 3288.2 An Example: TC3 3288.3 Design Targets 3298.4 The Problem Table 3298.5 Composite Curves 3318.6 The Grand Composite Curve 3348.7 Significance of the Pinch 3358.8 Threshold Problems and Utility Pinches 3378.9 Feasibility Criteria at the Pinch 3378.10 Design Strategy 3398.11 Minimum-Utility Design for TC3 3408.12 Network Simplification 3448.13 Number of Shells 3478.14 Targeting for Number of Shells 3488.15 Area Targets 3538.16 The Driving Force Plot 3568.17 Super Targeting 3588.18 Targeting by Linear Programming 3598.19 Computer Software 361

C O NT E NT S vii

9 Boiling Heat Transfer 3859.1 Introduction 3869.2 Pool Boiling 3869.3 Correlations for Nucleate Boiling on Horizontal Tubes 3879.4 Two-Phase Flow 4029.5 Convective Boiling in Tubes 4169.6 Film Boiling 428

10 Reboilers 44310.1 Introduction 44410.2 Types of Reboilers 44410.3 Design of Kettle Reboilers 44910.4 Design of Horizontal Thermosyphon Reboilers 46710.5 Design of Vertical Thermosyphon Reboilers 47310.6 Computer Software 488

11 Condensers 53911.1 Introduction 54011.2 Types of Condensers 54011.3 Condensation on a Vertical Surface: Nusselt Theory 54511.4 Condensation on Horizontal Tubes 54911.5 Modifications of Nusselt Theory 55211.6 Condensation Inside Horizontal Tubes 56211.7 Condensation on Finned Tubes 56811.8 Pressure Drop 56911.9 Mean Temperature Difference 57111.10 Multi-component Condensation 59011.11 Computer Software 595

12 Air-Cooled Heat Exchangers 62912.1 Introduction 63012.2 Equipment Description 63012.3 Air-Side Heat-Transfer Coefficient 63712.4 Air-Side Pressure Drop 63812.5 Overall Heat-Transfer Coefficient 64012.6 Fan and Motor Sizing 64012.7 Mean Temperature Difference 64312.8 Design Guidelines 64312.9 Design Strategy 64412.10 Computer Software 653

Appendix 681Appendix A Thermophysical Properties of Materials 682Appendix B Dimensions of Pipe and Tubing 717Appendix C Tube-Count Tables 729Appendix D Equivalent Lengths of Pipe Fittings 737Appendix E Properties of Petroleum Streams 740

Index 743

Preface

This book is based on a course in process heat transfer that I have taught for many years. The coursehas been taken by seniors and first-year graduate students who have completed an introductorycourse in engineering heat transfer. Although this background is assumed, nearly all students needsome review before proceeding to more advanced material. For this reason, and also to make thebook self-contained, the first three chapters provide a review of essential material normally coveredin an introductory heat transfer course. Furthermore, the book is intended for use by practicingengineers as well as university students, and it has been written with the aim of facilitating self-study.

Unlike some books in this field, no attempt is made herein to cover the entire panoply of heat trans-fer equipment. Instead, the book focuses on the types of equipment most widely used in the chemicalprocess industries, namely, shell-and-tube heat exchangers (including condensers and reboilers),air-cooled heat exchangers and double-pipe (hairpin) heat exchangers. Within the confines of a sin-gle volume, this approach allows an in-depth treatment of the material that is most relevant from anindustrial perspective, and provides students with the detailed knowledge needed for engineeringpractice. This approach is also consistent with the time available in a one-semester course.

Design of double-pipe exchangers is presented in Chapter 4. Chapters 57 comprise a unit dealingwith shell-and-tube exchangers in operations involving single-phase fluids. Design of shell-and-tubeexchangers is covered in Chapter 5 using the Simplified Delaware method for shell-side calcula-tions. For pedagogical reasons, more sophisticated methods for performing shell-side heat-transferand pressure-drop calculations are presented separately in Chapter 6 (full Delaware method) andChapter 7 (Stream Analysis method). Heat exchanger networks are covered in Chapter 8. I nor-mally present this topic at this point in the course to provide a change of pace. However, Chapter8 is essentially self-contained and can, therefore, be covered at any time. Phase-change operationsare covered in Chapters 911. Chapter 9 presents the basics of boiling heat transfer and two-phaseflow. The latter is encountered in both Chapter 10, which deals with the design of reboilers, andChapter 11, which covers condensation and condenser design. Design of air-cooled heat exchang-ers is presented in Chapter 12. The material in this chapter is essentially self-contained and, hence,it can be covered at any time.

Since the primary goal of both the book and the course is to provide students with the knowl-edge and skills needed for modern industrial practice, computer applications play an integral role,and the book is intended for use with one or more commercial software packages. HEXTRAN(SimSci-Esscor), HTRI Xchanger Suite (Heat Transfer Research, Inc.) and the HTFS Suite (AspenTechnology, Inc.) are used in the book, along with HX-Net (Aspen Technology, Inc.) for pinchcalculations. HEXTRAN affords the most complete coverage of topics, as it handles all types of heatexchangers and also