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Thermal Energy Systems Design and Analysis Second Edition http://taylorandfrancis.com Thermal Energy Systems Design and Analysis Second Edition Steven G. Penoncello Professor Emeritus University of Idaho Moscow, Idaho, USA CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2019 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 Printed on acid-free paper International Standard Book Number-13: 978-1-138-73589-7 (Hardback) International Standard Book Number-13: 978-1-315-18626-9 (eBook) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materi- als or the consequences of their use. 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CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identifi- cation and explanation without intent to infringe. Library of Congress Cataloging in Publication Data Names: Penoncello, S. G. (Steven G.), author. Title: Thermal energy systems : design and analysis / Steven G. Penoncello. Description: Second edition. | Boca Raton : Taylor & Francis, CRC Press, 2018. | Includes bibliographical references and index. Identifiers: LCCN 2018014278| ISBN 9781138735897 (hardback : alk. paper) | ISBN 9781315186269 (e-book) Subjects: LCSH: Heat engineering. | Heat--Transmission. | Thermodynamics--Data processing. Classification: LCC TJ260 .P38 2018 | DDC 621.402--dc23 LC record available at https://lccn.loc.gov/2018014278 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents Preface to the Second Edition ....................................................................................................xiii Acknowledgments .....................................................................................................................xvii Author ...........................................................................................................................................xix 1. Introduction .............................................................................................................................1 1.1 Thermal Energy Systems Design and Analysis .......................................................1 1.2 Software ..........................................................................................................................2 1.2.1 Engineering Equation Solver (EES) ...............................................................2 1.2.2 REFPROP ...........................................................................................................2 1.2.3 CoolProp ...........................................................................................................3 1.2.4 User-Written Libraries .....................................................................................3 1.2.5 Software Approach Taken in This Book.......................................................3 1.3 Thermal Energy System Topics ...................................................................................3 1.4 Units and Unit Systems ................................................................................................4 1.5 Properties of Working Fluids in Thermal Energy Systems ....................................6 1.5.1 Thermodynamic Properties ...........................................................................7 1.5.1.1 Thermodynamic Properties in the Two-Phase Region ...............8 1.5.1.2 Important Thermodynamic Property Relationships ..................9 1.5.2 Evaluation of Thermodynamic Properties .................................................10 1.5.2.1 The Real Fluid Model ....................................................................10 1.5.2.2 The Incompressible Substance Model .........................................11 1.5.2.3 Estimation of Liquid Properties ...................................................13 1.5.2.4 The Ideal Gas Model ......................................................................16 1.5.3 Transport Properties ......................................................................................22 1.5.3.1 Dynamic Viscosity .........................................................................22 1.5.3.2 Kinematic Viscosity .......................................................................23 1.5.3.3 Newtonian and Non-Newtonian Fluids .....................................24 1.5.3.4 Thermal Conductivity ...................................................................25 1.6 Engineering Design and Analysis ............................................................................26 1.6.1 Workable Designs ..........................................................................................27 1.6.2 Optimum Designs .........................................................................................29 1.6.3 Engineering Design and Environmental Impact ......................................30 References ...............................................................................................................................31 Problems ..................................................................................................................................31 2. Engineering Economics .......................................................................................................41 2.1 Introduction .................................................................................................................41 2.2 Engineering Economics Nomenclature ...................................................................41 2.3 The Cash Flow Diagram ............................................................................................42 2.4 The Time Value of Money ..........................................................................................43 2.4.1 Future Value of a Present Sum: The Single Payment Compound Amount Factor ................................................................................................44 2.4.2 Present Value of a Future Sum: The Present Worth Factor ......................46 2.4.3 Future Value of a Uniform Series: The Compound Amount Factor.......46 v vi Contents 2.4.4 An Equivalent Uniform Series That Represents a Future Value: The Uniform Series Sinking Fund Factor ...................................................48 2.4.5 Present Value of a Uniform Series: The Uniform Series Present Worth Factor ...................................................................................................48 2.4.6 An Equivalent Uniform Series That Represents a Present Value: The Capital Recovery Factor.........................................................................49 2.4.7 Present Value of a Uniform Linearly Increasing Series—The Gradient Present Worth Factor ..............................................49 2.4.8 Summary of Interest Factors ........................................................................50 2.5 Nominal and Effective Interest Rates ......................................................................51 2.6 Time Value of Money Examples ................................................................................51 2.7 Using Software to Calculate Interest Factors ..........................................................55 2.8 Economic Decision Making .......................................................................................56 2.8.1 Present Worth Analysis ................................................................................57 2.8.2 Annual Cost Analysis ...................................................................................61 2.8.3 Selection of Alternatives ...............................................................................64 2.9 Depreciation and Taxes ..............................................................................................64 2.9.1 After-Tax Cash Flow ......................................................................................64 2.9.2 Straight-Line Depreciation (SLD).................................................................65 2.9.3 Sum of the Years’ Digits (SYD) .....................................................................65 Reference .................................................................................................................................70 Problems ..................................................................................................................................70 3. Analysis of Thermal Energy Systems ..............................................................................79 3.1 Introduction .................................................................................................................79 3.2 Nomenclature ..............................................................................................................79 3.3 Analysis Procedure .....................................................................................................80 3.4 Conserved and Balanced Quantities ........................................................................81 3.4.1 The Generalized Balance Law .....................................................................81 3.5 Conservation of Mass .................................................................................................82 3.6 Conservation of Energy .............................................................................................86 3.7 The Entropy Balance (The Second Law of Thermodynamics) .............................94 3.7.1 The Reversible and Adiabatic Process ........................................................96 3.7.2 Isentropic Efficiencies of Flow Devices.......................................................97 3.7.2.1 Turbines ...........................................................................................97 3.7.2.2 Compressors, Pumps, and Fans ...................................................98 3.7.2.3 Nozzles.............................................................................................99 3.7.2.4 Diffusers ........................................................................................100 3.7.3 Heat Exchanger Effectiveness ....................................................................103 3.7.3.1 Effectiveness of a Counter Flow Heat Exchanger ....................109 3.7.3.2 Effectiveness of a Parallel Flow Heat Exchanger .....................113 3.7.3.3 Significance of the Pinch Point Temperature Difference and Effectiveness ..........................................................................115 3.8 The Exergy Balance—The Combined Law ............................................................116 3.8.1 What Is Exergy? ...........................................................................................117 3.8.1.1 The Thermodynamic Definition of Exergy ..............................118 3.8.2 The Exergy Balance .....................................................................................118 3.8.3 Exergy Accounting and Exergy Flow Diagrams .....................................122 Contents vii 3.8.4 Exergetic Efficiencies of Flow Devices ......................................................123 3.8.4.1 Turbines .........................................................................................123 3.8.4.2 Compressors, Pumps, and Fans .................................................123 3.8.4.3 Heat Exchangers ...........................................................................123 3.9 Energy and Exergy Analysis of Thermal Energy Cycles ....................................126 3.9.1 Cycle Energy Performance Parameters ....................................................127 3.9.1.1 Maximum Thermal Efficiency of a Cycle .................................129 3.9.2 Exergetic Cycle Efficiency ...........................................................................132 3.9.2.1 Power Cycles .................................................................................132 3.9.2.2 Refrigeration and Heat Pump Cycles ........................................134 3.9.2.3 Significance of the Exergetic Cycle Efficiency ..........................135 3.9.2.4 The Energy/Exergy Conundrum ...............................................136 3.10 Analysis of Thermal Energy Systems ....................................................................137 3.10.1 Analysis of an Engine and Radiator System ............................................138 3.10.2 Analysis of a Brine Chilling System for Ice Rink Manufacture ............143 3.10.3 Analysis of a Gas Turbine System for Power Delivery ...........................149 References .............................................................................................................................157 Problems ................................................................................................................................157 4. Fluid Transport in Thermal Energy Systems ...............................................................175 4.1 Introduction ...............................................................................................................175 4.2 Piping and Tubing Standards ..................................................................................175 4.3 Fluid Flow Fundamentals ........................................................................................177 4.3.1 Head Loss due to Friction in Pipes and Tubes ........................................179 4.4 Valves and Fittings ....................................................................................................190 4.4.1 The Hooper 2K Method ..............................................................................192 4.4.2 The Darby 3K Method .................................................................................195 4.4.3 Reducers and Expansions ...........................................................................198 4.4.4 Check Valves .................................................................................................198 4.4.5 Branch Fittings—Tees and Wyes ...............................................................200 4.5 Design and Analysis of Pipe Networks .................................................................204 4.5.1 Parallel Pipe Networks ................................................................................208 4.6 Economic Pipe Diameter ..........................................................................................213 4.6.1 Cost of a Pipe System ..................................................................................214 4.6.2 Determination of the Economic Diameter ...............................................214 4.6.3 Cost Curves ...................................................................................................221 4.6.4 Economic Velocity Range ...........................................................................223 4.7 Pumps .........................................................................................................................225 4.7.1 Types of Pumps ............................................................................................225 4.7.2 Dynamic Pump Operation .........................................................................225 4.7.2.1 Dynamic Pump Performance .....................................................227 4.7.3 Manufacturer’s Pump Curves ....................................................................230 4.7.4 The System Curve ........................................................................................231 4.7.4.1 System Curve for a Two-Tank System Open to the Atmosphere ........................................................................231 4.7.4.2 System Curve for a Closed-Loop System ..................................234 4.7.5 Pump Selection .............................................................................................235 4.7.6 Cavitation and the Net Positive Suction Head ........................................240 4.7.6.1 Calculating the NPSHa ...............................................................241 viii Contents 4.7.7 Series and Parallel Pump Configurations ................................................245 4.7.8 Affinity Laws ................................................................................................249 4.8 Design Practices for Pump/Pipe Systems .............................................................253 4.8.1 Economics .....................................................................................................254 4.8.2 Environmental Impact ................................................................................254 4.8.3 Noise and Vibration .....................................................................................254 4.8.4 Pump Placement and Flow Control ..........................................................254 4.8.5 Valves .............................................................................................................255 4.8.6 Expansion Tanks and Entrained Gases ....................................................255 4.8.7 Other Sources for Design Practices ...........................................................255 References .............................................................................................................................256 Problems ................................................................................................................................256 5. Energy Transport in Thermal Energy Systems ............................................................277 5.1 Introduction ...............................................................................................................277 5.2 Heat Transfer Analysis of Heat Exchangers ..........................................................277 5.2.1 Thermal Resistance ......................................................................................279 5.2.2 The Convective Heat Transfer Coefficient ................................................284 5.2.2.1 Entry Length .................................................................................285 5.2.2.2 Forced External Cross Flow over a Cylindrical Surface .........286 5.2.2.3 Forced Internal Laminar Flow—Combined Entry ..................286 5.2.2.4 Forced Internal Laminar Flow—Thermal Entry .....................287 5.2.2.5 Forced Internal Turbulent Flow .................................................287 5.3 Fouling on Heat Exchanger Surfaces .....................................................................289 5.4 The Overall Heat Transfer Coefficient ...................................................................289 5.5 Heat Exchanger Types ..............................................................................................294 5.5.1 Double Pipe Heat Exchanger......................................................................294 5.5.2 Shell and Tube Heat Exchanger .................................................................295 5.5.3 Plate and Frame Heat Exchanger...............................................................297 5.5.4 Cross Flow Heat Exchanger .......................................................................297 5.6 Design and Analysis of Heat Exchangers .............................................................298 5.6.1 A Heat Exchanger Design Problem ...........................................................299 5.6.2 A Heat Exchanger Analysis Problem ........................................................300 5.6.3 Heat Exchanger Heat Transfer Analysis...................................................300 5.6.3.1 Logarithmic Mean Temperature Difference ............................301 5.6.4 The LMTD Heat Exchanger Model ...........................................................306 5.6.5 Effectiveness-NTU Heat Exchanger Model .............................................308 5.7 Special Application Heat Exchangers ....................................................................315 5.7.1 Counter Flow Regenerative Heat Exchanger ...........................................315 5.7.2 Heat Exchangers with Phase Change Fluids: Boilers, Evaporators, and Condensers ............................................................................................320 5.8 Double Pipe Heat Exchanger Design and Analysis .............................................327 5.8.1 Double Pipe Heat Exchanger Diameters ..................................................327 5.8.2 Overall Heat Transfer Coefficients for the Double Pipe Heat Exchanger ............................................................................................330 5.8.3 Hydraulic Analysis of the Double Pipe Heat Exchanger .......................330 5.8.3.1 Hydraulic Consequences of Fouling .........................................331 5.8.3.2 Pressure Drop through the Inner Tube .....................................333 5.8.3.3 Pressure Drop through the Annulus ........................................333 Contents ix 5.8.4 Fluid Placement in a Double Pipe Heat Exchanger ................................340 5.8.5 Double Pipe Heat Exchanger Design Considerations ............................340 5.8.6 Computer Software for Design and Analysis of Heat Exchangers ......341 5.8.7 Double Pipe Heat Exchanger Design Example ........................................342 5.8.7.1 Fluid Properties ............................................................................342 5.8.7.2 Fluid Placement ............................................................................343 5.8.7.3 Determination of Pipe and/or Tube Sizes ................................344 5.8.7.4 Calculation of Annulus Diameters ............................................346 5.8.7.5 Calculation of Reynolds Numbers .............................................346 5.8.7.6 Calculation of Friction Factors ...................................................346 5.8.7.7 Calculation of Nusselt Numbers ................................................346 5.8.7.8 Calculation of Convective Heat Transfer Coefficients ............346 5.8.7.9 Calculation of Overall Heat Transfer Coefficients ...................346 5.8.7.10 Application of the Heat Exchanger Model ...............................347 5.8.7.11 Heat Exchanger Length ...............................................................348 5.8.7.12 Calculation of Pressure Drops through the Heat Exchanger...349 5.8.7.13 Design Specifications of the Heat Exchanger ...........................349 5.8.8 Double Pipe Heat Exchanger Analysis Example .....................................350 5.8.8.1 Initial Guess of the Fluid Outlet Temperatures .......................350 5.8.8.2 Fluid Properties ............................................................................350 5.8.8.3 Calculation of Annulus Diameters ............................................350 5.8.8.4 Calculation of Fluid Velocities ....................................................351 5.8.8.5 Calculation of Reynolds Numbers .............................................351 5.8.8.6 Calculation of Friction Factors ...................................................351 5.8.8.7 Calculation of Nusselt Numbers ................................................351 5.8.8.8 Calculation of Convective Heat Transfer Coefficients ............351 5.8.8.9 Calculation of Overall Heat Transfer Coefficients ...................351 5.8.8.10 Calculation of the UA Values ......................................................352 5.8.8.11 Application of the Heat Exchanger Model ...............................352 5.8.8.12 Calculation of the Pressure Drops .............................................352 5.8.8.13 Heat Exchanger Specifications and Performance ....................352 5.9 Shell and Tube Heat Exchanger Design and Analysis ........................................352 5.9.1 LMTD for Shell and Tube Heat Exchangers ............................................357 5.9.2 Tube Side Analysis of Shell and Tube Heat Exchangers ........................357 5.9.3 Shell Side Analysis of Shell and Tube Heat Exchangers ........................358 5.9.4 Shell and Tube Heat Exchanger Design Considerations ........................361 5.9.4.1 Tube Side Considerations ............................................................361 5.9.4.2 Shell Side Considerations ............................................................361 5.9.4.3 General Considerations ...............................................................361 5.9.5 Shell and Tube Heat Exchanger Design....................................................362 5.9.6 Shell and Tube Heat Exchanger Analysis.................................................362 5.9.6.1 Initial Guess of the Fluid Outlet Temperatures .......................362 5.9.6.2 Fluid Properties ............................................................................363 5.9.6.3 Shell and Tube Parameters ..........................................................363 5.9.6.4 Fluid Velocities .............................................................................364 5.9.6.5 Calculation of Reynolds Numbers .............................................364 5.9.6.6 Calculation of Friction Factors ...................................................364 5.9.6.7 Calculation of Nusselt Numbers ................................................365 5.9.6.8 Calculation of Convective Heat Transfer Coefficients ............365