Integrating Electrical Heating Element Cap I

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Integrating Electrical Heating Elements in Appliance DesignStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation


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ELECTRICAL ENGINEERING AND ELECTRONICS

A Series of Reference Books and Textbooks

EXECUTIVE EDITORS

Marlin O. ThurstonDepartment of

Electrical EngineeringThe Ohio State University

Columbus, Ohio

William MiddendorfDepartment of

Electrical and Computer EngineeringUniversity of Cincinnati

Cincinnati, Ohio

EDITORIAL BOARD

Maurice BellangerTélécommunications, Radioélectriques,et Téléphoniques (TRT)Le Plessis-Robinson, France

Norman B. FuquaReliability Analysis CenterGriffiss Air Force Base, New York

Pradeep KhoslaCarnegie-Mellon UniversityPittsburgh, Pennsylvania

J. Lewis BlackburnBothell,Washington

Naim A. KheirDepartment of Electrical andSystems EngineeringOakland UniversityRochester, Michigan

Glenn ZelnikerZ-Systems, Inc.Gainesville, Florida

1. Rational Fault Analysis, edited by Richard Saeks and S. R. Liberty

2. Nonparametric Methods in Communications, edited by P. Papantoni-Kazakos and Dimitri Kazakos

3. Interactive Pattern Recognition, Yi-tzuu Chien

4. Solid-State Electronics, Lawrence E. Murr

5. Electronic, Magnetic, and Thermal Properties of Solid Materials, Klaus Schröder

6. Magnetic-Bubble Memory Technology, Hsu Chang

7. Transformer and Inductor Design Handbook, Colonel Wm. T. McLyman

8. Electromagnetics: Classical and Modern Theory and Applications, Samuel Seely and Alexander D.Poularikas

9. One-Dimensional Digital Signal Processing, Chi-Tsong Chen

10. Interconnected Dynamical Systems, Raymond A. DeCarlo and Richard SaeksStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation


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11. Modern Digital Control Systems, Raymond G. Jacquot

12. Hybrid Circuit Design and Manufacture, Roydn D. Jones

13. Magnetic Core Selection for Transformers and Inductors: A User's Guide to Practice and Specification,Colonel Wm. T. McLyman

14. Static and Rotating Electromagnetic Devices, Richard H. Engelmann

15. Energy-Efficient Electric Motors: Selection and Application, John C. Andreas

16. Electromagnetic Compossibility, Heinz M. Schlicke

17. Electronics: Models, Analysis, and Systems, James G. Gottling

18. Digital Filter Design Handbook, Fred J. Taylor

19. Multivariable Control: An Introduction, P. K. Sinha

20. Flexible Circuits: Design and Applications, Steve Gurley, with contributions by Carl A. Edstrom, Jr.,Ray D. Greenway, and William P. Kelly

21. Circuit Interruption: Theory and Techniques, Thomas E. Browne, Jr.

22. Switch Mode Power Conversion: Basic Theory and Design, K. Kit Sum

23. Pattern Recognition: Applications to Large Data-Set Problems, SingTze Bow

24. Custom-Specific Integrated Circuits: Design and Fabrication, Stanley L. Hurst

25. Digital Circuits: Logic and Design, Ronald C. Emery

26. Large-Scale Control Systems: Theories and Techniques, Magdi S. Mahmoud, Mohamed F. Hassan,and Mohamed G. Darwish

27. Microprocessor Software Project Management, Eli T. Fathi and Cedric V. W. Armstrong(Sponsored by Ontario Centre for Microelectronics)

28. Low Frequency Electromagnetic Design, Michael P. Perry

29. Multidimensional Systems: Techniques and Applications, edited by Spyros G. Tzafestas

30. AC Motors for High-Performance Applications: Analysis and Control, Sakae Yamamura

31. Ceramic Motors for Electronics: Processing, Properties, and Applications, edited by Relva C.Buchanan

32. Microcomputer Bus Structures and Bus Interface Design, Arthur L. Dexter

33. End User's Guide to Innovative Flexible Circuit Packaging, Jay J. Miniet

34. Reliability Engineering for Electronic Design, Norman B. Fuqua

35. Design Fundamentals for Low-Voltage Distribution and Control, Frank W. Kussy and Jack L. Warren

36. Encapsulation of Electronic Devices and Components, Edward R. Salmon

37. Protective Relaying: Principles and Applications, J. Lewis Blackburn

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38. Testing Active and Passive Electronic Components, Richard F. Powell

39. Adaptive Control Systems: Techniques and Applications, V. V. ChalamStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation


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40. Computer-Aided Analysis of Power Electronic Systems, Venkatachari Rajagopalan

41. Integrated Circuit Quality and Reliability, Eugene R. Hnatek

42. Systolic Signal Processing Systems, edited by Earl E. Swartzlander, Jr.

43. Adaptive Digital Filters and Signal Analysis, Maurice G. Bellanger

44. Electronic Ceramics: Properties, Configuration, and Applications, edited by Lionel M. Levinson

45. Computer Systems Engineering Management, Robert S. Alford

46. Systems Modeling and Computer Simulation, edited by Naim A. Kheir

47. Rigid-Flex Printed Wiring Design for Production Readiness, Walter S. Rigling

48. Analog Methods for Computer-Aided Circuit Analysis and Diagnosis, edited by Takao Ozawa

49. Transformer and Inductor Design Handbook: Second Edition, Revised and Expanded, Colonel Wm.T. McLyman

50. Power System Grounding and Transients: An Introduction, A. P. Sakis Meliopoulos

51. Signal Processing Handbook, edited by C. H. Chen

52. Electronic Product Design for Automated Manufacturing, H. Richard Stillwell

53. Dynamic Models and Discrete Event Simulation, William Delaney and Erminia Vaccari

54. FET Technology and Application: An Introduction, Edwin S. Oxner

55. Digital Speech Processing, Synthesis, and Recognition, Sadaoki Furui

56. VLSI RISC Architecture and Organization, Stephen B. Furber

57. Surface Mount and Related Technologies, Gerald Ginsberg

58. Uninterruptible Power Supplies: Power Conditioners for Critical Equipment, David C. Griffith

59. Polyphase Induction Motors: Analysis, Design, and Application, Paul L. Cochran

60. Battery Technology Handbook, edited by H. A. Kiehne

61. Network Modeling, Simulation, and Analysis, edited by Ricardo F. Garzia and Mario R. Garzia

62. Linear Circuits, Systems, and Signal Processing: Advanced Theory and Applications, edited byNobuo Nagai

63. High-Voltage Engineering: Theory and Practice, edited by M. Khalifa

64. Large-Scale Systems Control and Decision Making, edited by Hiroyuki Tamura and TsuneoYoshikawa

65. Industrial Power Distribution and Illuminating Systems, Kao Chen

66. Distributed Computer Control for Industrial Automation, Dobrivoje Popovic and Vijay P. Bhatkar

67. Computer-Aided Analysis of Active Circuits, Adrian loinovici

68. Designing with Analog Switches, Steve Moore

69. Contamination Effects on Electronic Products, Carl J. Tautscher

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70. Computer-Operated Systems Control, Magdi S. Mahmoud

71. Integrated Microwave Circuits, edited by Yoshihiro KonishiStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation


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72. Ceramic Materials for Electronics: Processing, Properties, and Applications, Second Edition, Revisedand Expanded, edited by Relva C. Buchanan

73. Electromagnetic Compatibility: Principles and Applications, David A. Weston

74. Intelligent Robotic Systems, edited by Spyros G. Tzafestas

75. Switching Phenomena in High-Voltage Circuit Breakers, edited by Kunio Nakanishi

76. Advances in Speech Signal Processing, edited by Sadaoki Furui and M. Mohan Sondhi

77. Pattern Recognition and Image Preprocessing, Sing-Tze Bow

78. Energy-Efficient Electric Motors: Selection and Application, Second Edition, John C. Andreas

79. Stochastic Large-Scale Engineering Systems, edited by Spyros G. Tzafestas and Keigo Watanabe

80. Two-Dimensional Digital Filters, Wu-Sheng Lu and Andreas Antoniou

81. Computer-Aided Analysis and Design of Switch-Mode Power Supplies, Yim-Shu Lee

82. Placement and Routing of Electronic Modules, edited by Michael Pecht

83. Applied Control: Current Trends and Modern Methodologies, edited by Spyros G. Tzafestas

84. Algorithms for Computer-Aided Design of Multivariable Control Systems, Stanoje Bingulac andHugh F. VanLandingham

85. Symmetrical Components for Power Systems Engineering, J. Lewis Blackburn

86. Advanced Digital Signal Processing: Theory and Applications, Glenn Zelniker and Fred J. Taylor

87. Neural Networks and Simulation Methods, Jian-Kang Wu

88. Power Distribution Engineering: Fundamentals and Applications, James J. Burke

89. Modern Digital Control Systems: Second Edition, Raymond G. Jacquot

90. Adaptive IIR Filtering in Signal Processing and Control, Phillip A. Regalia

91. Integrated Circuit Quality and Reliability: Second Edition, Revised and Expanded, Eugene R.Hnatek

92. Handbook of Electric Motors, edited by Richard H. Engelmann and William H. Middendorf

93. Power-Switching Converters, Simon S. Ang

94. Systems Modeling and Computer Simulation: Second Edition, Naim A. Kheir

95. EMI Filter Design, Richard Lee Ozenbaugh

96. Power Hybrid Circuit Design and Manufacture, Haim Taraseiskey

97. Robust Control System Design: Advanced State Space Techniques, Chia-Chi Tsui

98. Spatial Electric Load Forecasting, H. Lee WillisStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation


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99. Permanent Magnet Motor Technology: Design and Applications, Jacek F. Gieras and MitchellWing

100. High Voltage Circuit Breakers: Design and Applications, Ruben D. Garzon

101. Integrating Electrical Heating Elements in Appliance Design, Thor Hegbom

102. Magnetic Core Selection for Transformers and Inductors: A User's Guide to Practice andSpecification, Second Edition, William T. McLyman

Additional Volumes in Preparation

Statistical Methods in Control and Signal Processing, edited by Tohru Katayama and Sueo SugimotoStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation


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Page i

Integrating Electrical Heating Elements in Appliance Design

Thor Hegbom

Hallstahammar, Sweden

Start of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation

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Page ii

ISBN: 0-8247-9840-6

The publisher offers discounts on this book when ordered in bulk quantities. For more information, writeto Special Sales/Professional Marketing at the address below.

This book is printed on acid-free paper.

Copyright © 1997 by Marcel Dekker, Inc. All Rights Reserved.

Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronicor mechanical, including photocopying, microfilming, and recording, or by any information storage andretrieval system, without permission in writing from the publisher.

Marcel Dekker, Inc.270 Madison Avenue, New York, New York 10016Current printing (last digit):10 9 8 7 6 5 4 3 2 1

PRINTED IN THE UNITED STATES OF AMERICAStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation

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Page iii

Preface

This book starts by describing the standard resistance heating alloys and their properties. A short chapteron other metals and alloys that are also frequently used for heating purposes follows. Then an account ofthe laws of heat transfer and the basic formulas for calculating heating elements are presented. Becauseresistance heating wires are often formed in coils, coiling and the properties of coils are dealt with.Ceramic and plastic materials used for making such heating elements are mentioned briefly, as are safetyrules that affect the design of both elements and appliances. Chapters on resistance heating elementsmade of metallic materials follow. They are arranged in three groups according to how the resistanceheating wire is mechanically supported and how heat is dissipated from its surface. TheStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation

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three groups of elements are suspended, supported, and embedded. Short chapters on thin and thick filmelements as well as PTC elements are presented next. Table A1 in the Appendix compares the resistivityand the surface resistance of the resistance materials mentioned in this book. A survey of the differentappliances and heaters for domestic use is given, together with some possible element types. In theAppendix many less known and new formulas are explained and some sample calculations are shown.The formulas are written in a way suitable for Basic programming. The temperature-dependent materialconstants are expressed as functions of the temperature to enable readers to take temperature intoconsideration when making calculations.

Metric units have been used in the text. In the Appendix readers will find a table of conversions of unitsfrom the imperial to the metric system and vice versa. The Appendix also contains tables showingresistance per meter, surface per ohm, and weight per meter for the whole and half B&S wire sizes of themost common standard resistance alloys. Similar tables for B&S ribbon sizes are also given. The finalAppendix contains six calculating programs in Basic to show the reader how the equations can be used insimple Basic programming.

The book deals only with resistance heating elements for appliances and heaters. Elements for furnaces,which are covered in other publications, are not considered. No other reference book is currentlyavailable that deals with electrical heating elements for appliances. There has been a great need forinformation that covers the basic theory, equations, and underlying principles of designing heaters.Because of the lack of information, most of which comes from resistance alloy manufacturers, thestandard practice has been mainly empirical, based on trial-and-error methods.

My rationale for writing the book is to bring my more than 30 years of experience to engineers workingon electrical heating elements. This book will help those engineers who design heating elements and whohave had to rely on disparate information from wire suppliers. It will also give experienced manufacturerssome advice and hints to help them choose the correct wire types and dimensions for their needschoicesthat are of considerable economic importanceand to train young engineers. Finally, the book will guidemanufacturers of appliances in the choice of the right elements for their particular needs and will help themto take into account element sizes and properties when they design appliances. Today, the appliance isoften designed first, and only afterward is the element manufacturer asked for an element to suit it. Thissometimes leads to impossible requirements for elements.

The book will be useful to manufacturers of electrical heating elements; designers of domestic appliancesequipped with electrical heatingStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation

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Page v

elements; producers of all kinds of devices equipped with electrical heating elements; laboratories forR&D, quality assurance, and biotechnology; engineers and designers requiring a source of heat; andtechnical and university libraries.

Within these fields the designers, production people, laboratory engineers, and quality assuranceengineers will benefit from reading this book or using it as a reference. This represents a sizable audience.Resistance material manufacturers, for obvious commercial reasons, concentrate their support on volumebuyers. This leaves users in almost 190,000 small and medium-sized U.S. laboratories, who usuallyrequire just a few devices, completely without resources. This has been a historical problem becausedesign data are not available to this large group of small users. Yet there are hardly any laboratories inwhich heating devices are not needed or used. With the technical background and practical hints in thisbook, technicians will be able to design and build heating elements and appliances geared to their needs.The book could also be valuable as a college-level teaching manual.

To understand fully all the deductions and equations in the book, a college-level scientific background isrequired. However, anybody needing electrical heatingregardless of academic backgroundcan benefitfrom this book.

The book is based on knowledge gained during many years and several discussions with representativesfrom most of the world's leading manufacturers of heating elements and appliances. I would like to thankall the technical people with whom I have talked during these years for interesting and stimulatingdiscussions. In particular, I thank Kanthal AB for all the discussions and all the knowledge I have gainedworking in their laboratories and after my retirement. I thank the firms that have contributed withphotographs. In alphabetical order, they are:

Backer Elektro-Värme AB, Sösdala, SwedenCalesco Foil AB, Kolbäck, SwedenFritz Eichenauer GmbH and Co.KG, Hatzenbiihl, GermanyEncon Energy Convertors, Incorporated, Dallas, PennsylvaniaKanthal AB, Hallstahammar, SwedenTürk & Hillinger GmbH, Tuttlingen, GermanyWatlow Electric Manufacturing Company, St. Louis, Missouri

No liability is assumed for the information in this book or for any damage resulting from the use or misuseof its content.

THOR HEGBOMStart of Citation[PU]Marcel Dekker, Inc.[/PU][DP]1997[/DP]End of Citation

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Page vii

Contents

Preface iii

Symbols xi

1. Metallic Resistance Heating Wire 1

1.1 Standard Resistance Heating Alloys 1

1.2 Metallurgical Background 4

1.3 Oxidation Resistance and Heater Life 6

1.4 Influence of the Surroundings: Corrosion 24

1.5 Mechanical Properties 27

1.6 Magnetic Properties and Noise 31

1.7 Electric Resistance 33

1.8 Other Properties 43


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1.9 Wire Surface Load 49

1.10 Comparison of Different Wire Alloys 50

1.11 Wire Gauges 52

1.12 Ribbon and Ribbon Standard Sizes 54

1.13 Weight of Wire and Ribbon 58

1.14 Forms of Delivery 58

1.15 Tolerances 59

1.16 Checking Resistance Heating Wire 60

References 60

2. Wires (and Ribbons) Made of Materials Different From Resistance Heating Alloys 63

2.1 Metals and Alloys for Low Operating Temperatures 63

2.2 The Halogen Tubular Heater 74

2.3 Cermet Wire 75

References 78

3. General Information About Electrical Heating Elements 81

3.1 Definition of an Electrical Heating Element 81

3.2 Heat Transfer 82

3.3 The Straight Wire 96

3.4 The Coil 100

3.5 Terminals 131

3.6 Corrugated Ribbon 135

3.7 Insulating Materials 137

3.8 Safety Rules 151

3.9 Element Calculation 152

3.10 Element Surface Load and Temperature of Element and Wire 162

3.11 Requirements for Elements 164

3.12 Classification of Heating Elements 164

3.13 Limits for Use of Metal Wires 166

References 167

4. Suspended Elements 169

4.1 Elastically Suspended Wire or Ribbon 169

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4.2 Straight or Corrugated Wire or Ribbon on Fixed Supports 173

4.3 Suspended Coil 176

4.4 Zigzag Elements 181

4.5 Suspended Punched Strip 184

References 186


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5. Supported Elements 187

5.1 Wire and Ribbon on Ceramic Fiber 187

5.2 Coil on Flat Ceramic Plate 194

5.3 Wire on (Cylindrical) Ceramic 195

5.4 Open Mica Element 209

5.5 Tube Heaters 214

5.6 Porcupine 225

5.7 Bead-Insulated Coil 228

5.8 Cigarette Lighter 230

5.9 Coil in Water 231

References 232

6. Embedded Elements 235

6.1 Metal-Sheathed Tubular Element 236

6.2 Powder-Filled Cartridge Element 306

6.3 Embedded in Metal Groove 310

6.4 Embedded in Ceramic 314

6.5 Cement-Insulated Element 314

6.6 Sheathed Mica Element 315

6.7 Foil Element 319

6.8 Heating Cable and Rope Heater 336

6.9 Embedded Tube Heaters for Heating of Fluids 338

6.10 Embedded in Ceramic Fiber 339

References 340

7. Film Elements 343

7.1 Thin Film Elements 344

7.2 Thick Film Elements 348

7.3 Pressure-Sensitive Elements 352

References 352

8. PTC Elements 355

8.1 Survey 355

8.2 PTC Elements of the Ceramic Type 356

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8.3 PTC Elements of the Polymer Type 369

References 371

9. Silicon Carbide and Carbon Elements 373

References 375

10. Domestic Appliances and Heaters 377

10.1 Cooking 378

10.2 Heating of Water and Beverages 379

10.3 Drying and Ironing 380


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10.4 Space Heating and Room Comfort 380

10.5 Hair Care 381

10.6 Individual Body Comfort 381

10.7 Tools 381

10.8 Vehicles 382

10.9 Miscellaneous 382

Appendix 383

Index 449


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Integrating Electrical Heating Element Cap I

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