Heat is a branch of thermodynamics that occupies a unique position due to its involvement in the field of practice. Being linked to the management, transport and exchange of energy in thermal form, it impacts all aspects of human life and activity. Heat transfers are, by nature, classified as conduction, convection (which inserts conduction into fluid mechanics) and radiation. The importance of these three transfer methods has resulted – justifiably – in a separate volume being afforded to each of them, with the subject of convection split into two volumes.
This third volume is dedicated to convection, more specifically, the foundations of convective transfers. Various angles are considered to cover this topic, including empirical relationships and analytically approaching boundary layers, including the integral methods and numerical approaches. The problem of heat exchangers is presented, without aiming to be an exhaustive treatise. Heat Transfer 3 combines a basic approach with a deeper understanding of the discipline and will therefore appeal to a wide audience, from technician to engineer, from doctoral student to teacher-researcher.
Table des matières
Preface ix
Introduction xi
List of Notations xix
Chapter 1 General Notions 1
1.1 General notions 1
1.2 Forced convection, natural convection 3
1.3 The calculation of heat transfer 5
1.4 Convection coefficient 5
1.5 The program of our study 7
Chapter 2 Empirical Approaches 9
2.1 Introduction 9
2.2 The dimensionless numbers (or dimensionless criteria) of convection 10
2.2.1 The interest of the dimensionless representation is, at first sight, twofold 10
2.2.2 Vaschy-Buckingham theorem 10
2.2.3 Definition and significance of the dimensionless criteria of fluid mechanics and heat transfer 11
2.3 Calculation of convection coefficients: external convection 17
2.3.1 Case of a flat plate at constant temperature 17
2.3.2 External convection on an obstacle: case of a tube outside a flow 22
2.4 Internal convection 22
2.4.1 Convection in a tube 22
2.4.2 Forced convection between two plates 24
2.5 Natural convection 25
2.5.1 Let us recall useful dimensionless numbers 25
2.5.2 Nusselt calculation 26
2.6 Use of ‘standard’ formulas 28
2.7 Some examples of applications 28
Chapter 3 The Boundary Layer 59
3.1 Introduction 59
3.2 The notion of a boundary layer 59
3.2.1 Boundary layer characteristics 60
3.2.2 The boundary layers can be approached by different methods 63
3.3 The external boundary layers: analytical treatment 63
3.3.1 The laminar boundary layer developed by a flat plate in a uniform flow 63
3.3.2 The turbulent boundary layer 73
3.4 Problem of scale 79
3.5 Applications of the boundary layer theory 81
3.6 External boundary layers: integral methods 143
3.6.1 Principle of the integral method 143
3.6.2 Integral methods for an external boundary layer on a flat plate, in Cartesian coordinates 144
3.7 Examples of applications of integral methods 151
Chapter 4 Heat Exchangers 185
4.1 Introduction and basic concepts 185
4.1.1 Classification test 186
4.2 Method of calculation of exchangers 187
4.2.1 Types of exchangers 187
4.2.2 Logarithmic mean temperature difference method (DTLM) 190
4.2.3 Number of transfer units method (NUT method) 195
4.3 Conclusion 205
4.4 An example of the application of the methods 205
Appendices 217
Appendix 1 Physical Properties of Common Fluids 219
Appendix 2 Physical Properties of Common Solids 221
Appendix 3 Thermodynamic Properties of Water Vapor 225
Appendix 4 The General Equations of Fluid Mechanics 229
Appendix 5 The Dynamic and Thermal Laminar Boundary Layer 253
Appendix 6 Table of Functions: erf (x) erfc(x) and ierfc(x) 273
References 275
Index 283
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