Introduction to Fire Dynamics

Professor Dougal Drysdale recently retired from the University of Edinburgh, where he maintains the position of Emeritus Professor of Fire Safety Engineering. He is a past president of the International Association for Fire Safety Science. His research interests include spontaneous combustion, fire dynamics and behaviour, and fire investigation.

• About the Author xi Preface to the Second Edition xiiiPreface to the Third Edition xvList of Symbols and Abbreviations xvii1 Fire Science and Combustion 11.1 Fuels and the Combustion Process 21.1.1 The Nature of Fuels 21.1.2 Thermal Decomposition and Stability of Polymers 61.2 The Physical Chemistry of Combustion in Fires 121.2.1 The Ideal Gas Law 141.2.2 Vapour Pressure of Liquids 181.2.3 Combustion and Energy Release 191.2.4 The Mechanism of Gas Phase Combustion 261.2.5 Temperatures of Flames 30Problems 342 Heat Transfer 352.1 Summary of the Heat Transfer Equations 362.2 Conduction 382.2.1 Steady State Conduction 382.2.2 Non-steady State Conduction 402.2.3 Numerical Methods of Solving Time-dependent Conduction Problems 482.3 Convection 522.4 Radiation 592.4.1 Configuration Factors 642.4.2 Radiation from Hot Gases and Non-luminous Flames 722.4.3 Radiation from Luminous Flames and Hot Smoky Gases 76Problems 793 Limits of Flammability and Premixed Flames 833.1 Limits of Flammability 833.1.1 Measurement of Flammability Limits 833.1.2 Characterization of the Lower Flammability Limit 883.1.3 Dependence of Flammability Limits on Temperature and Pressure 913.1.4 Flammability Diagrams 943.2 The Structure of a Premixed Flame 973.3 Heat Losses from Premixed Flames 1013.4 Measurement of Burning Velocities 1063.5 Variation of Burning Velocity with Experimental Parameters 1093.5.1 Variation of Mixture Composition 1103.5.2 Variation of Temperature 1113.5.3 Variation of Pressure 1123.5.4 Addition of Suppressants 1133.6 The Effect of Turbulence 116Problems 1184 Diffusion Flames and Fire Plumes 1214.1 Laminar Jet Flames 1234.2 Turbulent Jet Flames 1284.3 Flames from Natural Fires 1304.3.1 The Buoyant Plume 1324.3.2 The Fire Plume 1394.3.3 Interaction of the Fire Plume with Compartment Boundaries 1514.3.4 The Effect of Wind on the Fire Plume 1634.4 Some Practical Applications 1654.4.1 Radiation from Flames 1664.4.2 The Response of Ceiling-mounted Fire Detectors 1694.4.3 Interaction between Sprinkler Sprays and the Fire Plume 1714.4.4 The Removal of Smoke 1724.4.5 Modelling 174Problems 1785 Steady Burning of Liquids and Solids 1815.1 Burning of Liquids 1825.1.1 Pool Fires 1825.1.2 Spill Fires 1935.1.3 Burning of Liquid Droplets 1945.1.4 Pressurized and Cryogenic Liquids 1975.2 Burning of Solids 1995.2.1 Burning of Synthetic Polymers 1995.2.2 Burning of Wood 2095.2.3 Burning of Dusts and Powders 221Problems 2236 Ignition: The Initiation of Flaming Combustion 2256.1 Ignition of Flammable Vapour/Air Mixtures 2256.2 Ignition of Liquids 2356.2.1 Ignition of Low Flashpoint Liquids 2416.2.2 Ignition of High Flashpoint Liquids 2426.2.3 Auto-ignition of Liquid Fuels 2456.3 Piloted Ignition of Solids 2476.3.1 Ignition during a Constant Heat Flux 2506.3.2 Ignition Involving a ‘Discontinuous’ Heat Flux 2636.4 Spontaneous Ignition of Solids 2696.5 Surface Ignition by Flame Impingement 2716.6 Extinction of Flame 2726.6.1 Extinction of Premixed Flames 2726.6.2 Extinction of Diffusion Flames 273Problems 2757 Spread of Flame 2777.1 Flame Spread Over Liquids 2777.2 Flame Spread Over Solids 2847.2.1 Surface Orientation and Direction of Propagation 2847.2.2 Thickness of the Fuel 2927.2.3 Density, Thermal Capacity and Thermal Conductivity 2947.2.4 Geometry of the Sample 2967.2.5 Environmental Effects 2977.3 Flame Spread Modelling 3077.4 Spread of Flame through Open Fuel Beds 3127.5 Applications 3137.5.1 Radiation-enhanced Flame Spread 3137.5.2 Rate of Vertical Spread 315Problems 3158 Spontaneous Ignition within Solids and Smouldering Combustion 3178.1 Spontaneous Ignition in Bulk Solids 3178.1.1 Application of the Frank-Kamenetskii Model 3188.1.2 The Thomas Model 3248.1.3 Ignition of Dust Layers 3258.1.4 Ignition of Oil – Soaked Porous Substrates 3298.1.5 Spontaneous Ignition in Haystacks 3308.2 Smouldering Combustion 3318.2.1 Factors Affecting the Propagation of Smouldering 3338.2.2 Transition from Smouldering to Flaming Combustion 3428.2.3 Initiation of Smouldering Combustion 3448.2.4 The Chemical Requirements for Smouldering 3468.3 Glowing Combustion 347Problems 3489 The Pre-flashover Compartment Fire 3499.1 The Growth Period and the Definition of Flashover 3519.2 Growth to Flashover 3549.2.1 Conditions Necessary for Flashover 3549.2.2 Fuel and Ventilation Conditions Necessary for Flashover 3649.2.3 Factors Affecting Time to Flashover 3789.2.4 Factors Affecting Fire Growth 382Problems 38510 The Post-flashover Compartment Fire 38710.1 Regimes of Burning 38710.2 Fully Developed Fire Behaviour 39610.3 Temperatures Achieved in Fully Developed Fires 40410.3.1 Experimental Study of Fully Developed Fires in Single Compartments 40410.3.2 Mathematical Models for Compartment Fire Temperatures 40610.3.3 Fires in Large Compartments 41810.4 Fire Resistance and Fire Severity 42010.5 Methods of Calculating Fire Resistance 42710.6 Projection of Flames from Burning Compartments 43510.7 Spread of Fire from a Compartment 437Problems 43911 Smoke: Its Formation, Composition and Movement 44111.1 Formation and Measurement of Smoke 44311.1.1 Production of Smoke Particles 44311.1.2 Measurement of Particulate Smoke 44711.1.3 Methods of Test for Smoke Production Potential 45011.1.4 The Toxicity of Smoke 45511.2 Smoke Movement 45911.2.1 Forces Responsible for Smoke Movement 45911.2.2 Rate of Smoke Production in Fires 46511.3 Smoke Control Systems 46911.3.1 Smoke Control in Large Spaces 47011.3.2 Smoke Control in Shopping Centres 47111.3.3 Smoke Control on Protected Escape Routes 473References 475Answers to Selected Problems 527Author Index 531Subject Index 545