Explosion Dynamics

Ali S. Rangwala is a Professor in the Department of Fire Protection Engineering at Worcester Polytechnic Institute (WPI) (2006 - present). He received his PhD in Mechanical and Aerospace Engineering from the University of California, San Diego (2006). Robert G. Zalosh has been a WPI Professor Emeritus of Fire Protection Engineering (FPE) since retiring from his position as FPE Professor in 2006. Before joining the WPI faculty, Dr. Zalosh worked for 15 years at Factory Mutual Research Corporation (FMRC), where he held several positions, including the Manager of the Applied Research Department.

• Preface xi1 Introduction 11.1 What Is an Explosion? Types of Explosions Covered in this Book 11.1.1 Nuclear Explosions 21.1.2 Pressure Vessel Bursts 31.1.3 Explosives 31.1.4 Closed Vessel Detonation 41.1.5 Steam Explosions 61.1.6 Closed Vessel Deflagrations 61.1.7 Building Deflagrations 81.1.8 Vapor Cloud Explosions 91.2 Controlling Parameters of a Combustible Gas/Vapor Explosion Hazard 101.3 Flame Propagation 121.4 Mixture Concentration – Definition of Flammability Limits 231.5 Minimum Ignition Energy (MIE) and Auto Ignition Temperature (AIT) 25Exercise Problems 27Nomenclature 27Greek Symbols 28Subscripts 28Other Notations 29References 292 Synopses of Explosion Incidents 312.1 Hydrogen Cylinder Trailer Module Explosion 312.2 Nylon Flock Dust Explosion 332.3 Flammable Vapor Explosion at Ink and Paint Manufacturing Plant 362.4 Jahn Foundry Dust Explosion 402.5 Upper Big Branch Coal Mine Explosion 45Nomenclature 51Subscripts 51Other Notations 51References 523 Explosion in a Closed Vessel 553.1 Introduction 553.2 The Movement of a Flame in a Premixed Gas–Air Mixture 573.3 Explosion Pressure Rise vs. Time in a Confined Vessel (Theory) 593.4 The Closed Vessel as an Experimental Platform for Standard Testing 683.5 Influence of Flame Wrinkling, Turbulence, and Dust on Flame Propagation 72Nomenclature 75Greek Symbols 75Subscripts 75Other Notations 76References 764 Explosion in a Vented Vessel 794.1 Introduction: How Does Pressure Develop in a Vented Vessel? 794.2 Explosion in a Vented Vessel Neglecting Transient Effects 814.3 Pressure Generation in a Vented Vessel with Transient Effects 834.4 Flame Instabilities 854.5 Flame Front Turbulence and the Concept of Turbulent Burning Velocity ST 864.5.1 What Happens with Dust? 884.6 Pressures Generated in Vented Vessels – Experiments 894.6.1 Influence of Ignition Location 894.6.2 Effect of Obstacles 914.6.3 Influence of Vent Size and Turbulence with Obstacles 924.6.4 Influence of Turbulence with Vented Dust Explosions 944.7 Modeling Pressure Generated as a Function of Time in a Vented Vessel 974.7.1 Conservation of Mass 984.7.2 Expression for mu in Terms of P 994.7.3 Expression for mb in Terms of P 994.7.4 Expression for mv in Terms of P 1004.7.5 Conservation of Energy: Expression for Vb in Terms of P 1024.7.6 Final Equations for the Model 1044.7.6.1 Calculation of Total Enthalpy of the Gas–Air Mixture 1054.7.6.2 Burning Velocity 1064.8 Pressure Developed Outside the Enclosure 1134.9 Vent Design in Engineering Codes and Standards 115Nomenclature 121Greek Symbols 122Subscripts 122Superscript 122Other Notations 122References 1225 Accumulation of a Flammable Mixture in an Enclosure 1275.1 Introduction 1275.2 Gas Filling in an Enclosure with Forced Ventilation 1285.3 Gas Filling in an Enclosure with Passive Ventilation 1305.4 Criteria for Mixture Uniformity 1345.5 Concentration Buildup in an Enclosure by a Liquid Spill 1375.5.1 Size of Spill 1375.5.2 Evaporation of a Flammable Liquid Spill 1375.6 Concentration Buildup in an Enclosure due to Dust 142Nomenclature 145Greek Symbols 146Subscripts 146Other Notations 147References 1476 Dimensionless Analysis 1496.1 Introduction 1496.2 Dimensional and Nondimensional Quantities 1496.3 The Buckingham Pi Theorem 1506.4 Procedure for Obtaining Pi Terms 1506.4.1 Creating a Correlation 154Nomenclature 161Greek Symbols 161Subscripts 161References 1627 Vapor Cloud Explosions 1637.1 Introduction 1637.2 Shape of Overpressure Curves: Pressure Wave, Shock Wave, and Blast Wave 1647.3 The Classical Model of Pressure Developed by a Spherically Expanding Flame 1667.4 TNT Equivalent Model 1687.5 The Multienergy Models 1727.6 Baker–Strehlow–Tang Model 1727.7 TNO Model 1757.8 The Williams Model 1867.9 Computational Fluid Dynamics (CFD) Modeling of VCE 1897.10 Summary 190Nomenclature 190Greek Symbols 191Subscripts 191Other Notations 191References 1928 Dust Flames and Dust Explosions 1958.1 Introduction 1958.2 Elements of a Dust Explosion 1968.3 Flame Structure – What Is a Dust Flame? 2008.4 Dust Explosion Test Platforms 2088.4.1 Hybrid Flame Analyzer 2088.4.2 The Standard 1 m3 and 20-l Explosion Spheres 2138.4.3 Minimum Ignition Energy (MIE) Tests 2168.4.4 Dust Ignition Temperature Tests 2188.4.5 Limiting Oxygen Concentration 2228.4.6 Open Dust Deflagration Test Apparatus by Dobashi 2238.5 Powder and Dust Processing Equipment 2238.5.1 Particle Size Reduction Equipment 2248.5.2 Ovens and Dryers 2268.5.3 Dust Collectors 2288.5.4 Other Powder and Dust Handling Equipment 2318.6 Dust Hazard Analyses 2318.7 Dust Explosion Venting 238Exercise Problems 242Nomenclature 242Greek Symbols 243Subscripts 243Other Notations 243References 2449 Other Explosion Protection Methods 2499.1 Introduction 2499.2 Gas/Vapor Concentration Dilution 2499.3 Inerting 2519.4 Explosion Suppression Systems 2539.5 Isolation 259Nomenclature 267Greek Symbols 268Subscripts 268Other Notations 268References 269Appendix A A Review of Chemistry and Thermodynamics 271A.1 Mole Fraction (Xi) and a Mass Fraction (Yi) 271A.1.1 Mole 271A.1.2 Molar volume of a gas 271A.1.3 Gram-mole 271A.2 Stoichiometry 273A.3 Combustion Chemistry 275A.3.1 Combustion of Propane 276A.3.2 Combustion of Butane 277A.3.3 Represent as a Mixture 277A.3.4 Determine Volume Percent of Fuel 278A.3.5 Determine Weight Percent of Fuel 278A.4 Pressure 279A.5 Energy Terms and Adiabatic Flame Temperature 280A.5.1 Ethane in Air 282A.6 Equivalence Ratio 284A.6.1 Stoichiometric Coefficient (s or r Depending on Reference) 285A.7 Heat and Heat Capacity 285A.8 Entropy and Isentropic Process 285A.8.1 Definitions 286A.8.2 Ideal Gas Temperature – Entropy Relationships 286A.8.3 Isentropic Relations 288Exercises 289References 289Appendix B Mathematica Code for Solved Examples 291Index 299