Smoke, dust, and haze : fundamentals of aerosol dynamics 2. ed

ONTENTS Preface xv Preface to the First Edition xix Chapter 1 AEROSOL CHARACTERIZATION 1 Parameters Detennining Aerosol Behavior 2 Particle Size 3 General 3 Equivalent Particle Diameter 5 Particle Concentration 6 Number COl/centralioll 6 Mass Concentraliolls 7 Volumetric COllcelllration 7 Coagllfarioll 8 Size Distribution Function 10 Dimensiollal Con.~ideratiolls II Relalion.rhips Among Distributioll Fllnctions t 1 Averagillg of Size Distributions 14 Moments of the Distribution Function 14 Examples of Size Di ~tribution Functions 16 Normal Distributions 17 Power LlIIV Distributiolls 18 Self-Similar DisrributioTl FUllctiollS 18 Chemical Composition 19 Size-Compo.titioll Probability Density Funclion 19 Average Chemical Composilioll 20 Distribution a/Chemical Composition with Respect to Particle Size 21 v vi Contents Aerosol Dynamics: Relation to Characterization 23 Problems 24 References 25 Chapter 2 PARTICLE TRANSPORT PROPERTIES 27 Equation of Diffusion 28 Coefficient of Diffusion 30 Friction Coefficient 33 Agglomerate Diffusion Coefficients 35 Path Length of a Brownian Particle 37 Migration in an Extemal Force Field 38 Electrical Migration 40 General COnCepf.l' 40 Field Charging 41 Ullipolar Diffllsion CJu/lgillg: Free Molecule Rallge 42 Unipolar Diffusion Chlllgillg: Comilllllflll Range 43 Ullipolar Diffusion Chmgillg: Sroc/lllsric Theory 46 Bipolar Chargillg 46 Thennophoresis 50 London-van der Waals Forces 52 Boundary Condition for Particle Diffusion 53 Problems 55 References 56 Chapter 3 CONVECTIVE DfFFUSION: EFFECTS OF FINITE PARTICLE DIAMETER AND EXTERNAL FORCE FIELDS 58 Equation of Convective Diffusion 59 Simi litude Considerations for Aerosol Diffusion 60 Concentration Boundary Layer 61 Diffusion to Cylinders at Low Reynolds Numbers: Concentration Boundary Layer Equation 63 Diffusion to Cylinders at Low Reynolds Numbers: Point Panicles 64 Diffusion at Low Reynolds Numbers: Similitude Law for Panicles of Finite Diameter 66 Low Re Deposition: Comparison of Theory with Experiment 69 Single-Element Particle Capture by Diffusion and Interception at High Reynolds Numbers 73 Contents vii High Re Deposition: Application to Deposition on Rough Surfaces 76 Diffusion from a Laminar Pi pe Row 78 Diffusion from a Thrbulent Pipe Row 80 Particle Deposition from Rising Bubbles 82 Convective Diffusion in an External Force Field: Electrical Precipitation 84 Thermophoresis: "Dust-Free Space" 87 Vertical Plate 88 Stagnation Flow 89 Effects of Brownian Diffusion on Deposition 90 Problems 90 References 92 Chapter 4 INERTIAL TRANSPORT AND DEPOSITION 94 Particle-Surface Interactions: Low Speeds 95 Particle-Surface Interactions: Rebound 98 Particle Acceleration at Low Reynolds Numbers: Stop Distance 100 Similitude Law for Impaction: Stokesian Particles 102 Impaction of Stokesian Particles on Cylinders and Spheres 104 Introdu ction 104 Critical Stoke~· Number for Inviscid Flow.s 105 Comparison of Experiment and Theory 107 Impaction of Non-Stokesian Particles 108 Deposition from a Rotating R ow: Cyclone Separator 111 Particle Eddy Diffusion Coefficient 113 Turbulent Deposition US Aerodynamic Focusing: Aerosol Beams U8 Transition from the Diffusion to Inertial Ranges 121 Problems 122 References 124 viii Contents Chapter 5 LIGHT SCATTERING 125 Scattering by Single Panicles: General Considerations 126 Scattering by Particles Small Compared to the Wavclenglh 128 Scattering by Large Particles: The Extinction Paradox 130 Scattering in the Intermedi<lIe Size Range: Mie Theory 130 General Consideralions 130 AlIgllfar Scauering 133 Scauering by Aerosol Clouds 134 Gel1eral COllsitieratiolls 134 Extinction Coefficient alld Oplical ThickJ/e.u 136 Scanering over the Visible Wavelength Range: Aerosol Contributions by Volume 138 Rayleigh Scauering: Self-S imilar Size Distributions 139 Mic Scatteri ng: Power Law Distributions 141 Quasi-Elastic Light Scattering 143 Specific Intensity: Equation of Radiative Transfer 145 Equation of Radiative Transfe r: Formal Solution 146 Light Transmission Through the Atmosphere: Visibility 148 Inelastic Scattering: R:unan Effect 151 Basic Concepts 151 Ramall Scouerillg by Panicles 152 Problems 154 References 155 Chapter 6 EXPERlMENTAL METHODS 157 Sampling 158 Microscopy 160 Mass Concentration: Fihration 162 Total Number Concentration: Condensation Partic le Counter 163 Tota l Light Scattering and Extinction Coefficients 165 Size Distribution Function 166 Ol'en /jew 166 Sillgle-Particle Optical COl/nter 166 DijJerelllilll Mobility Al/alyzerlEleclro.wtllic Cfa.uijier 168 DijJl/sion Battery 170 Mass and Chemical Species Distribution: The Cascade Impactor 171 Aerosol Chemical Analysis 174 8tlckgrowui 174 Contelll.\' ix MIIlIit' lemelll Allalysis /or Source Re~'ollllioll 175 Single-Parlic/e Chemical Allalysis by Mass S,Jectrometr)' 177 Summary Classification of Measurement Instruments 178 Monodisperse Aerosol Generators 181 Collt/ensaliol1 Generators 181 Atomizing Gel/eraton; J 82 Problems 184 References 186 Chapter 7 COLLISION AND COAGULATION: COALESCING PARTICLES 188 Introduction 188 Collision Frequency Function 189 Brownian Coagul ation 190 Browni;m Coagul ation: Dynamics of Discrete Distribution for an Initially Monodisperse Aerosol 192 Brownian Coagulation: Effect of Particle Force Fields 196 Effect of van der Waals Forces 197 Effect of Coulomb Forces 200 Collision Frequency for Laminar Shear 200 Simultaneous Laminar Shear and Brownian MOlion 202 Turbulent Coagulation 204 D)'lIfllllics o/TI/rbl/fellce: Kolmogorov Microscate 204 Turbulent Shear Coagulatiull 206 Tllrblilelll lllerti{/l Coagllllllioll 206 LimitatiOlIS all Ille Alialysi~' 207 Comparisoll o/Collisioll Mechanisms 208 Equation of Coagulation: Continuous Distribution Function 208 x Co1!tents Similarity Solution: Coagulation in the Continuum Regime 210 Similarity Solution for Brownian Coagulation 211 Similarity Solution: Coagulation in the Free Molecule Region 215 Time to Reach the Self-Preserving Distribution (SPD) 217 Problems 219 References 220 Chapter 8 DYNAMICS OF AGGLOMERATE FORMATION AND RESTRUcrURING 222 Agglomerate Morphology: Scaling Laws 223 IlItrO(illctiol! 223 Autocorrelation rllnction 223 Pre factor for tile POlller Law Relaliollslli,) 226 Computer Simulation of Agglomerate Formation 227 Diffusion-Limited Aggregation 227 Ballistic Aggregation 228 Reactioll-Limited Aggregation 228 Coordination Number alld Fractal Dimension 229 Langevin Simulations of Agglomeration 230 Smoluchowski Equation: Collision Kernels for Power Law Agglomerates 230 Self-Preserving Agglomerate Size Distributions 233 Time to Reach the Self-Preserving rOTm 234 Effect of Primary Particle Size on Agglomerate Growth 237 Effect of Of on Agglomerate Growth 240 Agglomerate Restruc turing 242 Themwl RestTllcturillg 242 RestTllcturill8 under Tension: Elastic Properlies of Chain Aggregmes 245 Problems 246 References 247 Chapter 9 THERMODYNAMIC PROPERTIES 249 The Vapor Pressure Curve and the Supersaturated State 249 SUfl/rwioll RlIfio 249 Condensation by Adiabatic &'pclIIsion 251 Com/ell.l'lIfioll by Mixing 252 Effect of Solutes on Vapor Pressure 254 Vapor Pressure of a Small Particle 256 rhe Kelvin Relation 256 Conlents xi Particle /Iltenwi Pressure: Ltlplace:~ Famlll/a 257 Limit of Applicabiliry of Kelvill Relation 258 Hygroscopic Particle-Vapor Equilibrium 259 Charged Particle- Vapor Equilibria 263 Solid-Particle-Vapor Equilibrium 265 ValJOr alld Surface Press!lre~' of Ctyswllille Particles 265 Melting Poilll Redllction oJ Small Solid Particles 266 Effect of Particle Size 0 11 the Equilibrium of a Heterogeneous Chemical Reaction 266 Molecular Clusters 269 IlI/lVdlle/ioll 269 Equilibrium Size Di.striblllion 270 Problems 273 References 274 Chapter 10 GAS-TO-PARTICLE CONVERSION 275 Condensation by Adiabatic Expansion: The Experiments of C. T. R. Wil son 276 Kinetics of Homogeneous Nucleation 277 Experimental Test of Nucleation Theory 280 Heterogeneous Condensation 283 Growth Laws 284 Transport-Limited Growth 285 Aero.ml Phase, Reaction-Limited Growth 286 Dynamics Of Growth: Continuity Relation in v Space 288 xii Cuntents Measurement of Growth Rates: Homogeneous Gas-Phase Reactions 290 Simuhaneous Homogeneous and Heterogeneous Condensation 293 Theoretical Aspects 293 Oscillatillg Aerosol Reactors: An Experimelltal Study 296 Effects of Turbulence on Homogeneous Nucleation 299 Scalillg Theory 299 Experimental Tests 0/ Scaling Theory 301 Effect o/Splitting the FlolV into Multiple Streams 303 Problems 304 References 305 Chapter IJ THE GENERAL DYNAMIC EQUATION FOR THE PARTICLE SIZE DISTRIBUTION FUNCfION 306 General Dynamic Equation for the Discrete Distribution Function 307 Coagulation and Nucleation as Limiting Processes in Gas-to-Particle Conversion 308 General Dynamic Equation for the Continuous Distribution Function 309 The Dynamic Equation for the Number Concentration Nco 310 The Dynamic Equation for the Volume Fraction 3U Simultaneous Coagulation and Diffusional Growth: Similarity Solution for Continuum Regime 313 Simultaneous Coagulation and Growth: Experimental Results 315 The GDE for Turbulent Flow 318 The GDE for Turbulent Stack Plumes 319 Coagulation and Stirred Settli ng 321 Coagulation and Deposition by Convective Diffusion 325 Continuously Stirred Tank Reactor 327 Problems 329 References 330 • Contellls xiii Chapter 12 SYNTHESIS OF SUBMJCRQN SOLID PARTICLES: AEROSOL REACTORS 331 Aerosol Reactors: Commercial and Pilot Scale 332 Flume Reactors 332 Pyroly,tis Reactors 334 Electroll -Beam Dry Scrubbing 335 Evaporation-Condensatio" Generators 336 The Collision-Coalescence Mechanism of Primary Particle Formation 338 Extension of the Smol uchowski Equation to Colliding, Coalescing Particles 339 Rate Equation for Particle Coalescence 340 General COllsiderations 340 Viscolls Flow Transport 341 Transport by Diffusion 341 Molecular Dynamic Simulatiolls: Solid-Liquid Transition 342 Solid-State Diffu sion Coefficienl 343 Temperature Depelldellce 343 l1dlles of D for Lattice Diffusion 345 High Diffllsil'ity Paths 346 Estimation of Average Primary Particle Size: Method of Characteristic Times 346 Primary Panicle Size: Effects of Aerosol Material Propenies 350 Panicle Neck Fonnation 353 Panicle Crystal Structure 355 Basic Concepts 355 experimental,Obsen 'at;olls 355 Problems 356 References 357 Chapler 13 ATMOSPHERIC AEROSOL DYNAMICS 359 Atmospheric Aerosol Size Distribution 360 Gel/eral Features 360 Coarse Mode (dp > 2.5 IJ.m) 361 Accumulation Mode (0.1 < dp < 2.5 j.Lm) 364 UV LOnU!IIfS Ullrajine Range (dp < O.l l-tlll) 366 ResilIence Time and Dry Deposition 366 Aerosol Dynamics in Power Plant Plumes 368 Chemical Composition of Urban Aerosols 370 llIIrodllClioll 370 Chemical COllllJosilion o/the Fine Aerosol 372 Distributions of Chemical Species with Particle Size 373 Sulfates (llld Nitrates 374 Primary Submicron Aerosols: PAHs and Elemelllal Carbon 376 Waler 376 Morphological Characteristics of the Submicron Aerosol 378 Common Measures of Air Quality for Particulate Matter: Federal Standards 380 Receptor Modeling: Source Apportionment 380 Basic Concepts 380 Chemical Mass Balance Melhod 381 Portland Aerosol Characterization Study 382 Relating the CM8 to Aerosol Dynamics 385 Statistical Variations of Ambient Aerosol Chemical Components 385 Field Measurements 385 Relation 10 Aerosol Dynamics 388 Problems 389 References 391 Common Symbols 393 Index 397