Aerosol Technology

134 7.4 Deposition by Diffusion 137 7.5 Diffusion Batteries 141 Problems 144 References 145 8 Thermal and Radiometric Forces 147 8.1 Thermophoresis 147 8.2 Thermal Precipitators 151 8.3 Radiometric and Concentration Gradient Forces 153 Problems 155 References 155 9 Filtration 157 9.1 Macroscopic Properties of Filters 157 9.2 Single-Fiber Efficiency 163 9.3 Deposition Mechanisms 165 9.4 Filter Efficiency 169 9.5 Pressure Drop 174 9.6 Membrane Filters 174 Problems 176 References 176 10 Sampling and Measurement of Concentration 179 10.1 Isokinetic Sampling 179 10.2 Sampling from Still Air 185 10.3 Transport Losses 188 10.4 Measurement of Mass Concentration 189 10.5 Direct-Reading Instruments 192 10.6 Measurement of Number Concentration 195 10.7 Sampling Pumps 197 Problems 199 References 200 11 Respiratory Deposition 203 11.1 The Respiratory System 203 11.2 Deposition 206 11.3 Deposition Models 210 11.4 Inhalability of Particles 213 11.5 Respirable and Other Size-Selective Sampling 215 Problems 223 References 224 12 Coagulation 227 12.1 Simple Monodisperse Coagulation 227 12.2 Polydisperse Coagulation 233 12.3 Kinematic Coagulation 238 Problems 240 References 241 13 Condensation and Evaporation 243 13.1 Definitions 243 13.2 Kelvin Effect 246 13.3 Homogeneous Nucleation 247 13.4 Growth by Condensation 248 13.5 Nucleated Condensation 251 13.6 Condensation Particle Counters 255 13.7 Evaporation 257 Problems 261 References 263 14 Atmospheric Aerosols 265 14.1 Natural Background Aerosol 265 14.2 Urban Aerosol 269 14.3 Global Effects 274 Problems 275 References 275 15 Electrical Properties 277 15.1 Units 277 15.2 Electric Fields 278 15.3 Electrical Mobility 280 15.4 Charging Mechanisms 283 15.5 Corona Discharge 289 15.6 Charge Limits 291 15.7 Equilibrium Charge Distribution 292 15.8 Electrostatic Precipitators 294 15.9 Electrical Measurement of Aerosols 297 Problems 301 References 302 16 Optical Properties 305 16.1 Definitions 306 16.2 Extinction 307 16.3 Scattering 313 16.4 Visibility 317 16.5 Optical Measurement of Aerosols 322 Problems 329 References 330 17 Bulk Motion of Aerosols 333 Problems 338 References 338 18 Dust Explosions 339 Problems 344 References 344 19 Bioaerosols 345 19.1 Characteristics 345 19.2 Sampling 347 Problems 350 References 351 20 Microscopic Measurement of Particle Size 353 20.1 Equivalent Sizes of Irregular Particles 353 20.2 Fractal Dimension of Particles 358 20.3 Optical Microscopy 362 20.4 Electron Microscopy 365 20.5 Asbestos Counting 369 20.6 Automatic Sizing Methods 371 Problems 371 References 372 21 Production of Test Aerosols 375 21.1 Atomization of Liquids 375 21.2 Atomization of Monodisperse Particles in Liquid Suspensions 380 21.3 Dispersion of Powders 382 21.4 Condensation Methods 387 Problems 388 References 389 Appendices 391 Appendix A1. Useful Constants and Conversion Factors 391 Appendix A2. Some Basic Physical Laws 393 Appendix A3. Relative Density of Common Aerosol Materials (Multiply Values by 1000 for Density in kg/m 3 and by 1.0 for Density in g/cm 3) 394 Appendix A4. Standard Sieve Sizes 394 Appendix A5. Properties of Gases and Vapors at 293 K [20 o C] and 101 kPa [1 atm] 395 Appendix A6. Viscosity and Density of Air versus Temperature 395 Appendix A7. Pressure (a), Temperature (b), Density (c), and Mean Free Path (d) of air versus altitude 396 Appendix A8. Properties of Water Vapor 397 Appendix A9. Properties of Water 398 Appendix A10. Particle Size Range of Aerosol Properties and Measurement Instruments: (a) Application Range for Aerosol Size Measuring Instruments and (b) Size Range of Aerosol Properties (See Also Fig. 1.6) 398 Appendix A11. (a) Properties of Airborne Particles at Standard Conditions (SI Units) 400 Appendix A12. Slip Correction Factor for Standard and Nonstandard Conditions: (a) Slip Correction Factor Minus One versus Particle Diameter and Standard Conditions; (b) Slip Correction Factor versus Particle Diameter Times Pressure (per atm) for Temperatures from 233 to 893K [-40 to 600 o C] 402 Appendix A13. Properties of Selected Low-Vapor-Pressure Liquids 403 Appendix A14. Reference Values for Atmospheric Properties at Sea Level and 293.15 Ki20 o C] 404 Appendix A15. Greek Symbols Used in This Book 405 Appendix A16. SI Prefixes 405 References 405 Index 407