CLIFFORD K. HOAND STEPHEN W. WEBB Sandia National Laboratories, P. O. Box 5800, Albuquerque, NM 87185, USA Gas and vapor transport in porous media occur in a number of important applications includingdryingofindustrialandfoodproducts,oilandgasexploration,environm- tal remediation of contaminated sites, and carbon sequestration. Understanding the fundamental mechanisms and processes of gas and vapor transport in porous media allows models to be used to evaluate and optimize the performance and design of these systems. In this book, gas and vapor are distinguished by their available states at stan- ? dard temperature and pressure (20 C, 101 kPa). If the gas-phase constituent can also exist as a liquid phase at standard temperature and pressure (e. g. , water, ethanol, toluene, trichlorothylene), it is considered a vapor. If the gas-phase constituent is non-condensable at standard temperature and pressure (e. g. , oxygen, carbon di- ide, helium, hydrogen, propane), it is considered a gas. The distinction is important because different processes affect the transport and behavior of gases and vapors in porous media. For example, mechanisms specific to vapors include vapor-pressure lowering and enhanced vapor diffusion, which are caused by the presence of a g- phase constituent interacting with its liquid phase in an unsaturated porous media. In addition, the heat-pipe exploits isothermal latent heat exchange during evaporation and condensation to effectively transfer heat in designed and natural systems.

Processes and Models.- Gas Transport Mechanisms.- Vapor Transport Processes.- Solid/Gas Partitioning.- Two-Phase Gas Transport.- Conservation Equations.- Gas-Phase Dispersion in Porous Media.- Gas Injection and Fingering in Porous Media.- Unstable and Fingering Gas Flow in Fractures.- Natural Convection Gas Transport in Porous Media.- Scaling Issues in Porous and Fractured Media.- Numerical Codes for Continuum Modeling of Gas Transport in Porous Media.- Lattice Boltzmann Method for Calculating Fluid Flow and Dispersion in Porous and Fractured Media.- Measurement and Monitoring.- Experimental Determination of Transport Parameters.- Air Permeability Measurements in Porous Media.- Analyzing Barometric Pumping to Characterize Subsurface Permeability.- Subsurface Flow Measurements.- Measurement of Vapor Concentrations.- In situ Measurement of Induced Contaminant Flux.- Applications.- Radon Transport.- Gas Transport Issues in Landmine Detection.- Environmental Remediation of Volatile Organic Compounds.- Yucca Mountain Heater Tests.- Impact of Gas Generation on the Performance of the Waste Isolation Pilot Plant.- Oil and Gas Industry Applications of Gas Flow in Porous Media.- Geologic Carbon Sequestration: CO2 Transport in Depleted Gas Reservoirs.- Industrial Gas Transport Processes Involving Heat Transfer.