Air - Diffusion Coefficients of Gases in Excess of Air
Diffusion coefficients (D12) for gases in large excess of air at temperatures ranging 0 - 400 °C.
Sponsored Links
Fick's first law states that a substance will flow from a region with high concentration to a region of low concentration. Fick's law can be expressed as
J = -D*dφ/dx [1]
where
J = diffusion flux - the amount of substance that flows through an unit area per unit time [mass or mol /(m2 s)]
D = diffusion coefficient [m2/s]
dφ = change in concentration of substance [mass or mol/m3]
dx = change in length [m]
For simple one-dimensional transport, the diffusion coefficient describes the time–rate of change of concentration. The diffusion coefficient varies from substance to substance and with temperature and pressure.
Figure and table below shows the diffusion coefficients, D12, for binary gas mixtures where air is in large excess.
See also Air Composition and molecular weight, Density at varying pressure, Density and specific weight at varying temperature, Diffusion coefficients for gases in air, Dynamic (absolute) and kinematic viscosity, Prandtl Number, Specific heat at varying temperature and Specific heat at varying pressure, Thermal conductivity, Thermal diffusivity, Properties at gas-liquid equilibrium conditions and Air properties, for other properties of air, as well as Diffusion coefficients of gases in water and Carbon dioxide concentrations in rooms with people
| Gases in large excess of air | Diffusion coefficient, D12, [cm2/s] at atmospheric pressure and given temperatures | ||||||
| 0 °C | 20 °C | 100 °C | 200 °C | 300 °C | 400 °C | ||
| Name | Formula | 32 °F | 68 °F | 212 °F | 392 °F | 572 °F | 752 °F |
| Argon | Ar | 0.167 | 0.189 | 0.289 | 0.437 | 0.612 | 0.81 |
| Methane | CH4 | 0.21 | 0.321 | 0.485 | 0.678 | 0.899 | |
| Carbon monoxide | CO | 0.208 | 0.315 | 0.475 | 0.662 | 0.875 | |
| Carbon dioxide | CO2 | 0.16 | 0.252 | 0.39 | 0.549 | 0.728 | |
| Hydrogen | H2 | 0.668 | 0.756 | 1.153 | 1.747 | 2.444 | 3.238 |
| Water vapour | H2O | 0.219 | 0.242 | 0.399 | 0.638 | 0.873 | 1.135 |
| Helium | He | 0.617 | 0.697 | 1.057 | 1.594 | 2.221 | 2.933 |
| Sulfur hexafluoride | SF6 | 0.15 | 0.233 | 0.329 | 0.438 | ||
Sponsored Links
Related Topics
-
Air Psychrometrics
Moist and humid air - psychrometric charts, Mollier diagrams, air-condition temperatures and absolute and relative humidity and moisture content. -
Fluid Mechanics
The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time. -
Gases and Compressed Air
Air, LNG, LPG and other common gas properties, pipeline capacities, sizing of relief valves. -
Material Properties
Material properties of gases, fluids and solids - densities, specific heats, viscosities and more.
Related Documents
-
Air - Composition and Molecular Weight
Dry air is a mechanical mixture of nitrogen, oxygen, argon and several other gases in minor amounts. -
Air - Density vs. Pressure and Temperatures
Air density at pressure ranging 1 to 10 000 bara (14.5 - 145000 psi) and constant selected temperatures. -
Air - Density, Specific Weight and Thermal Expansion Coefficient vs. Temperature and Pressure
Online calculator, figures and tables showing density, specific weight and thermal expansion coefficients of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units. -
Air - Dynamic and Kinematic Viscosity
Online calculator, figures and tables with dynamic (absolute) and kinematic viscosity for air at temperatures ranging -100 to 1600°C (-150 to 2900°F) and at pressures ranging 1 to 10 000 bara (14.5 - 145000 psia) - SI and Imperial Units. -
Air - Humidity Ratio
The mass of water vapor present in moist air - to the mass of dry air. -
Air - Moisture Holding Capacity vs. Temperature
The moisture holding capacity of air increases with temperature. -
Air - Molecular Weight and Composition
Dry air is a mixture of gases where the average molecular weight (or molar mass) can be calculated by adding the weight of each component. -
Air - Prandtl Number
Prandtl number for air vs. temperature and pressure. -
Air - Properties at Gas-Liquid Equilibrium Conditions
Properties of air change along the boiling and condensation curves (temperature and pressure between triple point and critical point conditions). An air phase diagram included. -
Air - Specific Heat vs. Pressure at Constant Temperature
Figures and tables with isobaric (Cp) and isochoric (Cv) specific heat of air at constant temperature and pressure ranging 0.01 to 10000 bara. -
Air - Specific Heat vs. Temperature at Constant Pressure
Online calculator with figures and tables showing specific heat (Cp and Cv) of dry air vs. temperature and pressure. SI and imperial units. -
Air - Speed of Sound vs. Temperature
Speed of sound in air at standard atmospheric pressure with temperatures ranging -40 to 1000oC (-40 to 1500oF) - Imperial and SI Units. -
Air - Thermal Conductivity vs. Temperature and Pressure
Online calculator with figures and tables showing air thermal conductivity vs. temperature and pressure. SI and imperial units. -
Air - Thermal Diffusivity vs. Temperature and Pressure
Figures and tables withdry air thermal diffusivity vs. temperarure and pressure. SI and Imperial units. -
Air - Thermophysical Properties
Thermal properties of air at different temperatures - density, viscosity, critical temperature and pressure, triple point, enthalpi and entropi, thermal conductivity and diffusivity and more. -
Air Conditioning - Cooling of Air and Condensate Generated
Water may condensate when air is cooled in air conditioning systems. -
Carbon Dioxide Concentration in Rooms Occupied with People
Carbon dioxide concentration in a room may indicate air quality and ventilation system efficiency. -
Compressed Air - Pressure Drop Diagrams, Metric Units
Pressure loss in compressed air pipe lines. -
Dry Air - Thermodynamic and Physical Properties
Thermodynamic properties of dry air - specific heat, ratio of specific heats, dynamic viscosity, thermal conductivity, Prandtl number, density and kinematic viscosity at temperatures ranging 175 - 1900 K. -
Gases Solved in Water - Diffusion Coefficients
Diffusion flux [kg/m2s] tells how fast a substanse solved in another substance flows due to concentration gradients. Diffusion constants [m2/s] for several gases in water. -
Moist Air - Specific Volume
Specific volume of moist air is defined as the total volume of humid air per mass unit of dry air -
Moist Air - Weight of Water Vapor
Weight of water vapor in air -
Solubility of Air in Water
The amount of air that can be dissolved in water decreases with temperature and increases with pressure.
