Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

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.

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 /(m2s)]
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, D 12 , 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



Diff coeff gas air temperature C

Air - Diffusion Coefficients of Gases in Excess of Air
Gases in large excess of air Diffusion coefficient, D 12 , [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

Related Topics

  • Air Psychrometrics

    Moist and humid air calculations. Psychrometric charts and Mollier diagrams. Air-condition systems temperatures, absolute and relative humidities and moisture content in air.
  • 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

    Properties of air, LNG, LPG and other common gases. Pipeline capacities and sizing of relief valves.
  • Material Properties

    Properties of gases, fluids and solids. Densities, specific heats, viscosities and more.

Related Documents

Search

Search is the most efficient way to navigate the Engineering ToolBox.

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

Translate this Page

Translate this page to Your Own Language .

About the Engineering ToolBox!

Privacy Policy

We don't collect information from our users. More about

We use a third-party to provide monetization technologies for our site. You can review their privacy and cookie policy here.

You can change your privacy settings by clicking the following button: .

Citation

This page can be cited as

  • The Engineering ToolBox (2018). Air - Diffusion Coefficients of Gases in Excess of Air. [online] Available at: https://www.engineeringtoolbox.com/air-diffusion-coefficient-gas-mixture-temperature-d_2010.html [Accessed Day Month Year].

Modify the access date according your visit.

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Unit Converter

















































4.19.9

.