Electrical Conductivity in Gas Species

[Sandeep Baskar]

Hi,

I am trying to find the electrical conductivity of a flow with specified temperature, pressure and species composition. I tried gas.electricalConductivity but I get a "not implemented" exception thrown. I have tried using the basic 'gri30', 'gri30_mix' and 'gri30_multi' and the same error gets thrown for each of those input files.

I do not need electrical conductivity directly (even though it would be simpler), I could also find electric density of the flow yet there seems to be no properties to yield that either.

[Steven DeCaluwe]

Hi Sandeep,

I have to admit that I don’t know exactly what you’re after, here, but have the following thoughts:

1.  The ‘gri30’ mechanisms are ideal gas model implementations.  They explicitly assume a gas phase with zero electrical conductivity.

2.  Broader picture, I would think that most gas-phase flows will assume the same, unless you are dealing with plasmas or ionized flows (I wade quickly out of my depth on those topics, though).  Are you thinking of a condensed phase (liquid or solid)?  Even in this case, though, I do not know of a Cantera thermophase class which calculates electrical conductivity based on state properties.  

3. If you wanted to calculate the charge density (Coulombs per m3), which is I think what you mean by “electric density,” then there may be a pathway for you. 

In Python, the calculation would look something like this:

import cantera as ct

import numpy as np

gas = ct.Solution(‘gri30.cti’, ‘mix’) #This can be any phase you wish.  

#Calculate number of electrons for each species:

nE = np.zeros(gas.n_species)

for i in range(gas.n_species):

nE[i] = gas.n_atoms(i,’E’)

<… set to some relevant state >

<… now calculate the charge density for that state:>

charge_density = -ct.faraday*np.dot(nE,gas.concentrations)

This will give you the charge density in Coulombs per m3.  Note it will only work if ‘E’ is listed as one of the elements of your phase.  So it would actually not work for gri30, in this case.  But if ‘E’ is not included as one of the elements, than it will by definition be charge neutral.

Best,

Steven

——————————————————————————————————

Steven DeCaluwe, PhD

Assistant Professor of Mechanical Engineering

Colorado School of Mines

Brown Building W410B

Golden, CO 80401

email: deca...@mines.edu

phone: (303) 273-3666

Twitter: @CORESresearch
http://inside.mines.edu/~decaluwe/

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[Ray Speth]

Sandeep,

Electrical conductivity calculations were recently added to Cantera, thanks to some work by Bang-Shiuh Chen, in the IonGasTransport class and the accompanying gri30_ion.cti file. Please note that this feature is currently only available in the development version of Cantera.

Regards,
Ray

[Steven DeCaluwe]

Oh, nice!

Sent from my iPhone