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 dynamic_sample Feb10-13 04:27 PM

Question about fluid dynamics (calculating concentration)

Hi all,

I have a question about calculating the concentration of continuous air and carbon monoxide flowing through a pipe. If the gas cylinder originally has 20% CO and 80% air and it will be diluted by another gas cylinder of air, how do you account for temperature, pressure, and 'viscosity' of the gases when calculating the concentration in ppm?

 cjl Feb10-13 04:40 PM

Re: Question about fluid dynamics (calculating concentration)

To a reasonable approximation, you can probably assume perfect mixing and get the concentration from that. Do you know the flow rates from both the original source and the diluting gas?

 dynamic_sample Feb10-13 05:11 PM

Re: Question about fluid dynamics (calculating concentration)

Yeah, I know the flow rates from both so, I can use C1*F1=C2*F2. I'm assuming perfect mixing. Do you know how I could correct for temperature or viscosity?

 cjl Feb10-13 05:33 PM

Re: Question about fluid dynamics (calculating concentration)

Viscosity shouldn't matter if you know the flow rate, and temperature will cause a change in the density (which could change the mass flow rate). I would probably calculate the molar flow rates of each first (based on volumetric flow rate and density), and then the concentration of the resultant mixture should be fairly easy to find.

 dynamic_sample Feb10-13 06:40 PM

Re: Question about fluid dynamics (calculating concentration)

You know a lot more about this than I do. Thank you for your help! I found the molar flow rate in mol/min. I know this might be obvious, but I can't figure out how to calculate concentration from here. Thank you again!

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