Question about fluid dynamics (calculating concentration)

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Discussion Overview

The discussion revolves around calculating the concentration of carbon monoxide (CO) in a mixture with air flowing through a pipe. Participants explore how to account for factors such as temperature, pressure, and viscosity in the concentration calculation, focusing on the implications of mixing gases and flow rates.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant inquires about calculating the concentration of CO in a gas mixture, specifically addressing the effects of temperature, pressure, and viscosity.
  • Another participant suggests assuming perfect mixing to simplify the concentration calculation and asks about the flow rates of the gases involved.
  • A participant confirms knowledge of the flow rates and mentions using the equation C1*F1=C2*F2 under the assumption of perfect mixing, seeking advice on correcting for temperature and viscosity.
  • It is proposed that viscosity may not significantly impact the calculation if flow rates are known, while temperature could affect density and mass flow rate, suggesting a method to calculate molar flow rates first.
  • A participant expresses gratitude for the assistance and seeks clarification on how to derive concentration from the molar flow rate they have calculated.

Areas of Agreement / Disagreement

Participants generally agree on the approach of assuming perfect mixing and the relevance of flow rates, but there is no consensus on the specific impacts of temperature and viscosity on the concentration calculation.

Contextual Notes

Participants mention various factors that could influence the calculations, such as changes in density due to temperature, but do not resolve how these factors should be quantitatively integrated into the concentration calculations.

Who May Find This Useful

This discussion may be useful for individuals interested in fluid dynamics, gas mixing processes, or those working on related calculations in engineering or environmental science.

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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?

Any advice would be appreciated.
Thanks for your help.
 
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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?
 
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?
 
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.
 
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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