I Have Some Questions About Gas-phase Device Measurement Points.

[boyu-dotcom]

I am using the Mass Flux in Z Direction measurement point in the gas-phase to measure the mass (kg) of co2 and co. However, the obtained data unit is kg/s/m².

I would like to ask if anyone can explain the meaning of this unit? Since I am trying to determine the mass (kg) of CO₂ and CO, I am wondering whether the m² is related to the grid cells? I have checked the FDS Guide, but I couldn't find a clear answer.

Alternatively, does anyone have suggestions on how to measure mass using FDS?
If I want to eliminate m² from the unit kg/s/m², should I multiply by the grid cell area or the measurement point opening area?

[drjfloyd]

Flux is a rate per unit area quantity, so mass flux is the rate that mass flows through an area or mass per area per time or kg/m2/s. You probably want to be using density or mass fraction possibly with a volume integral depending on exactly what it is you are doing with the quantity. You may also want to review 27.8 in the Guide for another option.

[boyu-dotcom]

Sorry, what I am working on is related to carbon emissions. I want to construct a building, set up a fire source, and detect its carbon dioxide emissions.
I want to know if this command meets my requirements.

[drjfloyd]

Make sure you have read the User's Guide and studied the various examples (all of which are provided to you). The only command you have given so far is an image for which none of those have anything to do with a fire or outputs from a fire. Again, if you know the heat release rate and you know the combustion reaction you are using, then you have the CO2 production.

[boyu-dotcom]

Sorry, let me put it this way. I want to confirm whether the command I set complies with the guidelines for 27.8 Gas Mass Data setup instructions.

[drjfloyd]

&DUMP MASS_FILE=T/ will output the mass of gasses in the domain. However, if you have any OPEN boundaries or leakage paths to the ambient, then this may not equal the amount produced as some combustion products might leave the domain.

If you have a heat release rate (which you have either specified explicitly or you can measure in FDS) and you know the combustion reaction (which you must specify explicitly) then you know the CO2 production.

[boyu-dotcom]

thank you