firemodels
DSC output for tga_analysis case is broken
The DSC plot for tga_analysis in the User's Guide is out of range.
[mcgratta@burn fds]$ git bisect bad
f28cbaa86a1bb179efc2823490d14b69b0605934 is the first bad commit
commit f28cbaa86a1bb179efc2823490d14b69b0605934
Author: Jason Floyd <[email protected]>
Date: Mon Feb 12 15:42:49 2024 -0500
FDS Source: Move assumed gas temp ramp, edit NIST 25 cone case
Source/ccib.f90 | 16 +-
Source/wall.f90 | 40 +-
.../FDS_Input_Files/NIST_Cone_Test_25kW.fds | 1324 +++++++++++++++++++-
.../FDS_Input_Files/pmma_properties.txt | 2 +-
Validation/NIST_Polymers/Run_All.sh | 2 +-
.../Sprinklers_and_Sprays/water_evaporation_6a.fds | 51 -
6 files changed, 1318 insertions(+), 117 deletions(-)
delete mode 100644 Verification/Sprinklers_and_Sprays/water_evaporation_6a.fds
I see the problem. I had noticed tga_analysis was broken and thought I had fixed it (all the columns were wrong before) but I missed the DSC which wasn't caught by firebot. We are plotting the FDS prediction against itself. We could commit a hand calc (python script and resulting csv file) and then switch metrics for MLR, MCC, and DSC to max to capture the peaks.
pushed up the fix. can work on getting an analytic tga result for firebot.
A simple interim hack for the "analytic result" could be to store the "correct" result from this run for comparison. Not ideal, but it would at least catch a change.
An alternative is to see if the area under the curve has a physical meaning that we can check against.
MLR should integrate to the intial mass * (1-char fraction) and MCC should integrate to initial mass * (1 - char fraction) * heat of combustion. DSC has a physical meaning but not one that is easily analytic. A goodly portion of the DSC is just the mass participating in each reaction time the heat of reaction but there is also the contribution of the specific heat over time and peak width impacts that.
DSC integrated over time comes to 1867 J/g. I can get close to this by summing the contributions of reaction energy and specific heat. But, yes, it's hard to pin down exactly.