HRR is zero, It seems like combustion is not occurring, the meterial is Trichlorosilane.

[HOYOUN NA]

Hello, I'm glad to be a member of FDS and Smokeview Discussions.
I want to learn about FDS through a lot of communication.

I would like to use FDS to determine the thermal radiation of trichlorosilane combustion.
I spent a lot of time to defining the stoichiometry according to the combustion reaction of trichlorosilane with many trials and errors.
Afterward, the simulation worked properly, and I confirmed the temperature changes accordingly.

However, upon examining the extracted data, I found that the Heat Release Rate (HRR) did not change from zero, and the fluctuation in temperature was essentially due to radiative heat and convection at the specified surface temperature.
I can't figure out whether the substance definition is incorrect or what the problem might be.
I have attached the FDS data I defined.
I would greatly appreciate any insights.

Best regards.

TCS_Test_anyway.fds

&HEAD CHID='TCS_Test_anyway'/
&TIME T_END=100.0/
&DUMP DT_BNDF=2.0, DT_DEVC=1.0, DT_HRR=1.0, DT_ISOF=2.0, DT_SL3D=1.0/

&MESH ID='MESH', IJK=50,50,50, XB=0.0,10.0,0.0,10.0,0.0,10.0/

&SPEC ID='HYDROGEN CHLORIDE'/
&SPEC ID='NITROGEN'/
&SPEC ID='WATER VAPOR'/
&SPEC ID='HYDROGEN ATOM', LUMPED_COMPONENT_ONLY=.TRUE./
&SPEC ID='OXYGEN', LUMPED_COMPONENT_ONLY=.TRUE./
&SPEC ID='SILICON DIOXIDE'/
&SPEC ID='SILICON', LUMPED_COMPONENT_ONLY=.TRUE./
&SPEC ID='CHLORINE ATOM'/
&SPEC ID='AIR01', BACKGROUND=.TRUE.,
  SPEC_ID(1)='OXYGEN',
  SPEC_ID(2)='NITROGEN',
  VOLUME_FRACTION(1)=1.0,
  VOLUME_FRACTION(2)=3.76/
&SPEC ID='TCS', MASS_FRACTION_0=1.0,
  SPEC_ID(1)='CHLORINE ATOM',
  SPEC_ID(2)='HYDROGEN ATOM',
  SPEC_ID(3)='SILICON',
  VOLUME_FRACTION(1)=3.0,
  VOLUME_FRACTION(2)=1.0,
  VOLUME_FRACTION(3)=1.0/

&REAC ID='Reaction_TCS',
      HEAT_OF_COMBUSTION=3745.0,
      FUEL='TCS',
      SPEC_ID_NU='AIR01','TCS','HYDROGEN CHLORIDE','WATER VAPOR','SILICON DIOXIDE','CHLORINE ATOM','NITROGEN',
      NU=-6.0,-5.0,1.0,2.0,5.0,14.0,22.56/

&SURF ID='fire',
      COLOR='RED',
      MLRPUA=0.033,
      TMP_FRONT=300.0,
      EMISSIVITY=1.0,
      MASS_FRACTION=1.0,
      SPEC_ID='TCS',
      TAU_MF=1.0/

&OBST ID='Obstruction', XB=3.0,6.0,3.0,6.0,0.0,1.0, SURF_IDS='fire','INERT','INERT'/

&VENT ID='Mesh Vent: MESH [XMAX]', SURF_ID='OPEN', XB=10.0,10.0,0.0,10.0,0.0,10.0, COLOR='INVISIBLE'/
&VENT ID='Mesh Vent: MESH [XMIN]', SURF_ID='OPEN', XB=0.0,0.0,0.0,10.0,0.0,10.0, COLOR='INVISIBLE'/
&VENT ID='Mesh Vent: MESH [YMAX]', SURF_ID='OPEN', XB=0.0,10.0,10.0,10.0,0.0,10.0, COLOR='INVISIBLE'/
&VENT ID='Mesh Vent: MESH [YMIN]', SURF_ID='OPEN', XB=0.0,10.0,0.0,0.0,0.0,10.0, COLOR='INVISIBLE'/
&VENT ID='Mesh Vent: MESH [ZMAX]', SURF_ID='OPEN', XB=0.0,10.0,0.0,10.0,10.0,10.0, COLOR='INVISIBLE'/
&VENT ID='Mesh Vent: MESH [ZMIN]', SURF_ID='INERT', XB=0.0,10.0,0.0,10.0,0.0,0.0, COLOR='INVISIBLE'/

&SLCF QUANTITY='TEMPERATURE', VECTOR=.TRUE., CELL_CENTERED=.TRUE., ID='z=3', PBZ=3.0/
&SLCF QUANTITY='TEMPERATURE', VECTOR=.TRUE., CELL_CENTERED=.TRUE., ID='y=4', PBY=4.0/
&SLCF QUANTITY='TEMPERATURE', VECTOR=.TRUE., CELL_CENTERED=.TRUE., ID='z=4', PBZ=2.0/


&TAIL /

[Kevin McGrattan]

Do you see that TCS is being produced? Create a slice (SLCF) for this gas species. I would check all gas species before you attempt to do combustion. Then, set SUPPRESSION=F to prevent FDS from extinguishing the reaction.

[HOYOUN NA]

Thank you for your advice.

I cannot see the TCS is being produced and also all gases too.
Mass fraction of all gases is not observed.
Is it not possible to simulate the combustion of TCS in FDS?
and what is the meaning of set SUPPRESSION=F?

2023년 9월 26일 화요일 오전 12시 2분 20초 UTC+9에 Kevin McGrattan님이 작성:

[Kevin]

You have specified MASS_FRACTION_0=1 for TCS. This means that the volume is filled with 100% of this gas at the start. Why?

You can learn the meaning of SUPPRESSION by searching on this word in the FDS User's Guide.

[dr_jfloyd]

In addition to Kevin's comment.

Your fuel is trichlorosilane. This the molecule SiCl3H.  You have specified this as the mixture of the HYDROGEN ATOM gas, CHLORINE ATOM gas, and SILICON gas. A mixture of atomic gases is not the same as a molecule.  You may want to define the gas species SiCl3H with appropriate thermophyscial properties.

You should read about the FDS radiation model, the default assumptions it makes,  and how it computes radiative emission and absoprtion and decide to what extent you feel those are appropriate for SiCl3H.

[HOYOUN NA]

I sincerely thank Kevin and Dr. Floyd for providing the answers.
The elemental gas issue you advised on has been resolved, and FDS is now functioning normally.
However, when selecting chlorine in FDS for Cl2, a combustion product of TCS,
it was observed to interpret it as C (carbon) and I (iodine).
Therefore, chlorine atoms were used to address this issue.
I hope that NIST can address this problem.

I have learned a lot. Thank you once again.

2023년 9월 26일 화요일 오전 4시 28분 7초 UTC+9에 dr_jfloyd님이 작성:

[dr_jfloyd]

Yes, the formula for CHLORINE had CI2 (Cee Eye two) rather than Cl2 (Cee ell two). The next test version of FDS (https://github.com/firemodels/test_bundles) will have that fixed.