FDS Source: dont include HRR_OX in summation of Q_TOTAL for hrr.csv file. Issue #14362

Author: ericvmueller

Manuals/FDS_User_Guide/FDS_User_Guide.tex

@@ -10299,14 +10299,14 @@ \subsection{Heat Release Rate and Energy Conservation}
 \begin{itemize}
 \item \ct{Q_ENTH} The change in the sensible enthalpy of the gas. $\rho$ is the density of the gas (kg/m$^3$). $h_{\rm s}$ is the \underline{s}ensible enthalpy of the gas (kJ/kg). The volume integral is over the entire domain.
 \item \ct{HRR} The heat release rate of the fire (kW) resulting from gas phase combustion.
-\item \ct{HRR_OX} The heat release rate (kW) of any surface oxidation reactions. This helps when comparing to heat release measurements obtained from oxygen consumption calorimetry, as the additional oxygen sink from surface reactions will be lumped into the measurement.
+\item \ct{HRR_OX} The heat release rate (kW) of any solid phase oxidation reactions. This should be summed with the \ct{HRR} column when comparing results to heat release measurements obtained from oxygen consumption calorimetry, as the additional oxygen sink from solid phase reactions will be lumped into the calorimetry measurement. This term does not appear in Eq.~(\ref{eqn_enthalpytransport}) because the effect of solid phase reactions on the gas phase occurs implicitly via sensible enthalpy transport (\ct{Q_CONV}) and heat transfer (\ct{Q_COND}, \ct{Q_RADI}) at the solid surfaces.
 \item \ct{Q_RADI} The thermal radiation {\em into} the domain from the exterior boundary or particles.  $\dot{\bq}_{\rm r}''$ is the \underline{r}adiation heat flux vector (\unit{kW/m^2}). Its divergence represents the net radiative emission from a volume of gas. Typically, \ct{Q_RADI} has a negative value, meaning that a fire or hot gases radiate energy out of the domain. $\dq_{\rm p,r}$ is the \underline{r}adiation absorbed by a droplet or \underline{p}article (kW). This term is added to \ct{Q_RADI} and subtracted from \ct{Q_PART} because it is implicitly included in $\nabla \cdot \dot{\bq}_{\rm r}''$ and needs to be separated off for the purpose of explicitly accounting for it in the energy budget.
 \item \ct{Q_CONV} The flow of sensible enthalpy {\em into} the computational domain. $\dm_{\rm p,\alpha}$ is the production rate of gas species $\alpha$ from a solid \underline{p}article or liquid droplet (kg/s). $h_{\rm s,\alpha}$ is the \underline{s}ensible enthalpy of gas species $\alpha$ (kJ/kg). $\rho$ is the gas density (kg/m$^3$), $\bu$ is the velocity vector (m/s). $h_{\rm s}$ is the \underline{s}ensible enthalpy of the gas. If the gas is flowing out of the domain, $\bu \cdot \d {\bf S}$ is positive.
 \item \ct{Q_COND} The convective heat flux {\em into} the computational domain. $\dq_{\rm c}''$ is the heat \underline{c}onvected from the gas to a surface. If the gas is relatively hot and the surfaces/particles/droplets relatively cool, \ct{Q_COND} is negative. At \ct{OPEN} boundaries, \ct{Q_COND} is $\int k \nabla T \cdot \d {\bf S}$, where $k$ (kW/(m$\cdot$K)) is the turbulent thermal conductivity of the gas and $\nabla T$ is the temperature gradient across the open boundary. $\dq_{\rm p,w}$ is the energy transferred from a solid surface (\underline{w}all) to a droplet or \underline{p}article adhering to it. Notice that it is subtracted off in \ct{Q_PART} because it makes no contribution to the energy of the gas.
 \item \ct{Q_PRES} The work done by volumetric expansion (kW).
 \item \ct{Q_PART} The rate of energy gained by the gas from liquid droplets or solid particles. $\dq_{\rm p,r}$ is the \underline{r}adiation absorbed by a droplet or \underline{p}article (kW). $\dq_{\rm p,c}$ is the energy transferred via \underline{c}onvection from the gas to a droplet or \underline{p}article (kW). $\dq_{\rm p,w}$ is the energy transferred from a solid surface (\underline{w}all) to a droplet or \underline{p}article adhering to it.
 \end{itemize}
-An additional column, \ct{Q_TOTAL}, includes the sum of the terms on the right hand side of the equation. Ideally, this sum should equal the term on the left, \ct{Q_ENTH}. All terms are reported in units of kW.
+An additional column, \ct{Q_TOTAL}, includes the sum of the terms on the right hand side of the equation. Note that this summation does not include \ct{HRR_OX}, as explained above. Ideally, this sum should equal the term on the left, \ct{Q_ENTH}. All terms are reported in units of kW.
 
 The other columns in the \ct{CHID_hrr.csv} file contain the total burning rate of fuel, in units of kg/s, and the zone pressures. Note that the reported value of the burning rate is not adjusted to account for the possibility that each individual material might have a different heat of combustion. For this reason, it is not always the case that the reported total burning rate multiplied by the gas phase heat of combustion is equal to the reported heat release rate.
 

Source/dump.f90

@@ -10268,6 +10268,7 @@ SUBROUTINE DUMP_HRR(T,DT)
 
 REAL(EB), INTENT(IN) :: T,DT
 REAL(FB) :: STIME
+REAL(EB) :: Q_DOT_TOTAL_SUM
 INTEGER :: I,N_ZONE_TMP
 REAL(EB), DIMENSION(:), ALLOCATABLE ::  P_ZONE_P
 
@@ -10276,6 +10277,9 @@ SUBROUTINE DUMP_HRR(T,DT)
 Q_DOT_SUM = Q_DOT_SUM/MAX(DT,T-T_LAST_DUMP_HRR)
 M_DOT_SUM = M_DOT_SUM/MAX(DT,T-T_LAST_DUMP_HRR)
 
+! Sum up Q_TOTAL, excluding Q_DOT_SUM(2) which is HRR_OX and does not contribute directly
+Q_DOT_TOTAL_SUM = SUM([Q_DOT_SUM(1),Q_DOT_SUM(3:N_Q_DOT-1)])
+
 N_ZONE_TMP = 0
 IF (N_ZONE>0) THEN
    ALLOCATE(P_ZONE_P(N_ZONE))
@@ -10287,10 +10291,10 @@ SUBROUTINE DUMP_HRR(T,DT)
 
 WRITE(TCFORM,'(A,I0,5A)') "(",N_Q_DOT+1+N_TRACKED_SPECIES+N_ZONE_TMP,"(",FMT_R,",','),",FMT_R,")"
 IF (N_ZONE_TMP>0) THEN
-   WRITE(LU_HRR,TCFORM) STIME,0.001_EB*Q_DOT_SUM(1:N_Q_DOT),0.001_EB*SUM(Q_DOT_SUM(1:N_Q_DOT-1)),&
+   WRITE(LU_HRR,TCFORM) STIME,0.001_EB*Q_DOT_SUM(1:N_Q_DOT),0.001_EB*Q_DOT_TOTAL_SUM,&
                         M_DOT_SUM(1:N_TRACKED_SPECIES),(P_ZONE_P(I),I=1,N_ZONE_TMP)
 ELSE
-   WRITE(LU_HRR,TCFORM) STIME,0.001_EB*Q_DOT_SUM(1:N_Q_DOT),0.001_EB*SUM(Q_DOT_SUM(1:N_Q_DOT-1)),&
+   WRITE(LU_HRR,TCFORM) STIME,0.001_EB*Q_DOT_SUM(1:N_Q_DOT),0.001_EB*Q_DOT_TOTAL_SUM,&
                         M_DOT_SUM(1:N_TRACKED_SPECIES)
 ENDIF