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FDS Manuals: Number of species and number of reactions symbol change in Tech Guide Appendix
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Manuals/FDS_Technical_Reference_Guide/Appendices.tex

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@@ -846,22 +846,22 @@ \chapter{Analytical Jacobian Calculation for Detailed Chemical Mechanism}
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847847
The system of ODEs to solve a detailed chemical mechanism is given by Eqs.~(\ref{eq:chemistry_ode_system}) and (\ref{eq:TemperatureDerivative})
848848
\begin{equation}\label{eq:chemistry_ode_system_appendix}
849-
\frac{\d C_k}{\d t} = \dot{\omega}_k = \sum_{i=1}^{N_{reac}} b_i \ \nu_{ki} \ r_i, j=1,2,3,...,N_{sp}
849+
\frac{\d C_k}{\d t} = \dot{\omega}_k = \sum_{i=1}^{N_{\text{r}}} b_i \ \nu_{ki} \ r_i, j=1,2,3,...,N_{\text{s}}
850850
\end{equation}
851851
\begin{equation}\label{eq:TemperatureDerivativeAppendix}
852-
\frac{\d T}{\d t} = \dot{T} = -\frac{1}{\rho c_p} \sum_{j=1}^{N_{sp}}h_j W_j \dot{\omega}_j
852+
\frac{\d T}{\d t} = \dot{T} = -\frac{1}{\rho c_p} \sum_{j=1}^{N_{\text{s}}}h_j W_j \dot{\omega}_j
853853
\end{equation}
854854
For Eq.~(\ref{eq:chemistry_ode_system_appendix}), $C_j$ is the molar concentration \si{(kmol/m^3)} of the $j$th species; $b_i$ is the reaction rate modification coefficient of the $i$th reaction due to third-body effects and pressure; $\nu_{ki} = {\nu}_{ki}^{''} - {\nu}_{ki}^{'}$; and $r_i$ is the reaction progress rate of the $i$th reaction.
855855
\begin{equation}\label{eq:reaction_progress_rate_appendix}
856-
r_i = k_{f,i} \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{'}} - k_{r,i} \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{''}}
856+
r_i = k_{f,i} \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{'}} - k_{r,i} \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{''}}
857857
\end{equation}
858858
For Eq.~(\ref{eq:TemperatureDerivativeAppendix}), $\rho$ is the density \si{(kg/m^3)}, $c_p$ is the specific heat of the mixture (J/kg/K), $h_k$ is the absolute enthalpy that includes enthalpy of formation (J/kg), $W_j$ is the molecular weight (kg/kmol) of species $j$, and $\dot{\omega}$ is the species production rate given by Eq.~(\ref{eq:chemistry_ode_system_appendix}).
859859

860860
The system of ODEs can be represented by:
861861
\be
862862
\begin{aligned}
863-
f &= \left[ \frac{\d C_1}{\d t} \ \frac{\d C_2}{\d t} \ldots \ \frac{\d C_{N_{sp}}}{\d t} \ \frac{\d T}{\d t} \right]^T \
864-
&= \left[ \dot{\omega}_1 \ \dot{\omega}_2 \ldots \ \dot{\omega}_{N_{sp}} \ \dot{T} \right]^T \
863+
f &= \left[ \frac{\d C_1}{\d t} \ \frac{\d C_2}{\d t} \ldots \ \frac{\d C_{N_{\text{s}}}}{\d t} \ \frac{\d T}{\d t} \right]^T \
864+
&= \left[ \dot{\omega}_1 \ \dot{\omega}_2 \ldots \ \dot{\omega}_{N_{\text{s}}} \ \dot{T} \right]^T \
865865
\end{aligned}
866866
\ee
867867

@@ -870,12 +870,12 @@ \chapter{Analytical Jacobian Calculation for Detailed Chemical Mechanism}
870870
\begin{aligned}
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J &=
872872
\begin{bmatrix}
873-
\frac{\partial\dot{\omega}_1}{\partial C_1}& \frac{\partial \dot{\omega}_2}{\partial C_1} & \ldots & \frac{\partial \dot{\omega}_{N_{sp}}}{\partial C_1} & | & \frac{\partial \dot{T}}{\partial C_1}\\
874-
\frac{\partial\dot{\omega}_1}{\partial C_2}& \frac{\partial \dot{\omega}_2}{\partial C_2} & \ldots & \frac{\partial \dot{\omega}_{N_{sp}}}{\partial C_2} & | &\frac{\partial \dot{T}}{\partial C_2}\\
873+
\frac{\partial\dot{\omega}_1}{\partial C_1}& \frac{\partial \dot{\omega}_2}{\partial C_1} & \ldots & \frac{\partial \dot{\omega}_{N_{\text{s}}}}{\partial C_1} & | & \frac{\partial \dot{T}}{\partial C_1}\\
874+
\frac{\partial\dot{\omega}_1}{\partial C_2}& \frac{\partial \dot{\omega}_2}{\partial C_2} & \ldots & \frac{\partial \dot{\omega}_{N_{\text{s}}}}{\partial C_2} & | &\frac{\partial \dot{T}}{\partial C_2}\\
875875
\ldots & \ldots & \ldots & \ldots & | & \ldots\\
876-
\frac{\partial \dot{\omega}_1}{\partial C_{N_{sp}}}& \frac{\partial \dot{\omega}_2}{\partial C_{N_{sp}}} & \ldots & \frac{\partial \dot{\omega}_{N_{sp}}}{\partial C_{N_{sp}}} & | & \frac{\partial \dot{T}}{\partial C_{N_{sp}}}\\
876+
\frac{\partial \dot{\omega}_1}{\partial C_{N_{\text{s}}}}& \frac{\partial \dot{\omega}_2}{\partial C_{N_{\text{s}}}} & \ldots & \frac{\partial \dot{\omega}_{N_{\text{s}}}}{\partial C_{N_{\text{s}}}} & | & \frac{\partial \dot{T}}{\partial C_{N_{\text{s}}}}\\
877877
---& --- & --- & --- & | & ---\\
878-
\frac{\partial \dot{\omega}_1}{\partial T}& \frac{\partial \dot{\omega}_2}{\partial T} & \ldots & \frac{\partial \dot{\omega}_{N_{sp}}}{\partial T} & | & \frac{\partial \dot{T}}{\partial T}\\
878+
\frac{\partial \dot{\omega}_1}{\partial T}& \frac{\partial \dot{\omega}_2}{\partial T} & \ldots & \frac{\partial \dot{\omega}_{N_{\text{s}}}}{\partial T} & | & \frac{\partial \dot{T}}{\partial T}\\
879879
\end{bmatrix}
880880
&=\begin{bmatrix}
881881
\frac{\partial \mathbf{\dot{\omega}}}{\mathbf{\partial C}}& \frac{\partial \dot{T}}{\partial \mathbf{C}}\\
@@ -888,16 +888,16 @@ \subsection*{Calculation of $\frac{\partial \mathbf{\dot{\omega}}}{\mathbf{\part
888888
By taking derivative of Eq.~(\ref{eq:chemistry_ode_system_appendix}) with respect to concentration, we can write:
889889
\begin{equation}\label{eq:Jac1st}
890890
\begin{aligned}
891-
\frac{\partial \dot{\omega}_k}{\partial C_l} &= \sum_{i=1}^{N_{reac}} \left[ \nu_{ki} \ r_i \ \frac{\partial b_i}{\partial C_l} + b_i \nu_{ki} \ \left( k_{f,i} \nu_{li}^{'} \ \frac{\prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{'}} }{C_l} - k_{r,i} \ \nu_{li}^{''} \ \frac{\prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{''}} }{C_l} \right) \right],
891+
\frac{\partial \dot{\omega}_k}{\partial C_l} &= \sum_{i=1}^{N_{reac}} \left[ \nu_{ki} \ r_i \ \frac{\partial b_i}{\partial C_l} + b_i \nu_{ki} \ \left( k_{f,i} \nu_{li}^{'} \ \frac{\prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{'}} }{C_l} - k_{r,i} \ \nu_{li}^{''} \ \frac{\prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{''}} }{C_l} \right) \right],
892892
\end{aligned}
893893
\end{equation}
894894
Here, the $\frac{\partial b_i}{\partial C_l}$ term can be calculated using Eqs.~(\ref{eq:reac_mod_coeff})-(\ref{eq:falloff_Fi}).
895895

896896
\subsection*{Calculation of $\frac{\partial \mathbf{\dot{\omega}}}{\partial T}$}
897897
By taking derivative of Eq.~(\ref{eq:chemistry_ode_system_appendix}) with respect to temperature, we can write:
898898
\begin{multline}\label{eq:Jac2nd}
899-
\frac{\partial \dot{\omega}_k}{\partial T} = \sum_{i=1}^{N_{reac}} \left[ \nu_{ki} \ r_i \ \frac{\partial b_i}{\partial T} + b_i \nu_{ki} \ \left\{ \frac{\partial k_{f,i}}{\partial T} \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{'}} + k_{f,i} \frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{'}} \right) \right. \right. \\
900-
- \left. \left. \frac{\partial k_{r,i}}{\partial T} \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{''}} - k_{r,i} \frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{''}} \right) \right\} \right]
899+
\frac{\partial \dot{\omega}_k}{\partial T} = \sum_{i=1}^{N_{reac}} \left[ \nu_{ki} \ r_i \ \frac{\partial b_i}{\partial T} + b_i \nu_{ki} \ \left\{ \frac{\partial k_{f,i}}{\partial T} \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{'}} + k_{f,i} \frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{'}} \right) \right. \right. \\
900+
- \left. \left. \frac{\partial k_{r,i}}{\partial T} \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{''}} - k_{r,i} \frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{''}} \right) \right\} \right]
901901
\end{multline}
902902
Similar to $\frac{\partial b_i}{\partial C_l}$, $\frac{\partial b_i}{\partial T}$ can be calculated using Eqs.~(\ref{eq:reac_mod_coeff})-(\ref{eq:falloff_Fi}).
903903
\begin{equation} \label{eq:kfTmpDerivative}
@@ -912,14 +912,14 @@ \subsection*{Calculation of $\frac{\partial \mathbf{\dot{\omega}}}{\partial T}$}
912912
Here, $K_i$ is the concentration equilibrium constant obtained using Eq.~(\ref{eq:equilibrium_const}). Through mathematical derivation, it can be shown that:
913913
\begin{equation}\label{eq:EqConstTmpDerivative}
914914
\begin{aligned}
915-
\frac{1}{K_i} \frac{\partial K_i}{\partial T} = -\frac{1}{T} \left( \sum_{i=1}^{N_{sp}} {\nu}_{ji}^{''} - \sum_{i=1}^{N_{sp}} {\nu}_{ji}^{'} \right) + \frac{1}{R T} \left( \frac{\Delta G_{\mathrm{rxn}}}{T} + \Delta S_{\mathrm{rxn}} \right)
915+
\frac{1}{K_i} \frac{\partial K_i}{\partial T} = -\frac{1}{T} \left( \sum_{i=1}^{N_{\text{s}}} {\nu}_{ji}^{''} - \sum_{i=1}^{N_{\text{s}}} {\nu}_{ji}^{'} \right) + \frac{1}{R T} \left( \frac{\Delta G_{\mathrm{rxn}}}{T} + \Delta S_{\mathrm{rxn}} \right)
916916
\end{aligned}
917917
\end{equation}
918918
Here, $\Delta S_{\mathrm{rxn}}$ is the change in entropy, and can be calculated similar to the process described in Section \ref{sec:equilChem}.
919919
\begin{equation}\label{eq:ConcTmpDerivative}
920920
\begin{aligned}
921-
\frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{'}} \right) &= - \frac{1}{T} \left( \sum_{j=1}^{N_{sp}} {\nu}_{ji}^{'} \right) \left( \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{'}} \right) \\
922-
\frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{''}} \right) &= - \frac{1}{T} \left( \sum_{j=1}^{N_{sp}} {\nu}_{ji}^{''} \right) \left( \prod_{j=1}^{N_{sp}} (C_j)^{{\nu}_{ji}^{''}} \right){}
921+
\frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{'}} \right) &= - \frac{1}{T} \left( \sum_{j=1}^{N_{\text{s}}} {\nu}_{ji}^{'} \right) \left( \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{'}} \right) \\
922+
\frac{\partial}{\partial T} \left( \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{''}} \right) &= - \frac{1}{T} \left( \sum_{j=1}^{N_{\text{s}}} {\nu}_{ji}^{''} \right) \left( \prod_{j=1}^{N_{\text{s}}} (C_j)^{{\nu}_{ji}^{''}} \right){}
923923
\end{aligned}
924924
\end{equation}
925925
In the above derivation, the relation $\frac{\partial C_j}{\partial T} = - \frac{C_j}{T}$ is used.
@@ -930,22 +930,22 @@ \subsection*{Calculation of $\frac{\partial \dot{T}}{\partial \mathbf{C}}$}
930930
By taking derivative of Eq.~(\ref{eq:TemperatureDerivativeAppendix}) with respect to concentration, we can write:
931931
\begin{equation} \label{eq:Jac3rd}
932932
\begin{aligned}
933-
\frac{\partial \dot{T}}{\partial C_l} &= \frac{\partial}{\partial C_l} \left( -\frac{1}{\rho c_p} \sum_{j=1}^{N_{sp}}h_j W_j \dot{\omega}_j \right) \\
934-
&= -\left( \frac{1}{\rho} \frac{\partial \rho}{\partial C_l} + \frac{1}{c_p} \frac{\partial c_p}{\partial C_l} \right) \dot{T} - \frac{1}{{\rho} c_p} \sum_{j=1}^{N_{sp}}h_j W_j \frac{\partial \dot{\omega}_j}{\partial C_l}
933+
\frac{\partial \dot{T}}{\partial C_l} &= \frac{\partial}{\partial C_l} \left( -\frac{1}{\rho c_p} \sum_{j=1}^{N_{\text{s}}}h_j W_j \dot{\omega}_j \right) \\
934+
&= -\left( \frac{1}{\rho} \frac{\partial \rho}{\partial C_l} + \frac{1}{c_p} \frac{\partial c_p}{\partial C_l} \right) \dot{T} - \frac{1}{{\rho} c_p} \sum_{j=1}^{N_{\text{s}}}h_j W_j \frac{\partial \dot{\omega}_j}{\partial C_l}
935935
\end{aligned}
936936
\end{equation}
937937
Using the relations $\frac{\partial \rho}{\partial C_l} = W_l$ and $\frac{\partial c_p}{\partial C_l} = - \frac{W_l}{\rho}\left( c_p -c_{p,l} \right)$, we can rewrite Eq. ~(\ref{eq:Jac3rd}) as:
938938
\begin{equation} \label{eq:Jac3rd_final}
939-
\frac{\partial \dot{T}}{\partial C_l} = \frac{W_l c_{p,l}}{\rho c_p} \dot{T} - \frac{1}{{\rho} c_p} \sum_{j=1}^{N_{sp}}h_j W_j \frac{\partial \dot{\omega}_j}{\partial C_l}
939+
\frac{\partial \dot{T}}{\partial C_l} = \frac{W_l c_{p,l}}{\rho c_p} \dot{T} - \frac{1}{{\rho} c_p} \sum_{j=1}^{N_{\text{s}}}h_j W_j \frac{\partial \dot{\omega}_j}{\partial C_l}
940940
\end{equation}
941941
Here, $c_{p,l}$ is the specific heat of species $l$. The last term Eq.~(\ref{eq:Jac3rd_final}) can be obtained using Eq. \ref{eq:Jac1st}.
942942

943943
\subsection*{Calculation of $\frac{\partial \dot{T}}{\partial T}$}
944944
By taking derivative of Eq.~(\ref{eq:TemperatureDerivativeAppendix}) with respect to temperature, we can write:
945945
\begin{equation} \label{eq:Jac4th}
946946
\begin{aligned}
947-
\frac{\partial \dot{T}}{\partial T} &= \frac{\partial}{\partial T} \left( -\frac{1}{\rho c_p} \sum_{j=1}^{N_{sp}}h_j W_j \dot{\omega}_j \right) \\
948-
&=\frac{\dot{T}}{T} - \frac{1}{c_p} \frac{\partial c_p}{\partial T} \dot{T} - \frac{1}{\rho c_p} \sum_{j=1}^{N_{sp}} \left[ h_j \frac{\partial \dot{\omega}_j}{\partial T} + \dot{\omega}_j c_{p,j} \right] W_j
947+
\frac{\partial \dot{T}}{\partial T} &= \frac{\partial}{\partial T} \left( -\frac{1}{\rho c_p} \sum_{j=1}^{N_{\text{s}}}h_j W_j \dot{\omega}_j \right) \\
948+
&=\frac{\dot{T}}{T} - \frac{1}{c_p} \frac{\partial c_p}{\partial T} \dot{T} - \frac{1}{\rho c_p} \sum_{j=1}^{N_{\text{s}}} \left[ h_j \frac{\partial \dot{\omega}_j}{\partial T} + \dot{\omega}_j c_{p,j} \right] W_j
949949
\end{aligned}
950950
\end{equation}
951951
To derive the above equation, the relations $\frac{\partial \rho}{\partial T} = -\frac{\rho}{T}$ and $\frac{\partial h_j}{\partial T} = c_{p,j}$ are used. The term $\frac{\partial \dot{\omega}_j}{\partial T}$ can be obtained using Eq.~(\ref{eq:Jac2nd}).

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