Merge remote-tracking branch 'firemodels/master' into pyro_depth

Author: mcgratta

Manuals/FDS_User_Guide/FDS_User_Guide.tex

@@ -3365,10 +3365,26 @@ \subsection{Simulating Bench-scale Measurements like the TGA, DSC, and MCC}
 Note: If applying \ct{TGA_ANALYSIS} to a case where the \ct{SURF} is associated with a \ct{PART} class yet to be inserted into the calculation, FDS may not find the \ct{SURF} and hence throw an error. In this case, create a simple case with a single particle that is inserted at the start.
 \end{warning}
 
-The result of the \ct{TGA_ANALYSIS} is a single comma-delimited file called \ct{CHID_tga.csv}. The first and second columns of the file consist of the time and sample temperature. The third column is the normalized sample mass; that is, the sample mass divided by its initial mass. The following columns list the mass fractions of the individual material components. The next column is the total mass loss rate, in units of s$^{-1}$, followed by the mass loss rates of the individual material components. The next column is the heat release rate per unit mass of the sample in units of W/g, typical of an MCC measurement. The final column is the heat absorbed by the sample normalized by its mass, also in units of W/g, typical of a DSC measurement. Results for a typical analysis of wood are shown in Fig.~\ref{tga_results}. In this case, a sample of wood containing about 10~\% water by mass heats up and undergoes three reactions, including the evaporation of water. Note that the TGA plots include both fuel and water vapor, while the MCC results only show fuel.
+The result of the \ct{TGA_ANALYSIS} is a single comma-delimited file called \ct{CHID_tga.csv}. The first and second columns of the file consist of the time and sample temperature. The third column is the normalized sample mass; that is, the sample mass divided by its initial mass. The following columns list the mass fractions of the individual material components. The next column is the total mass loss rate, in units of s$^{-1}$, followed by the mass loss rates of the individual material components. The next column is the heat release rate per unit mass of the sample in units of W/g, typical of an MCC measurement. The final column is the rate of heat absorbed by the sample normalized by its {\it original} mass, also in units of W/g, typical of a DSC measurement. 
 
 Details of the output quantities are discussed in Sec.~\ref{info:material_components}. Further details on these measurement techniques and how to interpret them are found in the FDS Verification Guide~\cite{FDS_Verification_Guide}.
 
+\subsubsection{Example}
+
+Results for an analysis (\ct{Pyrolysis/tga_analysis.fds}) of a simplified version of wood are shown in Fig.~\ref{tga_results}. The sample, referred to as ``wet wood'', contains 10~\% ``water'' by mass. It is heated at a rate of $\beta=5/60$~K/s and undergoes three reactions: the evaporation of ``water'', the conversion of ``dry wood'' to ``char'', and the conversion of ``char'' to ``ash''.
+
+The upper two plots in Fig.~\ref{tga_results} show the results of the TGA analysis; that is, the decrease in mass as a function of sample temperature. The left plot shows the total sample mass and the right shows the individual components. Below these are two plots that show the mass loss rates of the total sample and its components. These plots are simply the (negative) values of the first derivative of the upper plots.
+
+The lower left plot in Fig.~\ref{tga_analysis} shows the results of the MCC analysis; that is, the gas phase combustion heat release rate per unit mass of the original sample. Note that this MCC plot does not include evidence of the evaporation of water because water vapor does not combust. The integral (with respect to time) under the MCC curve yields $Q=12\,680$~J/g. The heat of combustion of the ``cellulose,'' which is the assumed gas phase fuel resulting from the pyrolysis of dry wood and char, is $h_{\rm c}=14\,988$~J/g. The dry wood and char constitute $Y=0.846$ of the original sample, thus $h_{\rm c} \, Y \approx Q$. 
+
+The lower right plot Fig.~\ref{tga_analysis} shows the results of the DSC analysis. The curve represents the rate of heat absorbed by the sample. The three peaks represent the endothermic reactions where heat from the hot gas is used to evaporate water or pyrolyze the wood and char. The plateaus between the reaction peaks represent the heating of the solid only. For example, at a temperature of 200~$^\circ$C, the value is $\dot{q}(200)=0.075$~W/g which corresponds to the specific heat of the dry wood which has not yet undergone its conversion to char:
+\be
+   c_p = \frac{\dot{q}(200)}{Y(200) \, \beta} = 1 \; \hbox{kJ/(kg K)}
+\ee
+The term $Y(200)=0.9$ in the denominator is the ratio of mass of the sample at 200~$^\circ$C to the original mass.
+
+
+
 \begin{figure}[ht]
 \begin{tabular*}{\textwidth}{lr}
 \includegraphics[width=3.2in]{SCRIPT_FIGURES/tga_analysis_mass} &

Manuals/FDS_Validation_Guide/Burning_Rate_Chapter.tex

@@ -978,6 +978,32 @@ \subsection{BST/FRS Wood Crib Experiments}
 
 \clearpage
 
+\subsection{Kashiwagi Gasification}
+\label{Kashiwagi_Gasification}
+
+In Fig.~\ref{fig:Kashiwagi_Gasification_mass_flux}, mass loss rates for different coflow oxygen concentrations and exposure heat fluxes are shown and compared to the FDS simulations.
+
+\begin{figure}[!h]
+\begin{tabular*}{\textwidth}{l@{\extracolsep{\fill}}r}
+\includegraphics[height=2.15in]{SCRIPT_FIGURES/Kashiwagi_Gasification/Kashiwagi_MFLUX_25_1C} &
+\includegraphics[height=2.15in]{SCRIPT_FIGURES/Kashiwagi_Gasification/Kashiwagi_MFLUX_40_1C}
+\end{tabular*}
+\caption[Kashiwagi Gasification: weigth loss mass flux]{Kashiwagi gasification mass flux (left) 25 \si{kW/m^2} and (right) 40 \si{kW/m^2}.}
+\label{fig:Kashiwagi_Gasification_mass_flux}
+\end{figure}
+
+In Fig.~\ref{fig:Kashiwagi_Gasification_tmp}, we plot time histories of in-depth temperatures.
+
+\begin{figure}[!h]
+\begin{tabular*}{\textwidth}{l@{\extracolsep{\fill}}r}
+\includegraphics[width=0.49\textwidth]{SCRIPT_FIGURES/Kashiwagi_Gasification/Kashiwagi_TMP_10p5O2_25_1C} &
+\includegraphics[width=0.49\textwidth]{SCRIPT_FIGURES/Kashiwagi_Gasification/Kashiwagi_TMP_10p5O2_40_1C} \\
+\includegraphics[width=0.49\textwidth]{SCRIPT_FIGURES/Kashiwagi_Gasification/Kashiwagi_TMP_Air_40_1C} &
+\includegraphics[width=0.49\textwidth]{SCRIPT_FIGURES/Kashiwagi_Gasification/Kashiwagi_TMP_N2_40_1C}
+\end{tabular*}
+\caption[Kashiwagi Gasification: in-depth temperatures]{Kashiwagi Gasification: in-depth temperatures.}
+\label{fig:Kashiwagi_Gasification_tmp}
+\end{figure}
 
 \subsection{NIST/NRC Transient Combustibles}
 

Manuals/FDS_Validation_Guide/Experiment_Chapter.tex

@@ -995,6 +995,80 @@ \section{JH/NIJ Materials}
 The cone calorimeter experiments from this study are used in validation of the scaling-based pyrolysis model.
 
 
+\section{Kashiwagi Gasification}
+\label{Kashiwagi_Gasification_Description}
+
+In the pine wood gasification experiments of Kashiwagi et al.~\cite{Kashiwagi:1987}, white pine cube blocks 3.8 cm on a side were irradiated at 25 \si{kW/m^2} and 40 \si{kW/m^2} with three different oxygen concentrations in the coflow: pure nitrogen (${\rm N}_2$), 10.5 vol.~\% ${\rm O}_2$, and air (21 vol.~\% ${\rm O}_2$).  The initial moisture content of each sample was 5 \% by mass. Mass fluxes obtained from weight loss measurements are reported, as well as temperature time histories at several depths within the solid.
+
+\subsubsection{Modeling Notes}
+
+The FDS domain is specified as a box twice as wide as the block, 0.076 m, with the cube centered in the domain.  The FDS grid resolution is 0.00475 m (16 cubic cells in each direction), which puts 8 cells across the width of the solid block (64 total wall cells).  The $-x$ face of the block is exposed to radiation using an \ct{EXTERNAL_FLUX}.  The lateral domain boundaries are specified as free slip, transparent walls (emissivity zero) with zero convective heat transfer.  The bottom boundary is a vent with a small coflow velocity of 0.005 m/s at $T_{\rm amb} = 30\;\si{\degreeCelsius}$ and the specified ${\rm O}_2$ concentration for the specific case.  The top boundary is set to \ct{OPEN}.  The radiation field is solved completely on each time step and the number of solid angles is set to 16.  The \ct{WALL_INCREMENT} is set to 1, meaning the solid phase is updated at every FDS time step.  The simulation is run to 900 s.
+
+The exposed surface specifies a convective length scale of 0.038 m with blowing. The solid phase model is 1D in depth from the center of an exposed wall cell.  The backing is ``exposed'', meaning the backside boundary condition considers convective heat transfer to the ambient.  The 1D domain is uniform (\ct{STRETCH_FACTOR=1}).  The default 1D grid resolution is automatically selected to satisfy the condition $\delta x_{\rm s}^2/\tau < k/(\rho c_v)$ with $\tau=1\;\si{s}$.  With the chosen physical parameters (see Table~\ref{tab:thermophysical_props}) this works out to $\delta x_{\rm s} = 1.2 \times 10^{-4}$ m, or 312 cells across the 3.8 cm block at the start of the simulation (note that there is a small amount of shrinking in the oxidative cases and the solid phase is remeshed accordingly).  Both the default resolution and 10 times this resolution are tested with no significant difference in the results.  Hence, the default resolution is considered converged.  The results presented below, however, are for the higher resolution runs.
+
+A device measuring the surface integral of surface density (which yields the total solid mass) is positioned in the center of the exposed face.  Also, devices for in-depth profiles of temperature, material component densities, and ${\rm O}_2$ mass fraction are positioned in the same location.  Time histories of temperature are recorded at the in-depth positions reported in \cite{Kashiwagi:1987} for comparison.
+
+\paragraph{Thermophysical Properties}
+
+The thermophsyical properties of the pine wood are adopted from \cite{Lautenberger:2009}.  The values of of the thermal conductivity and specific heat at a reference temperature, $T_{\rm ref}=300 \;\si{K}$, are denoted by $k_0$ and $c_{v,0}$, respectively. The temperature dependence is based on a power law as follows:
+\begin{align}
+k(T)   &= k_0 (T/T_{\rm ref})^{n_k} + \gamma \sigma T^3 \\
+c_v(T) &= c_{v,0} (T/T_{\rm ref})^{n_c}
+\end{align}
+where $\sigma=5.67\times10^{-8} \;\si{W/m^2/K^4}$ is the Stefan-Boltzmann constant. The reference values, exponents, and internal radiation factor, $\gamma$, are given in Table \ref{tab:thermophysical_props}.  For simplicity in adjusting the reaction energies, we opted to use constant specific heats ($n_c=0$), taken from the range obtained by \cite{Lautenberger:2009}.
+
+\begin{table}[h]
+\begin{center}
+\caption{Thermophysical properties.}
+\small
+\renewcommand{\arraystretch}{1.2}
+\begin{tabular}{lcccccc}
+\hline
+Component& $\rho$ & $k_{0}$ & $n_k$ & $c_{v,0}$ & $n_c$ & $\gamma$ \\
+\hline
+moisture & 1000                         & 0.062 & 0     & 4.18 & 0 & 0       \\
+pine     & 360                          & 0.176 & 0.594 & 2.50 & 0 & 0       \\
+char     & 108$^{\mbox{\scriptsize a}}$ & 0.065 & 0.435 & 1.50 & 0 & 3.3E-03 \\
+ash      & 5.0                          & 0.058 & 0.353 & 1.50 & 0 & 6.4E-03 \\
+\hline
+\multicolumn{7}{l}{$^{\mbox{\scriptsize a}}$ Used to approximate yield in Anca-Couce \cite{Anca-Couce:2012}.}
+\end{tabular}
+\label{tab:thermophysical_props}
+\end{center}
+\end{table}
+
+\paragraph{Material Model}
+
+The reaction model and kinetics parameters are based on the single component models from \cite{Anca-Couce:2012} (pine) and \cite{Kashiwagi:CF1992} (cellulose).  The model consists of four reactions (including moisture evaporation) as shown below.  The pine wood undergoes both aerobic and anaerobic pyrolysis.  The reaction energy for the anaerobic pyrolysis was taken from Anca-Couce et al.~\cite{Anca-Couce:2012} Table 8.  The heats of reaction for aerobic pyrolysis and char oxidation were based on \cite{Kashiwagi:CF1992}.  The activation energies and rate constants were optimized for the Kashiwagi gasification case \cite{Kashiwagi:1987} through a trial and error process that first looked at the nitrogen only case, then both aerobic and anaerobic pyrolysis (without char oxidation), and finally the full case including char oxidation.  The ash yield was chosen to be small based on the orientation of the block (horizontal relative to the exposed radiant panel) and comments in \cite{Kashiwagi:1987}.
+\begin{align}
+\mathrm{R1} &: \mbox{moisture} \rightarrow \mbox{water vapor} \\
+\mathrm{R2} &: \mbox{pine} \rightarrow \nu_{\rm char,2} \,\mbox{char} + \nu_{\rm fv,2} \,\mbox{fuel vapor} \\
+\mathrm{R3} &: \mbox{pine} + \nu_{{\rm O}_2,3} \, {\rm O}_2 \rightarrow \nu_{\rm char,3} \,\mbox{char} + \nu_{\rm fv,3} \,\mbox{fuel vapor} \\
+\mathrm{R4} &: \mbox{char} + \nu_{{\rm O}_2,4}\,{\rm O}_2 \rightarrow \nu_{\rm ash,4} \,\mbox{ash} + \nu_{{\rm C}{\rm O}_2,4} \,{\rm C}{\rm O}_2
+\end{align}
+
+\begin{table}[h]
+\begin{center}
+\caption{Kinetic parameters and yields.}
+\small
+\renewcommand{\arraystretch}{1.2}
+\begin{tabular}{lcccccccccr}
+\hline
+Reaction  & $A$ & $E$ & $n_{\rm s}$ & $n_{{\rm O}_2}$ & \multicolumn{5}{c}{component $\nu$} & $H_{\rm r}$ \\
+ \cmidrule(rl){6-10}
+  & \si{(kg/m^3)^{1-n_s}/s} & J/mol & & & $\nu_{{\rm O}_2}$ & $\nu_{\rm char}$ & $\nu_{\rm fv}$ & $\nu_{\rm ash}$ & $\nu_{{\rm C}{\rm O}_2}$ & kJ/kg\\
+\hline
+R1  & 4.29E+03 & 4.38E+04 & 1  & 0    &          &       &       &      &      & $2\,410$   \\
+R2  & 1.00E+06 & 1.05E+05 & 1  & 0    &          & 0.30  & 0.70  &      &      & $200$      \\
+R3  & 1.10E+05 & 8.80E+04 & 1  & 0.7  & $-0.5$   & 0.30  & 1.20  &      &      & $-5\,700$  \\
+R4  & 5.00e+08 & 1.40E+05 & 1  & 0.8  & $-2.67$  &       &       & 0.01 & 3.66 & $-20\,000$ \\
+\hline
+\end{tabular}
+\label{tab:m1_kinetics}
+\end{center}
+\end{table}
+
+
 \section{Lattimer Tilted Wall}
 \label{Lattimer_Tilted_Wall_Description}
 

Utilities/Matlab/FDS_verification_dataplot_inputs.csv

@@ -624,9 +624,9 @@ d,target_test,Radiation/target_test_git.txt,Radiation/target_test_devc.csv,2,3,T
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 d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,Total Mass,Expected,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,Total Mass,FDS,k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,TGA Results (tga\_analysis),Temperature (°C),Total Mass Fraction,0,600,1,0,1.2,1,no,0.05 0.90,,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_mass,N/A,end,0,Pyrolysis,kd,k,TeX
-d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,component 1 Mass|component 2 Mass,Component 1|Component 2,k-|r-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,residue Mass|water Mass,Residue|Water,g--|b--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,TGA Results (tga\_analysis),Temperature (°C),Component Mass Fraction,0,600,1,0,1.2,1,no,0.05 0.90,West,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_mass_components,N/A,end,0,Pyrolysis,kd,k,TeX
+d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,dry wood Mass|char Mass,dry wood|char,k-|r-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,ash Mass|water Mass,ash|water,g--|b--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,TGA Results (tga\_analysis),Temperature (°C),Component Mass Fraction,0,600,1,0,1.2,1,no,0.05 0.90,West,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_mass_components,N/A,end,0,Pyrolysis,kd,k,TeX
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-d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,component 1 MLR|component 2 MLR,Component 1|Component 2,k-|r-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,residue MLR|water MLR,Residue|Water,g--|b--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,TGA Results (tga\_analysis),Temperature (°C),Component Mass Loss Rate (1/s),0,600,1,-0.0015,0.0035,1,no,0.05 0.90,West,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_mlr_components,N/A,end,0,Pyrolysis,kd,k,TeX
+d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,dry wood MLR|char MLR,dry wood|char,k-|r-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,ash MLR|water MLR,ash|water,g--|b--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,TGA Results (tga\_analysis),Temperature (°C),Component Mass Loss Rate (1/s),0,600,1,-0.0015,0.0035,1,no,0.05 0.90,West,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_mlr_components,N/A,end,0,Pyrolysis,kd,k,TeX
 d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,MCC,Expected,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,MCC,FDS,k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,MCC Results (tga\_analysis),Temperature (°C),Heat Release Rate (W/g),0,600,1,0,30,1,no,0.05 0.90,,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_mcc,N/A,max,0,Pyrolysis,kd,k,TeX
 d,tga_analysis,Pyrolysis/tga_analysis_git.txt,Pyrolysis/tga_analysis_exact.csv,2,3,Temp,DSC,Expected,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_analysis_tga.csv,2,3,Temp,DSC,FDS,k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,DSC Results (tga\_analysis),Temperature (°C),Heating Rate (W/g),0,600,1,0,4,1,no,0.05 0.90,,,1,linear,FDS_User_Guide/SCRIPT_FIGURES/tga_analysis_dsc,N/A,max,0,Pyrolysis,kd,k,TeX
 d,tga_sample,Pyrolysis/tga_sample_git.txt,Pyrolysis/tga_sample_data.csv,1,2,Temp,Mass,Measured,k-,0,100000,,0,100000,-1.00E+09,1.00E+09,0,Pyrolysis/tga_sample_devc.csv,2,3,TGA temp,mpua,FDS (mpua),k--,0,100000,,0,100000,-1.00E+09,1.00E+09,0,TGA Mass (tga\_sample),Temperature (°C),Mass Fraction,0,900,1,0,1.2,1,no,0.05 0.90,South,,1,linear,FDS_Verification_Guide/SCRIPT_FIGURES/tga_sample_mass,Relative Error,end,0.01,Pyrolysis,ro,r,TeX