{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Batch Reactor Example\n", "## Ignition delay computation\n", "\n", "In this example we will illustrate how to setup and use a constant volume batch reactor. This reactor will then be used to compute the ignition delay of a gas at any temperature and pressure\n", "\n", "The reactor (system) is simply an insulated box." ] }, { "cell_type": "code", "execution_count": 1, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Runnning Cantera version: 2.5.0a2\n" ] } ], "source": [ "from __future__ import division\n", "from __future__ import print_function\n", "\n", "import pandas as pd\n", "import numpy as np\n", "\n", "import time\n", "\n", "import cantera as ct\n", "print('Runnning Cantera version: ' + ct.__version__)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### Import modules and set plotting defaults" ] }, { "cell_type": "code", "execution_count": 2, "metadata": {}, "outputs": [], "source": [ "%matplotlib notebook\n", "import matplotlib.pyplot as plt\n", "\n", "plt.rcParams['axes.labelsize'] = 18\n", "plt.rcParams['xtick.labelsize'] = 12\n", "plt.rcParams['ytick.labelsize'] = 12\n", "plt.rcParams['figure.autolayout'] = True\n", "\n", "plt.style.use('ggplot')\n", "plt.style.use('seaborn-pastel')" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### Define the gas\n", "In this example we will choose n-heptane as the gas. For a representative kinetic model, we use the 160 species [mechanism](https://combustion.llnl.gov/archived-mechanisms/alkanes/heptane-reduced-mechanism) by [Seier et al. 2000, Proc. Comb. Inst](http://dx.doi.org/10.1016/S0082-0784(00)80610-4). " ] }, { "cell_type": "code", "execution_count": 3, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", "\n", "**** WARNING ****\n", "For species c7h15o-1, discontinuity in h/RT detected at Tmid = 1391\n", "\tValue computed using low-temperature polynomial: 21.8343\n", "\tValue computed using high-temperature polynomial: 21.767\n" ] } ], "source": [ "gas = ct.Solution('data/seiser.cti')" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### Define reactor conditions : temperature, pressure, fuel, stoichiometry" ] }, { "cell_type": "code", "execution_count": 4, "metadata": {}, "outputs": [], "source": [ "# Define the reactor temperature and pressure\n", "reactorTemperature = 1000 #Kelvin\n", "reactorPressure = 101325.0 #Pascals\n", "\n", "gas.TP = reactorTemperature, reactorPressure\n", "\n", "# Define the fuel, oxidizer and set the stoichiometry\n", "gas.set_equivalence_ratio(phi=1.0, fuel='nc7h16', oxidizer={'o2':1.0, 'n2':3.76})\n", "\n", "# Create a batch reactor object and add it to a reactor network\n", "# In this example, the batch reactor will be the only reactor\n", "# in the network\n", "r = ct.IdealGasReactor(contents=gas, name='Batch Reactor')\n", "reactorNetwork = ct.ReactorNet([r])\n", "\n", "# now compile a list of all variables for which we will store data\n", "stateVariableNames = [r.component_name(item) for item in range(r.n_vars)]\n", "\n", "# use the above list to create a DataFrame\n", "timeHistory = pd.DataFrame(columns=stateVariableNames)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### Define useful functions" ] }, { "cell_type": "code", "execution_count": 5, "metadata": {}, "outputs": [], "source": [ "def ignitionDelay(df, species):\n", " \"\"\"\n", " This function computes the ignition delay from the occurence of the\n", " peak in species' concentration.\n", " \"\"\"\n", " return df[species].idxmax()" ] }, { "cell_type": "code", "execution_count": 6, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Computed Ignition Delay: 3.248e-02 seconds. Took 1.31s to compute\n" ] } ], "source": [ "#Tic\n", "t0 = time.time()\n", "\n", "# This is a starting estimate. If you do not get an ignition within this time, increase it\n", "estimatedIgnitionDelayTime = 0.1\n", "t = 0\n", "\n", "counter = 1;\n", "while(t < estimatedIgnitionDelayTime):\n", " t = reactorNetwork.step()\n", " if (counter%10 == 0):\n", " # We will save only every 10th value. Otherwise, this takes too long\n", " # Note that the species concentrations are mass fractions\n", " timeHistory.loc[t] = reactorNetwork.get_state()\n", " counter+=1\n", "\n", "# We will use the 'oh' species to compute the ignition delay\n", "tau = ignitionDelay(timeHistory, 'oh')\n", "\n", "#Toc\n", "t1 = time.time()\n", "\n", "print('Computed Ignition Delay: {:.3e} seconds. Took {:3.2f}s to compute'.format(tau, t1-t0))\n", "\n", "# If you want to save all the data - molefractions, temperature, pressure, etc\n", "# uncomment the next line\n", "# timeHistory.to_csv(\"time_history.csv\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Plot the result" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### Figure illustrating the definition of ignition delay" ] }, { "cell_type": "code", "execution_count": 7, "metadata": {}, "outputs": [ { "data": { "application/javascript": [ "/* Put everything inside the global mpl namespace */\n", "window.mpl = {};\n", "\n", "\n", "mpl.get_websocket_type = function() {\n", " if (typeof(WebSocket) !== 'undefined') {\n", " return WebSocket;\n", " } else if (typeof(MozWebSocket) !== 'undefined') {\n", " return MozWebSocket;\n", " } else {\n", " alert('Your browser does not have WebSocket support.' +\n", " 'Please try Chrome, Safari or Firefox ≥ 6. 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