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Plot specific heat vs. temperature for different species and thermo data.

This example demonstrates how to plot the specific heat of different species vs. temperature for different thermo data files.

The specific heat of a species is a function of temperature. The specific heat is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Kelvin.

Here, the specific heat is in J/kmol/K, and the temperature is in Kelvin.

Tags: thermo specific heat methane CH4 hydrogen H2 hydrocarbons CxHy

# This is an option for the online documentation, so that each image is displayed separately.
# sphinx_gallery_multi_image = "single"

Import the required libraries.

import cantera as ct
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns

from rizer.misc.utils import get_path_to_data

sns.set_theme("talk")

Define the thermo data files to load.

# Dictionary to store thermo data files.
# Key: name of the thermo data file.
# Value: color and linestyle, to use in the plot.
thermo_data: dict[str, str] = {
    "burcat_thermo_nasa9.yaml": "r",
    "grc_nasa9_all_C_H_species.yaml": "g",
    "mutationpp_burcat_thermo.yaml": "m--",
    "mutationpp_nasa9.yaml": "b--",
    "mutationpp_nasa9_new.yaml": "k-.",
    "nasa1993detchem2005_298-5000K_thermo.yaml": "c-.",
}

Set the species to plot.

# Dictionary to store species data.
# Key: species name
# Value: dictionary with:
#   key: name of the thermo data
#   value: Cantera Species object
species_to_plot: dict[str, dict[str, ct.Species]] = {
    "CH4": {},
    "CH4+": {},
    "C2H2": {},
    "C2H2+": {},
    "H2": {},
    "H2+": {},
}

Load species data from the various mechanisms.

for thermo in thermo_data:
    # Load species data.
    path_to_species = get_path_to_data("thermo", thermo)
    species_list: list[ct.Species] = ct.Species.list_from_file(str(path_to_species))

    # Look up for matching species in the list.
    for species_name in species_to_plot:
        for specie in species_list:
            if specie.name == species_name:
                species_to_plot[species_name][thermo] = specie

Plot the specific heat of the species vs. temperature.

# For each species, plot the specific heat vs. temperature.
for species_name in species_to_plot:
    fig, ax = plt.subplots(figsize=(12, 8), layout="constrained")

    for thermo in thermo_data:
        # Check if the species is present in the thermo data.
        if thermo not in species_to_plot[species_name]:
            print(
                f"Species {species_name} not found in {thermo}."
                "Check spelling and composition."
            )
            continue

        # Get the species object.
        species = species_to_plot[species_name][thermo]
        # Define the temperature range.
        min_temperature = species.thermo.min_temp
        max_temperature = species.thermo.max_temp
        temperatures = np.linspace(min_temperature, max_temperature, num=1000)  # K
        # Compute the specific heat for each temperature.
        cp = np.array([species.thermo.cp(T) for T in temperatures])  # J/kmol/K

        # Plot the specific heat vs. temperature.
        color = thermo_data[thermo]
        ax.plot(temperatures, cp, color, label=f"{species_name} - {thermo}")
        ax.set_title(f"Specific heat of {species_name} vs. temperature")

    # Set the labels and legend.
    ax.set_xlabel("Temperature [K]")
    ax.set_ylabel("Heat capacity [J/kmol/K]")

    # Plot
    plt.legend()
    plt.show()

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Species CH4 not found in burcat_thermo_nasa9.yaml.Check spelling and composition.
Species CH4+ not found in grc_nasa9_all_C_H_species.yaml.Check spelling and composition.
Species CH4+ not found in mutationpp_nasa9.yaml.Check spelling and composition.
Species CH4+ not found in nasa1993detchem2005_298-5000K_thermo.yaml.Check spelling and composition.
Species C2H2+ not found in grc_nasa9_all_C_H_species.yaml.Check spelling and composition.
Species C2H2+ not found in mutationpp_nasa9.yaml.Check spelling and composition.
Species C2H2+ not found in nasa1993detchem2005_298-5000K_thermo.yaml.Check spelling and composition.
Species H2+ not found in burcat_thermo_nasa9.yaml.Check spelling and composition.