```"""
Adiabatic flame temperature and equilibrium composition for a fuel/air mixture
as a function of equivalence ratio, including formation of solid carbon.

Requires: cantera >= 2.5.0, matplotlib >= 2.0
Keywords: equilibrium, combustion, multiphase
"""

import cantera as ct
import numpy as np
import sys
import csv

##############################################################################
# Edit these parameters to change the initial temperature, the pressure, and
# the phases in the mixture.

T = 300.0
P = 101325.0

# phases
gas = ct.Solution('gri30.yaml')
carbon = ct.Solution('graphite.yaml')

# the phases that will be included in the calculation, and their initial moles
mix_phases = [(gas, 1.0), (carbon, 0.0)]

# gaseous fuel species
fuel_species = 'CH4'

# equivalence ratio range
npoints = 50
phi = np.linspace(0.3, 3.5, npoints)

##############################################################################

mix = ct.Mixture(mix_phases)

# create some arrays to hold the data
xeq = np.zeros((mix.n_species, npoints))

for i in range(npoints):
# set the gas state
gas.set_equivalence_ratio(phi[i], fuel_species, 'O2:1.0, N2:3.76')

# create a mixture of 1 mole of gas, and 0 moles of solid carbon.
mix = ct.Mixture(mix_phases)
mix.T = T
mix.P = P

# equilibrate the mixture adiabatically at constant P
mix.equilibrate('HP', solver='gibbs', max_steps=1000)

print('At phi = {0:12.4g}, Tad = {1:12.4g}'.format(phi[i], tad[i]))
xeq[:, i] = mix.species_moles

# write output CSV file for importing into Excel
with open(csv_file, 'w', newline='') as outfile:
writer = csv.writer(outfile)
writer.writerow(['phi', 'T (K)'] + mix.species_names)
for i in range(npoints):
writer.writerow([phi[i], tad[i]] + list(xeq[:, i]))
print('Output written to {0}'.format(csv_file))

if '--plot' in sys.argv:
import matplotlib.pyplot as plt