def _calculate_DH298_coal(self):
m_C = <NUM_LIT:0>  <EOL>m_H = <NUM_LIT:0>  <EOL>m_O = <NUM_LIT:0>  <EOL>m_N = <NUM_LIT:0>  <EOL>m_S = <NUM_LIT:0>  <EOL>T = <NUM_LIT>  <EOL>Hin = <NUM_LIT:0.0>  <EOL>for compound in self.material.compounds:<EOL><INDENT>index = self.material.get_compound_index(compound)<EOL>if stoich.element_mass_fraction(compound, '<STR_LIT:C>') == <NUM_LIT:1.0>:<EOL><INDENT>m_C += self._compound_masses[index]<EOL>Hin = thermo.H(compound, T, self._compound_masses[index])<EOL><DEDENT>elif stoich.element_mass_fraction(compound, '<STR_LIT:H>') == <NUM_LIT:1.0>:<EOL><INDENT>m_H += self._compound_masses[index]<EOL>Hin = thermo.H(compound, T, self._compound_masses[index])<EOL><DEDENT>elif stoich.element_mass_fraction(compound, '<STR_LIT:O>') == <NUM_LIT:1.0>:<EOL><INDENT>m_O += self._compound_masses[index]<EOL>Hin = thermo.H(compound, T, self._compound_masses[index])<EOL><DEDENT>elif stoich.element_mass_fraction(compound, '<STR_LIT:N>') == <NUM_LIT:1.0>:<EOL><INDENT>m_N += self._compound_masses[index]<EOL>Hin = thermo.H(compound, T, self._compound_masses[index])<EOL><DEDENT>elif stoich.element_mass_fraction(compound, '<STR_LIT:S>') == <NUM_LIT:1.0>:<EOL><INDENT>m_S += self._compound_masses[index]<EOL>Hin = thermo.H(compound, T, self._compound_masses[index])<EOL><DEDENT><DEDENT>m_total = m_C + m_H + m_O + m_N + m_S  <EOL>Hout = <NUM_LIT:0.0>  <EOL>Hout += thermo.H('<STR_LIT>', T, cc(m_C, '<STR_LIT:C>', '<STR_LIT>', '<STR_LIT:C>'))<EOL>Hout += thermo.H('<STR_LIT>', T, cc(m_H, '<STR_LIT:H>', '<STR_LIT>', '<STR_LIT:H>'))<EOL>Hout += thermo.H('<STR_LIT>', T, m_O)<EOL>Hout += thermo.H('<STR_LIT>', T, m_N)<EOL>Hout += thermo.H('<STR_LIT>', T, cc(m_S, '<STR_LIT:S>', '<STR_LIT>', '<STR_LIT:S>'))<EOL>if self.HHV is None:<EOL><INDENT>HHV = Hout - Hin / m_total  <EOL><DEDENT>else:<EOL><INDENT>HHV = self.HHV / <NUM_LIT>  <EOL><DEDENT>return HHV + Hout / m_total<EOL>
Calculate the enthalpy of formation of the package at the specified temperature, in
case the material is coal.

:returns: [kWh/kg] enthalpy of formation of daf coal