code: def HHV(self, HHV):
          
  
          self._HHV = HHV  # MJ/kg coal
          if self.isCoal:
              self._DH298 = self._calculate_DH298_coal()
docs: Set the higher heating value of the stream to the specified value, and
          recalculate the formation enthalpy of the daf coal.
  
          :param HHV: MJ/kg coal, higher heating value