Thermodynamic Analysis of Wood Pellet Gasification in a Downdraft Reactor for Advanced Biofuel Production

  • E. MadadianEmail author
  • L. Amiri
  • M. Lefsrud
Original Paper


Thermochemical biomass conversion technologies use renewable feedstocks to produce gaseous, liquid and solid fuels to produce electric power, heat, chemicals or other types of fuel. Biomass gasification has emerged as a promising conversion technology to meet increasing global energy demands. In this study, a thermodynamic model programmed with MATLAB and CANTERA was used to study the effect of equivalence ratio on reaction temperature and producer gas during the decomposition of woody biomass in a downdraft gasifer. The composition of the producer gas was estimated by minimizing the Gibbs free energy for calculation of the equilibrium constants. A Newton–Raphson algorithm was used to find the final equilibrium state. This process began with an initial estimate for temperature of the chemical composition at equilibrium. The results of the modeling were reported based on the variation in the main indicators of the process such as cold gas efficiency and higher heating value Higher heating value. As such, variations in equivalence ratio were calculated for various moisture contents and the temperature of the reactor. Cold gas efficiency and higher heating values were maximized at optimum equivalence ratio 0.31. Gibbs free energy change through the main parts of the reactor was found to be negative and ranged from − 95 to − 280 kJ/mol. The enthalpy of oxidation was also found to be native at around − 250 kJ/mol indicating exothermic exothermic nature of the reactions in oxidation zone. However, the total enthalpy of the system increased with an increase in the temperature directing the system to be more endothermic in reduction zone (105 kJ/mol). Model predictions were satisfactorily consistent with experimental data in this study and the literature. The results of this study can be directly applied to develop gasification reactors in biorefineries to enhance process efficiency.


Gibbs energy Thermochemical equilibrium Equivalence ratio Partial combustion Gasification products Sustainable production 



Equivalence ratio


Cold gas efficiency


Lower heating value


Higher heating value


Total number of atoms present in the system




Entropy of formation at standard conditions


Thermal value of the air as gasifying agent


Enthalpy of vaporization of water


Number of atoms of the kth element present in each molecule of the chemical species


Ratio of number of moles in ith species over the total number of moles


Gasification control unit


Gibbs free energy


Chemical potential of ith species




Gas constants


Thermal value of the air as gasifying agent


Mass fraction of hydrogen in solid fuel


Number of moles and chemical potential of ith species


Total number of atomic masses of the kth element in the system


Enthalpy of formation at standard conditions



This research is funded by BioFuelNet Canada, a network focusing on the development of advanced biofuels.


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© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Department of Bioresource EngineeringMcGill UniversityMontrealCanada
  2. 2.Department of Mining and Material EngineeringMcGill UniversityMontrealCanada
  3. 3.Department of Process Engineering and Applied ScienceDalhousie UniversityHalifaxCanada

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