Banca de QUALIFICAÇÃO: MATHEUS ALMEIDA DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : MATHEUS ALMEIDA DA SILVA
DATE: 27/02/2026
TIME: 09:00
LOCAL: Virtual
TITLE:

Two-phase phenomenological modeling of a fuel reactor in a chemical recirculation combustion system: integration of hydrodynamics, kinetics, and mass transfer.

KEY WORDS:

Chemical looping combustion; glycerol; fluidized bed; mathematical modeling; parameter estimation; dimensionless analysis

PAGES: 79
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Operações Industriais e Equipamentos para Engenharia Química
SPECIALTY: Reatores Químicos
SUMMARY:

This work presents the development, parameter estimation, and validation of a mechanistic and distributed mathematical model for the fuel reactor of a glycerol chemical looping combustion system operating in a fluidized bed. The model explicitly accounts for the bed biphasic hydrodynamics (bubble–emulsion), heterogeneous gas–solid reaction kinetics, interphase mass transfer, and axial gas dispersion, enabling a detailed description of axial composition profiles and reaction regimes along the reactor height. Parameter estimation was performed using experimental data from 19 glycerol combustion tests, considering the outlet molar flow rates of CO₂, CO, H₂, CH₄, and H₂O as response variables. From a total of 32 defined model parameters, 14 kinetic parameters were effectively estimated via nonlinear least squares, while the remaining parameters were kept fixed. The estimation procedure yielded an excellent overall fit (R² = 0.9661), despite the strong nonlinearity of the system. Independent model validation using experiments not included in the estimation stage confirmed the robustness of the model (R² = 0.88). Sensitivity analysis revealed that the solid-to-fuel ratio (Φ) mainly controls the overall glycerol conversion, with limited influence on product selectivity, whereas the H₂O-to-glycerol ratio significantly affects product distribution by enhancing secondary reactions. The total gas flow rate was shown to play a key role in shifting the system toward transport-controlled regimes, suppressing reforming reactions at high velocities. An integrated dimensionless analysis based on the Damköhler, Reynolds, and effective Peclet numbers allowed the identification of transitions between reaction-controlled and transport-controlled regimes along the bed, evidencing a functional stratification of the reactor. Combustion occurs predominantly near the inlet region, while downstream zones act mainly as transport and mixing regions. The results demonstrate that appropriate hydrodynamic operation is essential to maximize CO₂ production and minimize secondary reactions, providing valuable guidelines for the design and optimization of chemical looping combustion reactors applied to renewable liquid fuels.

COMMITTEE MEMBERS:
Presidente - 1584174 - DOMINGOS FABIANO DE SANTANA SOUZA
Interno - ***.656.434-** - CARLOS EDUARDO DE ARAÚJO PADILHA - UFRN
Externo à Instituição - DANIEL SILVEIRA LIRA - UFRN
Externo à Instituição - JUAN ALBERTO CHAVEZ RUIZ - ISI-ER