Advanced modeling of nonspherical biomass particle motion in suspension combustion

To address the aerodynamic differences encountered during the co-firing of straw biomass particles in coal-fired power plants, this work extends the conventional modeling framework for dilute multiphase particle motion and proposes a novel, closed model for nonspherical particle dynamics and combustion. The model incorporates generalized correlations derived from previous particle-resolved direct numerical simulations and systematically accounts for drag, lift, pressure gradient force, virtual mass force, and torque induced rotational motion experienced by realistic cylindrical particles under various flow conditions. These aerodynamic effects are effectively coupled with an optimized combustion model, enabling high-fidelity simulation of both translational and rotational particle dynamics. Numerical simulations conducted in a 10 m long biomass co-firing burner validate the model of accuracy and broad applicability in predicting nonspherical particle trajectories, residence time, temperature evolution, and burnout performance. Results show that, compared to the conventional equivalent volume spherical particle model, the proposed novel model increases the average particle residence time by 20.21% and the average particle temperature by 28.31%. This promotes a more rapid release of volatiles and enhanced char oxidation, thereby improving the overall combustion efficiency of biomass particles. Under sufficient oxygen conditions, the combination of extended residence time and elevated particle temperatures facilitates more complete combustion of large biomass particles. Consequently, the proposed model demonstrates strong potential for simulating particle laden multiphase flows in engineering applications and serves as a powerful numerical tool for achieving efficient biomass co-firing utilization in coal-fired boilers.