CFD Simulation of Devolatilization of Biomass with Shrinkage Effect

In the present work, a computational fluid dynamics (CFD) model is used to assess devolatilization of biomass under high-temperature condition. The CFD code is based on a multiscale Eulerian-Lagrangian solver previously developed in the framework of OpenFOAM. A particle shrinkage model proposed by Colomba Di Blasi is implemented in this study to better calculate size evaluation of biomass particle. In addition, a two-step devolatilization model is added into the solver. The CFD model is validated against experimental data of rapid devolatilization of biomass in an electric heated drop tube reactor. Compared to the constant volume model and the simplified constant density shrinkage model, the applied model can better reflect changes of particle size at both 750 °C and 950 °C. In particular, the model gives very good prediction on the terminal particle size with the model constants α=0.3, β=0, and γ=0.3. The calculated composition of pyrolysis gas is fairly close to the experimental data as well.