Space-time integral method for simplifying the modeling of torrefaction of a centimeter-sized biomass particle

- A simplified particle-model (SPM) was developed based on space-time integral method.
- Experimental data was used to validate the simplified particle-model.
- Comprehensive finite element particle-model was used to test assumptions made in the SPM.
- SPM's predicted mass loss had mean deviation <3.0 wt.%, compared to experimental data.

A method to develop a simplified particle model (SPM) for the torrefaction of a centimeter-sized biomass particle has been proposed. The SPM was developed based on reasonable assumptions, and these assumptions were validated with a comprehensive particle model (CPM) from Shi et al. (2016), which considers the detailed transport phenomena and chemical reactions inside a three-dimensional (3D) biomass particle and which was experimentally validated. The SPM was validated against the experimental data with respect to the evolution of the particle's mass loss during torrefaction (mean deviation of lower than 3.0 wt.%, feedstock dry basis). The accuracy of the SPM in predicting the intraparticle temperature distribution was further assessed by comparing to the CPM predicted data. Finally, the applicability of the SPM was studied. Results show that the SPM can predict results with acceptable accuracy when comparing to the experimental data or to the CPM predicted data. In addition, the SPM runs over 100 times faster compared to the CPM for a single particle, which indicates that the SPM would be promising for integration into reactor models that needs to calculate many thousands or more particles at the same time.