(81d) Continuum Modeling of Corn Stover Feedstock through a Compression Feed Screw

Controllable continuous feeding of biomass through a compression feed screw in an ethanol biorefinery is essential for economic operation. A coupled Eulerian-Lagrangian finite element method model is developed to simulate the feeding of corn stover through a pilot-scale compression feed screw. The bulk corn stover is modeled using an isotropic modified (density-dependent) Drucker Prager Cap (mDPC) constitutive relation. The yield surfaces of the mDPC model capture plastic densification and shear failure of the material. A uniaxial single-ended die compaction test in an instrumented punch-die is used to calibrate compression characteristics, elastic properties, and wall friction properties of biomass. Direct shear tests are performed to partially calibrate shear failure properties of biomass. A sensitivity analysis of compression feed screw performance to mDPC model parameters is presented to assess the possibility of calibrating only a subset of material properties.