(187f) Heat Transfer Simulations in Multi Size Particle Riser Flow

In practical applications of gas-multi size particle flow, heat transfer is mostly important. In this work, heat transfer between particles with different sizes in a riser flow was evaluated. For the numerical validation of the particle hydrodynamics, Particulate Solid Research, Inc. (PSRI) challenge problem 2 experimental data were used. In this step, simulations of single size and three different size particle flow in a two dimensional riser were performed using MFIX. The simulations are based on Eulerian view for all phases in the flow and employed different kinetic theory of granular flow (KTGF) models for each of the simulations. The single size simulations are based on the kinetic theory of granular flow (KTGF) model developed by Lun et al.[1]; the multi size simulations are based on the Iddir&Arastoopour kinetic theory[2] for multi size particles. The numerical results are compared with the available experimental data for pressure drop, solid axial velocity, solid concentration, and solid mass flux presented in PSRI challenge problem 2. Heat transfer in the riser is compared to published experimental data showing the effect of the presence of multi-size particles on heat transfer. Combined Eulerian-Lagrangian approach is applied for the simulations using MFIX in that Lagrangian approach provides detailed information of each solid particle. It is assumed that particle-particle collisions follow a hard sphere model, and that heat transfers from particle to particle is due to conduction through the gas layer near the contact point. The amount of heat transferred between different size particles is given by the simulation results and the effect of particle size on heat transfer in the riser flow is examined.

[1] Lun CKK, Savage SB, Jeffrey DJ, Chepurniy N. ?Kinetic theories of granular flows: inelastic particles in Couette flow and slightly inelastic particles in a general flow field?, J Fluid Mech., 140, pages 223?256, (1984)

[2] Iddir, Hadjira, ?Modeling of the multiphase mixture of particles using the kinetic theory approach?, Ph.D. Thesis, Illinois Institute of Technology, (2004)