We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system be...

Gas exchange in human lungs is established by several flow mechanisms. In the present study, the features of gas displacement in the distal bronchioles of a human lung are investigated by both numerical calculation and experimental observation with particle image velocimetry. The effect of respiration frequency is considered, such as high frequency oscillatory ventilation. By comparing the obta...

This paper presents a numerical study of the gas-powder flow in a typical Lapple cyclone. The gas flow is obtained by the use of the Reynolds stress model. The resulting pressure and flow fields are verified by comparison with the measured results and then used in the determination of powder flow that is simulated by the use of a Stochastic Lagrangian model. The separation efficiency and trajec...

The numerical simulation of solid-gas two-phase flow is an important tool in the prediction of its flow behavior. Predicting the axial pressure profile is one of the major difficulties in modeling of solid-gas two-phase flow. A model using a Particle Based Approach (PBA) is developed to accurately predict the axial pressure profile in a vertical annular tube. The simulation model accounts for t...

Heat and mass transfer problem in a fixed-bed tubular reactor is one of the major concerns in the chemical engineering. The two dimensional axial plug flow model was used for a water gas shift reactor to compare heat conduction or mass diffusion with convective effect. In the case of fast fluid flow in highly permeable catalyst-bed, convective heat transfer was dominant compared to heat conduct...

The packing fraction and the pressure drop across gas-fluidized beds of granular media exhibit hysteresis as the gas-flow rate is cycled up and down across the fluidization transition. Presumably this is due to contact forces and transfer of stress to the surrounding walls, and hence should vary nontrivially with the aspect ratio of the sample. Here we present systematic measurements of the var...

The novel electrohydrodynamically-assisted electrostatic precipitator (EHD ESP) was developed to suppress particle reentrainment for collection of low resistive diesel particulates. The collection efficiency was compared between the EHD ESP and the conventional ESP using two large diesel engines; 2.3 L and 3.2 L engines. The gas velocity was varied in the range of 1.35 to 7.3 m/s and the load w...

A simulation scheme is proposed for flowfield and radiation analysis of solid rocket exhaust plumes at high altitude. Several recently developed numerical procedures are used to determine properties of the gas and condensed phase Al2O3 particles, and spectrally resolved plume radiation calculations are performed using a Monte Carlo ray trace model. Simulations are run for a representative plume...