الفهرس Only 14 pages are availabe for public view
 |  | from | 283 |  |  |
| | | from | 283 | | |
Abstract
Gas-solid two-phase flow in bends and elbows occurs in many engineering applications such as pneumatic conveyor; coal fired power plants, food processing, chemical industries, pneumatic dryers and moving of dusty gas in heat exchanger.
The effects of operating parameters on the behaviour of gas-solid two-phase flow are numerically simulated in 90o and 180o bends. The numerical calculations are performed by Eulerian approach for gas- phase taking into account the mutual effects of the solids on the gas, and Lagrangian approach for the dispersed-phase. The effects of lift forces and particle rotation are included in the particle tracking model. Two particulate turbulence models have been studied to predict turbulent gas-solid flows in bends. The first one is the standard k-E model, while the second model is RNG (Renormalization Group) based k-E model. The governing equations for gas phase are discretized by finite volume scheme over a staggered grid, and pressure- velocity coupling is released by SIMPLE algorithm. On the other hand, fourth order Rounge-kutta method is used to integrate the particle equations of motion. The prediction procedure of the proposed model comprises three stages, namely: flow modeling, particle tracking and erosion calculations. Several cases were chosen from the literature as benchmark test cases to perform a comprehensive validation of the present model. The comparisons show agood agreement between the published data and present predictions .The present results show that the behaviour of gas-solid two-phase flow in bends and erosion rate are affected greatly by flow conditions, solids properties and bend geometry. In addition, based on many CDF predictions of erosion rate and on the curve fitting of maximum penetration rate results, new CDF based correlations are developed and are recommended as approximate engineering calculations to account for the effect of different parameters on the maximum penetration rate in 90o as well as 180o bends. The present correlation is found to have acceptable agreement with the published experimental data