Fluidodynamics characteristics of a vertical gas-solid and liquid-solid flow
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The research of vertical two-phase gas-solid and liquid-solid flow is generally important in chemical, biochemical and mechanical processes. The modeling of a vertical gas-solid and liquid-solid flow, where the solid is coarse spherical particles, is very important for practical applications such as spouted beds and modified spout-fluidized beds with draft tube. For modeling of these systems two-phase flow equations must be used. For vertical non-accelerating fluid-solids flow of coarse spherical particles the one-dimensional steady-state model has been presented. The theoretical bases of the model are the continuity and momentum equations for the fluid and particle of Nakamura and Capes , and the variational model for calculating the fluid-particle interphase drag coefficient (Grbavcic et al. ). The main model objective is establishing relations for: the fluid-particle interphase drag coefficient, the fluid-wall friction coefficient and the particle-wall friction coefficient. A ...new method for the indirect determination of the particle-wall friction coefficient in the vertical pneumatic and hydraulic transport of coarse particles is presented. The proposed procedure simplifies experimental work since it does not require experimental determination of the voidage in the transport system. In vertical gas-solid flow two major flow regimes are exist. There is dilute flow with an apparently uniform distribution of solid in the flowing mixture and the dense phase flow. In vertical liquid-solid flow two different flow regimes are identified: "turbulent" and "parallel". The method for predicting the regime transition for the gas-solid flow is the choking criterion proposed by Day et al. . Besides that, choking criterion for vertical gas-solid flow could be used for predict of the regime transition in liquid-solid flow (Grbavcic et al. , Garic-Grulovic et al. [5-7]).
Ključne reči:Flow regimes / Modeling / Vertical two-phase flow
Izvor:Fluid Transport: Theory, Dynamics and Applications, 2013, 1-44
- Nova Science Publishers, Inc.