An advanced EMMS scheme for the prediction of drag coefficient under a 1.2 MWth CFBC isothermal flow-Part II: Numerical formulation

Nikolopoulos, A; Atsonios, K; Nikolopoulos, N; Grammelis, P; Kakaras, E

dc.contributor.author	Nikolopoulos, A	en
dc.contributor.author	Atsonios, K	en
dc.contributor.author	Nikolopoulos, N	en
dc.contributor.author	Grammelis, P	en
dc.contributor.author	Kakaras, E	en
dc.date.accessioned	2014-03-01T02:00:01Z
dc.date.available	2014-03-01T02:00:01Z
dc.date.issued	2010	en
dc.identifier.issn	0009-2509	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/29072
dc.subject	EMMS	en
dc.subject	Multiphase flow	en
dc.subject	Hydrodynamics	en
dc.subject	Numerical analysis	en
dc.subject	CFD	en
dc.subject	CFBC	en
dc.subject.classification	Engineering, Chemical	en
dc.subject.other	CIRCULATING FLUIDIZED-BED	en
dc.subject.other	GAS-SOLID FLOW	en
dc.subject.other	CFD-SIMULATION	en
dc.subject.other	EULERIAN SIMULATION	en
dc.subject.other	MULTISCALE CFD	en
dc.subject.other	KINETIC-THEORY	en
dc.subject.other	GRANULAR FLOW	en
dc.subject.other	RISER	en
dc.subject.other	MODEL	en
dc.subject.other	PARTICLES	en
dc.title	An advanced EMMS scheme for the prediction of drag coefficient under a 1.2 MWth CFBC isothermal flow-Part II: Numerical formulation	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	The arithmetic results from the formulation of an EMMS analysis for the calculation of drag coefficient between the co-existing phases in a CFB riser were implemented in a CFD code and three dimenisonal simulations of the isothermal flow of a 1.2 MWth CFBC unit were performed. Gas and inert material were modeled in an Eulerian fashion. Except from EMMS scheme, Gidaspow's correlation was also tested for reasons of comparison. Gidaspow's drag model is based on the assumption of homogeneous conditions inside a control volume, whilst the EMMS analysis encounters the effect of spatiotemporal multi-scale gas-particle structures on the induced drag force. Moreover, regarding the grid density, grid density on the numerical results was also examined, using two uniform computational grids, consisting of hexaderal computatioanlcells. Numerical reults were compared with available experimental data, as far as the pressure drop along the bed is concerned. A good agreement with the experimental data was achieved in the case of the dense grid (43 mm/cell) using both approaches. In the case of the coarse grid (86 mm/cell), Gidaspow's correlation clearly under-predicted the experimentally measured pressure drop along the bed. This under-prediction was more signficant in the lower part of the bed. On the other hand, the implementation of the EMMS scheme increased the accuracy of the model, mainly in the bottom region. In this area the drag force calculated via EMMS method is considerably less than the drag force calculated by Gidaspow's correlation. Overall, it is proven that the EMMS modle is a very promising numerical tool for the accurate drag force this complicated pheonomenon, increasing the accuracy of the predictions without the need of denser numerical grids. (C) 2010 Elsevier Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	CHEMICAL ENGINEERING SCIENCE	en
dc.identifier.isi	ISI:000278603400018	en
dc.identifier.volume	65	en
dc.identifier.issue	13	en
dc.identifier.spage	4089	en
dc.identifier.epage	4099	en