Change search
ReferencesLink to record
Permanent link

Direct link
On the Influence from Turbulence Modeling on Particle Suspension Flow in Cyclone Gasifiers
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
2014 (English)Conference paper, Poster (Refereed)
Abstract [en]

Air-blown cyclone gasification is an entrained flow gasification process in which biomass powder fuel is burnt in a gasifier that operates similarly to a cyclone separator. Cyclone separators are widely used in industry to separate a dispersed solid phase (e.g. particles) from a continuous flow of gas based on density differences. Due to its simple design, the cyclone is a reliable apparatus with low cost for manufacture and maintenance.The performance of an isothermal cyclone separator can be predicted satisfactorily with the model developed by Muschelknautz et al. However, the flow in a non-isothermal cyclone gasifier has additional complexities, e.g. the production of gas from the fuel particles, that are outside the scope of the Muschelknautz model. In order to incorporate these effects more advanced modeling based on Computational Fluid Dynamics is needed. One problem with the CFD approach in combination with turbulent heat transfer and chemical reactions is that the complexity of the global model makes it difficult to assess the accuracy of the sub-models. Recently published models are based on relatively simple eddy-viscosity turbulence models. The agreement between these models and experiments has been encouraging but one cannot rule out the possibility that the apparently good performance of the model is a lucky coincidence due to cancellation of errors in the different sub models.The present paper is focusing on the fluid dynamics modeling of the flow in a cyclone gasifier in order to develop a better foundation for continued modeling. Since simulation of dispersed phase behavior is based on a precise modeling of the continuous phase flow field, it is valuable to assess different numerical approaches to find the most promising one for simulating the turbulent gas phase flow. Due to the complexity of turbulent swirling flow in a cyclone gasifier, a careful selection of turbulence models is needed to fulfill accurate numerical calculations of flow parameters. Two families of turbulence models are supposed to be tested: the two-equation eddy viscosity models including k-epsilon and k-omega, and the Reynolds stress model. For the k-epsilon model, steady-state and transient simulations are implemented. The gas cyclone of Obermair et al. with relevant operating conditions was chosen as a benchmark. The simulation results are compared to the Laser Doppler Anemometry (LDA) velocity measurements of the gas cyclone. The simulations are implemented in the commercial CFD (computational fluid dynamics) code ANSYS CFX 14.5; which uses an element-based finite volume approach. The method involves discretization of the spatial domain using a three-dimensional mesh to build up finite volumes over which relevant quantities like mass, momentum, and energy are conserved. In all, the capability of the mentioned approaches for representing the flow field in general and the precessing vortex core and its related fluctuations in particular will be discussed.

Place, publisher, year, edition, pages
Research subject
Energy Engineering; Fluid Mechanics; Renewable energy (AERI)
URN: urn:nbn:se:ltu:diva-34819Local ID: 91eab852-665f-4f77-82fc-8cbb0e78e656OAI: diva2:1008070
Symposium on Thermal and Catalytic Sciences for Biofuels and Biobased Products : 02/09/2014 - 05/09/2014
Godkänd; 2014; 20141223 (panhad)Available from: 2016-09-30 Created: 2016-09-30Bibliographically approved

Open Access in DiVA

fulltext(1058 kB)1 downloads
File information
File name FULLTEXT01.pdfFile size 1058 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Search in DiVA

By author/editor
Jafari, Pantea HadiGebart, RikardHellström, J. Gunnar I.
By organisation
Energy ScienceFluid and Experimental Mechanics

Search outside of DiVA

GoogleGoogle Scholar
Total: 1 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

ReferencesLink to record
Permanent link

Direct link