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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-483-0

ISBN Online: 978-1-56700-482-3

4th Thermal and Fluids Engineering Conference
April, 14–17, 2019 , Las Vegas, NV, USA

NUMERICAL INVESTIGATION OF HEAT TRANSFER IN DENSE FIXED BEDS OF ARBITRARY SHAPED PARTICLES WITH IMMERSED BOUNDARY METHODS

Get access (open in a dialog) pages 407-411
DOI: 10.1615/TFEC2019.cmd.028008

摘要

Fixed bed systems, such as slagging gasifiers, are promising candidates for co-gasification of waste materials. Solid particles are fed from top, falling on top of a gasifying fixed packed bed, undergoing drying, devolatization, gasification and finally slagging, resulting in a residual slag which is removed at the bottom. Due to high temperatures and a pressurized atmosphere, there is no direct possibility for experimental investigations of particle heat transfer in the system. Moreover, the feed material has arbitrary particle shapes and a broad size distribution. A proper description of heat transfer in high temperature slagging fixed beds is a challenging task and of immense importance not only for the product yield and selectivity but also for the operational safety. Immersed boundary methods offer the ability to investigate arbitrary complex geometries in computational fluid dynamics analysis. We numerically investigate the influence of different modeling approaches on the heat transfer using fixed temperatures, fixed heat fluxes and heat transfer coefficients, i.e. Dirichlet, Neumann and Robin boundary conditions, respectively. The in-house CFD code reads geometries of individual particles described by stereo lithography (stl) format and generates its result in the open source CGNS (CFD General Notation System) format to make its results interchangeable with other free and commercial CFD codes. Especially the external walls are best modeled with an external heat transfer approach to include the bed to wall heat transfer in the analysis.