Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Iowa State University

Series

Chemical Engineering

Hydrodynamics

Publication Year

Articles 1 - 4 of 4

Full-Text Articles in Physics

Modeling A Biomass Fluidizing Bed With Side Port Air Injection, Mirka Deza, Francine Battaglia, Theodore J. Heindel Aug 2009

Modeling A Biomass Fluidizing Bed With Side Port Air Injection, Mirka Deza, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Fluidized beds are used to gasify materials such as coal or biomass in the production of producer gas. Modeling these reactors using computational fluid dynamics is advantageous when performing parametric studies for design and scale-up. While two-dimensional simulations are easier to perform than three-dimensional simulations, they may not capture the proper physics. This paper compares two- and three-dimensional simulations with experiments for a reactor geometry with side port air injection. The side port is located within the bed region so that the injected air can help promote mixing. Of interest in this study is validating the hydrodynamics of fluidizing biomass ...


A Validation Study For The Hydrodynamics Of Biomass In A Fluidized Bed, Mirka Deza, Francine Battaglia, Theodore J. Heindel Aug 2008

A Validation Study For The Hydrodynamics Of Biomass In A Fluidized Bed, Mirka Deza, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Computational modeling of fluidized beds can be used to predict operation of biomass gasifiers after extensive validation with experimental data. The present work focused on computational simulations of a fluidized bed using a multifluid Eulerian-Eulerian model to represent the gas and solid phases as interpenetrating continua. Hydrodynamic results from the simulations were quantitatively compared with X-ray flow visualization studies of a similar bed. It was found that the Gidaspow model can accurately predict the hydrodynamics of the biomass in a fluidized bed. The coefficient of restitution of biomass was fairly high and did not affect the hydrodynamics of the bed ...


Gas Holdup In Opaque Cellulose Fiber Slurries, Sarah M. Talcott, Theodore J. Heindel Jun 2005

Gas Holdup In Opaque Cellulose Fiber Slurries, Sarah M. Talcott, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Three different cellulose fiber types are used to study their effect on gas holdup and flow regime transition in a 10.2 cm semi-batch bubble column. The three natural fiber types include bleached softwood chemical pulp (softwood), bleached hardwood chemical pulp (hardwood), and bleached softwood chemithermomechanical pulp (BCTMP). Gas holdup is recorded over a range of fiber mass fractions (0 ≤ C ≤ 1.6%) and superficial gas velocities (Ug ≤ 23 cm/s). Experimental results show that gas holdup decreases with increasing fiber mass fraction. Homogeneous, transitional, and heterogeneous flow is observed for all three fiber types at low fiber mass fractions ...


Gas Holdup In A Cocurrent Air-Water-Fiber Bubble Column, Chengzhi Tang, Theodore J. Heindel Jul 2004

Gas Holdup In A Cocurrent Air-Water-Fiber Bubble Column, Chengzhi Tang, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Effects of superficial liquid velocity (Ul ), superficial gas velocity (Ug ), and fiber mass fraction (C) on gas holdup (ε) and flow regime transition are studied experimentally in well-mixed water-cellulose fiber suspensions in a cocurrent bubble column. Experimental results show that the gas holdup decreases with increasing Ul when C and Ug are constant. The gas holdup is not significantly affected by C in the range of C < 0.4%, but decreases with increasing C in the range of 0.4% ≤ C ≤ 1.5%. When C > 1.5%, a significant amount of gas is trapped in the fiber network and recirculates with the ...