Predictive models of circulating fluidized bed combustors. 12th technical progress report
Abstract
Steady flows influenced by walls cannot be described by inviscid models. Flows in circulating fluidized beds have significant wall effects. Particles in the form of clusters or layers can be seen to run down the walls. Hence modeling of circulating fluidized beds (CFB) without a viscosity is not possible. However, in interpreting Equations (8-1) and (8-2) it must be kept in mind that CFB or most other two phase flows are never in a true steady state. Then the viscosity in Equations (8-1) and (8-2) may not be the true fluid viscosity to be discussed next, but an Eddy type viscosity caused by two phase flow oscillations usually referred to as turbulence. In view of the transient nature of two-phase flow, the drag and the boundary layer thickness may not be proportional to the square root of the intrinsic viscosity but depend upon it to a much smaller extent. As another example, liquid-solid flow and settling of colloidal particles in a lamella electrosettler the settling process is only moderately affected by viscosity. Inviscid flow with settling is a good first approximation to this electric field driven process. The physical meaning of the particulate phase viscosity is described in detail inmore »
- Authors:
- Publication Date:
- Research Org.:
- Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering
- Sponsoring Org.:
- USDOE, Washington, DC (United States)
- OSTI Identifier:
- 10184041
- Report Number(s):
- DOE/PC/89769-T12
ON: DE93000938
- DOE Contract Number:
- FG22-89PC89769
- Resource Type:
- Technical Report
- Resource Relation:
- Other Information: PBD: Jul 1992
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 01 COAL, LIGNITE, AND PEAT; COAL; FLUIDIZED-BED COMBUSTION; FLUIDIZED-BED COMBUSTORS; MATHEMATICAL MODELS; PROGRESS REPORT; EXPERIMENTAL DATA; CIRCULATING SYSTEMS; 014000; COMBUSTION
Citation Formats
Gidaspow, D. Predictive models of circulating fluidized bed combustors. 12th technical progress report. United States: N. p., 1992.
Web. doi:10.2172/10184041.
Gidaspow, D. Predictive models of circulating fluidized bed combustors. 12th technical progress report. United States. https://doi.org/10.2172/10184041
Gidaspow, D. 1992.
"Predictive models of circulating fluidized bed combustors. 12th technical progress report". United States. https://doi.org/10.2172/10184041. https://www.osti.gov/servlets/purl/10184041.
@article{osti_10184041,
title = {Predictive models of circulating fluidized bed combustors. 12th technical progress report},
author = {Gidaspow, D},
abstractNote = {Steady flows influenced by walls cannot be described by inviscid models. Flows in circulating fluidized beds have significant wall effects. Particles in the form of clusters or layers can be seen to run down the walls. Hence modeling of circulating fluidized beds (CFB) without a viscosity is not possible. However, in interpreting Equations (8-1) and (8-2) it must be kept in mind that CFB or most other two phase flows are never in a true steady state. Then the viscosity in Equations (8-1) and (8-2) may not be the true fluid viscosity to be discussed next, but an Eddy type viscosity caused by two phase flow oscillations usually referred to as turbulence. In view of the transient nature of two-phase flow, the drag and the boundary layer thickness may not be proportional to the square root of the intrinsic viscosity but depend upon it to a much smaller extent. As another example, liquid-solid flow and settling of colloidal particles in a lamella electrosettler the settling process is only moderately affected by viscosity. Inviscid flow with settling is a good first approximation to this electric field driven process. The physical meaning of the particulate phase viscosity is described in detail in the chapter on kinetic theory. Here the conventional derivation resented in single phase fluid mechanics is generalized to multiphase flow.},
doi = {10.2172/10184041},
url = {https://www.osti.gov/biblio/10184041},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jul 01 00:00:00 EDT 1992},
month = {Wed Jul 01 00:00:00 EDT 1992}
}