skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A REDUCED ORDER MODEL OF TWO-PHASE FLOW, HEAT TRANSFER AND COMBUSTION IN CIRCULATING FLUIDIZED-BEDS

Abstract

This report summarizes the objectives, tasks and accomplishments of the second year of this research project. The report presents the following program deliverables: (1) visualization tools for reconstructing simulated data; (2) algorithms for reducing the partial differential equations to ordinary differential equations; and (3) visualization tools for Galerkin ordinary differential equations.

Authors:
Publication Date:
Research Org.:
Texas Engineering Experiment Station (US)
Sponsoring Org.:
(US)
OSTI Identifier:
813624
DOE Contract Number:
FC26-00NT40903
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Dec 2002
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 01 COAL, LIGNITE, AND PEAT; COMBUSTION KINETICS; FLUIDIZED-BED COMBUSTION; HEAT TRANSFER; TWO-PHASE FLOW; FLOW MODELS; FLOW VISUALIZATION

Citation Formats

Paul Cizmas. A REDUCED ORDER MODEL OF TWO-PHASE FLOW, HEAT TRANSFER AND COMBUSTION IN CIRCULATING FLUIDIZED-BEDS. United States: N. p., 2002. Web. doi:10.2172/813624.
Paul Cizmas. A REDUCED ORDER MODEL OF TWO-PHASE FLOW, HEAT TRANSFER AND COMBUSTION IN CIRCULATING FLUIDIZED-BEDS. United States. doi:10.2172/813624.
Paul Cizmas. Sun . "A REDUCED ORDER MODEL OF TWO-PHASE FLOW, HEAT TRANSFER AND COMBUSTION IN CIRCULATING FLUIDIZED-BEDS". United States. doi:10.2172/813624. https://www.osti.gov/servlets/purl/813624.
@article{osti_813624,
title = {A REDUCED ORDER MODEL OF TWO-PHASE FLOW, HEAT TRANSFER AND COMBUSTION IN CIRCULATING FLUIDIZED-BEDS},
author = {Paul Cizmas},
abstractNote = {This report summarizes the objectives, tasks and accomplishments of the second year of this research project. The report presents the following program deliverables: (1) visualization tools for reconstructing simulated data; (2) algorithms for reducing the partial differential equations to ordinary differential equations; and (3) visualization tools for Galerkin ordinary differential equations.},
doi = {10.2172/813624},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Dec 01 00:00:00 EST 2002},
month = {Sun Dec 01 00:00:00 EST 2002}
}

Technical Report:

Save / Share:
  • This report presents the research activity completed during the first year of the project. The report describes the tasks assigned for the reviewing period, the accomplishments and challenges of this period, as well as the results obtained so far. The next section briefly presents the research objectives of the first year of the project. The following sections describe how these tasks were accomplished. These sections also present a sample of the results obtained. There were no changes in the approach originally proposed to complete the research program.
  • The report summarizes the objectives, tasks and accomplishments of this research project. The report presents the following program deliverables: (1) database generation using MFIX code, (2) development and implementation of an algorithm to calculate the proper orthogonal decomposition (POD) basis functions, (3) visualization tools for reconstructing simulated data, (4) algorithms for reducing the partial differential equations to ordinary differential equations, (5) visualization tools for Galerkin ordinary differential equations, (6) verification and validation of the code by comparing POD and conventional solution results, and (7) development of POD strategy for best energy cut-off values.
  • Cold modeling studies of fluidized-bed behavior related to coal combustion were conducted to provide information required for the design and optimization of fluidized-bed systems for power generation. Data for flow regime, bed expansion (void fraction), transverse thermal conductivity, and bare- and finned-tube heat transfer were obtained for beds of single and mixed particle sizes fluidized with air and refrigerant R-12 at room temperature. The ranges of primary variables covered in the experimental work reported here include bed cross sections of 0.3 meter by 0.3 meter and 0.6 meter by 0.6 meter, static bed heights from 25 cm to 70 cm,more » glass particle sizes of 650 ..mu..m and 2600 ..mu..m, and silica sand sizes in the same range, air at pressures from one to ten atmospheres and refrigerant R-12 at vapor densities equal to those of air at five and ten atmospheres, air velocities up to 6.5 m/s and 3.2 m/s at one and ten atmospheres pressure, respectively. The staggered horizontal tube banks investigated in the flow and heat transfer experiments included 3.2-cm o.d. bare tubes and 2.5-cm i.d. helically finned tubes having a 5.1-cm fin o.d. The stainless steel fins were 0.27 cm and 0.15 cm thick at fin spacings of 0.98 fin/cm to 1.97 fins/cm, respectively. Five- and ten-row tube banks were tested. Generalized predictive models for the bed flow regimes, the bed expansion, the solids circulation rates, and the heat transfer to tube banks were developed and shown to be qualified by the data for both local and average bed quantities. The information and observations described here lend sufficient support to the use of higher energy density fluidized-bed combustors at increased superficial gas velocities to justify further work at high temperature aimed at validating this performance improvement.« less
  • The ability to predict gas-liquid flow patterns is crucial to the design and operation of two-phase flow systems in the microgravity environment. Flow pattern maps have been developed in this study which show the occurrence of flow patterns as a function of gas and liquid superficial velocities as well as tube diameter, liquid viscosity and surface tension. The results have demonstrated that the location of the bubble-slug transition is affected by the tube diameter for air-water systems and by surface tension, suggesting that turbulence-induced bubble fluctuations and coalescence mechanisms play a role in this transition. The location of the slug-annularmore » transition on the flow pattern maps is largely unaffected by tube diameter, liquid viscosity or surface tension in the ranges tested. Void fraction-based transition criteria were developed which separate the flow patterns on the flow pattern maps with reasonable accuracy. Weber number transition criteria also show promise but further work is needed to improve these models. For annular gas-liquid flows of air-water and air- 50 percent glycerine under reduced gravity conditions, the pressure gradient agrees fairly well with a version of the Lockhart-Martinelli correlation but the measured film thickness deviates from published correlations at lower Reynolds numbers. Nusselt numbers, based on a film thickness obtained from standard normal-gravity correlations, follow the relation, Nu = A Re(sup n) Pr(exp l/3), but more experimental data in a reduced gravity environment are needed to increase the confidence in the estimated constants, A and n. In the slug flow regime, experimental pressure gradient does not correlate well with either the Lockhart-Martinelli or a homogeneous formulation, but does correlate nicely with a formulation based on a two-phase Reynolds number.« less