Emulsion layer model for wall heat transfer in a circulating fluidized bed

Mahalingam, M.; Kolar, Ajit Kumar

doi:10.1002/aic.690370804

Cited by 25 publications

(22 citation statements)

References 26 publications

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“…During the test, the volumetric flow of flue gas recirculation into the furnace chamber was kept at the level of 20.5 m 3 n /s. The analyzed CFB boiler is described in detail in the works by Blaszczuk et al [7,8,31,38,56], particularly presenting the construction data, cross-sectional area, geometry of membrane wall, arrangement of measuring points and also data acquisition system. Besides, more detailed information on the flue gas recirculation system, flue gas analysis system and properties of such flue gases fed to the combustion chamber are described by Blaszczuk [57].…”

Section: Input Data To Heat Transfer Modelingmentioning

confidence: 99%

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A comparison of fuzzy logic and cluster renewal approaches for heat transfer modeling in a 1296 t/h CFB boiler with low level of flue gas recirculation

Błaszczuk¹,

Krzywański²

2017

Archives of Thermodynamics

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The interrelation between fuzzy logic and cluster renewal approaches for heat transfer modeling in a circulating fluidized bed (CFB) has been established based on a local furnace data. The furnace data have been measured in a 1296 t/h CFB boiler with low level of flue gas recirculation. In the present study, the bed temperature and suspension density were treated as experimental variables along the furnace height. The measured bed temperature and suspension density were varied in the range of 1131-1156 K and 1.93-6.32 kg/m 3 , respectively. Using the heat transfer coefficient for commercial CFB combustor, two empirical heat transfer correlation were developed in terms of important operating parameters including bed temperature and also suspension density. The fuzzy logic results were found to be in good agreement with the corresponding experimental heat transfer data obtained based on cluster renewal approach. The predicted bed-to-wall heat transfer coefficient covered a range of 109-241 W/(m 2 K) and 111-240 W/(m 2 K), for fuzzy logic and cluster renewal approach respectively. The divergence in calculated heat flux recovery along the furnace height between fuzzy logic and cluster renewal approach did not exceeded ±2%.

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Section: Input Data To Heat Transfer Modelingmentioning

confidence: 99%

“…Any part of the wall does not come in contact with the up-flowing gas jointly with the dispersed phase. Chen et al [28], Leckner [29] and Mahalingam et al [30,31] have used the continuous film model to calculate the heat transfer coefficient.…”

Section: Introductionmentioning

confidence: 99%

A comparison of fuzzy logic and cluster renewal approaches for heat transfer modeling in a 1296 t/h CFB boiler with low level of flue gas recirculation

Błaszczuk¹,

Krzywański²

2017

Archives of Thermodynamics

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“…The overal emissivity is calculated considering the gas as a mixture of grey gases and the particles obeying the Geometrical Optics Theory. The convection heat transfer coefficient, h, is predicted according to the model of Mahalimgam and Kolar (1991) for circulating fluidized beds.…”

Section: Dilute Flow Regimementioning

confidence: 99%

Numerical computation of a circulating fluidized bed combustor

Huilin

Bie

Yang

et al. 1998

Int. J. Energy Res.

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“…[5,15,16] Mahalingam and Kollar [15] proposed a heat-transfer model that incorporates a wall-emulsion-layer model. They also used an alternate-slab model to predict the radiative component for a high-temperature CFB.…”

Section: Introductionmentioning

confidence: 99%

“…According to the recent experimental observations, the CFB flow regime can be described as relatively denser at the lower part and a dilute suspension at the upper part of the bed, which consists of a lean core with an average voidage exceeding 0.9 and a denser annulus with an average void fraction in the range of 0.7 to 0.8. [15,21,22] In this study, a core-annulus type of flow structure is assumed.…”

Section: Introductionmentioning

confidence: 99%

Wall-to-bed heat transfer in a circulating fluidized bed for the reduction of iron ore particles

Hahn

1997

Metall Mater Trans B

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A model is presented that describes the wall-to-bed heat transfer in a circulating fluidized bed (CFB) used for the prereduction of iron ore in the smelting-reduction iron-making process. The model incorporates the core-annulus type flow structure and the wall emulsion layer growing downward along the surface. Model predictions showed good agreements with measured data taken from the literature. The hydrodynamic behavior near the wall surface was able to be properly described by the core-annulus flow structure. A higher heat-transfer coefficient with higher solid circulation flux was obtained in the upper part of the bed because of the heat input caused by the lateral diffusion of particles from the core. The predicted and measured data also showed the minima in the heattransfer coefficients in the lower part of the bed. Model predictions indicated that in the CFB for the reduction of iron ore particles, it is important to properly control the inlet temperature of the reducing gas, rather than that of the solid particles. The implications of the behavior of heat transfer in the CFB are discussed for the reduction of iron oxides.

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Emulsion layer model for wall heat transfer in a circulating fluidized bed

Cited by 25 publications

References 26 publications

A comparison of fuzzy logic and cluster renewal approaches for heat transfer modeling in a 1296 t/h CFB boiler with low level of flue gas recirculation

A comparison of fuzzy logic and cluster renewal approaches for heat transfer modeling in a 1296 t/h CFB boiler with low level of flue gas recirculation

Numerical computation of a circulating fluidized bed combustor

Wall-to-bed heat transfer in a circulating fluidized bed for the reduction of iron ore particles

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