Solids movement in liquid fluidised beds—I Particle velocity distribution

Carlos, Cabarcas Reyes Juan; Richardson, John F.

doi:10.1016/0009-2509(68)80016-8

Cited by 86 publications

(22 citation statements)

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“…This theory also allows the computation of viscosity of particles from measurements of granular temperature (Gidaspow andHuilin, 1996a: Gidaspow et al, 1995;Shao et al, 1995) or from measurements of granular pressure (Chen et al 1994). Carlos and Richardson (1968) used a photographic technique to measure particle oscillations in a liquid-solid fluidized bed, while Arastoopour et al (1992) used a laser Doppler velocity meter to show that the particlevelocity distribution for flow of a dilute solid-gas mixture in a tube is approximately Maxwellian. Gidaspow et al (1995) and Bahary (1994) developed a digital camera technique to measure the granular temperature.…”

Section: Introductionmentioning

confidence: 99%

Equation of state and radial distribution functions of FCC particles in a CFB

1998

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Section: Introductionmentioning

confidence: 99%

Equation of state and radial distribution functions of FCC particles in a CFB

1998

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“…Both Garside &Al Dibouni 1977, andCouderc 1977, have observed a change in the slope of their data on such a plot at ε≈0.85 and suggested correlations for low ε (ε < 0.85) and high ε (ε> 0.85) systems. Carlos &Richardson, 1968, andKmiec, 1978, concluded, analyzing the movement of labelled particles in fluidized beds, that probably there is a change in the mechanism of momentum transfer at voidage ε≈0.85. Our investigations in liquid fluidized beds showed agreement with mentioned literature results (Fig.…”

Section: Hydrodynamics and Mass Transfer 41 Hydrodynamics In Heterogmentioning

confidence: 99%

Hydrodynamics and Mass Transfer in Heterogeneous Systems

Garić‐Grulović¹,

Bošković‐Vragolović²,

Grbavčić³

et al. 2011

Advanced Topics in Mass Transfer

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“…Experimental observations (e.g., Houghton, 1966;Carlos and Richardson, 1968) of the behavior of particles in liquid-solids fluidized beds have revealed that flow of the fluidizing medium induces not only convective flow of groups of particles but also random motion of the individual particles. A mechanism is proposed here for the fluctuations of particle motion, i.e., the microscopic change in the movement of particles, in a macroscopically stationary fluidized bed.…”

Section: Mechanism Of Particle Motionmentioning

confidence: 99%

Behavior of particles in a liquid‐solids fluidized bed

1983

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The mechanics of particle motion in a fluidized bed were studied by focusing on the microscopic behavior of the particles. The local displacements of nylon particles fluidized by liquid were measured by the microcapacitance method, and the resultant time series was analyzed by determining its auto-correlation function and the corresponding power spectrum. This has given rise to a stochastic or statistical model of particle displacements in the fluidized bed. This model visualizes the particle motion in a fluidized bed to consist of the random movement, generating irregular signals, and the linear movement, generating wave-like signals. Recently, Yutani and Ototake (1980) analyzed the motion of particles in a liquidsolids fluidized bed by a statistical method. To enhance the theoretical basis of their approach, additional microscopic measurements need to be made, and a mechanistic model for the particle motion needs to be developed. N. YUTANIIn this study, local displacements of nylon particles fluidized by a fluidizing medium were measured by the micro-capacitance method. The resultant time series were analyzed by determining their autocorrelation function and power spectrum. An autocorrelation function gives rise to the variance of particle displacements and the relaxation time of particle movement in the field; it can provide useful information for estimating the local particle diffusivity which is of practical importance in understanding mechanism and in determining the mass or heat transfer between the fluid and particles in a fluidized bed. The power spectrum yields information related to the local velocity distribution of particles. CONCLUSIONS AND SIGNIFICANCEA new technique, which utilizes a micro-capacitance probe, has been developed to measure local fluctuations of particle motion in a liquid-solids fluidized bed. The results indicate that the recorded signals are composed of a sine wave component and a stochastic component. A model has been proposed by taking these two components into account, and the auto-correlation function of the model has been fitted to experimental data by adjusting the frequency of the sine wave, fo, and the intensity of transition of particles, A. In addition, fo/A has been found to be independent of the void fraction of the fluidized bed, c, but dependent on the viscosity of the fluidizing medium, p. The power spectral density function derived from the model has been compared with that from the data. Although a liquid-solids fluidized bed is used in this study, there is no reason to suspect that the methodology developed here can not be applied to a gas-solids fluidized bed. In fact, it is easier to use the microcapacitance probe in the latter than in the former because the probe need not be insulated in the gas-solids bed. THEORETICAL Mechanism of Particle MotionExperimental observations (e.g., Houghton, 1966;Carlos and Richardson, 1968) of the behavior of particles in liquid-solids fluidized beds have revealed that flow of the fluidizing medium induces not only convective fl...

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Solids movement in liquid fluidised beds—I Particle velocity distribution

Cited by 86 publications

References 1 publication

Equation of state and radial distribution functions of FCC particles in a CFB

Equation of state and radial distribution functions of FCC particles in a CFB

Hydrodynamics and Mass Transfer in Heterogeneous Systems

Behavior of particles in a liquid‐solids fluidized bed

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