Heat and Mass Transfer for Spherical Particles in a Fluid Field

Hughmark, G. A.

doi:10.1021/i160074a012

Cited by 15 publications

(6 citation statements)

References 16 publications

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“…As a first approximation, the terminal velocity for particles in quiescent fluid was used by Harriott 38 to estimate minimum k SL in STRs when particles are completely suspended. Some attempts have been made theoretically and experimentally to evaluate particle−fluid effective relative velocity in turbulent dispersions and to correlate k SL using it. ,,,− ,, These studies modified and used the equation of motion for small spherical particles suspended in a turbulent flow given by Tchen . The equation of motion proposed by Tchen is In eq 19, subscripts P and f refer to the particle and fluid, respectively.…”

Section: Slip Velocity Theory-based Approachmentioning

confidence: 99%

Particle−Liquid Mass Transfer Coefficient in Two-/Three-Phase Stirred Tank Reactors

Pangarkar

Yawalkar

Sharma

et al. 2002

Ind. Eng. Chem. Res.

101

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Knowledge of particle-liquid mass transfer coefficient (k SL ) is important for a rational design of a solid-liquid/solid-liquid-gas stirred tank reactor (STR). Considerable efforts have been made by different investigators to study and correlate the behavior of k SL in STRs for a variety of geometric and operating conditions. This review attempts to put together and analyze the information available in the literature on k SL in STRs systematically. Different approaches used by researchers to correlate k SL are critically discussed. The effect of system configurations (type of the impeller, D/T, and C/T), operating parameters (impeller speed/power input, particle loading, and gas flow rate), and physical properties (d P , D m , µ, and ∆F) on k SL have been discussed elaborately. Some new data for six-bladed impellers have been generated to determine the optimum geometric configuration and operating conditions for particle-liquid mass transfer in three-phase STRs. It is concluded that k SL in two-/three-phase STRs can be correlated reliably over a wide range of system configurations and operating parameters by a relative particle suspension term, N/N S(G) . Scope and need for further studies have been suggested.

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Section: Slip Velocity Theory-based Approachmentioning

confidence: 99%

Particle−Liquid Mass Transfer Coefficient in Two-/Three-Phase Stirred Tank Reactors

Pangarkar

Yawalkar

Sharma

et al. 2002

Ind. Eng. Chem. Res.

101

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“…Combining the mathematical forms of (3.45) and (3.46), we can specify the dependence of on in the following form: which reduces to pure conduction for and scales with for large Reynolds numbers. The parameter shall be determined with the help of the Frossling formula (Hughmark 1980; McAllister, Chen & Fernandez-Pello 2011). The detailed procedures are presented as follows.…”

Section: The Effect Of Temperature Inhomogeneity On Ignition By a Hot...mentioning

confidence: 99%

“…The Frossling formula (Hughmark 1980; McAllister et al. 2011) interprets the total heat transfer from the particle in terms of the Nusselt number, which can be equivalently correlated to an average temperature gradient, i.e.…”

Section: The Effect Of Temperature Inhomogeneity On Ignition By a Hot...mentioning

confidence: 99%

Theoretical analysis on the ignition of a combustible mixture by a hot particle

Chen

2022

J. Fluid Mech.

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Mechanical spark is an important ignition source in various industrial processes involving combustible mixtures and it may cause serious safety issues. In this work, we analysed the ignition induced by hot particles in a combustible mixture. In Semenov's transient ignition criterion, we introduced a hypothetical heat loss coefficient accounting for the temperature inhomogeneity and obtained a revised ignition criterion which allows us to calculate the ignition delay time. Explicit expressions for the critical ignition temperature were derived and used to demonstrate the primary impacts of temperature inhomogeneity on the ignition process. Consistent with experimental and numerical results, the temperature inhomogeneity is intensified by either reducing the particle size or convective heat transfer at the particle surface, resulting in an increase of the critical ignition temperature. For flow separation on the particle surface, the boundary layer problem was solved based on a Blasius series. A temperature gradient for ignition was defined at the location of flow separation to reproduce the experimentally observed phenomenon that ignition prefers to occur first near the flow separation position. It is shown that the unsteadiness of particle cooling makes negligible contribution to the ignition process because of the exceedingly large density ratio between the particle and the ambient gas. In addition, the finite residence time of ignition for a fluid parcel due to its elevation from the particle surface leads to additional growth in the critical ignition temperature. However, such a correction appears to be inconsequential because the ignition of the fluid parcel restricted to the Frank–Kamenetskii region is close to the particle surface.

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“…In such circumstances, fundamentally understanding the heat and mass transport processes as well as the fluid flow is of tremendous importance. In the last century, numerous correlations obtained from experiments have been proposed for heat and mass transfer between the fluid and the solid phase for both fixed and fluidized systems (Gunn, 1978;Wakao and Funazkri, 1978;Hughmark, 1980;Kumar and Fan, 1994;Kim and Kang, 1997;Wagner et al, 1997). Although utilization of these correlations is quick and convenient to obtain average heat and mass transfer rates, detailed information is not easily quantified.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of fluid flow and dependently coupled heat and mass transfer in fluid-particle systems

Peters

Kuipers

2019

Chemical Engineering Science

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Heat and Mass Transfer for Spherical Particles in a Fluid Field

Cited by 15 publications

References 16 publications

Particle−Liquid Mass Transfer Coefficient in Two-/Three-Phase Stirred Tank Reactors

Particle−Liquid Mass Transfer Coefficient in Two-/Three-Phase Stirred Tank Reactors

Theoretical analysis on the ignition of a combustible mixture by a hot particle

Direct numerical simulation of fluid flow and dependently coupled heat and mass transfer in fluid-particle systems

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