Single‐particle motion and heat transfer in fluidized beds

Wong, Yee Sun; Seville, Jonathan

doi:10.1002/aic.11012

Cited by 31 publications

(24 citation statements)

References 13 publications

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“…As pointed by Achim et al (2002), the factors can be classified as particle characteristics, mechanical design and operating conditions. Some previous experimental studies have focused on bubble and particle behaviors (Kobayashi et al, 2000, Ozawa et al, 2002, tube attrition, erosion or wastage (Bouillard and Lyczkowski, 1991;Lee and Wang, 1995;Fan et al, 1998;Wiman, 1994), heat transfer (Wong andSeville, 2006, Wiman andAlmstedt, 1997) and gas flow regimes (Wang et. al, 2002).…”

Section: Introductionmentioning

confidence: 99%

CFD Modelling of Fluidized Bed with Immersed Tubes

Costa¹,

Colman²,

Paraíso³

et al. 2012

Advances in Chemical Engineering

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Section: Introductionmentioning

confidence: 99%

CFD Modelling of Fluidized Bed with Immersed Tubes

Costa¹,

Colman²,

Paraíso³

et al. 2012

Advances in Chemical Engineering

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“…This may be due to the cylinder height of the simulation (=200 mm) being lower than that of experiment (= 230 mm). Previous experimental study showed that the HTC increases with the increase of cylinder height [16]. The HTC of cylinder-bed consists of two parts: i.e., convection heat transfer between the cylinder and gas, and conduction heat transfer between the cylinder and particles (See Eq.…”

Section: Resultsmentioning

confidence: 99%

Discrete particle simulation of heat transfer in pressurized fluidized bed with immersed cylinders

Wahyudi

2013

AIP Conference Proceedings

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Abstract. The combined computational fluid dynamics and discrete element method (CFD-DEM) has been extended and used in recent years to study heat transfer between bed and an immersed cylinder in fluidized beds at the particle scale. The previous models usually assume the gas flow to be two-dimensional. This does not fully represent the reality in which both the gas motions and particle-gas interactions naturally have more than six degrees of freedom. Here, a full 3DCFD-DEM model is developed to study the heat transfer in 3D gas-fluidized beds with immersed cylinders. For the purpose of the model validation, the simulations are conducted first for a single cylinder under different superficial gas velocities. It is shown that the predicted heat transfer coefficients between the cylinder and bed as a function of superficial gas velocity qualitatively agree with the measurements reported in the literature. The v-shaped curve is also reproduced. Then the simulations are conducted for a fluidized bed with cylinder banks (inline and staggered configurations) at a moderate superficial gas velocity. It is also shown that there is no significant difference in the averaged heat transfer coefficient between inline and staggered arrangements at a moderate superficial gas velocity. This work demonstrates that the developed 3D CFD-DEM approach could be a useful tool to study the coupled flow phenomena and heat transfer in such complex systems.

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“…It is therefore not possible to determine unambiguously that the tracer has made contact with a given surface. An approach which can be followed, as in previous work by Wong and Seville (2006), is to define virtual surfaces which are concentric with the surface of interest but at a certain distance from it, and to measure the residence time of the tracer within each surface, i.e. within a ''wall region" of a certain thickness.…”

Section: Residence Time At the Wall And Its Relationship To Heat Tranmentioning

confidence: 99%

“…The first attempt to interpret fluidised bed heat-transfer results using single-particle trajectories obtained from Positron Emission Particle Tracking (PEPT) was made by Wong and Seville (2006). PEPT is ideally suited to this task since it enables a single particle of the bed material to be tracked at speeds up to the maximum experienced in this application, to a precision of ± about 1 mm, within a bed of opaque material and within a retaining tube with metal walls.…”

Section: Introductionmentioning

confidence: 99%

Particle motion and heat transfer in an upward-flowing dense particle suspension: Application in solar receivers

García‐Triñanes

Seville

Ansart

et al. 2018

Chemical Engineering Science

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. Particle trajectories are determined within a dense upward-moving fluidised bed.Particle-to-wall heat transfer coefficients have been measured experimentally.Heat transfer coefficients are in the range 180-320 W/m 2 K.Particle residence times at the wall were found to be distributed according to a log-normal distribution.Experimentally-obtained heat transfer coefficients were found to be in good agreement with prior predictions. g r a p h i c a l a b s t r a c t a b s t r a c tConcentrated solar power (CSP) plants conventionally make use of molten salt as the heat transfer medium, which transfers heat between the solar receiver and a steam turbine power circuit. A new approach uses particles of a heat-resistant particulate medium in the form of many dense upward-moving fluidised beds contained within an array of vertical tubes within the solar receiver. In most dense gas-solid fluidisation systems, particle circulation is induced by bubble motion and is the primary cause of particle convective heat transfer, which is the major contributing mechanism to overall heat transfer. The current work describes experiments designed to investigate the relationship between this solids convection and the heat transfer coefficient between the bed and the tube wall, which is shown to depend on the local particle concentration and their rate of renewal at the wall. Experiments were performed using 65 mm silicon carbide particles in a tube of diameter 30 mm, replicating the conditions used in the real application. Solids motion and time-averaged solids concentration were measured using Positron Emission Particle Tracking (PEPT) and local heat transfer coefficients measured using small probes which employ electrical resistance heating and thermocouple temperature measurement. Results show that, as for other types of bubbling beds, the heat transfer coefficient first increases as the gas flow rate increases (because the rate of particle renewal at the wall increases), before passing through a maximum and decreasing again as the reducing local solids concentration at the wall becomes the dominant effect. Measured heat transfer coefficients are compared with theoretical approaches by Mickley and Fairbanks packet model and Thring correlation. The close correspondence between heat transfer coefficient and solids movement is here demonstrated by PEPT for the first time in a dense upward-moving fluidised bed.

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Single‐particle motion and heat transfer in fluidized beds

Cited by 31 publications

References 13 publications

CFD Modelling of Fluidized Bed with Immersed Tubes

CFD Modelling of Fluidized Bed with Immersed Tubes

Discrete particle simulation of heat transfer in pressurized fluidized bed with immersed cylinders

Particle motion and heat transfer in an upward-flowing dense particle suspension: Application in solar receivers

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