Studies on heat transfer near wall surface in packed beds

Yagi, Shuhei; Kunii, Daizo

doi:10.1002/aic.690060119

Cited by 220 publications

(102 citation statements)

References 7 publications

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“…When the flow rate is increased, the value of the heat transfer coefficient increases linearly for both materials. This tendency was previously observed by Yagi and Kunii [29] and Kunii and Suzuki [7]. Furthermore, when the particles are surrounded by motionless fluid, the thermal conductivity of a layer of solids adjacent to the surface aids in the transport of heat.…”

Section: Fixed Bedsupporting

confidence: 61%

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Experimental heat transfer coefficients between a surface and fixed and fluidized beds with PCM

Izquierdo-Barrientos

Sobrino

Almendros-Ibáñez

2015

Applied Thermal Engineering

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This work presents an experimental study to determine the capacity of a phase change material (PCM) in granular form to be used in fixed and bubbling fluidized beds for thermal energy storage. The experimental measurements are focused on determination of the heat transfer coefficient between a heated surface immersed in the bed and the granular PCM. The flow rate is varied to quantify its influence on the heat transfer coefficient. The PCM used is Rubitherm GR50 with a phase change temperature of approximately 50• C. The PCM is available in two different particle sizes, 0.54 mm and 1.64 mm, of which the finer is used in the fluidized bed and the coarser is used in the fixed bed. In addition, the results obtained for the PCM are compared with the heat transfer coefficients measured for sand, a material commonly used for thermal storage. * Corresponding author. NOTICE: this is the author's version of a work that was accepted for publication in Applied Thermal Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Thermal Engineering 78 (2015) pp. 373-379. doi:10.1016/j.applthermaleng.2014.12.044 In comparing the heat transfer coefficients for fixed and fluidized beds, the heat transfer coefficients in the fluidized bed with PCM are nearly three times higher than those for the fixed bed at the same gas flow rate. This increase in the heat transfer is a result of two main factors: first, the continuous renewal of PCM particles from the heated surface when they are fluidized, and second, the large quantities of energy in latent form absorbed by the PCM. In the fixed bed there is no renovation of particles, consequently only a small percentage of particles are able to change its phase. Hence, there is no increase in the heat transfer coefficient due to this fact.

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Section: Fixed Bedsupporting

confidence: 61%

“…Yagi and Kunii [18] stated that the convective heat transfer coefficient between a wall surface and a packed bed h w can be expressed as:…”

Section: Introductionmentioning

confidence: 99%

Experimental heat transfer coefficients between a surface and fixed and fluidized beds with PCM

Izquierdo-Barrientos

Sobrino

Almendros-Ibáñez

2015

Applied Thermal Engineering

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“…Extensive investigations have been performed in order to determine heat transfer coefficients for packed beds [62], but most of these have covered the region of higher Reynolds numbers (Re p [ 50). Yagi and Kunii [63] developed a correlation for heat transfer near the wall surface, assuming from previous work that the effective thermal conductivity decreases near the wall surface. This could be because of more loose packing near the wall, thereby reducing the mixing and decreasing the heat conductivity.…”

Section: Effective Heat and Mass Transport In The Pseudo-homogeneous mentioning

confidence: 99%

Modeling and Simulation of an Integrated Micro Packed Bed Reactor-Heat Exchanger Configuration for Direct Dimethyl Ether Synthesis

et al. 2011

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The application of an integrated micro packed bed reactor-heat exchanger for highly exothermic syngas conversion to dimethyl ether was investigated by numerical simulation. A three-dimensional pseudo-homogeneous model was developed to describe concentration and temperature distributions inside a single reaction slit. The model was adopted at low Reynolds numbers (small catalyst particles and long residence times). The simulation results reveal that the micro packed reaction slit is close to isothermal, and a negligible temperature gradient is predicted also for a doubling of the critical reaction slit dimension, i.e. the reaction slit height. The flow in the reaction slit was modelled by Brinkman's equation and it was found that the pressure drop in wide range of gas velocity was not significant. The reactor simulation showed good agreement with experimental results and could be further developed to assess the potential of microstructured packed bed reactors to intensify large-scale industrial processes.

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“…ous studies involving a narrow annular packed bed NAPB D rdF 4 have been conducted. Wall heat-transfer coeffie cients and effective thermal conductivities for narrow annu-Ž lar beds have been investigated Yagi and Kunii, 1960;Melanson and Dixon, 1985;Fedoseev and Shanin, 1986; . Rimkevicius et al, 1991 .…”

mentioning

confidence: 99%

Narrow annular packed‐bed radial void fraction correlation

Mueller

2002

AIChE Journal

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Studies on heat transfer near wall surface in packed beds

Cited by 220 publications

References 7 publications

Experimental heat transfer coefficients between a surface and fixed and fluidized beds with PCM

Experimental heat transfer coefficients between a surface and fixed and fluidized beds with PCM

Modeling and Simulation of an Integrated Micro Packed Bed Reactor-Heat Exchanger Configuration for Direct Dimethyl Ether Synthesis

Narrow annular packed‐bed radial void fraction correlation

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