Drying characteristics in a packed fluidized bed dryer.

Katö, Kunio; Ohmura, Shinji; Taneda, Daisuke; Onozawa, Ichiro; Shimura, Kazuhiro; Iijima, Akira

doi:10.1252/jcej.14.365

Cited by 10 publications

(4 citation statements)

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“…Luikov [6] developed a model for the drying process by assuming that the transfer of moisture is analogous to heat transfer, and that capillary transport is proportional to moisture and temperature gradients. Kato [7] investigated a packed bed dryer in which the drying rate was studied, and combined it with heat transfer data to predict the drying of activated alumina. Hasatani and Arai [8] derived the basic differential equations controlling the temperature and concentration eld in a packed bed of ne particles, and solved the equations for the general case of unsteady heat and mass transfer.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional mathematical model of a packed bed dryer and experimentation

Tabrizi

Saffar‐Avval

Assarie

2002

Proceedings of the Institution of Mechanical Engineers, Part A:

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A comprehensive heat and mass transfer model, based on the Eulerian two uid model (TFM), developed for a packed-bed-drying process. The temperature and moisture content in a particle was considered with the conjugate effects between the gas and particles in a packed bed. Numerical study of the model was carried out on two-dimensional, axi-symmetrical cylindrical coordinates in order to investigate the effects of the different parameters such as particle size, variation of inlet gas temperature on the moisture content, and temperature of solid and gas outlet. For experimental observations, an experimental apparatus was designed and utilized. The theoretical results were then compared to the experimental data, which indicated good agreement. Keywords: packed bed, drying, two-uid model, heat and mass transfer NOTATION a speci c surface (l/m) C speci c heat (kJ/kg K) d particle diameter (m) D molecular diffusion (m 2 /s) g gravitation force (m/s 2 ) h heat transfer coef cient (W/m 2 K) I enthalpy (kJ/kg) J h heat transfer dimensionless k thermal conductivity (W/m K) lˆ0:001 m* source term moisture evaporation (kg/m 2 s) nˆ3:0 P w pressure of saturated water vapour (mmHg) Pr Prandtl number r radial distance from the centerline (m) Re Reynolds number t time T temperature (¯C) u radial velocity (m/s) v axial velocity (m/s) x moisture content x* pg moisture content of the drying gas on the surface of a particle z elevation (m) g o heat of vaporization (kJ/kg) e void fraction m viscosity (kg/m s) r density (kg/m 3 ) s evaporation coef cient (kg/m 2 s) f 1 , f 2 functional f s sphericity of a particle

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Section: Introductionmentioning

confidence: 99%

Two-dimensional mathematical model of a packed bed dryer and experimentation

Tabrizi

Saffar‐Avval

Assarie

2002

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…They considered the distribution effects of moisture content, temperature and gas pressure of the particle. Kato et al [12] studied a packed bed dryer using air as particles. They divided the bed into series of thin layers.…”

Section: Introductionmentioning

confidence: 99%

High Temperature Convective Drying of a Packed Bed with Humid Air at Different Humidities

Sghaier¹

2009

American J. of Engineering and Applied Sciences

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Problem statement: Drying a packed bed of porous particle at high temperature with varying humidity of hot air is an attractive process. Many researches on experimental and simulation on a fixed bed drying at low and average temperature are proposed. Few studies showed drying at high temperature with humid air or using superheated steam. The latest is compared to dry air. Approach: In this study, we present an experimental and numerical study of humid air drying of a fixed bed of moist porous alumina particles. The air velocity, the air temperature and the vapor pressure were varied from 1.7-2.3 m sec, 120-160°C and 0.1-0.6 bar, respectively and the experiments were performed at atmospheric pressure. Then a mathematical model describing heat and mass transfer during drying is developed. This model is based on the averaging volume approach using two scale changes. Results: From the experimental works, the solid temperature and the bed moisture content have been presented at different drying conditions. The previous results show that an increase in humidity leads to an increase of the wet bulb temperature and a decrease in the drying time. At the same drying temperature, the variation in the gas velocity affects also the drying time. In addition, we note that the drying time increases if the bed depth increases. The predicted results deduced from the developed model were compared with the experiment. Conclusion: The experimental and predicted results obtained from this study describing drying of a packed bed illustrate clearly the effect of the air humidity on the drying kinetics.

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“…The complexity of the mechanism of drying [2][3][4][5][6][7] and complicated hydrodynamic conditions in fluidized bed systems [5,8,9] are responsible for the difficulties associated with attempts to generalize the mathematical description of the kinetics of drying in a fluidized bed [9][10][11][12][13][14][15][16][17][18] and connected with them problems regarding scale-up. [19,20] The complex analysis of solids' drying in bubbling fluidized bed is presented in Tsotsas [18] and his coauthors' [21][22][23][24] researches.…”

Section: Introductionmentioning

confidence: 99%

Batch Drying Kinetics in a Two-Zone Bubbling Fluidized Bed

Ciesielczyk

2005

Drying Technology

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This article deals with investigation and modeling of batch drying process of solids in fluidized bed apparatus. There has been used model of fluidized bed drying, which consists two zones: emulsion zone and bubbling zone with taking into consideration the presence of solid particles in the bubbles. The results of theoretical expectations that arise from simulation calculations have been verified with experimental data obtained with the use of fluidized bed dryer 0.225 m in diameter. A drying process of silica gel, sand, and ammonium sulfate has been tested. To verify the model, the concept of a generalized drying curve has also been employed.

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Drying characteristics in a packed fluidized bed dryer.

Cited by 10 publications

References 0 publications

Two-dimensional mathematical model of a packed bed dryer and experimentation

Two-dimensional mathematical model of a packed bed dryer and experimentation

High Temperature Convective Drying of a Packed Bed with Humid Air at Different Humidities

Batch Drying Kinetics in a Two-Zone Bubbling Fluidized Bed

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