Drying of beans in a pulsed fluid bed dryer: Drying kinetics, fluid-dynamic study and comparisons with conventional fluidization

Nitz, Marcello; Taranto, Osvaldir Pereira

doi:10.1016/j.jfoodeng.2006.05.025

Cited by 54 publications

(32 citation statements)

References 5 publications

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“…Maximum pressure drop is approximately 400 Pa in all conditions, but a little higher when the pulsation frequency was 900 rpm. A possible explanation for that was presented in a previous work [7]: with a higher frequency, the intermittence interval is shortened and there is less time left for the bed to settle. As a consequence, there is more space between particles, which increases gas-solid contact and the pressure drop.…”

Section: Fluid Dynamicsmentioning

confidence: 79%

“…Data were recorded every 1.0 s. The whole apparatus is described in more detail in previous publications [7,9].…”

Section: Data Acquisition Systemmentioning

confidence: 99%

“…The amount of air necessary to fluidize a certain mass of material in a conventional system is roughly three or four times greater than in a PFB. Most of the studies confirming that, however, have been carried out with materials whose drying process is controlled by diffusion, such as beans [7,8] and rice [5]. In these cases, as long as the gas flow is well distributed across the bed, the intermittent feed of air does not affect the drying rate for the internal movement of moisture controls the drying process.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Drying of Sodium Acetate in a Pulsed Fluid Bed Dryer

Souza

Nitz

Lima³

et al. 2010

Chem Eng & Technol

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Sodium acetate crystals obtained from the reaction of acetic acid with sodium hydroxide are usually dried in rotary or fluidized beds. In this study, a batch pulsed fluid bed dryer with a 0.18 m 2 cross-sectional area was used in an attempt to reduce energy consumption and increase productivity. Drying curves of sodium acetate were determined for different conditions: inlet air temperature of 65 and 80°C and pulsation frequency of 0 rpm (conventional fluidized bed), 500 and 900 rpm (pulsed fluid bed). A 2 2 factorial design was used to analyze the results. The intermittent flow helped to break agglomerates and provided better contact between particles and the gas. Drying rates were higher under pulsed fluidization when compared to conventional fluidization. Conventional fluidized bed drying consumed 2.5 times more energy at 80°C. The influence of temperature on the drying rate was also evident.

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Section: Fluid Dynamicsmentioning

confidence: 79%

“…Data were recorded every 1.0 s. The whole apparatus is described in more detail in previous publications [7,9].…”

Section: Data Acquisition Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Drying of Sodium Acetate in a Pulsed Fluid Bed Dryer

Souza

Nitz

Lima³

et al. 2010

Chem Eng & Technol

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“…Fluid bed drying can be used for the uniform drying of powders with high heat and mass transfer rates (Senadeera et al 2000. Additionally, fluidization enhances the mixing of the particles ensuring more homogeneous conditions (Nitz and Taranto 2007;Srinivasakannan and Balasubramanian 2008). An important parameter to control is the horizontal transport rate of particles in the continuous fluidised bed.…”

Section: Introductionmentioning

confidence: 99%

Cross-flow deep fat frying and its effect on fry quality distribution and mobility

Koerten

Schutyser

Somsen³

et al. 2015

J Food Sci Technol

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Conventional industrial frying systems are not optimised towards homogeneous product quality, which is partly related to poor oil distribution across the packed bed of fries. In this study we investigate an alternative frying system with an oil cross-flow from bottom to top through a packed bed of fries. Fluidization of rectangular fries during frying was characterised with a modified Ergun equation. Mixing was visualized by using two coloured layers of fries and quantified in terms of mixing entropy. Smaller fries mixed quickly during frying, while longer fries exhibited much less mixing, which was attributed to the higher minimum fluidization velocity and slower dehydration for longer fries. The cross-flow velocity was found an important parameter for the homogeneity of the moisture content of fries. Increased oil velocities positively affected moisture distribution due to a higher oil refresh rate. However, inducing fluidization caused the moisture distribution to become unpredictable due to bed instabilities.

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“…The response surface method has been applied by Theppaya and Prasertsan [13] to optimise the drying of rubber wood, by Madamba and Lopez [14] to optimise the osmotic dehydration of mango slices and by Hammami and Rene [15] to determine the freeze-drying process variables for strawberries. Nitz and Taranto [16] investigated the drying of beans in a pulsed bed dryer using an experimental design whose results were used for creating a model of the process. An experimental design was also performed by Lopes da Cunha et al [17], who studied the drying of mango powder in a spout fluidised bed dryer.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Specific Moisture Extraction Rate and Leakage Ratio in a Condensing Tumble Dryer

Stawreberg

Nilsson

2010

Applied Thermal Engineering

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The use of tumble dryers in households is becoming more common. Tumble dryers, however, consume large amounts of electric energy. A statistical model over the tumble dryer is created from a design of experiments. The model will be used to find the best settings for the power supply to the heater, the internal airflow and the external airflow in order to reach a high specific moisture extraction rate (SMER) and a low leakage ratio of water vapour. The aim also involves explaining the trends of the SMER and the leakage ratio based on the physics of the tumble dryer drying process. A statistically significant model, which can be used for improving the SMER and leakage ratio, was established from 19 experiments in a condensing tumble dryer. The results show that a high power supply to the heater, a high internal airflow and a low external airflow give the highest SMER values. This combination of settings also results in the largest leakage ratio values for the dryer. Leakage is most affected by the external airflow.2

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Drying of beans in a pulsed fluid bed dryer: Drying kinetics, fluid-dynamic study and comparisons with conventional fluidization

Cited by 54 publications

References 5 publications

Drying of Sodium Acetate in a Pulsed Fluid Bed Dryer

Drying of Sodium Acetate in a Pulsed Fluid Bed Dryer

Cross-flow deep fat frying and its effect on fry quality distribution and mobility

Modelling of Specific Moisture Extraction Rate and Leakage Ratio in a Condensing Tumble Dryer

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