Pneumatic Drying in Diluted Phase: Parametric Analysis of Tube Diameter and Mean Particle Diameter

Paixão, Ana Eleonora Almeida; Rocha, Sandra Cristina dos Santos

doi:10.1080/07373939808917505

Cited by 12 publications

(10 citation statements)

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“…[1,[4][5][6] Kaensup et al, [1] for example, investigated the use of pneumatic drying for paddy and found that the moisture content of paddy could be rapidly decreased, especially at a higher inlet air temperature. Nevertheless, pneumatic drying suffers from some drawbacks; in particular, in terms of excessive cracks and discoloration of dried paddy kernels.…”

Section: Introductionmentioning

confidence: 98%

Comparative Evaluation of Hot-Air and Superheated-Steam Impinging Stream Drying as Novel Alternatives for Paddy Drying

et al. 2013

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An investigation was conducted on impinging stream drying of moist paddy using hot air and superheated steam as the drying media. Drying experiments were divided into two parts: namely, one-pass and two-pass drying. The volumetric water evaporation rate, volumetric heat transfer coefficient, and specific energy consumption of the drying system at various conditions were assessed; in the case of superheated-steam drying, the effect of steam recycle was also assessed. The quality of dried paddy was evaluated in terms of color, head rice yield, and degree of starch gelatinization. In the case of one-pass drying, an increase in the drying temperature led to a significant increase in the volumetric water evaporation rate and volumetric heat transfer coefficient. On the other hand, in the case of two-pass drying, an increase in the drying temperature led to a significant decrease in the volumetric heat transfer coefficient; the volumetric water evaporation rate was not significantly affected, however. The specific energy consumption decreased with an increase in the drying temperature. At the same temperature, using superheated steam as the drying medium led to lower specific energy consumption; higher level of steam recycle also led to more energy conservation. The color of the dried paddy was not affected by the change in the drying temperature; superheated-steam-dried paddy was redder and more yellow than the hot-air-dried paddy. An increase in the drying temperature led to decreased percentage of head rice yield. Superheated-steam drying helped enhance the level of starch gelatinization in comparison with hot-air drying at the same temperature. Nevertheless, drying at the highest tested temperature led to a lower level of starch gelatinization.

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Section: Introductionmentioning

confidence: 98%

Comparative Evaluation of Hot-Air and Superheated-Steam Impinging Stream Drying as Novel Alternatives for Paddy Drying

et al. 2013

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“…Paixao and Rocha [4] used the mathematical model developed earlier to perform a parametric study of the diameter of tube and particle in the pneumatic drying process. Initial conditions for the modeling were experimental results obtained from their pilot scale pneumatic dryer.…”

Section: Introductionmentioning

confidence: 99%

A Small-Scale Pneumatic Conveying Dryer of Rough Rice

Kaensup

Kulwong

2006

Drying Technology

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This article studies the possibility of reducing the high initial moisture content of wet rough rice using a small-scale low-cost pneumatic conveying dryer as a first stage dryer. The parameters investigated are final moisture content, surface temperature of rough rice, head rice yield, drying rate, power consumption per unit mass of evaporated water, and physical characteristics of rice. Parametric effects of the following variables are examined: velocity of drying air from 20 to 30 m/s, feed rate of rough rice from 150 to 350 kg/h, initial moisture content from 22 to 26% (wet basis), and drying air temperature from 35 to 70 C. From the experimental results, it is found that this drying method can be used for fresh rough rice with an initial moisture content of over 24% (wet basis). The drying process is able to lead to very rapid drying without any grain quality problems such as cracks in the rice kernel. The moisture content can be reduced to approximately 18% (wet basis) or about 5-6% of the initial moisture content within 3-4 s. The optimal drying air temperature is in the range of 50 to 60 C. A comparison of pneumatic conveying drying data obtained from the present study with fluidized bed drying data reported in the open literature is also discussed.

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“…As the gas meets the particles, particles temperature increases until it reaches the wet bulb temperature at which surface Paixao and Rocha (1998) [25] evaporation starts to occur. At this stage, convective mass transfer dominates the drying of surface moisture of particles during their residence time in the dryer.…”

Section: Casementioning

confidence: 99%

“…This equation can be used regardless of the method adopted to determine the critical moisture content. In cases when the critical moisture content is known, the FRP can then be expressed as shown in Equation (25) such that eq cr XX X   . When the critical value is not known, Equation (26) can then be used as shown below.…”

Section: Drying Model Equations -Heat and Mass Transfermentioning

confidence: 99%

See 1 more Smart Citation

Numerical Simulation of Pneumatic and Cyclonic Dryers Using Computational Fluid Dynamics

Jamaleddine¹,

Ray²

2011

Mass Transfer in Chemical Engineering Processes

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Pneumatic Drying in Diluted Phase: Parametric Analysis of Tube Diameter and Mean Particle Diameter

Cited by 12 publications

References 0 publications

Comparative Evaluation of Hot-Air and Superheated-Steam Impinging Stream Drying as Novel Alternatives for Paddy Drying

Comparative Evaluation of Hot-Air and Superheated-Steam Impinging Stream Drying as Novel Alternatives for Paddy Drying

A Small-Scale Pneumatic Conveying Dryer of Rough Rice

Numerical Simulation of Pneumatic and Cyclonic Dryers Using Computational Fluid Dynamics

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