Continuous and Intermittent Drying of Rough Rice: Effects on Process Effective Time and Effective Mass Diffusivity

Pereira, Joan Carlos Alves; Silva, Wilton Pereira da; Gomes, Josivanda Palmeira; Queiroz, Alexandre José de Melo; Figueirêdo, Rossana Maria Feitosa de; Melo, Bruno Adelino de; Santiago, Ângela Maria; Lima, Antônio Gilson Barbosa de; Macedo, Antônio Daniel Buriti de

doi:10.3390/agriculture10070282

Cited by 12 publications

(12 citation statements)

References 18 publications

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“…In general, it was found that all intermittency levels studied here, with intermittency ratio α = 2/3, had similar final process times, proving to be efficient in relation to energy consumption. Pereira et al (2020), in the drying of rough rice, also showed that intermittent drying produced a similar effect on drying kinetics, highlighting the feasibility of using intermittent drying of rough rice with intermittency ratio α = 2/3 for temperatures of 50 and 70 °C. The results also suggest that the 30-min tempering period was more adequate than the 20-min tempering period.…”

Section: Results Obtained By the Mathematical Modelsmentioning

confidence: 66%

“…According to Putranto et al (2011), intermittent drying reduces the effective drying time using hot air, thus reducing energy consumption per unit of removed mass, being an effective method to improve the drying rate and product quality. Pereira et al (2020), in their study on the continuous and intermittent drying of rough rice, with intermittency ratio of α= 2/3, concluded that, in a comparison between continuous and intermittent drying kinetics, drying time was reduced with the application of intermittency, promoting greater energy saving. It was verified that the boundary condition of the first type was the one which best describes the drying process of rough rice and that the effective mass diffusivity increased with intermittent drying.…”

Section: Intermittent Drying and Energy Efficiencymentioning

confidence: 99%

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Study of Continuous and Intermittent Drying of Pear Through Mathematical and Diffusion Models

Lima¹,

Silva²,

Pereira³

et al. 2021

JAS

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The methods for drying agricultural products are necessary to check the quality of the final product and feasibility of the process. The objective of this study was to perform the drying of pear by continuous and intermittent methods (α = 2/3) at two different temperatures, compare the two methods and describe the processes using mathematical and diffusion models to evaluate the saving of time and effective processing energy. For continuous drying, Page model was the one which best fitted to the experimental data, with highest coefficient of determination and lowest chi-square. Regarding intermittent drying Page model was also the one which best fitted to the experimental data for the two temperatures studied. When comparing the drying methods studied, it was found that intermittent drying produced a similar and considerably better effect on the energy saving aspect, compared with continuous drying: 41.7% at 50 °C and 25.8% at 70 °C. The effect of time intervals with the product out of the dryer, during the intermittent drying process, was reflected in the increase in the diffusion coefficient, so that the transport of moisture occurred more quickly for this type of drying, which contributes to justify the reduction of effective operating time and increased dry product quality.

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Section: Results Obtained By the Mathematical Modelsmentioning

confidence: 66%

Section: Intermittent Drying and Energy Efficiencymentioning

confidence: 99%

Study of Continuous and Intermittent Drying of Pear Through Mathematical and Diffusion Models

Lima¹,

Silva²,

Pereira³

et al. 2021

JAS

View full text Add to dashboard Cite

show abstract

“…In addition to empirical models, the process of water absorption by rice grains was also described by a diffusion model, fitted to the experimental data. Based on the literature, for grains, the usual boundary condition for the diffusion equation is of the first kind (Silva et al , 2012; Morais et al , 2013; Lima et al , 2018; Pereira et al , 2020). Thus, to solve the diffusion equation by separation of variables, it was assumed that the boundary condition could be considered as first kind.…”

Section: Methodsmentioning

confidence: 99%

“…In this process, rice grains, still with husk, are immersed in water at a temperature above 58 °C and then subjected to processes of partial or total gelatinization of starch. Thus, some water-soluble substances, such as vitamins and minerals, are transported to the center of the grain, increasing the nutritional value of this rice compared to polished rice (Buggenhout et al , 2013; Pereira et al , 2020). Finally, the parboiling process ends with the drying and refinement stages, where the rice grain becomes more resistant to breakage, in addition to reducing susceptibility to insect attack and increasing the industrial yield (Demont et al , 2012; Martins et al , 2020).…”

Section: Introductionmentioning

confidence: 99%

Use of empirical and diffusion models in the description of the process of water absorption by rice

Pereira

Silva²,

Silva

et al. 2021

Self Cite

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PurposeTo describe water absorption by the rice grains over time, diffusion and empirical models were used. Also, an optimization software was developed in this study to determine parameters and their uncertainties for the diffusion models (LS Optimizer, for partial differential equations). Parameters (and their uncertainties) for empirical models were determined by LAB Fit Curve Fitting Software.Design/methodology/approachHeat and mass diffusion phenomena are found in various processes of technological interest, including pasteurization, drying and water immersion of agricultural products, among others. The objective of this work was to study the process of water absorption by rice grains with and without husk, using diffusion and empirical models to describe the absorption kinetics. Rice grains were immersed (approximately 10 g for each experiment) in drinking water maintained at constant temperatures of 28, 40 and 50 C. In the experiments, the water contents absorbed by rice grains over time were obtained by the gravimetric method.FindingsAmong empirical models, Peleg was the most satisfactory to describe the kinetics of water absorption by rice without husk, while the Silva et alii model had the best statistical indicators for rice with husk. It was also verified that a diffusion model with boundary condition of the first kind showed the best (or equivalent) results in the description of all processes of kinetics of water absorption by rice grains, with and without husk. For grains without husk, the effective mass diffusivities were (1.186 ± 0.045) × 10−9, (1.312 ± 0.024) × 10−9 and (2.133 ± 0.028) × 10−9 m2 min−1, for the immersion temperatures of 28, 40 and 50C, respectively. For grains with husk, diffusivities were (0.675 ± 0.011) × 10−9 and (1.269 ± 0.017) × 10−9 m2 min−1, for temperatures of 28 and 50 C, respectively.Originality/valueThis work developed a solver for the diffusion equation in cylindrical geometry and presented the LS Optimizer software developed to determine differential equation parameters through experimental data sets.

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“…Chen, et al [12] carried out an orthogonal experiment involving hot air drying with variable temperature and humidity and established a comprehensive target model; the drying process was optimized by a genetic algorithm. Alves Pereira, et al [13] used empirical and diffusion models to describe rice drying kinetics, and considered only effective time of operation to compare and evaluate continuous and intermittent drying of rough rice. This study proved that a one-dimensional diffusion model could describe the drying process of rice properly, and found that the effective mass diffusivity was higher in intermittent drying as compared to continuous drying at the same temperature.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of Rice Drying Model and Analysis of Tempering Characteristics Based on Drying Accumulated Temperature

et al. 2021

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Previous research has shown that the accumulated temperature can describe drying processes as well as crop growth. To describe the mass and heat transfer processes in the rice drying process more accurately, a mathematical model of rice drying was proposed based on the drying accumulated temperature, and the optimal tempering ratio for conventional hot air drying was obtained through data comparison and analysis. First, it was proven that there was an exponential relationship between the moisture ratio and the drying accumulated temperature of rice. Second, by comparing and analyzing the fitting results of seven different drying mathematical models, the model with the highest fitting degree was selected and reconstructed to obtain the drying accumulated temperature–moisture ratio model. Finally, the new model was used to fit the results of two drying experiments without and with tempering, and the tempering characteristics of rice drying were proved by comparing and analyzing the coefficient difference between the two models. The results showed that the optimal tempering ratio was 3. This study thus provides a reference for rice drying process parameters.

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Continuous and Intermittent Drying of Rough Rice: Effects on Process Effective Time and Effective Mass Diffusivity

Cited by 12 publications

References 18 publications

Study of Continuous and Intermittent Drying of Pear Through Mathematical and Diffusion Models

Study of Continuous and Intermittent Drying of Pear Through Mathematical and Diffusion Models

Use of empirical and diffusion models in the description of the process of water absorption by rice

Reconstruction of Rice Drying Model and Analysis of Tempering Characteristics Based on Drying Accumulated Temperature

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