A liquid diffusion model for thin-layer drying of rough rice

Hacıhafızoğlu, Oktay; Cihan, Ahmet; Kahveci, Kamil; Lima, Antônio Gilson Barbosa de

doi:10.1007/s00217-007-0593-0

Cited by 47 publications

(55 citation statements)

References 13 publications

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“…Among these models, the liquid diffusion is very found in the drying description of agricultural products (Mulet et al 2005;Hacihafizoglu et al 2008;Silva et al 2009Silva et al , 2010a. In order to solve the diffusion equation, in many of these researches the boundary condition of the first kind is assumed in the solution.…”

Section: Described Drying Ofmentioning

confidence: 99%

“…In order to solve the diffusion equation, in many of these researches the boundary condition of the first kind is assumed in the solution. In addition, the effective mass diffusivity and the volume of the solid are considered constant during the whole process (Mulet et al 2005;Hacihafizoglu et al 2008;Silva et al 2009). For these assumptions, considering a simple geometry, the diffusion equation can be solved analytically (Mulet et al 2005;Hacihafizoglu et al 2008;Silva et al 2009Silva et al , 2012.…”

Section: Described Drying Ofmentioning

confidence: 99%

“…In addition, the effective mass diffusivity and the volume of the solid are considered constant during the whole process (Mulet et al 2005;Hacihafizoglu et al 2008;Silva et al 2009). For these assumptions, considering a simple geometry, the diffusion equation can be solved analytically (Mulet et al 2005;Hacihafizoglu et al 2008;Silva et al 2009Silva et al , 2012. On the other hand, if the boundary condition is of the third kind, normally the diffusion equation is solved numerically (Wu et al 2004;Mulet et al 2005;Olek and Weres 2007;Da Silva et al 2012), although a few analytical solutions are also found in the literature (Silva et al 2010a, b).…”

Section: Described Drying Ofmentioning

confidence: 99%

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Comparison of boundary conditions to describe drying of turmeric (Curcuma longa) rhizomes using diffusion models

Silva

2012

J Food Sci Technol

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Turmeric is harvested with high moisture content and should be dried before the storage. It is observed that drying is quickest when the rhizomes are peeled and cut in small cylindrical pieces. In order to describe the process, normally a diffusive model is used, considering boundary condition of the first kind for the diffusion equation. This article uses analytical solutions considering boundaries conditions of the first (model 1) and third (model 2) kinds coupled to an optimizer to describe the drying process. It is shown that, for model 1, the fit of the analytical solution to the experimental data is biased, despite the good statistical indicators (chi-square χ 2 equal to 1.7095×10 −3 and coefficient of correlation R 2 of 0.9988). For model 2, the errors of the experimental points about the simulated curve can be considered randomly distributed, and the statistical indicators are much better than those obtained for model 1: χ 2 03.5596×10 −4 and R 2 00.9996.

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Section: Described Drying Ofmentioning

confidence: 99%

Section: Described Drying Ofmentioning

confidence: 99%

Section: Described Drying Ofmentioning

confidence: 99%

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Comparison of boundary conditions to describe drying of turmeric (Curcuma longa) rhizomes using diffusion models

Silva

2012

J Food Sci Technol

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“…In order to describe the drying and cooling kinetics of foodstuffs, several authors use diffusion models (Dincer, 1996;Gastón et al, 2002;Doymaz, 2005;Amendola and Queiroz, 2007;Resende et al, 2007;Hacihafizoglu et al, 2008;Silva et al, 2008;Cuesta and Lamúa, 2009). If the thermo-physical parameters and the dimensions of the solid are considered constant, the diffusion equation has an analytical solution for several shapes such as a sphere, a cylinder and a slab, among others.…”

Section: Introductionmentioning

confidence: 99%

“…The discrepancy on the drying kinetics description due to the shape of the solid was studied by Hacihafizoglu et al (2008) using experimental data for rice. The geometries used to approach the grain's shape were: sphere, finite cylinder, and prolate spheroid.…”

Section: Introductionmentioning

confidence: 99%

Influence of the geometry on the numerical simulation of the cooling kinetics of cucumbers

Silva¹,

Silva²,

Nascimento³

et al. 1970

Span. j. agric. res.

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In this paper, the effect of the geometric representation of cucumbers on the numerical simulation of its cooling kinetics is studied. It is supposed that the diffusion model with boundary condition of the third kind satisfactorily describes the cooling, and that the thermo-physical parameters are constant during the process. The geometries used to represent the cucumber are: infinite cylinder, finite cylinder, and ellipsoid. The diffusion equation was solved through the finite volume method, with a fully implicit formulation, using cylindrical and generalized coordinates. The convective heat transfer coefficient and the thermal diffusivity were determined through optimization, using the inverse method. The best model in the representation of the cucumber's shape was the ellipsoid, but the time demanded in its optimization was about 66 times greater than the time for the infinite cylinder.Additional key words: convective heat transfer coefficient; Cucumis sativus; cylindrical coordinates; diffusion; finite volume method; generalized coordinates; thermal diffusivity. Resumen Influencia de la geometría en la simulación numérica de la cinética del enfriamiento del pepinoEn este trabajo se ha estudiado el efecto de la representación geométrica de los pepinos en la simulación numérica de su cinética de enfriamiento. Se ha supuesto que el modelo de difusión con la condición de frontera de tercera clase describe satisfactoriamente el enfriamiento y que los parámetros termofísicos son constantes durante el proceso. Las geometrías utilizadas para representar el pepino son cilindro infinito, cilindro finito y elipsoide. La ecuación de difusión se resolvió a través del método de volumen finito, con una formulación totalmente implícita, utilizando coordenadas cilíndricas y generalizadas. El coeficiente de transferencia de calor por convección y la difusividad tér-mica fueron determinados a través de la optimización, utilizando el método inverso. El mejor modelo en la representación de la forma del pepino fue el elipsoide, pero el tiempo exigido para su optimización fue cerca de 66 veces mayor que el tiempo para el cilindro infinito.

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Spatial reaction engineering approach as an alternative for nonequilibrium multiphase mass‐transfer model for drying of food and biological materials

Putranto

Chen

2012

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com).Drying is a complex process which involves simultaneous heat and mass transfer. Complicated structure and heterogeneity of food and biological materials add to the complexity of drying. Drying models are important for improving dryer design and for evaluating dryer performance. The lumped reaction engineering approach (L-REA) has been shown to be an accurate and robust alternative for cost-effective simulations of challenging drying systems. However, more insightful physics has to be shown spatially. In this study, the REA is coupled with the standard mechanistic drying models to yield the spatial-REA (S-REA) as nonequilibrium multiphase mass-transfer model. The S-REA consists of a system of equations of conservation with the REA representing the local evaporation and wetting rate. Results of the modeling using the S-REA match well with the experimental data reported previously. This is the first comprehensive REA approach to model the profiles of water vapor concentration during drying of food and biological materials. This study indicates that the S-REA can be an accurate nonequilibrium multiphase mass-transfer model with appropriate account of the local evaporation rate. The overall REA concept is expected to contribute substantially for better and cost-effective representation of transport phenomena of drying process.

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A liquid diffusion model for thin-layer drying of rough rice

Cited by 47 publications

References 13 publications

Comparison of boundary conditions to describe drying of turmeric (Curcuma longa) rhizomes using diffusion models

Comparison of boundary conditions to describe drying of turmeric (Curcuma longa) rhizomes using diffusion models

Influence of the geometry on the numerical simulation of the cooling kinetics of cucumbers

Spatial reaction engineering approach as an alternative for nonequilibrium multiphase mass‐transfer model for drying of food and biological materials

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