Effective Diffusivity
Mostrando 13-24 de 56 artigos, teses e dissertações.
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13. Energy efficiency and moisture diffusivity of apple slices during convective drying
Abstract The present study aimed at investigating the influences of drying air temperature and flow rate on energy parameters and dehydration behaviour of apple slices. For this purpose, apple slices were dried in a convective dryer at air temperatures of 50, 60 and 70 °C, and air velocities of 1, 1.5 and 2 m s–1. Dehydration rate increased as the air tem
Food Sci. Technol. Publicado em: 26/02/2016
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14. DETERMINATION OF THE EFFECTIVE RADIAL THERMAL DIFFUSIVITY FOR EVALUATING ENHANCED HEAT TRANSFER IN TUBES UNDER NON-NEWTONIAN LAMINAR FLOW
AbstractEnhanced heat transfer in tubes under laminar flow conditions can be found in coils or corrugated tubes or in the presence of high wall relative roughness, curves, pipe fittings or mechanical vibration. Modeling these cases can be complex because of the induced secondary flow. A modification of the Graetz problem for non-Newtonian power-law flow is p
Braz. J. Chem. Eng.. Publicado em: 2015-06
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15. Mathematical modeling of microwave dried celery leaves and determination of the effective moisture diffusivities and activation energy
Celery (Apium graveolens L. var. secalinum Alef) leaves with 50±0.07 g weight and 91.75±0.15% humidity (~11.21 db) were dried using 8 different microwave power densities ranging between 1.8-20 W g-1, until the humidity fell down to 8.95±0.23% (~0.1 db). Microwave drying processes were completed between 5.5 and 77 min depending on the microwave power densi
Food Sci. Technol. Publicado em: 30/05/2014
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16. Mathematical modeling of supercritical fluid extraction of oil from canola and sesame seeds
Mathematical modeling of supercritical fluid extraction of oil from canola and sesame seeds with a two-phase model was performed in this work. A model based on differential mass balance was used to correlate the experimental data. Different adsorption isotherm models (Henry, Freundlich and Brunauer, Emmet and Teller (BET)) were used to describe the equilibri
Braz. J. Chem. Eng.. Publicado em: 2013-03
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17. Effective transport properties for the pyridine-granular activated carbon adsorption system
In this work, the kinetics of pyridine adsorption onto granular activated carbon was studied from the point of view of an up-scaling process by using the method of volume averaging. The pore and surface effective diffusivities were estimated by supposing simple microscale geometries (ordered media of cylinders and spheres) and those of images processed from
Braz. J. Chem. Eng.. Publicado em: 2012-09
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18. Cinética del secado de tomillo
This work aimed to study the drying kinetics of thyme and subsequent adjustment of different mathematical models to the experimental data and to determine the effective diffusivity and the activation energy. In order to conduct the experiment the temperatures of 30, 40, 50, 60, 70 ºC were used. The experimental design employed was in randomized blocks with
Revista Brasileira de Engenharia Agrícola e Ambiental. Publicado em: 2012-06
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19. Mass transfer kinetics of osmotic dehydration of cherry tomato.
Cherry tomato samples were osmotically dehydrated in different hypertonic NaCI solutions (with or without sucrose) at two different concentrations. Mass transfer kinetics were modelled according to Peleg, Fick and Page equations. The Peleg equation presented the best fitting for water loss and Page model showed the best predictive capacity for salt gain data
Journal of Food Engineering. Publicado em: 2011
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20. Mass transfer coeficients in pulsed perforated-plate extraction columns
This study examined the mass transfer performance in a pulsed perforated-plate extraction column with diameter of 50 mm using two different liquid systems. Mass transfer coefficients have been interpreted in terms of the axial diffusion model. The effects of pulsation intensity and dispersed and continuous phase velocities on the mass transfer performance ha
Brazilian Journal of Chemical Engineering. Publicado em: 2010-06
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21. Prediction of mass transfer coefficients in a pulsed packed extraction column using effective diffusivity
The volumetric overall mass transfer coefficients have been measured in a pulsed packed extraction column using diffusion model for two different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phase flow rates on volumetric overall mass transfer coefficients have been investigated. Effecti
Brazilian Journal of Chemical Engineering. Publicado em: 2009-12
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22. Quality and technological aspects involved in watermelon (citrullus lanatus s.) peels and pulp improvement / Estudo dos aspectos tecnológicos e de qualidade envolvidos no aproveitamento da casca e da polpa da melancia (Citrullus Ianatus Schrad)
This study aimed to study and to model the drying process fresh and osmotically pretreated in sucrose solution watermelon (Citrullus lanatus S.). The osmotic dehydration process was studied through an experimental design, with independent variables as osmotic solution temperature (30 - 50oC) and concentration (40 - 60% w / w) and immersion time (90 - 240min)
Publicado em: 2009
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23. Desidratação osmotica e secagem convectiva de maçã : transferencia de massa e alterações de estrutura celular / Osmotic dehydrations and convective drying apple; : mass transfer and cellular structure changes
In this study it was investigated the osmotic dehydration of apples (Fuji variety) followed or not by convective drying with hot air. Concentration profiles were determined for water and solute(s) in samples of apples cut in half and osmotically dehydrated in binary aqueous solutions (30% and 50% sucrose, w/w) and ternary solution (50% sucrose and 10% sodium
Publicado em: 2009
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24. Mass transfer coefficients in a hanson mixer-settler extraction column
The volumetric overall mass transfer coefficients in a pilot plant Hanson mixer-settler extraction column of seven stages have been measured using toluene-acetone-water system. The effects of agitation speed and dispersed and continuous phases flow rates on volumetric overall mass transfer coefficients have been investigated. The results show that the volume
Brazilian Journal of Chemical Engineering. Publicado em: 2008-09