Drying kinetics of sunflower grains/Cinetica de secagem dos graos de girassol

The objectives of this study were to fit different mathematical models to experimental data of drying of sunflower grains, determine and evaluate the effective diffusion coefficient and obtain the activation energy for the process during the drying under various conditions of air. The sunflower grai...

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Published in:Revista brasileira de engenharia agrícola e ambiental 2017-03, Vol.21 (3), p.203
Main Authors: de S. Smaniotto, Thais A, Resende, Osvaldo, de Sousa, Kelly A, de Oliveira, Daniel E.C, Campos, Rafael C
Format: Article
Language:English
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Summary:The objectives of this study were to fit different mathematical models to experimental data of drying of sunflower grains, determine and evaluate the effective diffusion coefficient and obtain the activation energy for the process during the drying under various conditions of air. The sunflower grains were collected with an initial moisture content of 0.5267 dry basis (d.b.) and dried in an oven with forced air ventilation under five temperature conditions: 35, 50, 65, 80 and 95[degrees]C, until reaching the moisture content of 0.0934 [+ or -] 0.0061 (d.b.). Among the analyzed models, Wang and Singh showed the best fit to describe the drying phenomenon. The effective diffusion coefficient of sunflower grains increased with the increment in air temperature and has activation energy for liquid diffusion in the sunflower drying of 29.55 kJ [mol.sup.-1]. Key words: mathematical modeling Heliantus annus liquid diffusivity Objetivou-se, neste trabalho, ajustar diferentes modelos matematicos aos dados experimentais da secagem dos graos de girassol, determinar e avaliar o coeficiente de difusao efetivo e obter a energia de ativacao para o processo durante a secagem em diversas condicoes de ar. Os graos de girassol foram colhidos com teor de agua inicial de 0,5267 base seca (b.s) e submetidos a secagem em estufa com ventilacao de ar forcada em cinco condicoes de temperatura: 35, 50, 65, 80 e 95[degrees]C, ate atingir o teor de agua de 0,0934 [+ or -] 0,0061(b.s). Dentre os modelos analisados, o de Wang e Singh, apresentou os melhores ajustes e foi escolhido para descrever o fenomeno de secagem. O coeficiente de difusao efetivo aumenta com a elevacao da temperatura do ar e apresenta uma energia de ativacao para a difusao liquida na secagem do girassol de 29,55 kJ [mol.sup.-1]. Palavras-chave: modelagem matematica Heliantus annus difusividade liquida
ISSN:1415-4366