Mathematical models applied to drying assists in sizing dryers, predicting drying rate, improvement of drying conditions and assessment of process quality. Thus, the aim of this study was to evaluate the fitting of Page, Midilli, Newton and second law of Fick models to the experimental data of convective drying with application of infrared radiation of Moringa oleifera L. grains. The effects of factors - air temperature (30-60 °C), air velocity (0.55 to 1.05 m s-1), infrared radiation application time (120-300 s) and infrared radiation intensity (1500-4500 W) on the effective diffusivity, moisture content, water activity and drying time was also evaluated. The models explained more than 98% of the drying behavior and the Midilli model showed the best fit for the experimental data. The effective diffusivity was calculated using the equation proposed by the solution of second law of Fick, for spherical shape, and the values ranged from 6.44x10-10 to 9.89x10-10 m2 s-1. The factors air temperature and infrared radiation application time were significant for all studied variables, considering 90% of confidence.
effective diffusivity; Fick’s second law of diffusion; Page model; Midilli model; Newton model
(1) Tampa da câmara de secagem; (2) Ventilador centrífugo; (3) Resistências
elétricas; (4) Sistema de aquisição de dados de temperatura; (5) Medidor de energia; (6)
Caixa de controle de acionamento; (7) Bomba de vácuo; (8) Corpo do secador; (9) Sistema de
alimentação; (10) Movimentação de sólidos; (11) Caixa com inversor de frequência do
ventilador (ABB, ACS150) e (12) Inversor de frequência do sistema de movimentação de
sólidos (WEG, CFW08)
