Drying characteristics and modeling of tomato thin layer drying in combined infrared-hot air dryer

Rasool Sadin, Gholamreza Chegini, Mehdi Khodadadi

Abstract


In this study tomato slices were dried with three thicknesses (3, 5 and 7 mm), three temperatures (60°C, 70°Cand 80°C) and air speed of 1.1 ms-1 in a combined infrared-hot air dryer.  Distance from infrared source was 70 cm, while, input air temperature was 60°C.  The experiment was conducted as factorial based on a completely randomized design.  Results showed that energy consumption reduced along with the increase in temperature and slice thickness.  Decrease in the slice thickness from 7 to 3 mm resulted in a significant decrease in drying time.  Maximum diffusion coefficient was related to the thickness of 7 mm and the temperature of 80°C, while, the minimum value was related to the thickness of 3 mm and the temperature of 60°C.  Effective diffusion coefficient and activation energy is, respectively, 9-10 m2 s-1 to 10-11 m2 s-1 and 12.7-110 kJ mol-1.  Middili's model had the maximum R2 and the minimum RMSE and SSE at different temperatures and speeds, thus, it was considered as the fittest model to predict the moisture.


Keywords


drying time of tomato, diffusion coefficient, effective diffusion coefficient, activation energy, tomato thin-layer drying, infrared-hot air dryer

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