A Review on Thin-Layer Drying-Curve Equations

This paper presents a comprehensive review of thin-layer drying-curve models available in the literature and their comparisons for single-layer drying applications from 2003 to 2013. In this regard, a total of 67 models are selected and classified under 28 performance assessment criteria for comparison purposes. These models are then evaluated by considering the following parameters: (1) product type; (2) pretreatment type; (3) drying parameters, such as temperature, air velocity, layer thickness, microwave power levels, amount of solar radiation, vacum pressure, frequency of sound wave, excitation amplitude, relative humidity, bed depth, product shape, pH, salt content, absolute pressure, etc.; and (4) drying method employed. Furthermore, the best models obtained are employed for product drying applications and compared for different drying methods, drying parameters, and dried products.