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Drying plays a critical role in processing of various food and bioproducts as significant amount of moisture need to be removed for further processing. The rate of moisture removal could impact not only the drying kinetics and efficiency but also the product quality which eventually will decide the acceptance of the final dried products in the market. In an attempt to achieve better process efficiency and product quality as well as to make drying process a more sustainable operation, researchers have embarked to envisage and to improve current dryer design by combining the benefits of various drying mechanisms into a single or combined/sequential operations known as hybrid drying. Hybrid dryers could offer several advantages over conventional dryers such as better drying efficiency, higher energy efficiency, more efficient moisture removal process, better product quality and enhanced retention of nutritional/bioactive compounds. In this paper, hybrid drying literatures published mainly from the recent decade are reviewed to provide researchers and industrial practitioners an up-to-date reference material that could contribute to current research and knowledge transfer especially in the development of more sustainable and efficient drying processes. [ABSTRACT FROM AUTHOR]

Drying as a simultaneous heat and mass transfer process can be modeled via the reaction engineering approach (REA) where the apparent activation energy of the material is established and related to its moisture content during drying. This relationship is unique as the normalized activation energies can be collapsed into a single equation irrespective of the drying conditions and dryer types. Here, REA was applied to model the drying kinetics of sawdust using convective hot air in a laboratory setup. The normalized (relative) activation energy curve generated from one drying experiment was employed to predict the drying kinetics and temperature profiles. The REA can describe well the convective drying kinetics of sawdust, and major physics of the drying process was captured well with this technique. [ABSTRACT FROM AUTHOR]