An innovative dryer for Arabica coffee (Coffea arabica L.) drying: Investigating heat and mass transfer

In the pursuit of advancing post-processing techniques for Arabica coffee, our research introduces a rotary dryer, known as a roto-aerated dryer, marking its first application in coffee drying and surpassing conventional methods. This study delves into the evaluation of heat and mass transfer dynamics between coffee and drying air within the innovative dryer. Characterization of raw materials precedes a series of drying experiments under varied conditions, forming the basis for a mathematical two-phase model elucidating the underlying dynamics of the drying process. Noteworthy is the significantly reduced material residence time (14.60-27.47 min) compared to conventional dryers. Drying rates (0.09-0.24 g water/100 g solid/min) surpass those achieved by other methods. Simulated results from the numerical solution of the two-phase model closely align with experiments (average error of 2.39% for moisture content and 0.89% for temperature). The effective preservation of material quality, particularly acidity, underscores the valuable insights offered for optimizing drying processes, holding substantial potential for advancing the specialty coffee industry.