Drying is important in many food processing applications, and particularly so in the dry fruits industry. This work is focused on developing computational models for simulating drying of almonds in a tray dryer. It is important to quantitatively understand heat and mass transfer within and around single almond particle as well as particle – particle interactions and their implications for dryer design. In this work, we have developed a systematic CFD modelling framework for modelling almond drying in a tray dryer. A single tray filled with almonds (~2 kg) were dried at three set temperatures viz., 55, 65 and 75 °C. Air relative humidity at inlet, outlet locations, and weight of almonds were measured to quantify the moisture loss of almonds for each experiment. An additional set of experiments were conducted in which almonds were filled only in the half section of tray, keeping the other half empty. Same amount of almonds were used, to have multiple layers of almonds in the tray and the set temperature for the experiment was 75 °C. Flow, heat and mass transfer in tray dryer were simulated using commercial CFD software Ansys Fluent. The values of effective diffusivity and average heat transfer coefficient determined from single and multiple particle system, were used for tray dryer simulations. The simulated results were compared with the experimental measurements. The validated computational model was used to simulate various cases including larger and more trays. The developed approach and models will be useful to select appropriate dryer configuration and optimize its design. The developed models will also be useful to identify suitable operation conditions for drying of almonds as well as other food products.
- Tray dryer