Modeling of the rice drying process in a custom-made lab-scale fluidized bed dryer

Abstract. Drying of rice is a complex process as it involves many heat and mass transfers. Modeling of the drying process can help understand the process better and leads to process design, optimization, energy and exergy analysis, and process automation and control. There are many well-developed empirical models for rice drying, but none have been fitted to check their relevance with ambient air dehumidification and fluidized bed drying of rough rice. Thus, the goal of the study was to investigate the drying kinetics of rough rice in the fluidized bed dryer using ambient air dehumidification. In the current study, nine mathematical models were fitted for the experimental data of rough rice fluidized bed drying at temperatures of 40°C, 45°C, and 50°C. Ambient air dehumidification was a novel factor, also included in the study with the drying duration constant at 60 minutes. Nonlinear regression analysis found that Verma et al. and Modified Henderson and Pabis were the two best models overall for describing fluidized bed drying characteristics of rough rice. The model goodness of fit was determined using Coefficient of determination (R2), reduced chi-square (χ2), and root mean square error (RMSE) with values for the two best models ranging from 0.9760 to 0.9990, 0.0040 to 0.0180, and 0.0000 to 0.0022, respectively.