Energy and Exergy Analysis of Rough Rice Drying in a Fluidized Bed and Fixed Bed with Ambient Air Dehumidification

Abstract. Fluidized bed drying of rough rice in the U.S. has not been utilized to its full potential due to the lack of research to address quality reduction and higher energy consumption. Not much research was done to analyze the energy and exergy of the rough rice's fluidized bed drying. Drying air temperature (40°C, 45°C, 50°C), drying bed condition (fluidized and fixed), drying duration (30 min, 45 min, 60 min), and ambient air dehumidification (yes, no) were the factors of this study. Lab-scale dryer units designed by Sadaka et al. (2018) were used. Three replicates were performed to eradicate any bias or human errors. All factors did significantly affect the energy and exergy of the drying except dehumidification and replication. The minimum and maximum EU values were 0.01 kJ/s and 0.55 kJ/s for drying at fixed bed drying at 40°C for 30 min with dehumidification and at 50°C for 60 min under fluidized bed condition without dehumidification, respectively. Minimum and maximum exergy efficiency values were 13.46% and 49.14%, achieved at 45°C air temperature for fixed bed with dehumidification for 45 min duration, and fluidized bed drying using 40°C air temperature for 60 min with dehumidification, respectively. At the drying process's primary stages, fluidized bed drying had higher exergy efficiency, energy utilization, and energy utilization ratio than the fixed bed drying method. 40°C air temperature using fluidized bed drying with or without ambient air dehumidification worked best as per the energy and exergy utilization in the drying system.