Corn Drying in a Laboratory Scale Ultrasound-Assisted Fluidized Bed Dryer

Several studies have been conducted on equipping conventional fluidized bed with some technologies to increase drying efficiency and its performance. The objective of the study was to investigate the influence of high power ultrasound on fluidized bed drying of corn in terms of drying kinetics and quality characteristics of corn in three levels of ultrasound power density (11.1, 14.6 and 18.7 kW m-3), three levels of drying air temperature (30, 40, and 50 ºC) and four levels of frequency (20, 25, 28, and 30 kHz) in which the moisture content reduced from 32±0.5 (%d.b.) to 17±0.5 (%d.b.). Results revealed that the frequency of 25 kHz was the most efficient in terms of drying time. The frequency of 25 kHz and power density 14.6 kw m-3 was the most efficient frequency and caused reduction of the drying time by 43% in comparison with no ultrasound condition (control). The sponge effect caused by ultrasound application led to reduction of failure strength and toughness of the dried samples. According to the results, toughness compared to the failure strength was an appropriate index of the grain hardness.