科研之友
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摘要
A hybrid drying system for high-intensity airborne ultrasound applied in convective drying was investigated for the drying of salted codfish (clipfish). Convective drying with ultrasonic assistance at 10, 20, and 30 degrees C was compared to the same process without ultrasound. The Weibull model was used to model and investigate the drying behavior, and the effective diffusion in Fick%26apos;s law was determined. The ultrasound decreased the drying time more at lower drying temperatures. The drying time was reduced by over 90% at a drying temperature of 10 degrees C. For an industrial drying process at a temperature of 20 degrees C, the drying time was reduced by 32.2%. The ultrasonic, convective drying of clipfish at a temperature of 20 degrees C was faster than the same process without ultrasound at 30 degrees C. The investigations showed a thermal effect for all products when ultrasound was applied. The specific moisture extraction ratio (SMER) in the investigated system was improved by 0.2kg(water) kWh(-1). The heat transfer coefficient in the system used was increased by 32.6% for a heating process in a separate investigation, whereas for a cooling process no increased heat transfer coefficient was determined. The thermal effect might (at least partially) explain the faster drying of ultrasonic-assisted convective drying. The results obtained demonstrate the potential of airborne ultrasound in convective drying with regard to drying time, energy consumption, and product quality. Documentation of the thermal effect should be included in future R%26D on this topic.
- 出版日期2013-8-18
