Experimental study of the drying of papaya seeds in a spouted bed and simulation of the fluid dynamics behaviour of the material

Abstract

Papaya is widely cultivated in Brazil for use as fresh fruit and in the preparation of various products. During its consumption and processing, its seeds, a source of oil rich in fatty acids such as oleic, palmitic, linoleic and stearic, are discarded. The seeds contain large amounts of moisture and rapidly degrade, and therefore, drying is essential for their use. In the present study, the effect of drying of papaya seeds in a conventional spouted bed with large dimensions was investigated under various temperatures (40, 50, and 64 °C) and air velocities (21, 34, and 36 m/s). In addition, computational fluid dynamics (CFD) techniques were applied in order to provide a better understanding of the characteristics of the flow within the bed. The seeds were characterized and classified as belonging to particulate group D. The characteristic curve of the spouted bed showed a behaviour consistent with the typical pattern, allowing the identification of a minimum spouting velocity and minimum spouting pressure drop of 22 m/s and 21 Pa, respectively. The simulations were able to represent the fluid dynamic behavior of the seeds inside the bed. The results of the present study show that spouted bed drying is a promising technique because it is effective in drying papaya seeds when operating for short periods of time and at low air temperatures.