Drying kinetics of Cissus quadrangularis dried in a Fluidized bed dryer

Abstract

Cissus quadrangularis is an extensively utilized medicinal plant in India which has numerous health benefits. Hence, the drying kinetics of Cissus was studied using fluidized bed dryer to identify suitable drying conditions and to understand moisture remov-al and its connection to process variables. The present research aimed to determine a suitable drying model of fluidized bed drying of Cissus quadrangularis Linn., determine the effective moisture diffusivity of the drying process and the activation ener-gy, and investigate the effects of temperatures on the drying kinetics of Cissus. The drying experiments were conducted at three different air temperatures (40, 50 and 60 ºC), bed thickness of 5 cm, constant air velocity of 8 m/s and 0.5-1 cm length Cissus samples. The experimental drying data was fit into thirteen thin layer models and the best model describing the drying of Cissus was selected based on the correlation coefficient (R), root mean square error (RMSE), and reduced chi-square (χ2). The drying process occurred in a falling rate period for all the drying air temperatures and a constant rate period was not ob-served. Among all the thirteen models tested, approximation of diffusion was found to explain the thin layer drying behavior of C. quadrangularis accurately. The effective moisture diffusivity for Cissus was in the range of 1.54-3.12x 10-10 m2/s and the activation energy was 30.76 kJ/ mole, respectively. Hence, fluidized bed drying is more effective for convective drying of Cissus and the drying models are useful for selecting the best operational condition for fluidized bed dryer and design of an equipment.