The Simulation of Fluid Flow with a Vortex Generator 35° toward the Y-axis to Heat Transfer in Spray Dryer

Abstract

The Spray Dryer is a spray drying machine to change liquid into dry powder. The spray drying machine can be defined by the drying process in a cylinder, utilizing air heated in the heater and flowing through a blower connected to a vortex generator with an angle of 35° to the Y-axis. The vortex generator causes the formation of turbulence of airflow. Heat transfer occurs between the hot air flow and the milk droplets so that the liquid milk becomes a dry powder. This research aims to see the vortex phenomenon, namely the turbulence intensity, airflow velocity, heat flux, and temperature distribution in a cylinder, compared with an experiment that used four conditions of temperature inlet. There is 80°C, 90°C, 100°C and 110°C. The liquid used in this research is dairy cow’s milk mixed with water and maltodextrin, which has a density value of 1056 kg/m3 and a specific heat value of 3930 J/kg K. The machine’s cylinder has a diameter of 0.5 m with a wall thickness of 1 x 10−3 m and a height of 2 m with a capacity of 1.27 l/hour with a drying time of 80 minutes. The speed airflow of this machine into the cylinder has 16 m/s with a cross-sectional diameter of 9,5 x 10−2 m and a thickness of 1 x 10−3 m which has a debit of 0.11 m3/s. In addition, the injector used has a diameter of 2 x 10−4 m and a speed of 13,54 m/s with a flow rate of 4,5 x 10−4 kg/s with a spray angle of 45° u. Besides that, the analysis results show that the airflow turbulence area is in the form of a vortex so that the drying process of heat transfer that occurs between the product material and the airflow becomes faster.