Modelling and CFD Simulation of Temperature and Airflow Distribution Inside a Forced\nConvection Mixed-Mode Solar Grain Dryer with a Preheater

Abstract

In this study, a 3D Computational Fluid Dynamics\n(CFD) model was developed to simulate the drying process of\nmaize ears/cobs in a mixed-mode solar grain dryer. The dryer\nsystem is aimed to operate under forced convection and is\nintegrated with a preheater to heat air prior to entering the solar\ncollector. The 3D model was developed with great accuracy using\nSolidWorks software and the CFD simulation was carried out\nusing ANSYS Fluent software. The study was aimed at analyzing\nand predicting temperature and airflow distribution in the\nmixed-mode solar dryer system. The CFD simulation was\nconducted at different airflow velocities varying from 0.5 m/s to 2\nm/s for different temperature values of the preheater. Results from\nthe simulation of the solar collector were satisfactory, indicating a\nminimum and maximum temperature of 59.7 ℃ and 70.5 ℃ at\nminimum and maximum drying conditions, respectively. The\nvariation of temperature inside the drying chamber was predicted\nwith an average maximum of 64.1 ℃ at the inlets. Results of\nairflow distribution in the solar collector and drying chamber\nindicated high turbulence and flow recirculation. This is a\ndesirable flow combination that promotes good moisture\nevaporation from the maize ears during the drying process. This\nstudy proves that the use of computer software can allow one to\nclearly gain an understanding of the development, heat and mass\ntransfer process, and performance of dryers used in the food\ndrying industry. This approach can promote improvements in\nexisting drying processes and increase food productivity.