Design and Optimization of Trapezoidal Duct in a Fixed-bed Rice Dryer based on CFD Approach
Ubaidillah Ubaidillah*, Darmanto Darmanto, Dwi Setiawan, Rizqi Maulana

Department of Biosystems Engineering, Universitas Brawijaya
Jalan Veteran, Malang 65145, Indonesia

*Email: ubaidillah88[at]ub.ac.id

Abstract

Batch dryer is the most common dryer used for grain crop such as rice due to its simplicity and economical. However, the major problem in the performance of batch dryers is uneven hot air distribution. Zones which receive a higher temperature and airflow rate dry faster, and this heterogeneity reduces dryer efficiency by increasing energy consumption and drying time. A fixed-bed rice dryer with 250 kg in capacity was designed, and consist of air blower, biomass powered furnace as heat source, and plenum chamber under rice drying bin. Two trapezoidal ducts were installed, i.e. between blower and furnace, and between furnace and plenum. In this study, computational fluid dynamics (CFD) techniques were introduced into the design process of the drying system. CFD analysis was used to simulate nine different ducting configurations to examine the impact of configuration changes on hot air uniformity. The distribution of air pressure, air temperature, and air velocity were taken as assessment parameters for nine configurations of trapezoidal duct. Within the trapezoidal duct configurations examined, the fifth configuration demonstrated the best hot air uniformity, followed by the second and eighth ducting configurations. The results showed that the CFD techniques are capable of predicting hot air distribution in fixed-bed rice dryer. These results are helpful in the design and optimization of trapezoidal duct to minimize hot air non-uniformity.

Keywords: CFD- Fixed-bed dryer- Rice- Trapezoidal duct- Uniform drying

Topic: Agricultural and bioprocess engineering