Simulation of Drying Uniformity inside Hybrid Solar Biomass Dryer using ANSYS CFX


  • Jackis Aukah
  • Mutuku Muvengei
  • Hiram Ndiritu
  • C. Onyango


ANSYS CFX, Drying uniformity, Hybrid solar biomass dryer, Simulation


In a hybrid solar biomass system, a combined solar radiation with biomass heating source is employed in order to have a double heating of the drying air. The dryer is of tunnel type where the collector and the drying tunnel are fabricated as one unit. The trays in the drying chamber are arranged horizontally at the same level slightly above the absorber plate. Solar hybrid dryers present a viable option for drying of maize since continuous drying can be achieved. However, non-uniform drying of the product may occur in the drying chamber due to poor air flow distribution. The aim of this study was to develop a mathematical model for predicting the drying uniformity within the drying chamber of a hybrid solar biomass tunnel dryer. The model consists of the full set of partial differential equations that describe the conservation of mass, momentum and heat inside the dryer. The standard k- model was used to describe turbulence in addition to the governing conservation equations. The simulation was done using ANSYS CFX which is a general purpose Computational Fluid Dynamics (CFD) package. The simulated air flow pattern and temperature distribution on the horizontal and vertical planes in the drying chamber was analyzed and the result revealed spatial homogeneity of drying air condition. However the velocity profile was higher at the inlet and outlet. The increase of the velocity at the exhaust stack was due to the reduction of flow cross-section area as well as chimney effect.

Author Biographies

Jackis Aukah

 Kenya Industrial Research and Development Institute, KIRDI

Mutuku Muvengei

Department of Mechanical Engineering, JKUAT

Hiram Ndiritu

Department of Mechanical Engineering, JKUAT

C. Onyango

Kenya Industrial Research and Development Institute, KIRDI