Modelling of hot air chamber designs of a continuous flow grain dryer

Abstract

The pressure loss, flow distribution and temperature distribution of a number of designs of the hot air chamber in a continuous flow grain dryer, were investigated using CFD. The flow in the dryer was considered as steady state, compressible and turbulent. It is essential that the grain is uniformly dried as uneven drying can result in damage to the end-product during storage. The original commercial design was modified with new guide vanes at the inlets to reduce the pressure loss and to ensure a uniform flow to the line burner in the hot air chamber. The new guide vane design resulted in a 10% reduction in pressure loss and a γ-value of 0.804. Various design changes of the hot air chamber were analysed in terms of pressure loss and temperature distribution with the aim of a temperature variation of ±5 K at the outlet ducts. An obstruction design was analysed, which improved mixing and gave a temperature distribution within the limits. However, the pressure loss was six times larger than the original design with new guide vanes. Finally, The static mixer design resulted in a 23% reduction in the pressure loss, but had a mean absolute deviation of 22.9 K.