Data for: Rotating Orifice Feeding System for Continuous and Uniform Discharge of Makhana Seeds (Euryale ferox)
Description
The consistent and slow flow rate of granular materials through a small diameter orifice (D) at the centre of the bottom of a hopper is difficult to obtain when D is less than 5 times the characteristic seed size. Rotation of the bottom in the horizontal plane with the location of the orifice at an off-center distance (R) from the center of hopper can sustain controlled flow rates even at small D. In this study, a simple feeding system has been developed to discharge roasted makhana seeds of different sizes (7.48-12.40 mm diameter) to maintain 10-30 kg.h-1 consistent flow rate. The feeding system consists of a rotating orifice plate at an off-center distance placed inside a pipe connected with the bottom of a trapezoidal hopper. The effects of rotation rate (ω), D, and R on the mass flow rates of makhana seeds of different sizes have been investigated. The discharge of seeds did not take place when the orifice remains stationary. The mass flow rate increased with the increase in ω, D and R. Finite mass flow rates in the range of 2.25-29.81 kg.h-1 were obtained for all size of seeds at varying D (15-20 mm), R (20-30 mm), and ω (0.52-7.86 rad.s-1). The mass flow rates >30 kg.h-1 were obtained for D ≥ 25 mm, however, finite flow rate ranges may not be obtained for all seed sizes at R ≥20 mm. The discharge was in funnel flow regime for all the values of D, R, ω and seed sizes due to the geometry of the hopper and feeding system. The existing Beverloo equation was not appropriate to describe the mass flow rate adequately for the developed system and therefore modified using a function similar to the Froude number to describe the mass flow rate satisfactorily. The developed feeding system performed well in feeding makhana seeds of different sizes and maintained finite mass flow rates.