Piping design and bellows optimization for pneumatic conveying systems based on EDEM-fluent coupled methods for rice

Currently, the main optimization of pneumatic conveying seed-discharge systems targets distributors, ignoring the important role of pipelines. In this study, simulations were used to determine an improved structure of the conveying pipe. The horizontal pipe was determined to be a 300 mm straight pipe, which was connected under the vertical bellows as a transition. This study adopted the L9(34) orthogonal test method to optimize the bellows parameters, using as index the coefficient of variation of the uniformity of the bellow outlets. The indoor bench test was designed to validate different flow rate and bellows length combinations. The optimal bellows parameter combination of the corrugated circle had a radius of 8 mm, bellows length of 500 mm, corrugation distance of 40 mm and corrugation length of 16 mm, achieving a 3.46% coefficient of variation of the particle distribution in the plumbing. Under various particle mass flow rates (33.5, 67.0, 101 g·s−1), the bellows length of the optimal solution was verified to be in the interval of 400−500 mm, and the consistency coefficients of the variations in row displacements of the system satisfied the requirements. This study provides guidance for the design and application of piping in pneumatic seed-discharge systems.