A Numerical-Experimental Assessment of the Dilute Phase and Erosion in a Larvae-Killing Processing System: Considering the Geometry Variation

In the present study, the pneumatic conveying of wheat in the dilute phase focused on four different pipe cross-section ratios including a/b = 1.5, a/b = 2, b/a = 1.5, and b/a = 2 has been experimentally and numerically examined. The system consists of the conveying pipe used inside the larvae system, which is used to transfer materials. Due to the Reynolds number calculations, the conveying is conducted in the turbulent regime. The combination of Reynolds Stress and Discrete phase models (RSM-DPM) was used to model the fluid and solid phases, respectively. The dimensionless velocity magnitude, static and dynamic pressures, erosion, vorticity magnitude, and turbulence intensity contours were investigated in the four mentioned scenarios using ANSYS Fluent commercial software. According to the results, the inner radius of the elbows, and especially the first elbow, were the areas where the maximum velocity was observed in these sections. As a negative parameter, the maximum pressure drop was obtained with a value of 322 Pa at the cross-section ratio of a/b = 2, which made the selection of this ratio a great challenge. Also, the maximum erosion rate occurred at the cross-section ratio of a/b = 2, which is considered a negative parameter. Moreover, due to the rotational flows created in the inlet ratios b/a = 1.5 and b/a = 2, these ratios are not very practical in terms of application and will cause energy loss in the system through the interaction between the various flows. Finally, considering all scenarios among the four cross-section ratios, the ratio of a/b = 1.5 was proposed as the most appropriate selection.