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

## TL;DR

This study evaluates how different pipe shapes affect wheat conveying and erosion in a larvae-killing system, finding that certain pipe ratios cause high pressure drops and erosion.

## Contribution

The study introduces a numerical-experimental analysis of pipe cross-section effects on erosion and pressure in wheat conveying systems.

## Key findings

- The cross-section ratio a/b = 2 caused the highest pressure drop and erosion rate.
- Pipe ratios b/a = 1.5 and b/a = 2 led to rotational flows and energy loss.
- The ratio a/b = 1.5 was identified as the most suitable for practical use.

## Abstract

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.

The Reynolds stress (RSM) and Discrete phase models (DPM) were used to model the conveying of wheat in the dilute phase. The contours related to the velocity magnitude, static pressure, dynamic pressure, erosion, vorticity magnitude, and turbulence intensity were investigated in four different cross‐section ratios.