Simulation and Experiment of Gas-Solid Flow in a Safflower Sorting Device Based on the CFD-DEM Coupling Method

Zhizheng Hu,Haifeng Zeng,Jiangkun Wang,Yun Ge,Wendong Wang

doi:10.3390/pr9071239

Abstract

To study the movement characteristics and separation mechanism of safflower petals and their impurities under the action of airflow and lower the impurity rate in the cleaning operation process, integration of computational fluid dynamics (CFD) and discrete element method (DEM) codes was performed to study the motion and sorting behavior of impurity particles and safflower petals under different airflow inclination angles, dust removal angles and inlet airflow velocities by establishing a true particle model. In this model, the discrete particle phase was applied by the DEM software, and the continuum gas phase was described by the ANSYS Fluent software. The Box-Behnken experimental design with three factors and three levels was performed, and parameters such as inlet airflow velocity, airflow inclined angle, and dust remover angle were selected as independent variables that would influence the cleaning impurity rate and the cleaning loss rate. A mathematical model was established, and then the effects of various parameters and their interactions were analyzed. The test results show that the cleaning effect is best when the inlet airflow velocity is 7 m/s, the airflow inclined angle is 0°, and the dust remover angle is 25°. Confirmatory tests showed that the average cleaning impurity rate and cleaning loss rate were 0.69% and 2.75%, respectively, which dropped significantly compared with those from previous optimization. An experimental device was designed and set up; the experimental results were consistent with the simulation results, indicating that studying the physical behavior of safflower petals-impurity separation in the airflow field by using the DEM-CFD coupling method is reliable. This result provides a basis for follow-up studies of separation and cleaning devices for lightweight materials such as safflower petals.

Highlights

Safflower is a special cash crop that can be used as oil, medicine, feed, natural pigment and dye
At present, the harvesting of safflower is not automated yet, we are still harvesting safflower artificially rather than mechanically, and there are problems that too many impurities mixed in the process of picking and drying safflower affect the subsequent intensive processing [1]
Joseph et al (2000) and Ketterhagen et al simulated seed flow with different funnel geometries [8,9,10]. These results show that the discrete element method (DEM) is an effective tool to simulate particle flow

Summary

Introduction

Safflower is a special cash crop that can be used as oil, medicine, feed, natural pigment and dye. It has strong adaptability, resistance to drought and cold and is easy to manage. Xinjiang has advantageous planting conditions and is the main area of safflower production in China. The annual planting area is more than 40,000 hm , and the yield is 3000~4000 t. Yumin County alone has an annual planting area of approximately 11,300 hm. Impurities and safflower silk have fewer confounding differences, and safflower silk is blown out with dust by air flow during operation using traditional grain cleaning machines, causing loss of safflower silk; at the same time, impurities cannot be effectively separated. It is important to reduce losses during safflower cleaning and improve the sorting quality

Methods

Results

Conclusion