Abstract
In order to study the movement characteristics and separation mechanism of rice and its impurities under the action of airflow, and lower the impurity rate in the cleaning operation process, rice and its impurities were modeled based on the “overlapping multi-sphere clump method”, the DEM-CFD coupling method was used to simulate rice cleaning process under different airflow velocity and airflow inclined angle, and combined with aerodynamics, the motion state and separation behavior of rice and its impurities in the flow field. The results showed that under horizontal airflow conditions, the average impurity rate of rice was the lowest when the airflow velocity was 9 m/s. When the flow velocity remains unchanged and the airflow inclined angle was set at 10°, the average impurity rate decreased, while the entrainment loss rate increased. The airflow velocity was negatively correlated with the impurity rate and positively correlated with the entrainment loss rate, while the airflow inclined angle was negatively correlated with the impurity rate and positively correlated with the entrainment loss rate. By designing and setting up an experimental device, an experiment was carried out with airflow velocity and airflow inclined angle as the factors, and the experimental results were consistent with the simulation results, indicating that it was reliable to study the physical behavior of rice-straw separation in the airflow field by using the DEM-CFD coupling method. Keywords: DEM-CFD, rice cleaning, airflow velocity, airflow inclined angle, experiment DOI: 10.25165/j.ijabe.20201305.5225 Citation: Ma X D, Zhao L, Guo B J, Dang H. Simulation and experiment of rice cleaning in air-separation device based on DEM-CFD coupling method. Int J Agric & Biol Eng, 2020; 13(5): 226–233.
Highlights
As an important process in agricultural production to improve harvest quality and reduce rice doping rate, rice cleaning is an operation of separating fine debris such as rice straw, broken rice straw, chaff and dust from the rice by using the difference in physical properties between rice, rice straw and others components[1,2,3]
The cleaning device used in agricultural production is generally divided into two types, i.e., air-screen separating device and air-separating device, wherein the air-screen separating device separates the materials by utilizing the joint action of airflow and vibrating screen, while the air-separating device relies on the airflow to separate materials with different physical properties
The agricultural air-separating device has been applied for centuries, the study on the movement of particles and the separation behavior of different particles in the airflow field has been stagnant due to the limit of methods and means
Summary
As an important process in agricultural production to improve harvest quality and reduce rice doping rate, rice cleaning is an operation of separating fine debris such as rice straw, broken rice straw, chaff and dust from the rice by using the difference in physical properties between rice, rice straw and others components[1,2,3]. The agricultural air-separating device has been applied for centuries, the study on the movement of particles and the separation behavior of different particles in the airflow field has been stagnant due to the limit of methods and means. This study uses the DEM-CFD coupling method to simulate the particle cleaning process of rice, rice straw and broken rice straw with the air-separating device as the research object. Combined with aerodynamics it analyzes the motion state and separation behavior of the three particles in the flow field and studies the relationship among the airflow velocity, the airflow inclined angle and the rice impurity rate and entrainment loss. An experimental device was designed in this study, so as to verify the reliability of the simulation of the DEM-CFD coupling method
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