| The process of drying plays a crucial role in the overall processing and utilization of alfalfa.Therefore,it is imperative to explore cost-effective and efficient methods for drying alfalfa,which would aid in scaling up production and optimizing energy utilization.Presently,dynamic drying equipment has been successful in achieving uniform drying;however,the drying effect is not yet optimal.This is because the equipment still requires manual feeding to achieve cyclic drying.This thesis explores the attainment of continuous and fully automated drying through the examination of various drying equipment and dynamic drying experiments conducted on the research group’s developed dynamic drying device.To achieve this,a circulating return device was proposed and its design was validated through the utilization of Computational Fluid Dynamics(CFD)technology and the Discrete Element Method(DEM)simulation software EDEM.The main contents and conclusions of this thesis are as follows:(1)The focus of this study was primarily on alfalfa,and dynamic drying experiments were conducted using a solar-heat pump combined drying system.The study aimed to analyze the impact of various factors,including temperature,wind speed,pile thickness of alfalfa,speed of conveyor belt,and rotational deviation angle of the turntable,on the drying rate and specific energy consumption for dehumidification.The study suggests a drying process that utilizes variable temperature and wind speed.Additionally,the optimal thickness pile of the alfalfa,rotational deviation angle of the turntable,and speed of conveyor belt range were determined.The necessary process and structural parameters are provided for the design of the circulating return device.(2)The overall structural of the circulating return device was determined based on the results of dynamic drying experiments.The key components,inclined drum,baffle,pressure wheel,belt,and electric motor,were carefully designed and selected.To ensure accuracy and precision,a 3D solid model of the circulating return device was created,and the overall structural design was finalized.(3)Through CFD simulation,we analyzed the temperature field and wind velocity distribution in the drying room.Through a comparison of the experimental and numerical simulation results,we discovered that placing the recycling device on the side opposite the air inlet and outlet,can more efficiently direct the flow of hot air.In turn,this reduces heat loss and improves the drying rate.These results validate the accuracy of our numerical simulation method and parameter settings.(4)Based on the basic principles of the Discrete Element Method(DEM)and the physical dimensions of the dynamic drying device developed by the research group,simplified physical models of dynamic drying device and circulating return device were constructed.Using EDEM software,simulation experiments were conducted to analyze and test the distribution and movement trajectories of alfalfa particles on each device.This validates the rationality of the structure of the circulating return device and suggests the optimal parameters for the drying process. |
