Research On The Influence Of Spiral Feeder And Ventilation Network On Grain Storage Regulatio

Food security is an essential component of China’s national security,and ensuring it is of great significance.To guarantee food security,it is necessary to achieve sufficient production,stable supply,and timely allocation.The smooth and orderly implementation of these processes depends on the efficient storage of food.The main cause of storage losses in the storage process is the overheating and moldiness of grain particles due to temperature and humidity exceeding the safe range.Currently,the mainstream method of regulating temperature and humidity is to set up various forms of air ducts inside the warehouse and use them to introduce various airflows to ensure that the temperature and humidity are within the safe range.In practical engineering,there are two main factors that affect ventilation effectiveness: the form of air ducts and the porosity inside the grain heap.In terms of air duct forms,the early form was to set up air ducts at the bottom of the warehouse for vertical ventilation.However,in the development process of grain storage technology,this form was gradually replaced by the more superior horizontal ventilation system.As for porosity inside the grain heap,common free-fall heap can lead to serious automatic grading,affecting the uniformity of porosity inside the grain heap,and thus affecting the effectiveness of ventilation and temperature regulation.In summary,researching the mechanism of the internal air duct form and the different grain intake methods affecting the effectiveness of ventilation and temperature regulation in the shallow circular warehouse,and exploring effective measures to reduce grain losses in the storage process,is of great significance for ensuring food security.Based on the above statements,the main research content and conclusions of this thesis are as follows:(1)Under the condition of uniform pore distribution,numerical simulations were conducted on the ventilation process of vertical,radial,and combined ventilation networks.Validation experiments were carried out in a small-scale warehouse to verify the feasibility and accuracy of the numerical simulation scheme adopted in this paper.The performance differences of various ventilation networks were compared and analyzed in terms of temperature distribution uniformity,cooling rate,and energy consumption,providing theoretical support for the selection of actual grain storage wind path forms.The study found that the closer the grain filling height is to the shallow circular bin radius,the more difficult it is to demonstrate the energy-saving effect of the radial ventilation network.(2)A new type of screw feeder was designed to reduce the grading and crushing phenomena of grain during storage.The device consists mainly of a loading hopper above and a helical chute surrounding a central air collecting duct.The discrete element method was used to simulate the grain loading process of this structure.By analyzing the distribution of porosity inside the grain pile formed by stacking,the structural parameters of the feeder were continuously adjusted to determine the optimal geometric structure.Furthermore,the distribution of porosity inside the static grain pile was analyzed and compared with the porosity distribution obtained by gravity feeding.It was found that the porosity distribution obtained by using the screw feeder is more uniform.(3)By using the DEM-CFD coupling calculation,the ventilation and temperature adjustment process of a static grain pile under different ventilation networks was simulated,and the ventilation effects of three ventilation networks under the actual porosity distribution were obtained.The changes in parameters such as temperature uniformity and cooling rate inside the grain pile under different working conditions were compared and analyzed in depth.It was found that different loading methods resulted in significant differences in porosity distribution inside the grain pile,which in turn had a certain impact on the ventilation and cooling effect.The higher the porosity value and the more uniform the distribution,the more favorable it is for ventilation and temperature adjustment.