Numerical Simulation And Experimental Study On Horizontal And Vertical Ventilation Of Different Grains

China as the world’s largest developing country,food security is not only the basic condition to achieve and rapid development of the national economy,but also an important strategic basis for ensuring national security.The most important task to ensuring that is the safe storage of food,which is to reduce and eliminate the large loss of food caused by mold and insects while ensuring the quality of grain.Mechanical ventilation is a conventional method.Therefore,studying the characteristics of porous media in grain can effectively improve ventilation efficiency and solve the problems such as excessive energy consumption.At the same time,it is possible to accurately predict the change of temperature and humidity in the grain pile during the ventilation process,and reasonably plan the ventilation time and reduce the cost of grain storage.In this paper,the combination of experimental research and numerical simulation is used to study the horizontal and vertical ventilation resistance and permeability of the porous media during the mechanical ventilation process,The temperature and humidity data of the grain pile are tested.The ventilation process was reproduced by numerical simulation,analyzing the temperature and humidity change of grain pile under different cases to study the difference of heat and mass transfer characteristics in different ventilation directions.The specific work content is as follows:1.The ventilation test bench was designed and set up.The pressure loss,the temperature and humidity data and porosity of the grain pile under different ventilation cases were measured to calculate the permeability and the inertia resistance of the grain pile.Analyzing the difference in the resistance characteristics of porous media in horizontal and vertical ventilation shows that the ventilation resistance of the vertical ventilation is greater than that of the horizontal ventilation,the permeability of the horizontal ventilation is greater than that of the vertical ventilation,and the correlation about the horizontal ventilation layer resistance was formed.2.The numerical model was established.The boundary conditions and initialconditions were selected according to the experimental situation to simulate the ventilation process.It was found that the heat and humidity change rate of the horizontal ventilation was higher than that of the vertical ventilation,and the difference of horizontal and vertical ventilation characteristics was verified from the perspective of heat and moisture transfer.The simulation results were compared with the experimental data to verify the accuracy of the model.3.Analyzing the law of temperature and humidity migration in horizontal and vertical ventilation can find that the temperature change is faster than that of humidity under the same conditions,that is,the velocity of temperature front migration is higher than that of humidity front,and the frontal migration velocity of temperature and humidity in horizontal ventilation is greater than that in vertical ventilation.The correlation between time of the temperature front migration and apparent wind speed was formed.4.The Research object of the study was changed to rice in the husk,and the difference of temperature and humidity changes between different ventilation processes was compared and analyzed.At the same time,the feasibility and accuracy of the ventilation model were further verified by comparing experimental data with simulation results.