Study On The Principle And Numerical Prediction Of Radial Ventilation For Squash

As the largest developing country in the world,ensuring food security is an important strategic basis for China.To solve the problem of 1.3 billion people eating,we must stand on our national conditions,hold the key to the safety gate in our own hands,and then we can serve our country.In order to achieve this goal,how to keep food and ensure the safety of grain storage is also a very important part.The silo is a new type of bin which is developing vigorously in our country.Mechanical ventilation is a conventional method for grain storage quality assurance and regulation of grain storage storage ecosystem.Therefore,this paper studies the temperature and moisture change law and ventilation resistance in the interior of the grain pile when using different ventilation modes,explores and designs the radial ventilation technology of the silo.In order to control the temperature and moisture content of stored grain storage,ensure the safety of stored grain,and provide theoretical basis for the design and operation of ventilation system of the siloIn this study,firstly,the radial ventilation technology of the silo is designed according to the principle of hydrodynamics,and then,using the method of numerical simulation and experimental research,the cooling rate and energy consumption of radial ventilation in the silos are simulated,the influence of various process parameters on radial ventilation efficiency of the silo is studied,and the temperature and moisture change law as well as their advantages and disadvantages of the inside of the grain pile in the radial and vertical ventilation of the silo are compared.Finally,the in-bin investigation of the radial ventilation test bin and the vertical ventilation were conducted,and the data of temperature and moisture content is measured and recorded during the ventilation,the paper analyzes the cooling rate,temperature and moisture uniformity,ventilation resistance and energy consumption in different ventilation modes,and studies the feasibility and rationality of radial ventilation in the silo.The specific work is as follows:1.Based on the theory of aeration within stored grain,air flow,heat and mass transfer in porous medium,the radial ventilation scheme of the silo is proposed,the radial ventilation technology of the silo is designed2.Establish the mathematical and physical model of radial ventilation of the silo,use the method of numerical simulation analysis to optimize the radial ventilation process,simulate and compare the cooling effect and operation cost of radial ventilation under different central air header and vertical air duct structure size,and determine the best process scheme of radial ventilation of the silo3.A comparative study on the radial ventilation and the traditional vertical ventilation of the silo is carried out.Based on CFD method,the ventilation resistance and cooling effect of radial and vertical ventilation in the silo are compared.It is found that the higher the grain loading height is,the higher the vertical ventilation resistance will be,but while the higher the radial ventilation resistance is,the less obvious.Therefore,when the grain loading height is large,the radial ventilation resistance has obvious advantages.At the end of ventilation,the results of cooling rate and uniformity of radial and vertical ventilation are similar.Considering the actual situation,the cooling rate and uniformity of radial ventilation have certain advantages.4.The experimental study on radial ventilation and vertical ventilation of the silo was completed.Cooperate with related grain depot to carry out ventilation experiment,record temperature,moisture and ventilation energy consumption.It is found that compared with the conventional mechanical vertical ventilation,the radial ventilation of the silo has no ventilation dead angle,better uniformity of temperature and moisture,and high efficiency of ventilation and cooling.During the normal storage period of grain,the chimney effect of the central air collector can also be used to improve the stability of grain storage in the center,prevent the local hot spots in the grain pile,improve the quality of grain and reduce the loss Compared with the traditional vertical ventilation,the installation cost of the radial ventilation system is lower.Because of the high cooling rate,short ventilation time and small ventilation resistance,the operation cost of the radial ventilation system is lower.Through the comparison of experimental data and simulation data,the trend of temperature change is basically the same,and the data error is small,which can basically verify the accuracy and feasibility of mathematical and physical models.It is proved that the application of radial ventilation in the silo is feasible through the experiment of grain cooling ventilation.