Experimental Study And Numerical Simulation Of Different Mechanical Ventilation

Mechanical ventilation technology as an important technology for grain storage and transportation to maintain safe storage of paddy through the control of rice internal temperature and moisture.Based on the theory of stratified ventilation and drying,this paper puts forward the ventilation system of three-dimensional intubation and studies the drying process of three_dimensional intubation through real warehouse test.In this paper,using different ventilation methods(ground cage ventilation,horizontal ventilation,full hole ventilation)respectively on the paddy cooling experiments and study the unit grain layer resistance under different ventilation.At the same time,this paper used a CFD(computational fluid dynamics)commercial software Fluent 14.0 to numerically analyze the process of the aeration cooling and verified by the experimental data.Results of this research involve that:(1)Study on Paddy Quality in Ventilation Process of Three-dimensional Intubation.Three-dimensional Intubation ventilation and drying,using a layered dry way.After the ventilation stage of the upper cage,the ventilation of the eastern half of the canal ventilation,the second half of the intubation ventilation stage,the rice layer of water was significantly decreased,and the stratification phenomenon has been significantly improved in ventilation and drying test.After drying,the quality of rice was rough,the whole milled rice rate and the fatty acid were kept within the good quality range,and the energy consumption per unit ventilation of the intubation system was 7.7KW · h/(1%H2O · t)and the cost was lower.(2)Study on the change of temperature field of rice pad in three-way mode.The process of mechanical ventilation cooling is the process of stratification cooling.Under the action of pressure,the outside heat is exchanged with the rice paddy rice at the position of the inlet,until the cold air reaches a position of the rice heap and reaches the equilibrium temperature.The temperature drop of 0.5m,1.0m,1.5m and 2.0m in paddy layer was 10.2℃8.3℃,6.7℃and 4.1 ℃respectively.The ventilation temperature of 0.5m,1.0m M,1.5m and 2.0m,respectively,which arell.11℃,8.1℃,6.3 ℃Cand 4.7 ℃respectively.The temperature drop of 0.5m,1.5m,2.5m and 3.5m after 30 hours of lateral ventilation cooling are 12℃,9.8℃,8 ℃,5.3 ℃ respectively.(3)Three kinds of ventilation cooling CFD simulation.CFD simulation technology can imagine vividly show the different ventilation mode under the cooling front of the movement of the law and ventilation cooling process whether there is ventilation dead.The results show that the ventilation dead angle problem is improved during the ventilation process of horizontal ventilation and full hole ventilation.And the simulation results of different grain temperature are compared with the experimental data.It is not difficult to find that the trend of temperature simulation is basically the same as the change of experimental value.At the same time,the ventilation uniformity was analyzed by MATLAB software,and the uniformity of horizontal ventilation and full ventilated ventilation system was better than that of aboveground ventilation system.(4)Study on the Resistance of Grain Layer in Three Ventilation Modes.The static pressure of paddy heave is linearly related to the wind speed,and the static pressure value increases gradually with the increase of wind speed.The heap pressure of rice pad decreases with the distance from the outlet.The equations of the unit grain layer under the three kinds of ventilation conditions are fitted by four equations:linear equation,quadratic function curve equation,power function curve equation and exponential function curve equation.The fitting results show that the fit of grain resistance quadratic function and power function is better than the linear function and the exponential function.According to the engineering calculation,it is recommended to describe the resistance of the grain layer,and the equation of horizontal ventilation isY =3.95X1.33;the equation of the ground cage ventilation isY = 4.80X1.35;The equation of full hole ventilation isY = 7.71X1.11.