Numerical Simulation And Experimental Study On Coupled Heat And Moisture Of Corn Pile During Static Storage

Ensuring food security is a major issue that concerns China's rapid economic development and national security.Warehousing is a common way of grain storage.During the storage process,the grain pile as a complex artificial ecosystem,the life activities of grain particles,the metabolism of microorganisms in the warehouse,and changes in the external environmental temperature will cause the temperature and moisture of the grain in the warehouse changed.The temperature and moisture of grain piles are two important indicators that determine it safe storage.Through the combination of experiments and numerical simulations,this paper studies the temperature and moisture distribution rules of corn piles in the model experiment warehouse and large warehouse under static storage.The simulation results are compared with the measured data.The article includes the following research content:(1)Taking corn grain piles as the research object,the macro-level method was used to analyze the existence of moisture and heat in grain piles and their transfer mechanisms,and the temperature and moisture transfer routes in the static storage model were clarified.The main parameters of the porous media of the corn pile stack were obtained,including porosity,equivalent diameter,permeability,porosity,thermal conductivity and specific heat capacity.They will be used for the numerical simulation research of the static storage process of the corn grain stack.(2)The multi-field coupling theory method was used to study the heat and moisture transfer process of the corn pile.A small static storage experimental platform was designed and completed.The control system of the experimental platform was tested for uniformity,which verified the experimental platform accuracy.The relevant model experiments of static storage of corn piles were carried out to provide data support for constructing the mathematical model of coupled heat and moisture of grain piles.(3)Based on the theory of heat transfer in porous media and the principle of local thermal equilibrium,according to mass conservation,energy conservation,momentum conservation law,and moisture conservation equations,the respiration during grain storage is considered,and the mathematical theory of coupled heat and moisture during static storage ofcorn pile is constructed model.And the model was used to simulate the change process of heat and moisture transfer in the corn silo experimental silo.The numerical simulation results are consistent with the measured data of the experimental warehouse in temperature and moisture distribution.(4)Based on the constructed mathematical model of heat and moisture transfer,a numerical simulation of the static storage process of corn piles in a warehouse was carried out.Taking the local daily average temperature and moisture and considering the effect of solar radiation as the boundary conditions,the thermal-moisture coupling law inside the grain pile was obtained,and the accuracy of the numerical simulation was verified using the measured data.The comparison of numerical simulation and actual measurement results shows that during the static storage process,the grain pile near the warehouse wall changes greatly with the external environment,and the temperature of the grain pile changes slowly.The temperature of the grain pile shows a trend that changes with the season.During the summer,the temperature near the warehouse wall rises rapidly,and the high temperature airflow to the center of the warehouse will increase the moisture near the grain surface,resulting in mildew of the grain;During the winter,the outside temperature drops,and a high-temperature gathering area will form near the warehouse wall,which will cause condensation to occur in the grain pile.