Numerical Study of Thermal Conductivity Characteristics of Wheat Grain Bulk Considering the Effects of Pressure and Water Content
[Purposes]The research aimed to study the law of pressure-thermal conductivity and moisture content-thermal conductivity of wheat grain bulk.[Methods]The porosity measurement device was used to measure the porosity of wheat grain piles under different pressures(0 kPa,50 kPa,100 kPa,200 kPa,300 kPa)and different moisture contents(8.50%,11.21%,14.45%,16.97%,20.72%),and the simulation analysis was carried out in COMSOL finite element numerical simulation software.[Findings]The effects of pressure and moisture content on the porosity of grain bulk were obtained.By establishing the numeri-cal model of pressure-thermal conductivity characteristics of wheat grain bulk,the thermal conductivity characteristics of wheat particles under different pressures and moisture contents were simulated,and the law of pressure-thermal conductivity characteristics of grain bulk was obtained.[Conclusions]The equivalent thermal conductivity and porosity of wheat particles were basically linear distribution.The equivalent thermal conductivity of the unit particles ranges from 0.109 5 W/(m·K)to 0.157 2 W/(m·K).The equivalent thermal conductivity of the grain pile increases with the increase of the overlying pres-sure.When the moisture content is 8.5%～20.72%and the overlying pressure is 300 kPa,the thermal conductivity increases by 17.5%～27.5%.
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