The Experimental Study Of Corn Straw Particles’s Pneumatic Drying And The Simulation Of Heat Transfer Process

Currently, our country’s energy is in short supply, especially the fossil energyare gradually depleted, and the environmental pollution caused by the fossil energy isgrowing, the outlook is not optimistic. Our country has a large number of biomassenergy, based on the national circumstances, we should devote major efforts todeveloping biomass energy. Corn straws are the major biomass energy in our country,they will be crushed into particles and to be used as boiler fuel instead of coal, thecorn straws have characters of high burning rate and low-polluting and so on, usingcorn straws can be effective in reducing the greenhouse effect, easing energyshortages, and promoting the development of rural areas in China. But fresh watercontent in corn straws is larger, when they are directly used as a fuel, they are hard tobe burnt and hard to be stable kindled. We can solve the problems by drying thecrushed corn straws particles and then injecting them into the fire grate above.Therefore, to large-scale use of straw resource, studying the the drying problem ofcorn straws is with some realistic significance.This topic we used the corn straws which are the north China’s maincrop as theresearch object, and we did many sets of experimental research to study the influenceof different variables such as the feed rate of unit time, hot air temperature, materialinitial moisture content and air flow speed on the drying rate, summed up the dryingcurve; And analysisd drying process by using the method of orthogonal combination,got four impact factors on the drying rate from the primary to the minor. Test resultsshowed that the drying process is divided into two stages, the drying rate of the firsthalf of drying tube is quickly, in the second half of the tube, the drying rate decreases gradually as the difference of gas-solid temperature and moisture content reduce;Improve the hot air temperature, speed up the air flow, reduce the material initialmoisture content and feed rate of unit time can improve the drying rate; Throughorthogonal test, we found the the degree of influence of the four factors on the dryingrate, in order: air temperature> the feed rate> air flow speed> material initialmoisture content.In addition, in order to more intuitive understanding of the flow and heattransfer process of gas-solid two-phase flow, combining with the characteristics ofphysical properties of corn straw particles, this paper simulated the pneumatic dryingprocess of corn straws through the CFD software FLUENT. Combining with theexperimental results shows that the established mathematical model can accuratelysimulate the state of the flow and heat transfer in the drying process.