Research On Characteristics Of High Moisture Corn Combination Of Hot Air And Vacuum Drying

Hot air drying, having the advantage of high drying speed, is a most widely usedway to dry corn in our country at present. But because the main impetus of the dryingis hot air, so when there is only bound water in the corn, the efficiency of hot airdrying will significantly drop, to make more waste of the energy. And the power ofvacuum drying is divided to two parts, temperature and pressure, especially thepressure difference has obvious effect on the drying speed. Therefore, when the cornhas a low moisture, vacuum drying can raise the drying efficiency.This paper based on the experiment of combination of hot air drying and vacuumdrying. Research content as follows:1)Through drying corn by combination of hot air drying and vacuum drying,respectively use the initial moisture content25%and30%to experiment, discoverthat the corn with initial moisture content25%has greatly difference in the differentdrying condition, and the higher the temperature is,the high drying rate is. And stilluse the orthogonal experiment to study the mechanism of the combination of drying,and confirmed the best drying technology index combination parameter which aimedto the energy consumption and the germination rate and optimized the drying process.2)Combined with the concept of water potential, to analyze the law of watermigration in the corn drying, consider drying is a process of water transfer, the powerfrom water potential difference made by temperature gradient and pressure gradient.In the drying process, water in the corn migrate from the internal with high waterpotential to the surface with low water potential, and evaporation there, to achieve thepurpose to dry the corn. But in vacuum condition, the pressure gradient provides moremotivation for water migration, makes the frying faster. The paper makes a model ofcorn drying based on water potential, and seek the analytical expression of the partialdifferential equation through Laplace transform, so the model can get more extensiveapplication. 3)Through laboratory scale of combination drying experiment, and estimate itsunit energy consumption, found the combination drying can save energy10%—20%compare with the single hot air drying. And based on this, forecast the economicbenefit of combination drying. And in the process, the condenser in the vacuumdrying equipment can absorb the dust of the corn, the heat emission to the outside areless, meet environmental protection and low carbon production requirement in thecurrent.