Study On Process Parameters Of Heat Pump Drying Rice

Rice is one of the most important crops in China.Water content must be measured and considered in the process of rice storage and transportation.Therefore,drying is an essential step after harvest of fresh rice.The moisture content of rice in the drying process is greatly affected by the drying process parameters,among which the drying temperature and initial moisture content of rice have great influence on the drying process.In this paper,the mechanism of heat and mass transfer,drying principle,water transfer mode and other aspects of rice drying process were theoretically analyzed,and the effects of different drying temperature,different initial moisture content and different varieties on the drying characteristic curve and burst waist rate of rice in the drying process were studied.The experimental data were recorded.Then the temperature field of rice under different drying conditions was simulated by computational fluid dynamics software.The mathematical model of heat transfer in rice drying process was established,and the porous medium was considered.Then a physical model of rice drying was established by reasonable simplification and hypothesis,Then the whole mechanism and working principle of the heat pump system used in the experiment are introduced.Then,CFD software was used to simulate the change of temperature field of rice during drying,which was basically consistent with the experimental results.Then the change of temperature field in rice drying process under different drying temperature,different drying wind speed and different bulk volume was simulated.The results show that the higher the drying temperature,the faster the heating rate;The higher the drying wind speed is,the closer the average temperature of grain pile cross section is to the drying temperature.The larger the bulk of grain pile is,the slower the temperature rise rate of grain pile is,the lower the average cross section temperature of grain pile.The effects of drying temperature,initial water content of rice,rice varieties and other factors on the decreasing trend of drying rate and water content of rice and on the rate of waist burst after drying were analyzed.KNN algorithm is used to predict the drying stage of the data in the experimental process,and the predicted results are compared with the actual results.The results show that the prediction success rate of the algorithm is high,and the data mining algorithm can be applied to the drying process of rice to improve the drying quality and solve the problems of measuring and adjusting parameter lag in the drying process.