| The traditional grain drying process is the typical large inertia, multivariable and nonlinear process system. The objective potential energy existing in the drying system is possible to solve the problems including the higher energy consumption, poor quality in the process of rice hot-air drying likely. By means of the exergy within the rice itself carried and natural air to dry the rice,the effects of technological process parameters for the rice accumulation drying, the optimal technological parameters of rice energy-saving drying was determined, and energy efficiency evaluation and process analysis method in drying system was analyzed. The high wet dry rice storage warehouse was designed, and the similar type experience model in the drying process was established. The energy-saving drying technology and the theory basis is provided to obtain the energy-saving drying technology for high wet rice.Based on the dry exergy transfer theory, the essence of the energy loss in the rice drying system was revealed, as well as the energy transmission characteristics, the exergy standard point,the enthalpy and energy structure of drying chamber, and the exergy efficiency in the grain drying system were deeply analysed. It was established for the change process of the exergy standard point and standard function at the figure of enthalpy-moisture content, and it was indicated how to obtain the suitable using way according to the energy and mass at the same time. The influence of exergy efficiency in drying system showed the effect on the parameters of drying operation, and utilizing energy for drying system was scientically evaluated. There is realistic significance to achieve the saving-energy drying.According to the Center Combination Experimental Design with paddy drying ratio and energy consumption as the objective factors, the influence of different parameters of process was researched on the rice drying ratio and energy consumption, and the regression model was establishing between the response value and the test factors. The results indicated that the impact degree of various factors on rice drying ratio was as follows from high to low: initial moisture content of rice, wind speed of draught fan, forced draft time, and it is the same with the influence of various factors on the energy consumption. By optimizing and validating for the accumulation drying process of rice, the optimum technology parameters range were as follows: initial moisture content of 21%~25%, wind speed for draught fan of 4.20 m/s, forced draft time of 8.50 minutes.Comparing with the traditional hot-air drying, the fissure ratio down to 5%, precipitation was5.95%, the final moisture content of 16.8%, and save energy consumption of 30% in theaccumulation drying process, and there is advantage in rice quality and energy consumption.In order to achieve the saving-energy effect, the dry rice storage system was designed according to using the natural air and objective exergy carried by rice itself, combining with the optimum parameters of the rice accumulation drying on the basis of the exergy theory. In accordance with the similarity theory and to select the main influence factors on drying process,the empirical model,which is relative with instant moisture content M, the rice temperature t1, the rice medium velocity v, the initial moisture content M0, the environmental temperature t2, the total dry time T, the rice bulk density G, the rice specific heat capacity C, was established by the dimensional analysis method, and the saving-energy process could be popularized based on this empirical model.This study proposes are to dry the rice by natural air and objective exergy which is carried by the rice itself, and to effectively reduce the energy consumption of rice drying process, as well as to saving energy and to lower the cost without damaging the quality of the rice. It is helpful for providing a new direction in the saving-energy technology for the grain drying technology. |
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