Study On The Combined Drying Technology Of Rice Straw Nutrient Plug Microwave Hot Air

straw-based nutrient seeding-growing tray is prepared by using crop straw and cow dung as the main raw materials,and is processed by air pressure forming and drying and shaping.It is an upgraded product of rice plant quality and breeding tray.straw-based nutrient seeding-growing tray combines the structural characteristics of flattening and breeding,which not only ensures the seedlings become acupoints but also joins the carpet,realizing the independence,integrity and continuity of the seedlings.It can also produce good economic,ecological and social benefits,and therefore has a very large market development potential.In the production process of straw-based nutrient seeding-growing tray,drying stereotype is one of the important steps in the production process of straw-based nutrient seeding-growing tray.It is aimed at the warping,fracture,deformation and some rice straw nutrition points of straw-based nutrient seeding-growing tray drying technology.The problem of uneven drying of the disk was carried out.The optimization design of the microwave coupled with hot air dry device was carried out.The feasibility of the microwave coupled with hot air dry of the straw-based nutrient seeding-growing tray was discussed.The variation of the quality of the straw-based nutrient seeding-growing tray was studied by different drying processes.The result not only avoids the problems in the traditional drying,but also saves the drying time and energy consumption,has high drying efficiency and dry quality,and provides a theoretical basis for the industrial production of the straw-based nutrient seeding-growing tray microwave hot air combined drying technology.The main research contents are as follows:1.The microwave hot air combined drying device has been improved,including:(1)the design of the initial distribution stabilizer of the airflow.In order to ensure the stability of the airflow pressure and flow rate of the initial distribution stabilizer into the airflow,and to conveniently and accurately measure the temperature and hot air velocity in the drying chamber,an airflow primary distribution stabilizer is designed.(2)Optimized design of the air distribution room.The flow field simulation analysis of the air distribution chamber of the microwave hot air combined drying device was carried out by using computational fluid dynamics software.Combined with the design theory of Central Composite Design,the quadratic regression orthogonal rotation combined simulation experiment was carried out to obtain the optimalstructural parameters of the air distribution chamber.On this basis,the spoiler is constructed for the air distribution chamber with optimized structural parameters,and the internal flow field is disturbed to further improve the uniformity of the outlet airflow velocity distribution,and the optimal air distribution chamber structure is determined;2.Explore the better drying process of straw-based nutrient seeding-growing tray.On the basis of single factor,the application range of microwave pulse ratio,hot air temperature and hot air speed was determined.According to the combination design of Box-Behnken Design Center,the test was carried out by three-factor and three-level test schemes,and the analytic hierarchy process and comprehensive scoring method were used to determine The weight of each drying index and the mathematical model of comprehensive evaluation are used to determine the influence of each evaluation index on each factor and the optimal drying process for the comprehensive evaluation index.It is verified by experiments that when the microwave pulse ratio is 1.526,the hot air temperature is 61°C,and the hot air velocity is 1 m/s,the comprehensive evaluation index is0.8054.The relative error is 1.6%.It proves the reasonable reliability of the model and provides a theoretical basis for the industrial production of nutrient plugs.