The Research And Manufacture Of Drying Equipment For Licorice

Licorice is rich in licorice acid, flavonoids and other chemical elements, with ant i-inflammatory, anti-cancer and other medicinal value. The amount of plantation and r eserve is abundant in China. Meanwhile the lack of theoretical research and practical application in the processing of raw materials limits the productivity of semi-finished products such as licorice slices. On the one hand, the high moisture of fresh licorice without drying leads to decay and rot during long term storage. Hence large amount of licorice is not digging to prevent wasting. On the other hand, the lack of semi-finished products which contain many chemical constituents and medicinal value makes the market demand has not been met. Therefore the key to solve these problems is to enhance the theoretical research and practical application of drying equipment.The tunnel drying equipment is widely used in the drying process of fruits and vegetables, which is convenient in operation, simple in structure and low in cost, and is suitable for large batch drying. The application of tunnel drying equipment is capable of reducing the drying time, increasing the productivity and guaranteeing the quality.The stream field’s even distribution is the key influencing factors of the quality during drying process. The main work is shown as below:Firstly, the main parameters-activation energy and diffusivity constant-are calculated to provide evidences for heat and mass transfer procedure during drying.Secondly, the flow field of conventional tunnel dryer is studied by simulation. The result shows that the variation of airflow velocity difference is acutely in lengthwise direction and to reach stabilization velocity experiences a long distance. The slow diffusion of airflow in width direction and height direction leads to uneven distribution of airflow velocity in first half. The product quality can be severely influenced by uneven distribution of flow field.Afterwards, the structure modification is proposed for uneven distribution of flow field in tunnel dryer, and the flow field of the proposed structure is simulated to reveal the obvious improvement of flow field in every aspects. The homogeneity of flow field is significantly improved.Finally, the air inlet with different diameter of tunnel dryer is simulated on the basis of structure modification. The comparison of minute changes in different diameter shows that the flow field is most evenly when the diameter of inlet is 0.5m.