Research On Cylinder Tea Fixation Machine With Porous Hot Air Pipe

China is a tea production and consumption country,but is relatively backward for the study of Green Tea processing technology and equipment.As the first step of Green Tea early fabrication,fixation can directly affect the quality of tea.In order to obtain tea with high quality,it is necessary to optimize tea fixation technology and equipment to ensure the follow-up process of tea fabrication.Aiming at improving the quality and quantity of tea and low utilization rate of heat energy,based on the research of the characteristics of the fluid and particles in the cylinder fixation machine,simulating the tea fixation process by using the coupling method of the discrete element software EDEM and fluid dynamics software FLUENT.Then we optimize the fixation machine from the discrete field,flow field and temperature field.The main work and achievements of this paper are as follows:(1)Determine the flow characteristics by the fluid type judgment according to the discriminant criterion,select suitable turbulence model and wall function.Select hexahedral mesh division method by comparing the grid type,the results show that the grid can have the advantages of fast calculation of flow field characteristics and the basic performance.(2)The feasibility and process of the EDEM and FLUENT coupling simulation was analyzed.Selecting the suitable particles shape and contact mechanics model and contact judgment algorithm according to the particle model theory in the discrete particle model element method,then built the particle resistance model and heat transfer model based on particle trajectory model.The coupling results show that the parameters of particle can be caculated well.(3)Completing the structure of discrete phase tea model and continuous phase heat flow model.Simulating and analyzing the fixation process by designing a single factor experiment,Selecting the cylinder rotation rate and the number of guide vanes and cylinder obliquity as the experiment factors.The results show that the rising rate of tea particle temperature increases along with cylinder rotation rate,number of guide vanes,cylinder obliquity in a certain range,but it will decline when the parameters exceed a certain level.(4)Simulating and analyzing the separation ratio and material screen area of tea particles in the fixation process by designing orthogonal experiment with four factors and three levels.Selecting the cylinder rotation rate,the number and height of the guide vanes,cylinder obliquity as the experiment factors.The results showed that cylinder rotation rate and cylinder obliquity had big influence on the rising rate of tea particles temperature,but the number and the height of guide vane had little influence on the rising rate of tea particles temperature.The optimal combination of the factors of the orthogonal experiment is selected.Based on the above research,the structure and motion parameters of cylinder tea fixation machine with porous hot air pipe can be optimized.The comparative experiments show that the optimized model can ensure the production efficiency and improving tea quality.