基于Fluent-EDEM耦合的茶叶红外杀青机滚筒内流场数值模拟

针对目前茶叶杀青机存在杀青不均匀、热能利用率低等缺陷,提出了一种以红外辐射为热源的滚筒式杀青机,将红外热源置于滚筒中心,采用Fluent-EDEM耦合杀青过程中的离散场、流场和温度场,并进行耦合分析,在流体软件Fluent中设置湍流模型和辐射模型,在离散元软件EDEM中建立茶叶与茶叶及茶叶与滚筒的接触模型,耦合求解计算得到杀青机滚筒内流场温度分布和杀青叶升温曲线,实现对茶叶杀青过程中流场的数值模拟,并与同型号的电加热滚筒内流场模拟结果进行比较。模拟结果表明,电加热结构的温度流场在滚筒内均匀分布,热能利用率低;而红外杀青机滚筒内流场温度分布主要集中在滚筒右部及底部,能将大部分热能直接辐射到杀青叶上,热能利用率高,该杀青装置能使杀青叶在短时间内快速升温,从而快速钝化酶的活性,提高茶叶品质。红外杀青机滚筒内的温度实测值与模拟值的相对误差约为0.99%,说明模拟过程中参数设置是合理的。

The numerical simulation on temperature field inside the radiation de-enzyme machine based on Fluent-EDEM coupling

The temperature distribution inside the drum of tea cylinder water-removing machine is the main factor affecting the quality of the tea.In view of the defects of the current tea cylinder water-removing machine,including the uneven water-removing and low thermal energy utilization,a tea cylinder water-removing machine was designed with infrared radiation as the heat source in the present study.The infrared heat source was placed in the center of the cylinder.The approach of combining EDEM and Fluent was used to analyze the discrete field,flow field and temperature field during the de-enzyme process The turbulence model and the radiation model were installed in the software Fluent,then the contact model of tea leaves and cylinder was established by the discrete element software EDEM.The temperature distribution of the flow field in the drum and the temperature rise curve of deenzyme green leaves were obtained through coupled calculation,realizing the numerical simulation of the de-enzyme process,then the simulation results with the same type of electric heating machine were compared.The simulation results showed that the temperature flow field of electric heating structure was evenly distributed in the drum,and the utilization rate of heat energy was low.While filming for the infrared temperature distribution in the flow field in the cylinder was mainly concentrated in the right and bottom rollers,and could put most of thermal radiation on the steamed directly.With the utilization of the high heat energy,the editing device could make the steamed quickly to heat up and warm effect,thus the enzyme activity was passivated in a short time,improving the quality of the tea.The relative error between the measured temperature and the simulated value was about 0.99%,indicated a reasonable parameter setting.