| Statistics in recent years show that,the demand for tea,especially bulk green tea,has increased year by year in domestic and abroad markets.As the first process of green tea production,green tea fixation is very important to the formation of its quality.At present,there are many small and medium-sized green tea fixation machines in the market for famous and high-quality tea,but there are few bulk green tea fixation machines relevant to this research.Furthermore,the design and parameter optimization of green tea fixation machine is of great significance to the mechanized production of bulk green tea.Different from famous and high-quality tea machine,bulk green tea machine has a larger overall size,higher yield and greater energy consumption,there are still many problems in the process of green tea fixation,such as the cylinder is too long so that the water vapor gathers in the cylinder leads to high water content of green leaves,as well as heat dissipation and waste problems.In terms of the above problems,this study designed the whole machine structure and key components of the green tea fixation machine,combined with the simulation analysis of concerned software,designed a bulk green tea air-intake cylinder fixation machine,the research contents and conclusions of this paper could be summarized and shown as follows:(1)In this paper,the design scheme of the whole machine was determined based on the technical requirements of tea scattering.The process of tea scattering was analyzed,the movement dynamics of tea scattering and the critical speed of the cylinder were obtained.The factors affecting the tea fixation finishing time were analyzed theoretically.(2)Through theoretical analysis and combined with the actual production situation,the key components of this research for machine including cylinder structure,guide vane plate structure,transmission mechanism,feeding mechanism,cylinder air-inlet structure and other components were designed,and the specific parameters of the relevant structure were determined.(3)On the basis of the complete machine structure design,the Fluent software was used to analyze the temperature field and velocity field of the air-inlet in the cylinder,and it was concluded that the air-inlet structure can accelerate the water vapor flow in the cylinder and improve the water vapor aggregation to achieve the design purpose.EDEM software was used to analyze the movement of tea leaves under the action of cylinder and guide vane plate to determine the working feasibility of key components.Taking cylinder speed,feeding rate and cylinder temperature as simulation factors and separation ratio and temperature rise rate as evaluation indexes,the changes of evaluation indexes with simulation factors were comprehensively analyzed.(4)The prototype was produced and the performance comparison test was conducted,the test results showed that: from the fixation of green leaves,the water vapor gathering in the cylinder,the fixation efficiency and the fixation of green leaves moisture content,the design of the bulk green tea air-intake cylinder fixation machine can achieve the design purpose and meet the needs of large green tea fixation operation.(5)The optimum orthogonal test of working parameters was carried out.The optimum index was the maximum appropriate rate of green tea fixation,and the water content was the secondary index.The results showed that when the cylinder speed was 19r/min,the feeding rate of tea was 17kg/min,and the cylinder temperature was 299℃,the appropriate rate of green tea fixation leaves reached 96.32%,and the water content also met the requirements of green tea fixation leaves.The verification test results are consistent with the optimization results. |
