POROUS HOT AIR TEA DE-ENZYMING AND CARDING MACHINE UNDER GAS–SOLID COUPLING CONDITIONS: NUMERICAL SIMULATIONS AND PERFORMANCE TESTING

Abstract

The gas–solid coupling of a porous hot-air tea de-enzyming and carding machine was studied by means of computational fluid dynamics and discrete element coupling. In the numerical model, the discrete phase of tea particles was simulated using Rocky-DEM software, while the gas phase was described by ANSYS Fluent software. A mathematical model of the movement characteristics of tea particles in air was established according to the principle of fluid mechanics, to carry out dynamic analysis of tea particles’ movement process and derive how the motion of gas and tea particles is governed. Three sets of prototype tests were carried out on the basis of the design and simulation, and the average of their results taken. This showed that the hourly output of the test prototype was 3.89 kg/h, the bar-type rate was 89.14%, the de-enzyming moderation rate was 91.67%, and the average value of the measured effective operating temperature of the pot slot was 189 °C. The performance of the prototype was also tested and analyzed. After conducting a tea sensory evaluation expert appraisal, the sensory evaluation indices of the prototype-processed tea satisfied all current market requirements, being superior to those of the conventional de-enzyming and carding machine. The quality of the finished tea also met the agronomic standards and the operational requirements of the de-enzyming and carding machine.