Drying Mechanism Of Tea And Improvement About Dryer Energy-Saving

In the tea processing it is absolutely necessary process steps for drying. At present, the thermal energy efficiency relatively lower generally in which is needed a large of energy. Based on the comprehensively description of the biological wet porous material drying study and development, this paper has formulated the unsteady drying dynamic characteristics experiment scheme to test the thin layer drying and the internal moisture diffusion in the drying process research. By this way, it is revealed the heat and mass transfer mechanism of drying optimization process, as well as new models dryer Tea Research and Development provides a reliable theoretical basis and technical infrastructure. The main works of this topic are as follows:1. Unsteady drying dynamic characteristics experiment of teaAccording to analysis of the drying process and characteristics, thin-layer drying research was performed that the tea leaves-rolled was used as the representation in dry test platform.The Test control factors were based on Air temperature (70℃,85℃,100℃,115℃, 130℃), wind velocity (0.08 m/s,0.22 m/s,0. 47 m/s,1.37 m/s,2.05 m/s) and Dry basis moisture content (1.60 g/g,1.32 g/g,1.03 g/g), and selected more optimized the dry conditions, in which carried out variable-temperature (100℃-55℃,100℃-70℃,100℃-85℃,100℃-100℃) drying process and analyzed drying process of tea. The results show that compared with the constant temperature drying, although having the same reduction of moisture content and drying period, the optimized variable-temperature drying has different drying process and energy saving. The form of equation (2-10) can be described the characteristics of the whole drying process; On the base of the above researches, the experiment data are analyzed with the Matlab, and obtain the single item's spreading equation (2-21) to express the characteristic, which revealed the controlling factors of hot air drying air temperature, wind speed and drying processes.2. The investigation about heat energy utilization of tea dryerBased on heat energy utilization, the common problem was analyzed about several commonly tea dryer, for the carrier of heat and hot air momentum, the way of bottom inlet winds which made the presence of temperature field and wind speed uneven distribution in tea dryer, and have a poor humidity elimination in larger dryers especially. With the drying process, the utilization of heat energy of tea dryer was decreased gradually. 3. Improved design of tea dryer for energy-savingHaving combined a large of experimental research and theoretical analysis, technical Improvement of tea dryer for energy-saving should be carried out follow two sides behind. On the one hand, the principle of drying kinetics was combined with drying characteristics of tea for system energy-saving about producing process in which it should be Strengthen during constant drying while be designed with variable temperature during falling rate drying, and in this way it could be fulfilled cascaded contra-aperture and reasonable utilization of thermal potential while be prevented over-drying and reduced unnecessary prodigality. On the other hand, heat-pump would be introduced as advance equipment for energy-saving which be utilized for recycling the latent heat and sensible heat to achieve residual heat reutilization and drying on energy saving.