Design Of Vertical Dryer And Study On The Uniformity Of The Velocity Field In Chamber Of Vertical Drying Unit

The uneven distribution of the air velocity in drying chamber is the main reason of drying low efficiency and uneven of various types of dryers. Based on vertical dryer equipment, this paper studies the air velocity field in the designed vertical dryer unit through Computational Fluid Dynamics (CFD) numerical simulation method and experiments method, after the analysis of the physical characteristics parameters of the material and dryer structural performance. We analyze the distribution uniformity of the air field in drying chamber of the drying unit, when the air into the chamber in two different wind road program. The main research conclusions are listed:(1) Before the experiments and CFD numerical simulation of the air field, Experimental study on the basic physical parameters of the material and thermal parameters is necessary. The results of experiments show that the average porosity materials is0.346, and the true density and bulk density of the materials are831.6kg.s-3and705.3kg.s-3, under the conditions of the initial moisture20.47%. Measuring the thermal conductivity of materials under different moisture and temperature, the result indicated that the thermal conductivity of materials is positively correlated with moisture and temperature. The thermal conductivity increases with moisture content and temperature increasing.(2) Through research and analysis the process and the principle of vertical dryer, complete the design of the structure and the selection of the key components. The drying method of vertical dryer uses the counter-current combination drying method, with the multi-layer of inlet and exhaust pipe in the dyer. Hot air medium cycle to dry materials in the chamber, and this method can reduce energy consumption.(3) On the basis of experimental results, the CFD simulation method of the vertical drying unit is established with CFD model. Fluent simulated the air velocity field in the drying chamber with the two forms wind roads. Compare between the model results and simulation results, the conclusions are following:CFD simulation method simulating the air field in the drying chamber of vertical drying unit is feasible. Through the setting of homogeaezings in the inlet of wind roads, both of experimental results and simulation results are more uniform.(4) The experimental research on the air field in vertical drying chamber shows that:the air amount in both sides of the wind roads of the chamber on is basically the same. When the wind roads with non-homogeaezing, the air velocity in drying chamber is relatively uneven. The settings of the homogeaezing can significantly improve the uniformity of the air velocity in the main dry areas of the chamber. The material height and flatness affect the uniformity of the air velocity field in chamber. By the study on the uniformity of the air velocity field in the chamber of vertical drying unit, the experimental results are consistent with the CFD simulation resultsNumerical simulation and experiments study verified the feasibility of the principle of vertical dryer and accurately and clearly understand the airflow distribution in vertical dryer. Setting the homogeaezings in the inlet of wind roads to change the airflow direction, it can optimize the uniformity of the air velocity in the drying chamber to improve drying effect and quality of vertical dryer. This study provides a theoretical basis to design and optimization of vertical dryer structural.