Wood Drying Medium Circulation Velocity Simulation And Analysis Of The Impact On The Drying Process

This study is numerical simulation the medium circulation velocity in wood drying process and comparing the result of numerical simulation with experimental test, analyzing and solving the medium state and medium circulation velocity affect on the heat and mass exchenge on the surface of the wood, researching and analysising medium circulation velocity impact on wood drying process. This study sought to change the status of conventional wood drying production technology to reduce the energy consumption of wood drying,and provide a reference for realizing multi-variable control of the production process.This study was carried out following specific numerical simulation analysis and experimental analysis:1 Using computational fluid dynamics method to simulate the medium circulation velocity in drying chamber, at the same time using conventional methods measure the inlet medium velocity of the wood pile, comparing analysis calculations fluid dynamics numerical simulation and conventional experimental, researching medium circulation velocity size and uniformity in wood drying indoor.2 According to the wood surface medium circulation velocity and temperature distribution by numerical simulation of computational fluid dynamics calculated heat and mass transfer coefficients of timber surface.3 The effects of indoor medium circulation velocity on wood drying was studied. The moisture content of 70% of Philippine mahogany was dried at low medium circulation velocity, the moisture content of 30% larch sawn was dried at high medium circulation velocity, the moisture content of 50% Philippine mahogany was dried at high medium circulation velocity. Through research and experimental analysis, the following conclusions:1 Comparing Conventional Fluent numerical simulation results and measured results found that, in addition to measuring point 1 and point 2 deviation is greater than 1m/s on which were influence by structure of test equipment, the other measuring points deviations within 1m/s. Fluent numerical simulation can be used for the study of media circulation state about wood drying room designing and the analysis of technical performance.2 Using Fluent numerical simulation found that medium circulation velocity and temperature affect on the heat and mass exchanging on the surface of timber. At the same temperature, the higher medium circulation velocity, the larger surface heat and mass transfer coefficients of timber, which can be beneficial to the initial of wood drying rate at certain extent.3 In this study, during the drying test of larch and Philippines mahogany sawn timber, when the moisture content of wood more than 30%, the medium circulation velocity should be set 2-3m/s, when the moisture content of wood down to 30%, the medium circulation velocity should be adjusted to 1-2m/s, when the moisture content of wood down to 15%, the medium circulation velocity should be adjusted to less than lm/s, this crafts can meet the wood drying requirements. When the medium circulation velocity was reduced, fans frequency decreasing, the corresponding power consumption of fan would be reduced.As the moisture content of dried sawn timber is reduced, the influence which medium circulation velocity on wood drying will gradually decrease. During actual production, the moisture content of the wood drying process is divided into three stages, namely the moisture content of greater than 30%, moisture content 15-30%, moisture content less than 15%, respectively adjusting medium circulation velocity at the different stages, in order to reduce the power consumption of circulation fan.