Research And Application Of Key Technologies For Mass Drying Of Multifunctional Wood Panel

In recent years,the production of green and clean artificial panels has become increasingly important due to the reduction of forest resources and the continuous growth of economic demands.Multifunctional wood-based panels,prepared from the waste generated during wood processing,possess advantages such as environmental friendliness,sound insulation,fire resistance,water resistance,mold resistance,and insect resistance.They have found extensive applications in areas like laminate flooring and prefabricated construction.The drying process,as the final step in the production of multifunctional wood-based panels,plays a crucial role in determining the final drying quality and mechanical performance of the products.However,the current drying quality of wood-based panels is poor,with numerous drying defects,which hampers the commercialization and further development of their applications.Thus,further improvements are needed.This study focuses on optimizing the drying kiln structure and process parameters for multifunctional wood-based panels to provide experimental evidence and guidance for the design of energy-saving and high-yield drying kilns,as well as wood-based panel drying processes.Firstly,to address the issue of non-uniform airflow within the drying kiln,an optimization method combining the Inventive Problem-solving Algorithm ARIZ 85-AS with Computational Fluid Dynamics(CFD)is proposed to optimize the kiln structure.The simulation is conducted to visualize the airflow distribution within the kiln,and three airflow evaluation indices,namely,average velocity difference,average velocity,and coefficient of variation,are proposed to analyze the initial problem.The inventive problem-solving algorithm is utilized to optimize the kiln structure iteratively from three aspects: the air inlet,installation of baffles,and gaps between upper and lower layers of wood-based panels.The actual airflow velocities before and after optimization are measured,indicating a 19.5%increase in average hot air velocity and a 15% reduction in the coefficient of variation.This validates the feasibility of the optimization approach.Subsequently,a novel drying process is developed to address issues such as cracking and warping deformation that occur during the drying process of multi-functional woodbased panels.Drying experiments are conducted based on the technical requirements of wood-based panels.A comparison-based method is employed to summarize the drying process parameters based on a time-based drying benchmark,which is divided into three stages: preheating,drying,and adjustment.To provide a more intuitive understanding of the moisture content variation and drying curve during the wood-based panel drying process,the moisture content variation and drying curve are investigated.Productive trials are conducted using the novel drying process,resulting in an average reject rate of 9.4%.The drying quality of the panels meets the national drying quality standard,Grade II,with a 25%reduction in drying time and a 57.4% decrease in the reject rate.The panels show no apparent drying defects,validating the rationality of this novel drying process.Finally,in order to improve the static bending strength and density of multifunctional wood-based panels,response surface analysis is employed to optimize the process parameters in the third stage of drying.Through PB screening experiments and steepest ascent experiments,the influential factors and their value ranges that significantly affect the static bending strength and density are determined.Response surface models for static bending strength and density are established using the response surface methodology,and the significance of individual factors and their interactions is analyzed.Multi-objective optimization yields optimal drying process parameters: drying temperature of 70°C,drying time of 17.2 hours,and drying airflow velocity of 2.5 m/s.The feasibility of the optimized parameters is validated by comparing the static bending strength and density before and after optimization.The optimized wood-based panels show significantly improved sound insulation performance,indicating the feasibility of using response surface analysis to optimize process parameters.