基于“边界层”理论的纸张干燥动力学模型及其数值仿真

摘要

A kinetic model of water evaporation on the surface of paper was derived based on the boundary layer theory in the current study.In addition,the mass and energy balance model was established for paper drying process.Using numerical analysis method,a paper drying process of corrugated paper machine was simulated,and the paper temperature,paper moisture,and the drying rate during paper drying process were calculated,three stages during paper drying process were analyzed quantitatively:the temperature-rising drying stage (1# ～ 4# cylinder),the drying at constant rate (5# ～ 39# cylinder) and decelerating drying stage (40# ～48# cylinder).When paper moisture dropped to 0.22 kg/kg,the paper entered into the decelerating drying stage.%利用“边界层”理论推导出纸张表面水分蒸发动力学模型,建立了纸张干燥过程物料与能量衡算模型,并采用数值分析方法,模拟某一瓦楞纸机的干燥过程,得到纸张在于燥过程中的温湿度变化曲线以及水分蒸发速率变化曲线,并定量分析了该干燥过程纸张干燥的3个阶段:升温干燥阶段(1 #～4#烘缸)、恒速干燥阶段(5#～39#烘缸)、减速干燥阶段(40# ～ 48#烘缸).当纸张湿含量下降到0.22 kg/kg时,进入减速干燥阶段.在线测量结果与模型仿真结果的对比分析表明,模拟结果和实际在线测量结果非常接近,验证了基于“边界层”理论推导的纸张干燥动力学模型的准确性.