木材蒸汽预处理过程非均匀传热特性的数值模拟研究

Numerical Simulation of Heterogeneous Heat Transfer in Wood Steam Pretreatment Process

对木材蒸汽爆破预处理过程中热量传递规律进行了数值模拟研究,建立了木材蒸汽爆破预处理过程中三维传热数学模型,并通过试验验证了数值模型准确性。模型定量分析了木材初含水率、孔隙率、环境温度对蒸汽爆破预处理过程中传热的影响,结果表明:1)随着初含水率增加,木材升温速率逐渐减小,但当初含水率低于30%,含水率对升温速率的影响不明显;2)随着孔隙率增加,木材升温速率逐渐增加,孔隙率对传热影响大于木材初含水率对传热的影响;3)随着环境温度增加,木材升温速率逐渐增加,环境温度对传热影响弱于木材初含水率及孔隙率对传热的影响。

A three-dimensional orthotropic mathematical model of heat transfer was formulated and a numerical code based on finite difference method was implemented in order to allow a more comprehensive numerical investigation of the steam explosion of wood to be undertaken.Meanwhile,the model were taken into account the effect of the initial moisture content(MC)of wood,porosity and environment temperature on heat transfer during the steam explosion process.Results from the mathematical model were in closest agreement with the experiment data.The heating rate inside wood gradually decreased as the initial moisture content of wood increased.However,when the initial MC lowered than 30%,it had no significant effects on wood heating rate.With the increase of porosity,the wood interior heating rate gradually increased.The heating rate inside wood gradually increased when the environment temperature was raised.