多层高温绝热层绝热性能理论分析

Theoretical Heat Transfer Analysis on High Temperature Multi-layer Thermal Insulating Layers

绝热材料内部添加反射屏是实现高温绝热的有效方法和手段,主要通过数值模拟研究绝热材料与反射屏组成的多层绝热系统的传热特性。采用能量守恒定律和双通量方程近似法建立多层绝热系统的辐射导热耦合换热模型,通过方程的离散化数值求解,在保证绝热层低温侧温度不变的情况下,分析反射屏发射率,反射屏数目,绝热材料消光系数,绝热材料气固耦合导热系数等参数对高温绝热层厚度的影响特性。研究结果表明,绝热材料消光系数越小,材料气固耦合导热系数越小,反射屏发射率越小,则反射屏对绝热层绝热效果的影响越显著,该文的研究对于多层高温绝热层的设计具有指导作用。

Adding reflecting screen in insulating materials is an effective method to achieve high temperature thermal insulation. This paper mainly discusses the heat transfer characteristics through numerical simulation of the multi-layer insulation system, which is consisted of thermal insulation material and reflecting screens. The energy conservation laws and two-flux approximation were used to establish the coupled radiation-conduction heat transfer model in multi-layer thermal insulation system. Through numerical simulation of discretizated equation in the situation of assuring a constant temperature at the lower side, it analyses the influence of the parameters such as reflecting screens emissivity, reflecting screens number, the extinction coefficient of thermal insulation material, the gas-solid coupled thermal conductivity of thermal insulation material on the thermal insulation layer thickness. The results show that the reflecting screens have more significant effect on the insulating layer when the extinction coefficient, the gas-solid coupled thermal conductivity of the insulation material, as well as the reflecting screens emissivity is small. It may play a guiding role on design of high temperature multi-layer thermal insulation layers.