绝热材料的优化设计

以热流在多孔绝热材料中的传输理论为基础 ,综述和分析了热流与多孔绝热材料的相互作用。对影响绝热材料导热系数因素的分析表明 ,每一种绝热材料在特定温度下都有一个最佳体积密度 ,绝热材料并非越轻其隔热性能就越好。气孔尺寸对绝热材料在高温下的导热系数有非常大的影响。在高温状态下气孔尺寸的减小可使绝热材料的导热系数大幅度下降。纳米级绝热材料是建立在超低体积密度和超微细孔 (小于50nm)结构基础上的 ,其导热系数可低于静止空气的导热系数。

The interaction between heat flow and porous thermal insulation material is outlined and analyzed on the basis of transfer theory of heat flow in porous thermal material. The analysis of influence of thermal conductivity on thermal insulation material shows that each thermal insulation material has an optimum volume density under a definite temperature, the thermal insulation material is not the more lighter, the better of thermal insulation property. The pore size has large impact on thermal conductivity of thermal insulation material under high temperature. The reduction of pore size under high temperature may greatly lower thermal conductivity of the material. The nanometer scale thermal insulation material is based on structure of super low volume density and super micropore (less than 50 nm). Its thermal conductivity may be lower than one of standstill air.