基于最小热阻理论的混凝土导热系数计算模型

Calculation model of thermal conductivity of concrete based on minimum thermal resistance theory

针对传统混凝土导热系数计算模型机械地按照混凝土组成来划分热流途径而导致计算结果偏大的问题,基于最小热阻理论,并考虑到混凝土中孔隙作用,对传统混凝土导热系数计算模型进行了改进.通过引入传热面积比例系数的方法,使混凝土中热流途径的划分不仅满足了混凝土组成的要求,而且满足了最小热阻理论.采用该模型分别计算了8种混凝土的导热系数,其计算结果与实测结果的误差率在-14.0%～+5.1%范围内,而Harmathy模型和Campbell-Allenand Throne模型的计算结果与实测结果误差率分别在4.9%～29.3%和11.0%～32.1%范围内.相比于传统的混凝土导热系数计算模型,基于最小热阻理论建立的混凝土导热系数计算模型精度有了较大的提高.

The traditional calculation model of thermal conductivity of concrete that mechanically compartmentalizes the transfer path of heat flow in concrete material according to its compositions can seldom meet the minimum thermal resistance theory and may lead to large simulation results. Based on the minimum thermal resistance theory, an improved model considering the role of pore inconcrete is presented. By introducing the heat transfer area proportion coefficient method, the comp- artmentalization of heat flow in concrete can meet not only the requirements of the concrete composi- tions, but also the minimum thermal resistance theory. The thermal conductivity of eight kinds of concrete is calculated by using the model. The deviation between the calculated results and experi-mental results ranges from - 14. 0% to ＋ 5. 1%, while the corresponding deviation scope by the Harmathy model and the Campbell-Allen and Throne model are 4.9 % - 29.3 % and 11.0% -32.1%, respectively. It can be found that the presented model is more accurate than the traditional calculation models of thermal conductivity.