大体积混凝土结构表面保温计算方法研究

【目的】通过算例对比分析等效表面散热系数法、等效厚度法、导热系数法、导温系数法在计算保温板保温效果方面的异同，为大体积混凝土结构表面保温的计算提供依据。【方法】从热量平衡原理出发，推导了直接以导热系数、表面散热系数和热量为热传导方程基本参数的温度场计算方程，据此修改了以导温系数为基本参数的温度场有限元计算程序RCTS。【结果】利用修改后的温度场有限元计算程序RCTS，能够合理地计算由不同热学性能材料组成的复合结构的温度场，能模拟计算大体积混凝土结构任意部位在任意时段的表面保温效果。实例计算结果表明，导热系数法与等效表面散热系数法的计算结果比较接近；由于等效厚度法是等效表面散热系数法的近似处理，计算结果与前二者有一定差异，但相差不大；导温系数法往往得不到合理的结果。【结论】等效表面散热系数法计算方便，工作量小，效率高，精度能满足工程要求，具有工程应用价值。

Research on the calculation method of superficial heat preservation of massive concrete structure

【Objective】 According to the calculation example,the similarities and differences of the heat preservation effect in the heated board calculation by using the follouring methods:the equivalent surface coefficient of heat transfer method,the equivalent thickness method,the thermal coefficient method and the thermal diffusivity are analyzed,which would provide the basis of the calculation superficial heat preservation of massive concrete structure.【Method】 In this paper,based on the principle of heat balance,the computing equation of temperature field which used the thermal coefficient,surface coefficient of heat transfer and quantity of heat as the basic parameters of the heat conduction equation is derived,and thereafter the FEM computation procedure about temperature field named RCTS which used the thermal diffusivity as basic parameter is modified.【Result】 Use of modification of the temperature field RCTS finite element program,the modified procedure can reasonably reflect the temperature field of composite construction which is made of a great variety of materials with different thermal properties,and also can simulate the effect of surface heat preservation at arbitrary periods and arbitrary parts of the bulk concrete structure.The calculation results show that the computing results of the thermal coefficient method are close to the result of the equivalent surface coefficient of heat transfer method,the result of the equivalent thickness method has certain difference but not too much because it is the approximation process of the equivalent surface coefficient of heat transfer method,and the reasonable result is often unobtainable by using the thermal diffusivity method.【Conclusion】 The equivalent surface coefficient of heat transfer method has high project application value because it calculates conveniently with small amount of work,high efficiency and high precision.