Previously published hot-box data have been used to construct equations for the thermal resistance of enclosed reflective air spaces (reflective insulation assemblies) for a wide range of temperatures, air gap dimensions, thermal emittances, and heat flow directions. The thermal resistances or R-values (RSI) calculated with the equations compare favorably with previously published thermal resistances. Significant differences from RSI values (m2 K/W) calculated using ISO 6946 were observed. Equations for calculating heat transfer coefficients for conduction–convection with constants for the heat flow directions up, 45° up, horizontal, 45° down, and down are contained in this article. The conduction–convection coefficient for planar air spaces oriented at any angle and heated above can be obtained by interpolation between heat flow down and heat flow at a downward angle of 45° or heat flow down at an angle of 45° and horizontal heat flow. The overall heat transfer coefficient is obtained by adding the thermal radiation contribution to the conduction–convection contribution. The RSI of enclosed reflective air spaces is the reciprocal of the overall heat transfer coefficient for the air space. This air space RSI is especially useful as input for the calculation of U-values for ceiling–roof assemblies located in hot climates.

中文翻译：

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用于天花板上应用的反射绝缘组件

先前发布的热箱数据已用于构建封闭反射空气空间（反射绝缘组件）在各种温度、气隙尺寸、热发射率和热流方向下的热阻方程。使用公式计算的热阻或 R 值 (RSI) 与之前公布的热阻相比更胜一筹。观察到与使用 ISO 6946 计算的 RSI 值 (m2 K/W) 存在显着差异。本文包含用于计算传导-对流传热系数的方程，其中热流方向为向上、向上 45°、水平、向下 45° 和向下的常数。可以通过向下热流和向下 45° 角的热流或向下 45° 角的热流和水平热流之间的插值来获得以任何角度取向并在上面加热的平面空气空间的传导-对流系数。总传热系数是通过将热辐射贡献添加到传导-对流贡献中获得的。封闭反射空气空间的 RSI 是空气空间总传热系数的倒数。该空气空间 RSI 作为输入用于计算位于炎热气候中的天花板 - 屋顶组件的 U 值特别有用。总传热系数是通过将热辐射贡献添加到传导-对流贡献中获得的。封闭反射空气空间的 RSI 是空气空间总传热系数的倒数。该空气空间 RSI 作为输入用于计算位于炎热气候中的天花板 - 屋顶组件的 U 值特别有用。总传热系数是通过将热辐射贡献添加到传导-对流贡献中获得的。封闭反射空气空间的 RSI 是空气空间总传热系数的倒数。该空气空间 RSI 作为输入用于计算位于炎热气候中的天花板 - 屋顶组件的 U 值特别有用。