真空玻璃传导和对流传热机理研究

利用传导和对流传热原理,建立了真空玻璃热量的流动和传递数学模型,推导了真空玻璃自由分子状态的导热量、支撑柱及边料的固体导热及真空玻璃的外表对流换热方程.分析了自由对流传热、纯气体、稀薄气体、支撑柱及边料的固体导热机理,探讨了真空玻璃的外表对流换热问题.研究结果表明,在低真空状态下的真空玻璃夹层厚度越小,越有利于由自由对流向纯气体导热方向发展,越有利于真空玻璃传热系数的降低.真空玻璃结构只要保持夹层真空度小于0.313 Pa就使得夹层内成为自由分子导热状态.

Study on the Mechanism of Conductive and Convective Heat Transfer in Vacuum Glass

The mathematics model for heat flowing and transferring in vacuum glass was established by the principle of conductive and convective heat transfer, and the equations , such as vacuum glass conductive heat quantity by free molecule, solid transferring heat through the brace and the margin , exterior convection and heat transfer, were de- duced. The mechanisms of thermal conduction by free convection, pure air, low density gas, the brace and margin solid were analyzed, and exterior convection thermal exchange of vacuum glass was discussed. The results show that the smaller vacuum space of vacuum glass is favorable for converting from free convection to pure air conduction under low vacuum, which is befit to reduce conductive heat coefficient of vacuum glass. When vacuum degree keeps less than 0. 313Pa, the free molecule conduction status will be established in the space.