肋片强化传热的热力学判据

Thermodynamic Criterion of Enhanced Heat Transfer on Finned Surface

以热力学第二定律为基础 ,提出了肋片强化传热的热力学判据———加肋片后与加肋片前单位传热量的熵产之比eⅡ ,并以矩形直肋片为例 ,在工程上常见的第三类边界条件及恒热流和恒壁温两种工况下 ,对以上热力学判据进行了分析和讨论 ,并把结果与传统的肋化判据结果进行了比较。研究结果表明 ,对肋片的强化传热 ,存在一临界雷诺数 ,且临界雷诺数随肋片的结构参数和热流密度的不同而有所差异 ,同时 ,肋片的强化传热效果还取决于肋片和流体的导热性能。

Based on the second law of thermodynamics, a thermodynamic criterion of enhanced heat transfer on finned surface—the ratio of entropy generation for unit heat flux between finned and smooth surface is suggested. Considering rectangle straight fin as an example, the thermodynamic criterion is analyzed and discussed on the condition of constant heat flux and constant wall temperature with the third boundary condition, and compared with the traditional criterion of enhanced heat transfer on finned surface, some useful conclusions are gotten.The results show that a critical Reynolds Number exists for enhanced heat transfer on finned surface and which varies with the structure parameters and heat flux of finned surface,furthermore,the effect of enhanced heat transfer on finned surface depends on the heat conduction performance of finned surface and fluid.