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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。
On the basis of the second law of thermodynamics, the thermodynamics criterion of heat transfer enhancement of finned fin is proposed. The ratio of entropy yield of heat transfer between finned fin and finned fin is E Ⅱ. Taking rectangular straight fin as an example, The thermodynamic criteria are analyzed and discussed under the third type of boundary conditions common to engineering, constant heat flow and constant wall temperature, and the results are compared with the results of the traditional ribification criterion. The results show that there exists a critical Reynolds number for the enhanced heat transfer of the fins, and the critical Reynolds number varies with the structural parameters and heat flux density of the fins. Meanwhile, the heat transfer enhancement effect of the fins depends on Thermal conductivity of fins and fluids.