组合管径圆弧翅片换热性能的数值模拟

针对空调器室内机换热器空气侧的流动和换热问题,利用FLUENT软件,本文研究了开缝圆弧翅片以及组合管径开缝圆弧翅片对换热器的换热量和空气侧压降的影响,并与原开缝三折翅片换热器进行比较。结果表明,开缝圆弧翅片换热器的换热量大于原开缝三折翅片换热器,而空气侧压降略有增大。随着小管径数量增大,开缝圆弧翅片换热器的换热量逐渐减小,但压降也逐渐减小。相比于开缝三折翅片换热器,当开缝圆弧翅片换热器为10根小管时,其压降增大5%左右,但换热量却有2%左右的提高,且铜管材料节省了14.5%,有很好的应用前景。

组合管径圆弧肋片换热器在空调器上的应用

采用Fluent软件对4根小管的新型肋片换热器空气侧的流动和换热特性进行了研究,并与开缝三折肋片换热器进行了比较。不同工况下的数值模拟结果表明,前者换热量提高了0~1.75%,压降增大了2.42%~4.86%;实验结果表明,二者COP几乎相等,但前者铜管节省5.8%。

气田集输管网最优管径组合

本文继文献〔1〕之后,进一步建立了气田管网规划布局中的最优管径组合问题的模型,介绍了求解方法,并用计算机程序求解典型网络实例,结果令人满意。

Investigation of a Network Failure Problem with a Significant Path, from the Perspective of Crisis Management

The objective of this study is to investigate a network failure problem with a significant path, emerging from the context of crisis management, such as in the case of natural disasters. For a given tree with m failed edges, we assume that we have sufficient resources to recover k edges of the m edges. Each node has a positive weight. In this situation, we consider which k edges should be fixed in order to maximize the sum of the weights of the nodes reachable from the significant path. In this paper, we formulate such a problem as a combinatorial problem. Further, we show that a part of our problem may be solved by translating it into the terms of the so-called tree knapsack problem.