Abstract

While most critical heat flux (CHF) studies focus on relatively straightforward geometries, actual equipment applications are complex. This paper summarizes literature which provides insights into the effects of selected inlet conditions on CHF and the occurrence of upstream CHF. Vertical smooth bore tube CHF tests found that the concept of “local conditions hypothesis”, though not universally defensible, provides an adequate basis for applying CHF data to design. Upstream CHF indications have been found to be associated with a minimum in the CHF versus quality curve which has been attributed to the transition from intermediate flow regimes to annular flow regimes. Design implications are discussed including: 1) for vertical smooth bore tubes, upstream CHF is generally not observed except at very high masses where specific data are required - at lower mass fluxes, special design procedures are needed where nonuiform circumferential heating is present, 2) for inclined smooth bore tubes, design specific data are needed as upstream CHF observations are more prevalent, 3) for vertical and inclined multi-lead ribbed bore tubes (common in the power industry), minimum mass fluxes are specified to avoid upstream CHF, and 4) coiled and serpentine tubes are discussed.

摘要

尽管大多数临界热通量（CHF）研究都集中在相对简单的几何形状上，但实际设备的应用却很复杂。本文总结了一些文献，这些文献对选定的入口条件对瑞士法郎的影响和上游瑞士法郎的发生提供了见识。垂直光滑管CHF测试发现，“局部条件假设”的概念虽然不能普遍辩护，但却为将CHF数据应用于设计提供了足够的基础。已经发现上游CHF指示与CHF对质量曲线中的最小值有关，这归因于从中间流动状态到环形流动状态的过渡。讨论了设计的含义，包括：1）对于垂直光孔管，