Abstract Supercritical water has great potential as a coolant for nuclear reactor. Its use will lead to higher thermal efficiency of Rankine cycle. However, in certain conditions heat transfer may get deteriorated which may lead to undesirable high clad surface temperature. It is necessary to estimate the operating conditions in which heat transfer deterioration (HTD) will take place, so as to establish thermal margins for safe reactor operation. In the present work, the heat flux corresponding to onset of HTD for vertically upward flow of supercritical water in a pipe is obtained over a wide range of system parameters, namely pressure, mass flux, and pipe diameter. This is done by performing large number of simulations using an in-house CFD code, which is especially developed and validated for this purpose. The identification of HTD is based on observance of one or more peak/s in the computed wall temperature profile. The existing correlations for predicting the onset of HTD are compared against the results obtained by present simulations as well as available sets of experimental data. It is found that the prediction accuracy of the correlation proposed by Dongliang et al. is best among the existing correlations.

中文翻译：

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用于预测管道中超临界水垂直向上流动的传热恶化开始的相关性评估

摘要 超临界水作为核反应堆的冷却剂具有巨大的潜力。它的使用将导致兰金循环更高的热效率。然而，在某些情况下，传热可能会恶化，这可能导致不希望的高包层表面温度。有必要估计将发生传热劣化 (HTD) 的运行条件，以便为反应堆安全运行建立热裕度。在目前的工作中，对应于管道中超临界水垂直向上流动的 HTD 开始的热通量是在很宽的系统参数范围内获得的，即压力、质量通量和管道直径。这是通过使用专门为此目的开发和验证的内部 CFD 代码执行大量模拟来完成的。HTD 的识别基于对计算出的壁温剖面中的一个或多个峰值的观察。将用于预测 HTD 发作的现有相关性与通过当前模拟获得的结果以及可用的实验数据集进行比较。发现 Dongliang 等人提出的相关性的预测精度。在现有的相关性中是最好的。