In this article, we present new data on the non-stationary heat transfer in supercritical water at different heating regimes with characteristic times from 5 ms to 15 ms. The pressure, being the parameter of the experiment, was varied from the critical pressure p_c up to 4.5 p/p_c (namely, up to 1 kbar). These data serve as a significant addition to the well-known picture of supercritical heat transfer by phenomena inherent in the non-stationary case. The impetus for the study came from the discovery of an unexpected result observed in conductive heat transfer experiments under a powerful heat release—namely, the effect of a decrease in the intensity of heat transfer in the course of a rapid transition of the compressed fluid to the supercritical region of temperatures along the supercritical isobar. The observed effect, which exhibits a threshold character in the vicinity of the critical temperature, occurs up to pressures of 3–4 p/p_c. The discussion is based on the hypothesis of a suppression of fluctuations by various external factors. It is assumed that under conditions of a short-term experiment, the complete thermodynamic equilibrium cannot be reached. This factor, along with the large temperature gradient and the presence of a heating surface, “cuts off” large-scale fluctuations responsible for the anomalous behaviour of thermophysical properties in the stationary conditions.

在本文中，我们提供了有关在不同加热方式下超临界水中非平稳传热的新数据，其特征时间为5毫秒至15毫秒。作为实验参数的压力从临界压力p _c一直变化到4.5 p / p _c（即，最大1 kbar）。这些数据大大增加了非稳态情况下固有现象对超临界传热的认识。这项研究的动力来自发现在传导性传热实验中在强大的热量释放下观察到的出乎意料的结果，即在压缩流体迅速过渡到压缩过程中，传热强度降低的结果。沿超临界等压线的超临界温度区域。所观察到的效应在临界温度附近表现出阈值特征，在压力为3-4 p / p _c时会发生。讨论基于各种外部因素抑制波动的假设。假定在短期实验条件下，无法达到完全的热力学平衡。这个因素，加上大的温度梯度和加热表面的存在，“切断”了导致稳态条件下热物理性质异常行为的大规模波动。