Short-term supercritical heat transfer: In memory of Anneke Levelt Sengers

The paper is dedicated to the memory of Anneke Levelt Sengers (Johanna/Anneke/Maria Henrica Levelt, 1929–2024), a world-renowned scientist on liquid-vapor critical phenomena. It summarizes the results of pulse heating experiments performed under conditions of short-term (units of ms) powerful heat release in supercritical-pressure water. The pressure, being the parameter of the experiment, was varied from a near-supercritical value (22.1 MPa) to 100 MPa. Initial temperature was 25 ºC, while its rise in the course of a pulse ranged from 230 ºC up to 680 ºC. Results obtained for pulse heating along the supercritical isobars are based solely on comparison with primary data. The surprising feature of the results is that a threshold drop in the intensity of heat transfer near the critical temperature occurs and becomes deeper, as the pressure approaches the supercritical pressure. The aim of the present paper is to suggest a relatively simple approach to reconciling pulse heating results with well-known peaks of thermophysical properties derived from experiments under stationary conditions. The variant suggested of such approach is based on the hypotheses of suppression of large-scale fluctuations in fast processes and the additional thermal resistance accompanying by the appearance of structural non-uniformity in an initially homogeneous fluid.