Investigation on the mechanism of abnormal heat transfer of supercritical pressure water in vertically‐upward tubes in the large specific heat region

The heat transfer characteristics of water at supercritical pressures in a vertically‐upward internally‐ribbed tube are investigated experimentally to investigate the mechanism of abnormal heat transfer of supercritical pressure water in the so‐called large specific heat region. One kind optimized internally‐ribbed tube is used in this study. The tube is made of SA‐213T12 steel with an outer diameter of 31.8 mm and a wall thickness of 6 mm and the mean inside diameter of the tube is measured to be 17.63 mm. According to experimental data, the characteristics and mechanisms of the heat transfer enhancement and also the heat transfer deterioration of supercritical pressure water in the large specific heat region are discussed respectively. The heat transfer enhancement of the supercritical pressure water in the large specific heat region is believed to be a result of combined effect caused by the rapid variations of thermophysical properties of the supercritical pressure water in the large specific heat reg...