Investigation on Characteristics of Experiment About Single-Beam Measurements of Supercritical Fluid

An experiment has recently been completed at Xi’an Jiaotong University (XJTU) to obtain thermo-physical characteristics of supercritical pressure water at supercritical pressures with upward flow of water inside a vertically-upward bare tube. The thermo-physical characteristics of supercritical pressure water were investigated experimentally by means of a non-intrusive measurement method, using a single-beam gamma densitometer generated from the radioactive sources (Cs-137). The purpose of this experiment is to investigate accurately the changes drastic thermo-physical characteristics process of supercritical pressure water at pseudocritical point, comparing and analyzing in-depth the experiment results at different pressures and mass fluxes. Several factors influencing the performance of the gamma densitometer are examined, including the distance between the source and the detector, the distance between the source and the test section, the measuring time, the intensity of source, and the ambient temperature.

Heat Transfer at Supercritical Pressures and the Onset of Deterioration

The comparison of the data on heat transfer at supercritical pressures (SCP) demonstrates that they have a considerable spread, which shows a complex nature of the process and a probable inaccuracy in the methods of data processing caused by a sharp change in thermophysical properties near the pseudocritical point. The recent experimental data at SCP for upward flow of water are compared with some correlations applicable to engineering analysis. The correlations for the onset of heat transfer deterioration against the experimental data were analyzed. The heat transfer deterioration in this data was far from test section inlet The generalization of data on the onset of heat transfer deterioration for various coolants (water, CO2, R12) was proposed.