PHASE DETECTION AIDED THERMOMETRY AND ITS APPLICATION TO NATURAL CONVECTIVE SUBCOOLED FLOW BOILING IN A NARROW GAP

摘要

Since temperature and void (or phase) fraction are important parameters to characterize multi-phase flow behaviors, various methods to measure these quantities have been developed. However, these multi-phase flow parameters have not been simultaneously measured at the same time and position until the present because individual sensors, such as an optical fiber void sensor, a conductance probe, and a sheath thermocouple (TC) are needed. This article summarizes the development of the Phase Detection aided Thermometry (PDaT) to detect the phase for two-phase flow and simultaneously measure the liquid/gas temperature with a miniature TC with high temporal-spatial resolutions. To demonstrate the applicability of PDaT, it was applied to the natural convective subcooled flow boiling in a narrow gap (1 mm) between a cylindrical heater rod and a transparent flat plate. This is a very simple model of a part of the subchannel of fuel rod bundle in a light water reactor core. It was confirmed that the PDaT is able to measure the temperature and void fraction simultaneously and is a useful tool for two-phase flow characterization.