Phase detection aided thermometry (PDaT) for two-phase flow

Abstract

Since temperature and void (or phase) fraction are important parameters to characterize and grasp multiphase flow behaviors, various methods to measure these quantities have been developed and applied to. However, these multi-phase flow parameters have not been simultaneously measured at the same time and position until now because they need the individual sensors, such as an optical fiber void sensor, a conductance probe and a sheath thermocouple (TC), and so on. This paper describes the development of a new thermometry to detect the phase for two-phase flow and simultaneously measure the liquid/gas temperature with a miniature TC with high temporal-spatial resolutions; hereafter, this method calls a Phase Detection aided Thermometry (PDaT). The principle of PDaT is that a miniature TC with 10 kHz of the sampling rate is used not only as a thermometer with the high temporal-spatial resolution, but also as an electrical conductance probe for phase detection. In statistically, PDaT can acquire the void fraction, the average temperature and that phase at the same time and position. In addition, temperature of the interface between liquid and gas phases can be locally and instantaneously measured, besides the bubble cord length measurement as same as the ordinary void sensor in case of the bubbly flow. To demonstrate the applicability of PDaT, a proof of principle experiment was conducted with liquid water and a static air bubble, simultaneously visualized by a high speed camera.