Abstract
Liquid film thickness measurements under temperature-varying conditions in a two-phase flow are of great importance to refining our understanding of two-phase flows. In order to overcome the limitations of the conventional electrical means of measuring the thickness of a liquid film, this study proposes a three-electrode conductance method, with the device fabricated on a flexible printed circuit board (FPCB). The three-electrode conductance method offers the advantage of applicability under conditions with varying temperatures in principle, while the FPCB has the advantage of usability on curved surfaces and in relatively high-temperature conditions in comparison with sensors based on a printed circuit board (PCB). Two types of prototype sensors were fabricated on an FPCB and the feasibility of both was confirmed in a calibration test conducted at different temperatures. With the calibrated sensor, liquid film thickness measurements were conducted via a falling liquid film flow experiment, and the working performance was tested.
Highlights
Understanding the characteristics of liquid films in gas-liquid two-phase flows is an important part of the safety and performance analyses of nuclear power plant systems
Though most optical methods have high spatial and time resolutions, they are limited when applied to complicated flow conditions, as the light is distracted at the boundary interface [2]
The objective of this study is to develop the concept of a liquid film sensor fabricated on an flexible printed circuit board (FPCB), which works accurately under temperature-varying flow conditions
Summary
Understanding the characteristics of liquid films in gas-liquid two-phase flows is an important part of the safety and performance analyses of nuclear power plant systems. As the velocity of sound is affected by its medium, the ultrasonic method has rather low precision [1] This method is limited when used to measure the thicknesses of thin films. Though most optical methods have high spatial and time resolutions, they are limited when applied to complicated flow conditions, as the light is distracted at the boundary interface [2]. Though the spatial resolution of this method is sufficiently high, only time-averaged data is provided. This method incurs high costs when setting up the measurement device. The electrical method is widely used in two-phase experiments given that it Sensors 2017, 17, 42; doi:10.3390/s17010042 www.mdpi.com/journal/sensors
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