Measurement of void fraction distribution with small wire mesh sensor

Abstract

Several refrigerants have been developed to solve environmental problems and to create efficient heat exchangers. The optimal design of the heat exchanger depends on the physical properties of the refrigerant. An electrical measurement for the flow characteristics is an effective experimental method. We developed a small wire mesh sensor to measure void fraction distribution parameters in refrigerant-air two-phase flow. Small wire mesh sensors without switching systems can be used for a refrigerant (e.g., HFE-71IPA), which can flow a small electric current under high voltage. For verification of the small wire mesh sensor, instantaneous and time averaged void fraction distribution in water-air two-phase flow in a vertical small diameter pipe was measured and analyzed for both bubble and slug flows. The test channel was a vertical circular 9 mm i.d. glass pipe. Each volumetric flux was 0.2-2.0 m/s for the gas phase and 0.1 m/s for the liquid phase in bubble flow, and 0.51.0 for the gas phase and 0.2-0.3 m/s for the liquid phase in slug flow. The resulting void fraction distribution data were compared with different flow regimes, and past data and literature. The result showed that detail void fraction distribution measurement by using the small wire mesh sensor without switching system is possible for bubble and slug flow.

Publication

H. Tsubone, T. Shiotsuka, T. Yamashiro, T. Fujino, “Measurement of void fraction distribution with small wire mesh sensor in water-air two-phase bubble and slug flows in vertical small diameter pipe,” in Multiphase Science and Technology 33 (4). [Paper]