There are a lot of requests to measure flow rate as well as temperature and pressure in a pipe flow with low temperature environment. It is because performances of pumps, valves, and vaporizers for cryogenic applications are evaluated by measuring temperature, pressure, and flow rate. Ultrasonic flowmeters become one of flow measurement techniques in the low temperature environment although pipe provers and Coriolis mass flow meters are the standard devices for flow metering at the cryogenic conditions. Waveguides, which are located in front of ultrasound sensors, provides thermal insulations on the ultrasound sensors within operating temperature ranges.In this study, low temperature testing on a pair of ultrasound sensors was performed to see if ultrasound waves could be transmitted normally through liquid nitrogen. A flowmeter cell with diameter of 300 mm (equivalently, 12”) was used as a container for liquid nitrogen. Three pairs of ultrasound sensors were installed in the flowmeter cell. Fiber-optic sensors were also attached on its inner wall to measure the temperature of liquid nitrogen. As a result, ultrasound waves were successfully transmitted between a pair of ultrasound sensors by careful settings. The fiber-optic sensors could measure the temperature of liquid nitrogen although the sensors were not calibrated with an appropriate temperature scale.Waveguides (GE FTPA/FIPA) were installed in front of three pairs of ultrasound sensors (GE BWT). The purpose of the waveguides was to extend the temperature range of ultrasound sensors from [-50 to 100] oC to [-190 to 315] oC. Our concern was to extend the lower temperature limit down to -196 oC, at which liquid nitrogen (LN2) boiled. A pair of ultrasound sensors successfully transmitted the ultrasound waved by careful settings. Fiber-optic sensors measured wavelength within optical fibers, which were influenced by temperature change.

Low Temperature Testing of Ultrasound Sensors in Liquid Nitrogen

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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