IIR document

Development of a capacitance based void fraction sensor for two-phase liquid nitrogen flow in horizontal pipes.

Summary

Cryogenic systems are often associated with heat influx due to the large difference between operating and ambient temperatures, which results in two-phase flow. The presence of the vapour phase can be detrimental to structural integrity due to phenomena such as cavitation and may reduce the overall efficiency of the systems. Hence, the measurement of void fraction becomes an essential prerequisite in cryogenic instrumentation. Techniques involving the use of radiations, electrical properties, differential pressure or optical methods are commonly used to measure the void fraction at ambient temperatures. A non-intrusive and non-energy absorbing method is required for the measurement of the void fraction of two-phase cryogenic flow to ensure minimum impact on the flow conditions. In this paper, a capacitance-based void fraction sensor with concentric electrodes for horizontal two-phase liquid Nitrogen flow is developed and tested. Experimental studies on the sensor gave a maximum percentage error of 8.1% and were found to be more accurate for the measurement of higher void fractions. The sensor also gave a full-scale variance of 13 pF. The sensitivity of the sensor was marginally higher for loading compared to unloading. A calibration curve was plotted for capacitance values as a function of void fraction, which was in turn obtained by weight analysis of the system.

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Details

  • Original title: Development of a capacitance based void fraction sensor for two-phase liquid nitrogen flow in horizontal pipes.
  • Record ID : 30029032
  • Languages: English
  • Source: Cryogenics 2021 online. Proceedings of the 16th IIR International Conference, October 5-7, 2021.
  • Publication date: 2021/10/05
  • DOI: http://dx.doi.org/10.18462/iir.cryo.2021.0045
  • Document available for consultation in the library of the IIR headquarters only.

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