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Study on quality measurement using multiple small holes.

Number: 2537

Author(s) : HARA S., FUKUTA M., MOTOZAWA M., HAGIWARA Y., INABA A., NISHIJIMA H.

Summary

Quality measurement of two-phase refrigerant is sometimes required in vapor compression refrigeration cycles to monitor and control the cycle properly. In a previous research, a new quality measurement was proposed based on a concept that the velocities of liquid and gas became almost the same in a narrow tube with flow pattern of plug flow. With applying many narrow tubes in a test section, the quality of the flow through the test section was obtained by liquid flow rate through pipes where only liquid phase flows, gas flow rate through pipes where only gas phase flows and gas-liquid flow rates through a pipe where the two-phase flow flows. Although the quality measurement was successfully achieved within a reasonable accuracy, applicable flow rate range was not enough for actual refrigeration cycles.
In this study, many small holes were adapted instead of the narrow tubes for the application to the larger flow rate and simplicity. When the two-phase flow is separated into the gas phase and the liquid phase in an upstream header and the number of holes through which two-phase flow flows is a few at the gas and liquid interface, the flow rate of the two-phase flow through those holes is negligible compared to the liquid-phase flow rate through lower holes and the gas-phase flow rate through upper holes. Therefore, only the number of holes through which the gas phase or liquid phase flows and the pressure difference across the holes are needed to obtain the flow rates of both phases and consequently the quality of whole two-phase flow. In the experimental setup, detection of liquid level in the upstream header was done to obtain the number of holes for the liquid-phase flow. The quality measurement applying the many small holes was examined by air-water two-phase flow by measuring the liquid level in the header and the pressure difference. It was confirmed that quality measurement with an error of about ±3% was achieved. Besides, when the pressure difference across the holes is larger than the liquid head in the upstream header, quality measurement without measuring the pressure difference was possible.

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  • Original title: Study on quality measurement using multiple small holes.
  • Record ID : 30030769
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2022

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