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Study on High-Void Fraction Gas-Liquid Two-Phase Flow in Tube Bundle

DOI: 10.1615/IHTC15.tpf.009023
pages 8495-8509

Yoshiyuki Kondo
Takasago Research and Development Center, Mitsubishi Heavy Industries, Ltd.

Ling Cheng
Takasago Research and Development Center, Mitsubishi Heavy Industries, Ltd.

Seiho Utsumi
Takasago Research and Development Center, Mitsubishi Heavy Industries, Ltd.

Takashi Ueno
Takasago Research and Development Center, Mitsubishi Heavy Industries, Ltd.

Ryoichi Kawakami
Steam Generator Designing Section, Mitsubishi Heavy Industries, Ltd.

Kengo Shimamura
Steam Generator Designing Section, Mitsubishi Heavy Industries, Ltd.


KEY WORDS: Two-phase/Multiphase flow, Heat exchanger, Annular-mist flow, Film-droplet flow, Tube bundle, Numerical simulation, Two-fluid model

Abstract

In this study, the annular-mist flow behaviors in tube bundle of shell and tube boilers have been investigated. Experimental works has been carried out for air-water two-phase flows. Tests have been performed inside an acrylic resin duct, which contains a triangular array tube bundle. The two-phase flow characteristics in the tube bundle have been recorded by a high speed video camera. Further, some sophisticated two-phase flow measurement devices have been developed, i.e. the liquid film thickness sensor and the droplet detector. Measured data clarified the details of mechanism of annular-mist flow in tube bundle. In this study, we call it film-mist flow based on the geometric effects on the flow. Within the current test matrix, measured liquid film thickness on a 19 mm O.D. tube varies from 0.05 mm to 0.5 mm. Measured droplet diameter distributes from approx. 0.05 mm to 1 mm, and its median ranges from 0.2 to 0.4 mm. Furthermore, it was clarified that flow pattern changes when the phase volumetric flow fraction, ?, increased from 0.990 to 0.996. Based on above experiment investigation, a new interfacial area concentration correlation (IAC) for film-mist flow has been proposed.
A numerical simulation method based on porous media approach has been developed in this study for predicting the shell side flow field in a boiler. The Eulerian multiphase flow model in FLUENT ver. 14.0, combined with user specified constitutive equations, including the new IAC correlation, frictional resistance correlations for flow passing tube bundle, the two-phase multiplier correlation, and the Wallis drag force model, have been utilized in this method. Validation calculation has been performed against above test data. Numerical simulation results agree well with the measurement data, with the prediction accuracy less than ±50% for holdup, and ±30% for pressure loss.

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