Void fraction measurement using NIR technology for horizontal wet-gas annular flow

Wang, Chao; Zhao, Ning; Fang, Luyuan; Zhang, Tao; Yue, Fangxin

doi:10.1016/j.expthermflusci.2016.03.014

Cited by 23 publications

(10 citation statements)

References 34 publications

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“…When NIR light passes through the gas-liquid twophase annular flow, the measurement accuracy is up to 0.1% depending on the absorption characteristics of the light in the gas phase (non-polar molecules in air) and in the liquid phase (O-H groups in water). NIR light absorption reflects real-time changes in the liquid film thickness and has high sensitivity [38], which follows Lambert's law.…”

Section: Measurement Principlementioning

confidence: 99%

“…Schubring et al [37] correlated the film thickness with critical friction factor model and wanted to obtain a closed equation for the liquid film thickness. Although the previous correlations were built based on different mechanisms, the correlations do not pay enough attention to the effects of pressure and entrainment [38]. The effects of pressure and entrainment on liquid film thickness are significant, therefore, this study focuses on the effects of pressure and entrainment.…”

Section: Introductionmentioning

confidence: 99%

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Liquid film characteristics measurement based on NIR in gas–liquid vertical annular upward flow

Zhao

Wang

Wang³

et al. 2022

Meas. Sci. Technol.

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Liquid film plays a crucial role in void fraction, friction pressure drops, the momentum and heat transfer in the two-phases flow. The film thickness measurement experiments of annular flow at four pressure conditions have been conducted by near infrared (NIR) sensor. The signal is processed by variational mode decomposition (VMD), of which parameters are optimized by sparrow search algorithm (SSA). Envelope spectrum and Pearson correlation coefficient (PCC) judgment criteria is adopted for signal reconstruction, and the value of liquid film thickness is obtained. The effect (Such as flow rate, pressure, entrainment, etc) of liquid film thickness are analyzed theoretically. The characterization parameters Weg”, Wel, Nμl and Xmod have been extracted and optimized, and then a new average liquid film thickness correlation is proposed. The laboratory results indicate that mean absolute percentage error (MAPE) of the predictive correlation is 4.35% (current data) and 12.02% (literatures’ data) respectively.

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Section: Measurement Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Liquid film characteristics measurement based on NIR in gas–liquid vertical annular upward flow

Zhao

Wang

Wang³

et al. 2022

Meas. Sci. Technol.

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“…Other techniques are based on the variation of the electrical impedance of the mixture as the vacuum fraction varies [4,5,6]. In some cases, these techniques are associated with high-speed photography [7] in transparent experimental pipes, or with the introduction of optical fibers inside the pipe [8].The alteration of the speed of sound as a function of the vacuum fraction can be related to the specific two-phase flow pattern by means of pressure transducers [9].Even thermometry and infrared analysis can give interesting results in the detection of anomalous conditions of two-phase flow [10,11].Last but not least is the technique based on the analysis of the vibrations induced by the two-phase flow on the pipe [12]. Vibration can be decoded by identifying characteristic frequencies by Fourier analysis or used by more sophisticated statistical techniques [13].This work presents a methodology for identifying the different two-phase flow patterns starting from vibrational data acquired using accelerometers, but processed using an innovative technique based on discriminant analysis.…”

Section: Introductionmentioning

confidence: 99%

Recognition of two-phase flow pattern inside evaporator tubes

et al. 2021

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The convective heat exchange mechanism in two-phase regime, can allow high exchange coefficients, as long as particular conditions are respected, in terms of vapor quality. In evaporator tubes this problem is particularly important as a deviation from the optimal flow conditions can drastically drop the efficiency of the heat exchange. This work describes an innovative methodology for identifying the different two-phase flow regimes in evaporator pipes, through the processing of the vibrational data acquired on the pipe itself. An experimental apparatus with transparent pipes has been built up to recognize flow patterns by a fast image acquisition camera. Images have been associated to vibration data acquired on pipes by accelerometer. The analysis of frequency spectrum, led to first interesting results thus it is possible to distinguish between “no bubbles” regimes and different “bubbles” regimes. A wide test campaign has been realized on vertical and horizontal pipes, simulating steam bubbles with nitrogen bubbles, reproducing the main flow patterns. The paper demonstrates the possibility to design smart and non-intrusive sensor to be applied on evaporated tubes for the recognizing of anomalous thermal flow condition and sets the stage for future engineering work.

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“…Gas-liquid two-phase flow is a common phenomenon occurring in petroleum, chemical, refrigeration and power generation industries [1][2][3]. Due to the unstable flow, heat and mass transfer process, the flow pattern and interface structure of two-phase flow are usually complex [4][5][6]. Therefore, the two-phase flow parameters are difficult to measure quickly and accurately [7].…”

Section: Introductionmentioning

confidence: 99%

A New Vector-Based Signal Processing Method of Four-Sensor Probe for Measuring Local Gas–Liquid Two-Phase Flow Parameters Together with Its Assessment against One Bubbly Flow

Guo

Zhang

et al. 2020

Applied Sciences

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A multiphase flow measurement technique plays a critical role in the studies of heat and mass transfer characteristics and mechanism of the gas–liquid two-phase, the practical measurement of the gas–liquid flow and the improvement of multiphase theoretical models. The four-sensor electrical probe as an emerging measurement method has been proved to be able to get the local flow parameters of multi-dimensional two-phase flow. However, few studies have been reported using the four-sensor probe to obtain the interface information (e.g., the interface direction and velocity). This paper presents a new signal processing method by which the interface direction and velocity can be obtained, besides void fraction, interfacial area concentration (IAC) and bubble chord length. The key solution is to employ the vector-based calculating method, which possesses the merits of simplicity and efficiency, to gain the interface velocity vector through legitimately assuming a direction of the interface velocity. A miniaturized four-sensor electrical probe was made and a gas–liquid two-phase flow experiment was performed to test the proposed signal process scheme. The two-phase flow was controlled to be in cap-bubble flow regime. To validate the availability and reliability of the proposed method, the local flow parameters obtained by the probe measurement were compared with the results from visual measurement technique in the same flow conditions. The comparison indicates that the above local flow parameters from four-sensor probe measurement are in good agreement with the visual measurement results, with maximum deviations of chord length of 8.7%, thereby proving the correctness of the proposed method.

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Void fraction measurement using NIR technology for horizontal wet-gas annular flow

Cited by 23 publications

References 34 publications

Liquid film characteristics measurement based on NIR in gas–liquid vertical annular upward flow

Liquid film characteristics measurement based on NIR in gas–liquid vertical annular upward flow

Recognition of two-phase flow pattern inside evaporator tubes

A New Vector-Based Signal Processing Method of Four-Sensor Probe for Measuring Local Gas–Liquid Two-Phase Flow Parameters Together with Its Assessment against One Bubbly Flow

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