Experimental investigation of two-phase flashing flows of a binary mixture of infinite relative volatility in a Venturi tube

Bertoldi, Dalton; Dallalba, Caio C.S.; Barbosa, Jader R.

doi:10.1016/j.expthermflusci.2015.02.011

Cited by 23 publications

(7 citation statements)

References 15 publications

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“…The larger velocity difference results in a small variation of gas-liquid phase interface and hence weakens the influence of bubbles on the liquid flowing. allowing validations with aforementioned works and current studies [18] [24], [29], [30].…”

Section: Void Fraction Estimation Based On One Dp Signalsupporting

confidence: 78%

“…Two-phase flow measurement using a Venturi meter is widely reported because of its advantages, including the short straight pipe length, small pressure loss, small flow pattern interference (Bertoldi et al [18]; Steven [19]; Sun et al [20]), small vibration noise disturbance, and large DP signal amplitude (Steven [21]). Recently, some researchers (Sun et al.…”

Section: Introductionmentioning

confidence: 99%

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Void Fraction Measurement of Gas-Liquid Two-Phase Flow Based on Empirical Mode Decomposition and Artificial Neural Networks

Wang

Sefiane

Duursma

et al. 2018

Heat Transfer Engineering

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Phone Number: 0 (+44) 131 650 4868, Fax Number: 0 (+44) 131 650 6551 2 ABSTRACT A new void fraction estimation method for gas-liquid two-phase flow combining two differential pressure (DP) signals acquired from a single Venturi tube and based on Empirical Mode Decomposition (EMD) and Artificial Neural Networks (ANN) was experimentally investigated. In order to study gas-liquid distribution in horizontal pipes, two DP signals from the top and bottom sections of the Venturi tube are acquired and EMD is adopted to extract stable and fluctuating components of the DP signals. Experimental data revealed that fluctuating index increases nearly linearly with increasing void fraction when void fraction is less than 0.4. When void fraction is larger than 0.4, this near-linearity ceases. A combination of ANN method and the fluctuating index of DP signals is developed to estimate void fraction. Experimental results show that void fraction based on DP signal from top section of Venturi tube is overestimated because of clustering of bubbles and the scarcity of liquid information when gas-liquid mixture velocity is low. Void fraction is underestimated when the mixture velocity is high. A high gas-liquid slip ratio results in void fraction underestimation. Void fraction prediction performance is satisfactory when void fraction is less than 0.4 and fluctuating index of DP signal less than 1.2. ll f ll kk p            (1)

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Section: Void Fraction Estimation Based On One Dp Signalsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Void Fraction Measurement of Gas-Liquid Two-Phase Flow Based on Empirical Mode Decomposition and Artificial Neural Networks

Wang

Sefiane

Duursma

et al. 2018

Heat Transfer Engineering

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“…The decrease in pressure increases the likelihood of cavitation generation at the throat. The findings of Bertoldi et al, (2015) support this. By experimentally evaluating the effect of the mass flow rate, they found that higher flowrates increased cavitation, due to larger pressure drops, friction, and flow acceleration in the throat.…”

Section: Cavitation Devicessupporting

confidence: 62%

Simulation of Venturi Tube Design for Column Flotation Using Computational Fluid Dynamics

Wang¹

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Froth flotation is the process of using physicochemical methods to separate valuable minerals from gangue. It is one of the most important methods in mineral processing. Previous studies have found that using cavitation bubbles can widen flotation particle size-range, increase the probability of bubble particle attachment, and reduce the probability of bubble particle detachment; all of which improve flotation recovery. Collector and frother dosages can also be reduced with cavitation-generated bubbles. Therefore, this technology reduces both energy consumption and operating costs. Hydrodynamic cavitation is the most economical method used for creating tiny bubbles for flotation. It is the development and growth of a gas and/or vapor filled void in a liquid. Cavitation bubbles are generated at the throat of devices, when liquid passes through a constricted area, such as a valve, orifice, venturi, or nozzle. Liquid velocity increases at the throat or vena-contracta. As the velocity increases, the kinetic energy associated with the liquid increases, and the pressure decreases. Once the local pressure falls below the vapor pressure of the liquid, hydrodynamic cavitation happens. The efficiency of cavitation bubble generating devices and their geometry design is analyzed using computational fluid dynamics (CFD) in this study. CFD is used to analyze multiple interacting phases, understand complex physical changes, and test all possible parameters without consuming a large amount of resources. Different geometries, venturi tubes, nozzles, and orifices from literature were used. Mathematical models were validated through comparison with experimental results. Critical cavitation velocities and volume fractions of venturi and orifices with different geometries, circular, square, and slot, were compared. Circular venturi tubes were found to be the best design for cavitation bubble generation. To optimize the geometric design of the venturi tube, six parameters were modified. These include the inlet diameter, throat and inlet diameter ratio, convergent angle, divergent angle, throat length, and entrance length. A response surface method central composite design was conducted for evaluating the effect of these six parameters affecting the efficiency of the Venturi tube. The response of the model is called critical velocity for cavitation, which means the minimum required velocity for cavitation is generated by each geometry. Because flotation column eliminates rotor and stator, the only energy supply is mixing and pumping prepared feed. The smaller critical cavitation velocity means the easier for cavitation to happen. Therefore the lower energy required, the better the design for hydrodynamic cavitation design is. 48 venturi tubes with designed geometry were created using ANSYS ICEM. Vapor volume fractions of each

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“…Over the past decades, Venturi tube has grown of importance in many applications such as cavitation bubbles [1], liquid flow metering [2], powder and particle transportation [3]. It's worth pointing out that Venturi tube plays an extremely important role in the transportation of medium (i.e.…”

Section: Introductionmentioning

confidence: 99%

Design Optimization Analysis of Venturi Tube for Medium Conveying in Strengthen Grinding Process

Xiao¹,

Liang²,

Liu³

et al. 2021

ENG

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Venturi tubes are widely used in manufacture and chemical industry and attract broad attention. To improve the transmission efficiency, the optimization of Venturi tube has been carried out, the transport substances involved in either liquid, solid, gas or two of them. The Venturi tubes that used for conveying of three-phase flow, which is consisted of solid, liquid and gas, are poorly investigated. In this paper, a Venturi tube employed in one surface treatment equipment was proposed. The velocity and pressure distribution in the flow field of Venturi tube with different key geometric parameters including diameter ratio, convergence angle and diffuser angle have been studied. One optimal solution has been selected. The negative pressure of suction port can reach a value as high as −1550 Pa to −1600 Pa. Such negative pressure offers the opportunities for transporting mixed abrasive.

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Experimental investigation of two-phase flashing flows of a binary mixture of infinite relative volatility in a Venturi tube

Cited by 23 publications

References 15 publications

Void Fraction Measurement of Gas-Liquid Two-Phase Flow Based on Empirical Mode Decomposition and Artificial Neural Networks

Void Fraction Measurement of Gas-Liquid Two-Phase Flow Based on Empirical Mode Decomposition and Artificial Neural Networks

Simulation of Venturi Tube Design for Column Flotation Using Computational Fluid Dynamics

Design Optimization Analysis of Venturi Tube for Medium Conveying in Strengthen Grinding Process

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