Numerical modelling of steam condensing flow in low and high-pressure nozzles

Dykas, Sławomir; Wróblewski, Włodzimierz

doi:10.1016/j.ijheatmasstransfer.2012.06.041

Cited by 79 publications

(51 citation statements)

References 14 publications

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“…As presented in [9], in order to reduce the number of equations down to 5 the following assumptions are made: i) the phases are in mechanical equilibrium, ii) the vapor velocity is equal to the liquid one and iii) the droplets temperature is determined through a simplified capillarity model. These assumptions are largely employed in literature [5,6] and proved to be adequate for low pressure steam test cases.…”

Section: Governing Equationsmentioning

confidence: 99%

“…Multiple models and numerical schemes potentially applicable to metastable condensation are described in detail in literature [4]. However, the great majority of them have been validated with steam-water experiments at low pressure [4,5,6]. It should be noted that the so called "high-pressure" validation is traditionally made with the experimental data by Bakhtar [7], and even in this case P 0 is lower than 35 bar, with a corresponding reduced pressure of only 0.15.…”

Section: Introductionmentioning

confidence: 99%

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Numerical investigation of high pressure condensing flows in supersonic nozzles

Azzini

Pini

2017

J. Phys.: Conf. Ser.

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Abstract.High-pressure non-equilibrium condensing flows are investigated in this paper through a quasi-1D Euler model coupled to the method of moments for the physical characterization of the dispersed phase. Two different numerical approaches, namely the so-called (a) the mixture and (b) continuum phase model, are compared in terms of computational efficiency and accuracy. The results are verified against experimental data of high-speed condensing steam measured at high pressure (100.7 bar).The analysis demonstrates that Model (b) markedly outperforms the mixture model in terms of computational cost, while retaining comparable accuracy. However, both models, in their original formulation, lead to considerable deviations in the nucleation onset prediction as well as an overestimation of the average droplet radius.A further investigation is then conducted to figure out the main physical parameters affecting the condensation process, i.e. the surface tension, the growth rate and the nucleation rate. It is eventually inferred that applying proper correction to these three quantities allows to obtain best fit with the experimental data. A final calculation is carried out to show the dependence of these three correcting factors from the thermodynamic conditions of the mixture.

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Section: Governing Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical investigation of high pressure condensing flows in supersonic nozzles

Azzini

Pini

2017

J. Phys.: Conf. Ser.

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“…The droplet size is strongly affected by the equation of state in the wet-steam model, as in Halama and Fort (2013) and Grubel et al (2014). However, the droplet radius has been underestimated in many numerical studies (e.g., Dykas & Wroblewski, 2012;Yang & Shen, 2009) and measurement uncertainty should be taken into account due to its small size. For wet-steam parameters (nucleation rate, wetness and supercooling level) there is no available experiment data.…”

Section: Moore Nozzle B (Moore Et Al 1973)mentioning

confidence: 99%

Numerical analysis of non-equilibrium steam condensing flows in various Laval nozzles and cascades

Kim

Park

Kim

et al. 2017

Engineering Applications of Computational Fluid Mechanics

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When steam is used in fluid machinery, phase transition can occur that affects not only the flow fields but also machine performance. Therefore, to achieve an accurate prediction of steam condensing flow using computational fluid dynamics (CFD), phase-transition phenomena should be considered and a non-equilibrium wet-steam model is required. Such a model is implemented in this study using the in-house code T-Flow, and the flow fields -including phase-transition phenomena -in various Laval nozzles are examined. The results for multi-phase flows can be obtained in relatively short time by using mixture assumption and an inner-iteration method. The calculated results reflect the characteristics of the condensing flows well and are comparable with those obtained experimentally. Also, it was found that the superheating level of incoming steam can explain the tendency of condensation in the nozzles considered in a simple way. In addition, steam condensing flows in the blade cascades were simulated. As a result, the predicted blade loading agreed well with the experimental data and the superheating level at inlet was responsible for the condensation trend not only in the nozzles but also in the cascades. In future work, the characteristics of steam condensing flow in a steam turbine where complex flows and phase transition occur can be investigated using the presented model. ARTICLE HISTORY

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“…However, the thermophysical models used in the study were defined by polynomial equations with many complicated terms. Dykas et al (2012) reported an experimental and numerical study considering a real gas equation of state for a wet-steam flow in a high-pressure nozzle. They continued to use a conventional condensation model based on classical condensation theory.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling and computation of high-pressure steam condensation in a transonic flow

Furusawa

Yamamoto

2017

JFST

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Wet-steam flows under high-pressure conditions are numerically investigated using a newly derived condensation model that assumes a real gas and uses a real gas Equation of State (EOS). Under high-pressure conditions, the present condensation model calculates the critical radius of a water droplet that is larger than that of the conventional model. The results indicate that nucleation is initiated farther downstream in the nozzle and the nucleation rate is smaller. Wet-steam nozzle flows under high-pressure conditions are simulated and the results are compared with experimental results. The present model simulates the pressure increase due to the release of latent heat of condensation more accurately than the conventional method based on the ideal gas assumption. The results obtained are also in good agreement with the experimental results.

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Numerical modelling of steam condensing flow in low and high-pressure nozzles

Cited by 79 publications

References 14 publications

Numerical investigation of high pressure condensing flows in supersonic nozzles

Numerical investigation of high pressure condensing flows in supersonic nozzles

Numerical analysis of non-equilibrium steam condensing flows in various Laval nozzles and cascades

Mathematical modeling and computation of high-pressure steam condensation in a transonic flow

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