Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

Yang, Yan; Zhu, Xiaowei; Yan, Yuying; Ding, Hongbing; Wen, Chuang

doi:10.1016/j.apenergy.2019.03.023

Cited by 114 publications

(37 citation statements)

References 53 publications

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“…The pressure-velocity coupling we used was the phase-coupled SIMPLE algorithm. The continuity equation, momentum equations, and turbulence equations were discretized with the second-order upwind scheme [40,41].…”

Section: Numerical Schemesmentioning

confidence: 99%

Sand Transport and Deposition Behaviour in Subsea Pipelines for Flow Assurance

2019

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Sand transport through tubing and pipeline could cause a series of problems to flow assurance, if not properly managed or controlled. The most serious problem is the accumulation and erosion in multiphase flow pipelines and the surface equipment. Therefore, the importance of understanding the transport and deposition behaviour of sands through multiphase flow pipelines cannot be overemphasized. This study presents the sand transport and deposition characteristics in the complicated multiphase flow pipeline. The numerical result shows that the slurry velocity presents a uniform distribution in the multiphase flow pipeline at the sand concentration of 5% and the sand diameter of 50 µm. However, the slurry velocity at the bottom of the pipeline is significantly smaller than that at the top when the sand concentration and diameter reach 30% and 300 µm, respectively. It indicates that the sand deposition at the bottom of the pipe declines the slurry velocity and transport capacity. The deposition thickness is approximately 10% of the pipe diameter even at the low concentration of 5% sand with a small sand diameter of 50 µm and a high slurry velocity of 1.8 m/s. The sand deposition reaches about 30% of the pipe diameter at the same low concentration and high slurry velocity when the sand diameter increases to 300 μm.

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Section: Numerical Schemesmentioning

confidence: 99%

Sand Transport and Deposition Behaviour in Subsea Pipelines for Flow Assurance

2019

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“…As for the non-equilibrium state in supersonic flows, the nucleation and condensation of condensable gases are overwhelmingly complicated [41,42]. Based on the single-fluid Eulerian model [41], several assumptions were implemented to ensure the simulation was numerically stable and efficient. Since the mass fraction of the condensed phase is quite small (<0.2), the effect of droplets size to the main flow stream is negligible and the interactions between droplets are not considered.…”

Section: Wet Steam Modelingmentioning

confidence: 99%

Computational Study of Wet Steam Flow to Optimize Steam Ejector Efficiency for Potential Fire Suppression Application

Yuen

Chen

et al. 2019

Applied Sciences

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The steam ejector is a core component of an ejector-based refrigeration system. Additionally, steam ejectors can also be potentially applied for a fire suppression system by using pressurized steam droplets to rapidly quench and extinguish the fire. The use of steam will significantly reduce the amount of water consumption and pipe flow rate compared to conventional sprinklers. However, the efficiency of the steam ejector nozzle is one of major factors that can influence the extinguishing mechanisms and the performance of pressurized steam for fire suppression. In this article, to formulate an assessment tool for studying the ideal entrainment ratio and initial flow wetness, a wet steam model has been proposed to enhance our understanding of the condensation and evaporation effects of water droplets from a numerical perspective. The entire steam-ejector system including the nozzle, mixing chamber, throat and diffuser were modeled to study the profiles in axial pressure and temperature across the system, and were compared with self-measured experimental data. In addition, the flow and heat transfer interactions between the fluid mixture and nucleating water droplets were numerically examined by comparing initial conditions with different liquid fractions, as opposed to the ideal gas assumption. With the application of the proposed wet-steam model, the numerical model showed vast improvement in the axial pressure distribution over the ideal gas model. Through numerical conditions, it was found that reducing the wetness of the secondary inlet flow will potentially optimize the system performance with a significant increase of the entrainment ratio from 0.38 to 0.47 (i.e., improvement of around 23%).

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“…White and Hounslow (2000) analyzed the shock structure in condensation flow and discussed the unsteady phenomena caused by condensation. Chandler et al (2014), Aditya and Prasad (2018), Dykas et al (2015Dykas et al ( , 2018, Starzmann et al (2018), Wang et al (2018), Yang et al ( 2019) and others have solved many basic problems, including the shock structure in condensation flow, distribution of condensation parameters, deposition of water droplets and formation mechanism of water films. Better simulation results can be obtained using the real steam equation and two-phase fluid model; however, the slip and temperature difference between phases are often neglected in most existing research.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the wet steam condensation flow characteristics in stator cascade with blade surface heating

Han

Yuan

Zhao

et al. 2020

Engineering Applications of Computational Fluid Mechanics

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The scientific and effective control of steam wetness in steam turbines is of great significance for improving power generation efficiency. Based on the research status of wet steam, the influence of different surface heating intensity in a stator cascade was studied. The distribution of condensation flow parameters in White cascade under 0-700 kW/m 2 surface heating intensity is calculated. On this basis, the positive heating intensity region was determined and refined to obtain the best heating condition with higher accuracy. The results show that the condensation is restrained and the outlet wetness is decreased as the blade surface heating intensity increases. The steam wetness and droplet diameter in the flow field can be controlled by adding heating intensity. Additionally, at the initial stage of applying heat to the blade, an increasing enthalpy drop occurs, and the entropy increase experiences a decline, while negative effects rapidly emerge if the heating intensity is too high. The optimum heating intensity is 120 kW/m 2. Compared with the 0 kW/m 2 , the average outlet wetness, total pressure loss coefficient and entropy increase of 120 kW/m 2 surface heating intensity can be reduced by 1.1266%, 15.5% and 1.7%, respectively, and the enthalpy drop can be increased by 1.7%.

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Performance of supersonic steam ejectors considering the nonequilibrium condensation phenomenon for efficient energy utilisation

Cited by 114 publications

References 53 publications

Sand Transport and Deposition Behaviour in Subsea Pipelines for Flow Assurance

Sand Transport and Deposition Behaviour in Subsea Pipelines for Flow Assurance

Computational Study of Wet Steam Flow to Optimize Steam Ejector Efficiency for Potential Fire Suppression Application

Numerical investigation of the wet steam condensation flow characteristics in stator cascade with blade surface heating

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