CFD-based shape optimisation of a CO 2 two-phase ejector mixing section

Palacz, Michał; Smołka, Jacek; Kuś, Wacław; Fic, A.; Buliński, Zbigniew; Nowak, Andrzej J.; Banasiak, Krzysztof; Hafner, Armin

doi:10.1016/j.applthermaleng.2015.11.012

Cited by 88 publications

(48 citation statements)

References 25 publications

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“…The definitions of the symbols used in this figure and the dimensions of the considered ejectors, EJ2 and EJ4, that compose the multi-ejector module are provided in Table 1. Descriptions of the ejector operation principle can be found in the works of Smolka et al (2013) and Palacz et al (2016).…”

Section: Ejector-based Refrigeration Systemmentioning

confidence: 99%

“…The conical needle approach was examined using shapeoptimised ejectors installed in the multi-ejector module, i.e., simulations were performed in which convergent-divergent motive nozzles were used for the EJ2 and EJ4 ejectors and a convergent motive nozzle was used for the EJ2 ejector. The optimisation method applied is described in the work of Palacz et al (2016). All of these ejectors were equipped with a needle inserted axially into the motive nozzle.…”

Section: Single Controllable-geometry Ejector With a Needlementioning

confidence: 99%

See 1 more Smart Citation

Performance comparison of fixed- and controllable-geometry ejectors in a CO2 refrigeration system

Smołka

Palacz

Bodys

et al. 2016

International Journal of Refrigeration

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Section: Ejector-based Refrigeration Systemmentioning

confidence: 99%

Section: Single Controllable-geometry Ejector With a Needlementioning

confidence: 99%

Performance comparison of fixed- and controllable-geometry ejectors in a CO2 refrigeration system

Smołka

Palacz

Bodys

et al. 2016

International Journal of Refrigeration

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“…Studies on implementation of the ejectors with converging-diverging nozzles in refrigeration, airconditioning and heat pumps demonstrated significant improvement of the energy efficiency of the discussed systems [1][2][3]. As a result, a growing interest in studying an operation and design of the ejector in mentioned systems can be observed [4][5][6]. The accurate prediction of a critical mass flow rate of the flow through the ejector motive nozzle is crucial for an appropriate design of the ejector [7].…”

Section: Introductionmentioning

confidence: 99%

“…The accurate prediction of a critical mass flow rate of the flow through the ejector motive nozzle is crucial for an appropriate design of the ejector [7]. The recent investigations of the CO 2 two-phase ejectors in refrigeration systems [4,8], heat pumps [6] and in other industry domains [9], provide experimental data in this field which gives an opportunity to study the prediction abilities of the available two-phase flow models. The schematic of a two-phase ejector with supercritical gas or subcooled liquid phase as a motive fluid and vapour phase as a secondary fluid is presented in Fig.…”

Section: Introductionmentioning

confidence: 99%

Application of a fast transonic trajectory determination approach in 1-D modelling of steady-state two-phase carbon dioxide flow

2019

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An original generalised procedure of determination of the transonic trajectory has been proposed. The procedure is much faster than the commonly used Newton Critical Point approach. The approach was applied in modelling of a carbon dioxide transonic two-phase flow through the converging-diverging nozzle by means of the Homogeneous Equilibrium Model and Delayed Equilibrium Model (DEM). The simulations concern flows that were experimentally and theoretically investigated in the literature. DEM was prev ously used only in choked water flow simulations. Its application in CO2 flow modelling and the supersonic trajectory part determination is a novel contribution. The adjusted for CO2 version of the closurelaw was proposed. The investigation revealed that the applied Darcy friction factor determination approach has a significant influence on the results. Moreover, the models are unable of producing physically acceptable solutions until theLockhartMartinelli approach is utilised. It was shown that the Friedel approach might be considered more proper for CO2 flows.

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“…An intensive study on the effect of the geometrical features of the primary nozzle on the ejector performance has been proposed by Fu et al [11]. For optimization efforts on the mixing chamber geometry, it could be pointed to the research published by Palacz et al [12]. Some scholars paid attention to changing the pressure and temperature operating conditions of ejectors with axial-radial [14] or axial-axial [15] flows.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Effects of Operating Conditions on the Performance of a Steam Jet-Ejector

Sabzpoushan¹,

Darbandi²,

Schneider³

2018

Proceedings of the 5th International Conference of Fluid Flow, Heat and Mass Transfer (FFHMT'18)

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-In this paper, the focus is on an existing steam jet-ejector, in which the primary flow is high pressure superheated steam and the suction flow is a mixture of saturated steam and air. The main goal of this work is to improve the ejector performance via proper setting of its working conditions such as setting motive, suction and discharge pressures and even primary and secondary streams composition, albeit if it is possible. From the computational perspective, the modelling and simulation of fluid flow are very complicated in an ejector because of facing with simultaneous subsonic and supersonic regimes, very high and very low pressure regions close to each other inside the ejector, complex turbulent mixing, and imperative heat transfer conditions. This study aims to improve the entrainment ratio of the existing steam jet-ejector by investigating its performance under different operating conditions and reduce the consumption of motive steam, which is a critical issue in the current human society because of facing with major global warming and water crisis conditions. The results show that by lowering the motive pressure, the achieved entrainment ratio increases up to 51% percent, while the ejector critical back pressure decreases. Obeying the current strategy, the annual water consumption of the vacuum system can be reduced about 3000 m 3 in the current combined power cycle unit.

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CFD-based shape optimisation of a CO 2 two-phase ejector mixing section

Cited by 88 publications

References 25 publications

Performance comparison of fixed- and controllable-geometry ejectors in a CO2 refrigeration system

Performance comparison of fixed- and controllable-geometry ejectors in a CO2 refrigeration system

Application of a fast transonic trajectory determination approach in 1-D modelling of steady-state two-phase carbon dioxide flow

Numerical Investigation on the Effects of Operating Conditions on the Performance of a Steam Jet-Ejector

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