Performance of fixed geometry ejectors with a swirl motion installed in a multi-ejector module of a CO 2 refrigeration system

Bodys, Jakub; Smołka, Jacek; Palacz, Michał; Haida, Michał; Banasiak, Krzysztof; Nowak, Andrzej J.; Hafner, Armin

doi:10.1016/j.energy.2016.07.037

Cited by 37 publications

(12 citation statements)

References 29 publications

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“…Additionally, the exergy efficiency and COP of the cascaded ejector system increased up to 25% and 28%, respectively, when compared to a single ejector system due to a higher pressure lift and better pre-compression. In another study, Bodys et al [96] introduced swirl motions at the inlet of the motive and suction nozzle of fixed ejectors of a CO 2 multi-ejector system. Swirl motion enhances the momentum exchange in the mixing section of the ejector and, thus, increases the contact time between the primary and secondary flow stream.…”

Section: Expansion Devicementioning

confidence: 99%

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Recent Advances in Transcritical CO2 (R744) Heat Pump System: A Review

et al. 2019

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Heat pump (HP) is one of the most energy efficient tools for address heating and possibly cooling needs in buildings. Growing environmental concerns over conventional HP refrigerants, chlorofluorocarbons (CFCs), and hydrofluorocarbons (HFCs) have forced legislators and researchers to look for alternatives. As such, carbon dioxide (R744/CO2) has come to light due to its low global warming potential (GWP) and zero ozone depleting characteristics. Even though CO2 is environmentally benign, the performance of CO2 HP has been of concern since its inception. To improve the performance of CO2 HP, research has been playing a pivotal role in developing functional designs of heat exchangers, expansion devices, and compressors to suit the CO2 transcritical cycle. Different CO2 HP cycles coupled with auxiliary components, hybrid systems, and refrigerant mixtures along with advanced control strategies have been applied and tested. This paper presents a complete overview of the most recent developments of transcritical CO2 HPs, their components, and applications.

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Section: Expansion Devicementioning

confidence: 99%

“…The ejector efficiencies for the unit with different diameters (mm) and rotational speeds (RPM) at the inlet duct of the motive nozzle. Reproduced with permission from[96]. Elsevier, 2016.…”

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confidence: 99%

Recent Advances in Transcritical CO2 (R744) Heat Pump System: A Review

et al. 2019

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“…Computational procedure and simulation range 3.1. Ejector geometry without bypass Simulations of the presented bypass-type ejector were performed on the basis of one of the standard ejector geometries that was used in the previous studies (Bodys et al 2016;Haida et al 2016;Palacz et al 2015;Smolka et al 2013Smolka et al , 2016. This geometry is presented in Fig.…”

Section: Bypass Ejector Ideamentioning

confidence: 99%

“…The reasons are related to reliability, no moving parts, relatively simple construction in comparison to direct expanders, e.g., a gear expander. Moreover, the ejector functionality allows for additional fluid circulation or operation as a pumping device (Haida et al 2016;Lawrence & Elbel, 2015). According to the efficiency improvement possibilities mentioned as well as the growing functionality of the carbon dioxide systems equipped in ejectors, a wide range of studies focused on a refrigeration cycle with this method of work recovery was provided in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…The authors investigated three European subclimates where mathematical simulations note that a reference system COP could be improved up to 20% under high ambient conditions and even up to 30% under winter conditions. In the study of Haida (Haida et al 2016), the solution proposed by Hafner (Hafner et al 2014) was experimentally investigated to compare the multi-ejector system with the previous generation of a parallel compression system. The global evaluation of both systems results in a COP improvement at the level of 7% and exergy efficiency improvement of up to 13% in the case of the system supported by the multi-ejector pack.…”

Section: Introductionmentioning

confidence: 99%

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Performance improvement of the R744 two-phase ejector with an implemented suction nozzle bypass

Bodys

Smołka

Banasiak

et al. 2018

International Journal of Refrigeration

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In this study, the concept of an R744 ejector with a bypass duct of a suction nozzle was presented. The design of the geometry and bypass positioning in a mixing section, and the idea of regulation, as well as integration, with a suction nozzle duct was described. A preliminary numerical analysis of the proposed bypass geometry was also presented. The computational platform ejectorPL integrated with an extensively validated mathematical model of transcritical R744 two-phase flow was used. Motive nozzle inlet and suction nozzle inlet conditions reflecting gas cooler and evaporator conditions characteristic of large systems, such as supermarket refrigeration units, were examined. Three different separation pressures in liquid receivers were assumed for two bypass geometries and six bypass inlet positions. The bypass positioning as a function of a mixer length was presented. Uniquely positive results were obtained for the lowest pressure conditions. Namely, the increment of the suction mass flow rate was substantial and equal to 36.9% for the bypass angle of 19°. Hence, the bypass implementation resulted in distinct potential of an efficiency improvement-from 22.2% to 30.4%. A higher pressure lift case did not result in any improvement of the ejector work. The influence of the bypass geometry on the overall ejector efficiency was preliminarily characterised. Finally, the pressure distribution in the bypass type ejector was described.

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A Parametric Study on the Effect of Mixing Chamber for Expansion Work Recovery CO2 Ejector

Zhang

et al. 2022

J. Therm. Sci.

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Performance of fixed geometry ejectors with a swirl motion installed in a multi-ejector module of a CO 2 refrigeration system

Cited by 37 publications

References 29 publications

Recent Advances in Transcritical CO2 (R744) Heat Pump System: A Review

Recent Advances in Transcritical CO2 (R744) Heat Pump System: A Review

Performance improvement of the R744 two-phase ejector with an implemented suction nozzle bypass

A Parametric Study on the Effect of Mixing Chamber for Expansion Work Recovery CO2 Ejector

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