Performance operation of liquid ejectors for a R744 integrated multi-ejector supermarket system using a hybrid ROM

Haida, Michał; Smołka, Jacek; Hafner, Armin; Palacz, Michał; Ostrowski, Ziemowit; Bodys, Jakub; Kriezi, Ekaterini K.; Försterling, Sven; Nowak, Andrzej J.; Banasiak, Krzysztof

doi:10.1016/j.ijrefrig.2019.10.020

Cited by 11 publications

(3 citation statements)

References 23 publications

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“…More complex and detailed ejector models can be implemented, and an example was a result of the project SuperSmart-Rack [28], funded by the Research Council of Norway. This model is based on extensive sets of measurements including various ejector operation points [29][30][31][32]. The model implemented ".bin" files that contain the sets of measurement data.…”

Section: Ejector Modelmentioning

confidence: 99%

Modeling of a CO2-Based Integrated Refrigeration System for Supermarkets

et al. 2021

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An integrated energy system that consists of a centralized refrigeration unit can deliver the entire HVAC&R (heating, ventilation, air conditioning, and refrigeration) demand for a supermarket. CO2 (R744) is a natural refrigerant that is becoming increasingly popular for these centralized units due to significant energy and cost savings, while also being sustainable, safe, and non-toxic. This study focuses on the fully integrated CO2 refrigeration system configuration for a supermarket in Porto de Mos, Portugal, which was equipped and fully monitored through the EU-funded project MultiPACK. A dynamic system model was developed in Modelica and validated against measurement data from the site recorded for one week. The model is used to provide additional ejector performance data supporting the obtained measurement data and to evaluate the system configuration at equivalent boundary conditions. The simulation results show that the installation of a vapor ejector (high-pressure lift) is sufficient to improve the efficiency of the unit compared to an ejector-less (high-pressure valve) system. However, more notable enhancements are achieved by including additional flooded evaporation with liquid ejectors and smart regulation of the receiver pressure, adding up to a global efficiency increase of 15% if compared to the high-pressure valve system during the validation week.

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Section: Ejector Modelmentioning

confidence: 99%

Modeling of a CO2-Based Integrated Refrigeration System for Supermarkets

et al. 2021

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“…Furthermore, additional six electric heaters each with a nominal power of 7.5 kW were integrated with the glycol tank for the MT evaporator section to enhance the cooling demand at very low evaporation temperature below -10 • C.A detailed description about the auxiliary loops can be found in Section 2.2. The main use case of the ejector-expansion rack presented in Figure 2 is to experimentally investigate the ejector performance for various ejector designs, i.e., vapour ejector [37], liquid ejector [38], or the bypass ejector [39]. The ejector section of the experimental rig is equipped with precise Coriolis-type mass flow meters, pressure sensors and temperature sensors installed at ejector primary and secondary inlets as well as at the ejector outlet.…”

Section: The R744 Vapour Compression Test Rig Equipped With Ejectorsmentioning

confidence: 99%

An experimental investigation of performance and instabilities of the R744 vapour compression rack equipped with a two-phase ejector based on short-term, long-term and unsteady operations

Haida

Palacz

Bodys

et al. 2021

Applied Thermal Engineering

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“…These technologies range from the most basic improvements such as the use of a desuperheater [14] to the main advanced systems for CO 2 boosters. Among the advanced improvements, there are the parallel compression [15,16], the dedicated [17] or integrated mechanical subcooling [18], the ejector technology [19] such as the multi-ejector arrangements [20], combinations of these systems [21], flooded evaporators [22], liquid ejectors [23], and the "all-in-one" systems that integrate the A/C and the tap water heating in the same refrigerating plant [24][25][26][27]. In addition, there are other improvements applied to the heat rejection zone for high ambient temperatures, such as adiabatic gas coolers [17] or desiccant wheels [28], which are able to increase the efficiency of all facilities, reducing the temperature by increasing the humidity in the heat rejection medium.…”

Section: Introductionmentioning

confidence: 99%

Improvements in CO2 Booster Architectures with Different Economizer Arrangements

et al. 2020

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CO2 transcritical booster architectures are widely analyzed to be applied in centralized commercial refrigeration plants in consonance with the irrevocable phase-out of HFCs. Most of these analyses show the limitations of CO2 cycles in terms of energy efficiency, especially in warm countries. From the literature, several improvements have been proposed to raise the booster efficiency in high ambient temperatures. The use of economizers is an interesting technique to reduce the temperature after the gas cooler and to improve the energy efficiency of transcritical CO2 cycles. The economizer cools down the high pressure’s line of CO2 by evaporating the same refrigerant extracted from another point of the facility. Depending on the extraction point, some configurations are possible. In this work, different booster architectures with economizers have been analyzed and compared. From the results, the combination of the economizer with the additional compressor allows obtaining energy savings of up to 8.5% in warm countries and up to 4% in cold countries with regard to the flash-by-pass arrangement and reduce the volumetric displacement required of the MT compressors by up to 37%.

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Performance operation of liquid ejectors for a R744 integrated multi-ejector supermarket system using a hybrid ROM

Cited by 11 publications

References 23 publications

Modeling of a CO2-Based Integrated Refrigeration System for Supermarkets

Modeling of a CO2-Based Integrated Refrigeration System for Supermarkets

An experimental investigation of performance and instabilities of the R744 vapour compression rack equipped with a two-phase ejector based on short-term, long-term and unsteady operations

Improvements in CO2 Booster Architectures with Different Economizer Arrangements

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