Theoretical analysis of a CO2–NH3 cascade refrigeration system for cooling applications at low temperatures

Dopazo, Joaquı́n; Fernández-Seara, José; Sieres, Jaime; Uhía, Francisco J.

doi:10.1016/j.applthermaleng.2008.07.006

Cited by 142 publications

(19 citation statements)

References 14 publications

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“…The same trend was observed when the degrees of subcooling and superheating are varied [58]. The work of Dopazo et al [60] is worth paying special attention as it provides details on how to attain the highest COP of a CO2-NH3 cascade system. They observe that maximum COP is attained when the evaporating temperature (TE) is as high as possible.…”

Section: Cascade Systemsupporting

confidence: 55%

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CO2 Refrigeration and Heat Pump Systems—A Comprehensive Review

2019

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An increased awareness of the impacts of synthetic refrigerants on the environment has prompted the refrigeration industry and researchers worldwide to seek better alternatives in terms of technical, economic and environmental performance. CO2 refrigerant, also known as R744, has re-emerged as a potential alternative to existing refrigerants with its zero ozone depletion potential (ODP) and impressively low global warming potential (GWP). A refrigeration system utilising this refrigerant, however, suffers performance degradation when it operates in warm or hot climatic regions due to its inevitable operation in the supercritical region. In addition, the CO2 refrigerant properties necessitate the need for components designed to withstand very high operating pressures. These challenges have not been let unnoticed; related industries and researchers are actively involved in research and development of various components and systems which in turn encourages increased applications of these systems. In this paper, a comprehensive review of CO2 refrigeration systems and the state of the art of the technology and its applications in various industries is presented. In particular, the paper reviews recent research and developments on various aspects of CO2 systems including cycle modifications, exergy analysis of the systems, system modelling, transcritical operation consideration and various existing and potential applications.

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Section: Cascade Systemsupporting

confidence: 55%

“…A theoretical study carried out by Dopazo et al [60] points to the existence of a maximum system COP at an optimum condensing temperature of the LT loop. The same trend was observed when the degrees of subcooling and superheating are varied [58].…”

Section: Cascade Systemmentioning

confidence: 99%

CO2 Refrigeration and Heat Pump Systems—A Comprehensive Review

2019

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“…When the studies in the literature on cascade cooling systems examined; Dopazo et al (2009) analyzed a CO2/NH3 cascade cooling system and determined the optimum CO2 condensation temperature from the energy and exergy perspectives. The effects of operating parameters on the performance of a CO2/NH3 cascade cooling system were experimentally investigated by (Bingming et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Investigation of efficiency of R717 refrigerant single stage cooling system and R717/R744 refrigerant cascade cooling system

Akan

Ünal

Özkan

2021

Turkish Journal of Engineering

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Cooling Cascade systems Refrigerant Efficiency Thermodynamic analysisThis study is an adaptation of ammonia cascade cooling systems using carbon dioxide on ice cream production machines and includes thermodynamic analysis of R717/R744 cascade refrigeration system with R717 refrigerant single-stage refrigeration system and investigation of its efficiency. As a result of the analyses, the COP value of the single-stage system was 3.67, the Carnot efficiency was 0.57, the second law efficiency was 0.19 and the power required to operate the compressor was 27.55 kW. In the cascade cooling system, the COP value was 4.46, the Carnot efficiency 0.59 and the compressor power 22.7 kW in the high-temperature part, while the COP value was measured as 14.65, the Carnot efficiency 0.58 and the compressor power 6.4 kW in the low-temperature part. For the whole cascade system, the COP 3.24 and the second law efficiency were found to be 0.43. When the results were compared, it was concluded that although the COP value of the cascade cooling system was 0.43 points lower than the single-stage ammonia system, when our country's climate conditions and the thermophysical properties carbon dioxide gas were considered together, one of the most suitable designs was the cascade cooling system.

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“…Dopazo et al investigated performance and exergy efficiency of cascade cooling system with CO2-NH3. Moreover, an optimization study was performed [6]. Rezayan and Behbahaninia carried out optimization and exergy analysis of cascade cooling system with CO2-NH3 [7].…”

Section: Introductionmentioning

confidence: 99%

Comparative exergy analysis of the cascade cooling system for alternative refrigerant couples

Dikmen

Şahin²

2020

International Journal of Energy Applications and Technologies

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In this work, a comparative exergy analysis of cascade cooling system working with alternative refrigerant couples has been carried out. In study; R454C and R-744 as low temperature cycle (LTC) refrigerant and R1234ze, R1234yf and R717 as high temperature cycle (HTC) refrigerant were used. The refrigerants used in the study have zero ODP and low GWP values. Exergy analysis was carried out to investigate the effect to exergy efficiency of operation parameters in cascade cooling system. The exergy efficiency values of the cascade cooling system decreases with increasing evaporator temperature for all refrigerant couples. The exergy efficiency values of the cascade cooling system decreases with increasing the condenser temperature. Obtained results show that in all cases, the refrigerant couple R454C/R717 has the highest exergy efficiency.

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Theoretical analysis of a CO2–NH3 cascade refrigeration system for cooling applications at low temperatures

Cited by 142 publications

References 14 publications

CO2 Refrigeration and Heat Pump Systems—A Comprehensive Review

CO2 Refrigeration and Heat Pump Systems—A Comprehensive Review

Investigation of efficiency of R717 refrigerant single stage cooling system and R717/R744 refrigerant cascade cooling system

Comparative exergy analysis of the cascade cooling system for alternative refrigerant couples

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