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Transcritical carbon dioxide refrigeration and air conditioning cycles and applications: State of the art

Author Affiliations

  • 1Beninese Center for Scientific Research and Innovation, Cotonou, Benin and Laboratory of Processes and Technological Innovations of Lokossa, UNSTIM, Benin
  • 2Beninese Center for Scientific Research and Innovation, Cotonou, Benin and Thermal and Energy Laboratory of Nantes (LTeN), UMR 6607 CNRS Nantes, France
  • 3Thermal and Energy Laboratory of Nantes (LTeN), UMR 6607 CNRS Nantes, France
  • 4Industrial Systems and Environmental Engineering Research Unit (URISIE), Bandjoun, Cameroon
  • 5Beninese Center for Scientific Research and Innovation, Cotonou, Benin

Res. J. Engineering Sci., Volume 13, Issue (1), Pages 28-40, January,26 (2024)


The use of less polluting refrigerants is now a reality in the framework of research to lessen the environmental impact of refrigeration units. The drive to employ ecologically benign and safer-to-handle refrigerants has resulted in the recent increased usage of carbon dioxide in refrigeration cycles, which develops substantial benefits, particularly in Western countries. CO2 systems are less efficient than conventional systems due to the transcritical nature of the CO2 refrigeration cycle. As a result, numerous cycle adjustments can be included to increase system performance. This review article contains a database showcasing the state of the art in theoretical, practical, and technological developments made on transcritical CO2 cycles, as well as their field of application. According to research, the biggest improvement in the transcritical cycle can be obtained by replacing the expansion device with a work-recovery expansion machine or by using numerous stages of compression. However, these are expensive upgrades in terms of buying price. As a result, recent research has mostly focused on ejector-driven transcritical cycles due to the large performance boost, lack of moving parts in the ejector, and low cost. Current developments and challenges in important application areas are summarised, and future research directions are highlighted.


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