Methods to increase the coefficient of performance of refrigeration cycles in low-temperature applications: a review

Abstract This study investigates the challenges posed by rising average outdoor temperatures due to global warming on the efficiency of refrigeration cycles, specifically for low-temperature (LT) applications in industrial refrigeration systems (temperatures ranging from −50 °C to −100 °C). As global temperatures increase, condenser temperatures in refrigeration systems are forced to rise, leading to higher electrical energy consumption and greater environmental impact. The importance of addressing these issues is critical in ensuring sustainable energy use and mitigating the environmental footprint of industrial refrigeration systems. The novelty of this work lies in its comprehensive evaluation of innovative strategies to enhance refrigeration cycle performance. Specifically, the study explores the utilization of ejectors to improve thermodynamic performance, the addition of nanoparticles to the refrigerant at optimized rates to enhance heat transfer and reduce energy consumption, and new cycle designs that can increase the coefficient of performance (COP). These advancements offer significant improvements over previous efforts in literature, providing practical solutions to reduce the impact of rising condenser temperatures on refrigeration system performance. The study’s findings suggest that incorporating these innovations can significantly improve the COP of refrigeration cycles, leading to reduced energy consumption and enhanced system performance. Furthermore, the paper discusses the potential of new refrigerants and cycle configurations to address the challenges posed by global warming. The scope of the work extends to both theoretical and practical applications in industrial refrigeration, offering a roadmap for future research and design improvements in refrigeration cycle technology. In conclusion, by carefully selecting an appropriate refrigeration cycle, incorporating an ejector, and adding nanoparticles to a suitably chosen refrigerant, a minimum 25% improvement in the COP can be achieved compared to conventional cycles used for low-temperature applications.