A comprehensive comparison between CO2 and Ethane as a refrigerant in a two-stage ejector-expansion transcritical refrigeration cycle integrated with an organic Rankine cycle (ORC)

• Published in: The Journal of supercritical fluids Vol. 133; pp. 494 - 502
• Main Authors: Nemati, Arash, Mohseni, Roya, Yari, Mortaza
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2018
• Subjects: CO2; Ejector; Ethane; Refrigeration; Transcritical cycle; Waste heat recovery; Transcritical cycle; Ejector; Waste heat recovery; Refrigeration; Ethane; CO2
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2017.11.024

[Display omitted] •A two-stage ejector-expansion transcritical refrigeration cycle is analyzed.•A comprehensive comparison between CO2 and ethane as refrigerant is performed.•An organic Rankine cycle is utilized for waste heat recovery of gas cooler.•The COP of system is optimized subject to the gas cooler and inter-stage pressures.•Results indicate that ethane could be a promising refrigerant for this system. In this paper, the performance of a two-stage ejector-expansion transcritical refrigeration cycle using ethane and CO2 as refrigerant is investigated. The theoretical analysis of cycle performance characteristics is carried out for both refrigerants from the first and second laws of thermodynamics viewpoints. Furthermore, a supercritical ORC is utilized for waste heat recovery of gas-cooler. Based on the results, it is found that the COP and second law efficiency for the ethane refrigerant are about 9.37 and 9.43% higher than that of the CO2. Moreover, the compressor discharge temperature for ethane compared to the CO2 in two-stage ejector-expansion transcritical refrigeration cycle is about 17–25% lower, which leads to a higher lifetime of the compressors for ethane. It is also concluded that the gas-cooler waste heat recovery improves the CO2 cycle performance more than ethane due to its higher potential for waste heat recovery.