Title: Energy and exergy analysis of bus refrigeration system using two-phase ejector with natural refrigerant R744

Authors: Çağrı Kutlu; Şaban Ünal; M. Tahir Erdinç; Ertuğrul Cihan

Addresses: Department of Mechanical Engineering, Osmaniye Korkut Ata University, Osmaniye, 80000, Turkey ' Department of Mechanical Engineering, Osmaniye Korkut Ata University, Osmaniye, 80000, Turkey ' Department of Mechanical Engineering, Osmaniye Korkut Ata University, Osmaniye, 80000, Turkey ' Department of Mechanical Engineering, Osmaniye Korkut Ata University, Osmaniye, 80000, Turkey

Abstract: In conventional bus refrigeration systems, R134a is used extensively as working fluid. According to the international agreements and European parliament directive, studies of mobile refrigeration systems have focused on the alternative refrigerants which have lower global warming potential (GWP). Natural refrigerant R744 (CO₂) is one of the best alternative refrigerants with low GWP value, but R744 transcritical refrigeration systems have very low coefficient of performance (COP) value with respect to artificial refrigerant systems. In this study, a two-phase ejector was added as an expansion valve in the transcritical refrigeration system in order to overcome low COP. Transcritical ejector refrigeration system is compared with a standard transcritical refrigeration system for different parameters based on energy and exergy analysis. Results show that COP improvement can be achieved by about 26% and exergy destruction decreased by about 22% for proper design in a Mediterranean climate zone.

Keywords: thermodynamics and exergy analysis; two-phase ejector; R744; bus refrigeration.

DOI: 10.1504/IJEX.2017.083946

International Journal of Exergy, 2017 Vol.22 No.4, pp.331 - 351

Received: 12 Jul 2016
Accepted: 26 Nov 2016
Published online: 26 Apr 2017 *

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