Title: Comparative thermodynamic performance assessment of two-stage cycle for various refrigerants

Authors: Fatih Yilmaz; Murat Ozturk; Reşat Selbaş

Addresses: Department of Electrical and Energy, Vocational School of Technical Science, Aksaray University, 68100, Turkey ' Department of Mechatronics Engineering, Faculty of Technology, Applied Science University of Isparta, Cunur West Campus, Isparta, 32200, Turkey ' Department of Energy System Engineering, Faculty of Technology, Applied Science University of Isparta, Cunur West Campus, Isparta, 32200, Turkey

Abstract: In this paper, the thermodynamic performance evaluations of the two-stage cooling cycle are investigated comparatively for different refrigerants under the same operating conditions. Due to their environmentally friendly properties, CO₂, R600, R600a, R161, and R134a are selected as the refrigerants. The change in energy performance coefficient (COP_en) and exergy performance coefficient (COP_ex) of the defined cycle are investigated according to the various indicators, such as reference temperature, gas cooler outlet temperature and pressure. Results are shown that, at the evaporator temperature of −5°C and the gas cooler outlet temperature of 40°C, the COP_en of the cooling cycle are 1.644, 1.603, 1.452, 2.0356 and 1.928 for the refrigerants CO₂, R600, R600a, R161 and R134a, respectively. Furthermore, COP_ex of the cycle are computed as 25.94%, 15.57%, 14.07%, 19.73% and 18.68% for the same refrigerants in the same order. In addition, the overall exergy destruction rate of the cooling cycle for CO₂ refrigerant is calculated as 145.69 kW.

Keywords: CO₂; energy; exergy; cooling; refrigerants.

DOI: 10.1504/IJEX.2019.100359

International Journal of Exergy, 2019 Vol.29 No.2/3/4, pp.110 - 130

Received: 27 Oct 2018
Accepted: 09 Jan 2019
Published online: 27 Jun 2019 *

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