Analysis and Optimization of Exergy Flows inside a Transcritical CO 2 Ejector for Refrigeration, Air Conditioning and Heat Pump Cycles

Sahar Taslimi Taleghani, Mikhail Sorin and Sébastien Poncet
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Sahar Taslimi Taleghani: Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC J1K2R1, Canada
Mikhail Sorin: Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC J1K2R1, Canada
Sébastien Poncet: Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC J1K2R1, Canada

Energies, 2019, vol. 12, issue 9, 1-15

Abstract: In this study, the exergy analysis of a CO 2 (R744) two-phase ejector was performed using a 1D model for both single and double choking conditions. The impact of the back pressure on the exergy destruction and exergy efficiencies was presented to evaluate the exergy performance under different working conditions. The results of two exergy performance criteria (transiting exergy efficiency and Grassmann exergy efficiency) were compared for three modes of an ejector functioning: Double choking, single choking and at the critical point. The behavior of three thermodynamic metrics: Exergy produced, exergy consumed and exergy destruction were evaluated. An important result concerning the ejector’s design was the presence of a maximum value of transiting exergy efficiency around the critical point. The impact of the gas cooler and evaporator pressure variations on the different types of exergy, the irreversibilities and the ejector global performance were investigated for a transcritical CO 2 ejector system. It was also shown that the transiting exergy flow had an important effect on the exergy analysis of the system and the Grassmann exergy efficiency was not an appropriate criterion to evaluate a transcritical CO 2 ejector performance.

Keywords: two-phase ejector; CO 2; transcritical system; exergy analysis; irreversibility; transiting exergy (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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