Title: Exergy analysis and optimisation of two CO₂-booster refrigeration systems

Authors: Yosra Ben Salem; Ahmed Bellagi

Addresses: National Engineering School of Monastir, Monastir, Tunisia ' National Engineering School of Monastir, Monastir, Tunisia

Abstract: The objective of this study is energetic and exergetic analysis, optimisation and comparison of two trans-critical CO₂-booster refrigeration systems for simultaneous heating and cooling applications: a unit with flash gas bypass (Config1) and a system with an auxiliary parallel compressor (Config2). The units are designed to produce cold at two temperatures levels, -10°C and -30°C, and hot water at 75°C. The study reveals that the system with parallel compression has improved performances in comparison with the installation with flash gas bypass. The gas cooler pressure affects largely the performances of Config1, while the refrigerant receiver pressures those of Config2. The quasi-totality of irreversibility in Config1 is observed in three of its components: HP-compressor, HP-expansion valve and gas cooler. Exergy destruction in the gas cooler of Config2 is reduced by 83%.

Keywords: CO₂-booster refrigeration; flash-gas by-pass; parallel compression; exergy analysis; RSM methodology; optimisation.

DOI: 10.1504/IJEX.2024.139225

International Journal of Exergy, 2024 Vol.44 No.2, pp.107 - 126

Received: 08 Sep 2023
Accepted: 15 Dec 2023
Published online: 26 Jun 2024 *

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