Title: Marine engine efficiency improvement with supercritical-CO₂ Rankine waste heat recovery

Authors: Turgay Koroglu; Irfan Cavus; Muhammed Umar Bayer

Addresses: Department of Naval Architecture and Marine Engineering, Bandırma Onyedi Eylul University, 10200 Balıkesir, Turkey ' Department of Naval Architecture and Marine Engineering, Bandırma Onyedi Eylul University, 10200 Balıkesir, Turkey ' Department of Naval Architecture and Marine Engineering, Bandırma Onyedi Eylul University, 10200 Balıkesir, Turkey

Abstract: The efficiency of marine energy systems gains more and more importance considering economic and environmental effects. Additional power is produced by annexation of a supercritical CO₂ Rankine cycle (sCO₂-RC) via utilisation of the exhaust of a marine engine. A parametric study on sCO₂-RC is carried out to optimise objective functions such as ECOP, maximum net power output with respect to the outlet temperature of the exhaust stack, and the maximum pressure of the cycle. Then, energy and exergy analyses are applied to the system. Results show that the sCO₂-RC system improves thermal efficiency by 8.17% and provides a 7.54% better fuel economy, while exergy efficiency of the sCO₂-RC is 51.3% with a net power output of 321.7 kW and ECOP of 1.09. Hence, the results lead to the optimisation order of the investigated system components for the improvement in overall efficiency, and the reduction of fuel consumption and environmental effects.

Keywords: supercritical CO₂ Rankine cycle; waste heat recovery; exergy; environmental effects; fuel economy; ECOP.

DOI: 10.1504/IJEX.2023.129801

International Journal of Exergy, 2023 Vol.40 No.3, pp.347 - 364

Received: 10 May 2022
Received in revised form: 09 Aug 2022
Accepted: 13 Aug 2022
Published online: 30 Mar 2023 *

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