Reducing the operational fluctuation via splitting CO2 transcritical power cycle in engine waste heat recovery

Ligeng Li, Hua Tian, Lingfeng Shi, Yonghao Zhang and Gequn Shu

Energy, 2022, vol. 252, issue C

Abstract: CO2 power cycle has been considered a promising technology to recover the engine waste heat at a fixed condition. Nevertheless, the large variation of engine conditions may bring about the operational fluctuation, which is reflected on the system performance deterioration. In this study, a splitting CO2 power cycle layout is proposed and optimized from the point of both design and off-design phases to match the large-fluctuated engine conditions. The mass flow through different heat exchangers can be adjusted when the engine heat sources are altered, which means that a higher system degree of freedom can be achieved. Results showed that the system operational fluctuation could be reduced effectively when the operation parameters were deviated from the design phase. Specifically, the total mass flow rate decreased apparently when the engine speed and torque decreased, whereas a moderate decrease was found in the splitting layout thanks to the flexible mass flow through each splitting branch. In addition, the deviation fluctuation of pressure ratio was also reduced especially at higher engine conditions. Average improvements of 12.2%, 17.5% and 8.5% in net generated power, exhaust utilization and exergy efficiency could be achieved, respectively. And the minimum brake specific fuel consumption could be improved by 5.5%.

Keywords: CO2 power cycle; Splitting; Deviation analysis; Engine; Waste heat recovery (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:252:y:2022:i:c:s0360544222008970

DOI: 10.1016/j.energy.2022.123994

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