Parameter optimization of supercritical CO2 Brayton cycle for flue gas waste heat recovery of Marine high-speed diesel engine

With the high-speed diesel engine test data of the flue gas as the initial conditions and the boundaries, the arrangement of the S-CO
2
recompression Brayton cycle (SCRBC) is established and the optimization of the S-CO
2
Brayton cycle (SCBC) system for CHD622V20 diesel engine are studied. Additionally, the model accuracy has been validated with the test data from Sandia National Laboratories (SNL). Finally, the feasibility of the SCBC applied in flue gas waste heat recovery (WHR) for marine engines is comprehensively assessed from the efficiency, the net output power, the fuel consumed rate and the exergy. The results show that with the recompression Brayton cycle layout in the optimal configuration, the high-speed marine diesel engine could reach 1.00% of the maximum total efficiency improvement and 5.58 g/kW$\cdot $h of the fuel consumed rate reduction at 25% load, the maximum net output power increased to 21.54 kW. The cooler, flue gas heat exchanger and high-temperature recuperator (HTR) modules are the weak points of the SCRBC system through the exergy analysis, and further optimization of the SCRBC system should first focus on improving these components.