EGR modeling and fuzzy evaluation of Low-Speed Two-Stroke marine diesel engines

[Display omitted] •Comparison of HP EGR system and LP EGR system on EGR rate and EGR cooling temperature.•Combining HP EGR system and Miller cycle to meet IMO Tier III limits.•Fuzzy evaluation of LP EGR system and HP EGR system. Exhaust gas recirculation (EGR) can be widely used to reduce the oxynitride (NOx) pollution in Low-Speed Two-Stroke Marine Diesel Engines. In this paper, two EGR systems (HP EGR11HP EGR: high pressure EGR. and LP EGR22LP EGR: low pressure EGR.) were investigated in terms of the influence of different rates on the brake specific fuel consumption (BSFC) and the NOx emissions. As for this simulation, the exhaust gas cleaning water treatment was not concluded. Besides, Miller Cycle was used to determine the influence of its valve timing on BSFC and NOx emissions. The combination of Miller Cycle and HP EGR system decreased the NOx emissions, which could meet the IMO33IMO: international maritime organization. Tier III standard, 3.4 g/kWh. Moreover, the influence of the EGR cooling temperature was discussed. Finally, a fuzzy comprehensive evaluation model was developed to evaluate the two EGR systems. The results showed that when the HP EGR system and the LP EGR system were all operating at a maximum EGR rate, LP EGR system showed more advantages.