Spatiotemporal regulation of methanol premixed and diffusion Co-combustion for marine methanol/diesel dual fuel engine

As a kind of green and renewable energy, methanol is getting more and more attention as engine fuel. To tackle the issues like limited cylinder head space for injector, engine startup, uneven methanol ignition in Methanol/diesel dual direct injection engine, a new scheme was proposed using spatiotemporal control to achieve effective combustion and enable flexible combustion mode switching. It features a centrally arranged methanol injector, with two diesel injectors on either side, designed specifically for large-bore marine engines. Numerical simulation was conducted in a 320 mm bore engine for comparative analysis among different schemes and exploring regularity of the new scheme. Under diesel model, the scheme can achieve 95 % IMEP of the original diesel engine, 10 % higher than the traditional dual direct injection scheme. Meanwhile, its IMEP exceeds 105 % of the traditional scheme under dual-fuel model, for the uniform methanol ignition and the premixed-diffusion synergistic combustion. In addition, the methanol premixing ratio can be adjusted by controlling the fuel injection timing and pressure, which furtherly affects engine performance, with up to 4 % increase in IMEP for every 10 MPa reduction in diesel injection pressure, and 3.4 % increase for every 5°CA delay in injection timing. Through proper regulation as described knocking trend and IMEP improvement can be balanced.