Quantification of φ-operating range with impact of exhaust gas recirculation under low-temperature combustion mode with polyoxymethylene dimethyl ether: A perspective study

Low-Temperature Combustion (LTC) especially Homogeneous charge compression ignition (HCCI) mode of combustion is a capable substitute mode of combustion to conventional diesel combustion (CDC) to provide better soot-NOx trade-off and HC-CO trade-off characteristics. The current study mainly focuses on the Exhaust Gas Recirculation (EGR) effects and equivalence ratio optimization on W20P20 (64% diesel, 16% WCO biodiesel, and 20% PODE) fuel along with exergy analysis in the HCCI mode of operation. The reason for inculcating exergy analysis in this research is to depict that low-temperature combustion provides a better heat transfer rate inside the cylinder. EGR has been varied in terms of 10%, 20%, and 30% in volume proportions along with the inlet fuel-air mixtures since, the fuel was injected through a pilot fuel injector in the inlet manifold. A novel factor in this research is considering both soot-NOx and HC-CO trade-off characteristics in optimizing the equivalence ratio with the influence of EGR over W20P20 fuel. The performance parameters such as BTE and BSEC show a mere decrement of about 6.67% and 29% of maximum with the influence of EGR while better combustion was found in terms of avoiding misfiring at a low equivalence ratio of 0.29-0.35 and knocking at a high equivalence ratio of 0.61-0.71 for W20P20 fuel. The operating range extension of the equivalence ratio was found with W20P20 fuel which further increased again with the increase in EGR addition. The emission limits of soot, NOx, CO, and HC particles were analyzed, in which the highest NOx reduction of 53% was obtained with 30% EGR irrespective of the equivalence ratio. The highest soot reduction was 61.85% with 20% EGR at a higher equivalence ratio. The highest HC reduction was 18% with 20% EGR at a lower equivalence ratio. The CO emissions seemed to reduce by 12% at a lower equivalence ratio while they increased by 47% at a higher equivalence ratio. The comparative results were studied for EGR influence with W20P20 fuel in the HCCI mode of combustion.