Feasibility of Employing Negative Valve Overlap for Enhanced Charge Homogeneity in PCCI Diesel Engine Using 1D Thermodynamic Simulation and 3D CFD Study 2019-26-0135
With stringent emission norms in place like BS-4 and upcoming BS-6, emission reduction is done primarily by means of exhaust after-treatment system. Low Temperature Combustion (LTC) concepts like Premixed Charge Compression Ignition (PCCI) are helpful in reducing the NOx and PM within the cylinder itself and thus minimize the after-treatment system noble metal loading. This work involves use of PCCI in combination with Negative Valve Overlap (NVO) so that a pre-mixed charge is effectively prepared which has the potential to reduce NOx and PM simultaneously. This study concerns a 3-cylinder, common rail, direction injection, turbocharged engine meeting BS-4 emission regulations. In this study, employing the NVO and early injection strategy helps to prepare a greater degree of homogeneous charge. NVO strategy provides nearly 33ºC increased in-cylinder temperature as compared to the base valve timing strategy. This helps in improved evaporation of early injected fuel and thus enhance the charge homogeneity. This study has shown that PCCI operation by employing NVO strategy with early injection can be a potential
case for simultaneous NOx and soot reduction.