| Abstract:Based on a heavy-duty diesel engine, a numerical simulation study of the scheme that move the minimum fuel consumption range to different conditions by matching different combustion systems was carried out. Results show that when the compression ratio was 19.5, the distribution of the lean mixture in the cylinder was reduced, and the heat release rate was faster, resulting in a higher thermal efficiency. The minimum brake specific fuel consumption (BSFC) range can be moved to various target conditions by matching turbocharger and combustion chamber appropriately. When the compression ratio was increased to 19.5, combined with turbocharger configurations optimized at low speed, the minimum BSFC range can be moved to low speed condition, with BSFC upmost reduction of 3.1%. When the compression ratio was increased to 18.5, together with turbocharger optimization, the minimum BSFC range can be moved to medium speed condition, with BSFC reduction of 1.6%. Similar approach has been applied at high speed and high load with elevated peak in-cylinder pressure limit, within which a relatively larger turbine was adopted, and the BSFC at high speed and high load can be reduced by 4.2%. |