Application of the SRM Engine Suite over the Entire Load-Speed Operation of a U.S. EPA Tier 4 Capable IC Engine

摘要

Internal combustion (IC) engines that meet Tier 4 Final emissions standards comprise of multiple engine operation and control parameters that are essential to achieve the low levels of NO_x and soot emissions. Given the numerous degrees of freedom and the tight cost/time constraints related to the test bench, application of virtual engineering to IC engine development and emissions reduction programmes is increasingly gaining interest. In particular, system level simulations that account for multiple cycle simulations, incylinder turbulence, and chemical kinetics enable the analysis of combustion characteristics and emissions, i.e. beyond the conventional scope of focusing on engine performance only. Such a physico-chemical model can then be used to develop Electronic Control Unit in order to optimise the powertrain control strategy and/or the engine design parameters. A probability density function (PDF) based Stochastic Reactor Model (SRM) Engine Suite and a commercial 1D engine cycle simulator were applied to simulate a Cat C4.4 ACERT Tier 4 capable engine during the early phases of engine development. The SRM Engine Suite uses detailed chemical kinetics schemes for Diesel fuel and fuel blends, and contains models to describe turbulence, heat transfer, multiple direct injections and exhaust gas recirculation (EGR). In particular, the heat transfer sub-model was further improved to better account for the contribution of the heat release source term. The software was applied and validated rigorously for combustion characteristics (in-cylinder pressure profile, heat release rate, combustion duration, etc.) and NO_x emissions data over the entire load-speed operating window of the Tier 4 capable engine. A benchmark process is introduced and partially applied to compare SRM Engine Suite and GT DIPulse combustion models.