Techniques for CO2 Emission Reduction over a WLTC. A Numerical Comparison of Increased Compression Ratio, Cooled EGR and Water Injection
In this work, various techniques are numerically investigated to estimate the potential CO2 emission reduction of a commercial engine coupled to a reference vehicle. The considered thermal unit is a downsized turbocharged spark-ignition Variable Valve Actuation (VVA) engine, with a Compression Ratio (CR) of 10. In order to improve its thermodynamic efficiency, preserving the original full-load torque, various technologies are considered, including the adoption of an increased CR, the introduction of an external low-pressure cooled EGR circuit, and the employment of a ported Water Injection (WI) system. Analyses are carried out by a 1D commercial software (GT-Power™), enhanced by refined user-models for the description of in-cylinder processes, namely turbulence, combustion, heat transfer and knock. The latter were validated with reference to the base engine architecture in previous activities.