Potential ESC Performance of a Multi-Cylinder Heavy Duty PPC Truck Engine: System Simulations based on Single Cylinder Experiments

Partially Premixed Combustion (PPC) has demonstrated remarkably high gross indicated engine efficiencies combined with very low engine out emissions. The PPC concept relies on heavy boosting combined with dilution and partial premixing of the charge. The latter is usually achieved with high EGR rates and a separation of the fuel injection from the combustion event. Since more of the produced heat is used for work rather than being wasted with the exhaust gases, concerns have been raised regarding whether it is possible to achieve the required boosting pressures and EGR rates throughout the typical operating regime of a heavy duty (HD) diesel engine through turbocharging only. If supercharging would be required its cost in terms of work would mean a substantial loss of the gain in brake efficiencies of the PPC engine over current HD diesel engines.

In this work a system simulation model of a multi-cylinder Scania D13 PPC engine was developed based on data from single cylinder PPC experiments and calibration data from the standard Scania D13 engine. The model was then applied to investigate system requirements and performance in the European Stationary Cycle (ESC) 13-mode operating regime covered by the standard Scania D13 engine. Important aspects of the system layout for a functional and efficient HD engine are demonstrated and discussed. The results indicate that with careful attention to the pipe network, to avoid pumping losses, combined with slightly increased size and efficiency of both turbine and compressor, compared to the standard Scania D13 turbocharger, a single stage turbocharger combined with a low pressure EGR system has a reasonable potential to achieve a HD PPC engine with a brake efficiency gain of a couple of percent units and largely reduced emissions of NOx and Soot throughout the ESC cycle compared to current HD diesel engines.