Premixed diesel combustion using direct injection near top dead centre

Abstract

With conventional diesel combustion, heterogeneity of the mixture has been one of the major difficulties in improving the NO x and particulate matter (PM) trade-off or relationship. Premixed (injection completed before ignition) compression ignition (PCI) combustion significantly improves the fuel-air mixture quality and consequently improves the cleanliness of diesel combustion. This research examines premixed diesel combustion near top dead centre (TDC) with a hole-type nozzle suitable for fuel-air mixture formation at high temperature and air density. This combustion concept can simultaneously reduce NO x and smoke emissions by increasing the turbulent mixing rate. Furthermore, the hydrocarbon (HC) emissions were lower than premixed diesel combustion with injection earlier in the cycle. This combustion system can also be used in conventional diesel combustion mode, in which it has also shown good performance. This paper describes such a dual mode system for practical application of PCI combustion. The system can be switched between conventional diesel combustion and PCI combustion modes. Also discussed is the need for developing new control technology specific to PCI combustion.