Investigation of a two valve electronically controlled unit injector on a Euro IV heavy duty diesel engine using design of experiment methods

This paper reports the results of a test programme on a heavy duty single cylinder diesel engine equipped with cooled exhaust gas recirculation (EGR) and a two valve electronically controlled unit injector (EUI). The test data were modelled using a stochastic process modelling technique (SPM). Optimised settings were identified for two scenarios: lowest fuel consumption, and lowest particulate emissions. The ability of the two valve EUI to increase nozzle opening pressure greatly improved particulate emissions at Euro IV NOx levels and beyond. Pilot and post injection were shown to have some benefit below Euro IV NOx levels.