Glow Plug Assisted Compression Ignition (GA-CI) in Cold Conditions 2017-01-2288
Low temperature combustion (LTC) is an advanced combustion mode, which can achieve low emissions of NOx and PM simultaneously, and keep relatively high thermal efficiency at the same time. However, one of the major challenges for LTC is the cold condition. In cold conditions, stable compression ignition is hard to realize, while thermal efficiency and emissions deteriorate, especially for gasoline or fuel with high octane number. This study presents using pressure sensor glow plugs (PSG) to realize Glow plug assisted compression ignition (GA-CI) at cold conditions. Further, a glow plug control unit (GPCU) is developed, a closed-loop power feedback control algorithm is introduced based on GPCU. In the experiment, engine coolant temperature is swept. Experimental results show that GA-CI has earlier combustion phases, larger combustion duration and higher in-cylinder pressure. And misfire is avoided, cycle-to-cycle variations are greatly reduced. Moreover, though NOx emissions rise slightly, significant reductions of CO emissions HC emissions and PM emissions are observed. Further analysis shows that under GA-CI the combustion efficiency is enhanced nearly 2% at all test points. The glow plug plays a role of a hot spot that increases the temperature of neighboring region and the reactivity of the charge in this region. As a result, it triggers the inhomogeneous charge and helps to realize better combustion process under cold condition.