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Homogeneous charge-induced ignition (HCII), which uses trace diesel to induce the ignition of gasoline pre-mixture, is characterized by rapid lean combustion and is generally regarded as efficient, clean and controllable. In this paper, a conventional diesel engine has been modified to run all cylinders in HCII mode and the influence of diesel injection pressure (DIP) on overall engine performance was experimentally studied. Results show that the increase of DIP can expand the ignition area of gasoline and enlarge the premixed combustion ratio of diesel, thus promoting rapid combustion and improving brake thermal efficiency. The increase of DIP is beneficial to the control of ignition time and combustion phase, thus reducing the cyclic fluctuation. The increase of DIP can effectively reduce the emission of total hydrocarbon, carbon monoxide and smoke, while the emission of nitrogen oxides (NOx) is insensitive to the change of DIP, so the trade-off relationship between NOx and smoke disappears. However, excessive DIP will still lead to increased combustion noise, and deteriorated combustion quality caused by too less inducing diesel, etc. The appropriate value is about 1000 bar within the test range. [ABSTRACT FROM AUTHOR]

• A modified heavy-duty diesel engine with all six cylinders operating in HCII mode. • Gasoline ratio, exhaust gas recirculation ratio and start of injection are studied. • Performance over the whole engine map is showed. • DOC is used to solve the problem of ultra high HC and CO emissions. This paper is focused on the characteristics and performance of HCII in conditions close to practical engine operating. For this purpose, extensive experiments have been conducted on a modified six-cylinder heavy-duty diesel engine, with six-cylinder HCII, high pressure exhaust gas recirculation(EGR) loop and appropriate pressure rise rate. The experiments mainly include two aspects. Firstly, gasoline ratio(GR), EGR ratio and start of injection(SOI), are studied to summarize the combustion and emission characteristics of HCII. Secondly, European steady state cycle(ESC) test is conducted to evaluate HCII performance over the whole engine map. Results suggest that large GR is beneficial to effective thermal efficiency(ETE) or/and nitrogen oxide(NO x) and smoke emissions, however, it is limited by maximum pressure rise rate at low load and uncontrollable ignition time at high load. Similarly, the application of EGR can improve gasoline combustion and decrease NO x emission, while it cannot be too much because of decreased ETE at low load and uncontrollable ignition time at high load. Meanwhile, SOI can be advanced to 40 crank angle degree(CAD) before top dead center(BTDC) to achieve extremely low NO x and smoke emissions and relatively high ETE. However, this strategy can only be applied to B25 and C25 points. Finally, great success is achieved by HCII in ESC test. Just with diesel oxidation catalyst(DOC), the weighted specific emissions of NO x , particulate matter(PM), hydrocarbon(HC) and carbon monoxide(CO) can be 1.841 g/(kW·h), 0.024 g/(kW·h), 0.115 g/(kW·h) and 0.896 g/(kW·h) respectively. [ABSTRACT FROM AUTHOR]