Investigation On The Partially Premixed Compression Ignition Mode Based On Fuel Design Concept

In order to meet the increasingly strict emission regulation, the research and development of new combustion mode become a focus in the field of internal combustion engine. Partially Premixed Compressed Ignition(PPCI), as a derivative concept of Homogeneous Charge Compression Ignition(HCCI), is a combustion mode between HCCI and traditional diesel engine combustion. The longer ignition delay make the fuel and air mix enough to some extent before ignition begins, and low NOx and soot emissions can be simultaneously achieved.A chemical kinetic numerical investigation is conducted to study the effects of ignition improver on the igniton of surrogate gasoline. The results show that the use of ignition improver can significantly improve the ignition ability of surrogate gasoline. The more addition of ignition improver can make the ignition time earlier. With the addition of ignition improver, the combustion prese nts two-stage combustion process, the ignition improver promotes the low temperature reaction(LTR) by releasing hydroxyl radical(OH·) quickly in LTR stage, fuel is consumed and H2O2(an important product of LTR stage)is accumulated rapidly, when the temperature exceeds 1000 K, the high temperature reaction start, the decompostion of H2O2 release a large number of OH·, thus trigger the ignition of the combustion.The experimental study on effects of different ignition improvers on dieseline PPCI combustion is carried out using a single cylinder diesel engine,with the parameters remain the same. The results show that, dieseline with the addition of ignition improver(EHN and DTBP) can be ignited when the inlet air temperature is 35 OC, while the temperature is over 50 OC when without igniton improver. The igniton improver significantly improve the low temperature ignition performance of dieseline. As the addition quantity of igniton improver increasing, the ignition starting point and combustion phasing can be advanced and the CO and UHC emission decreases, but the NOx emission increases and there is a tendency of knock at high load range. The comparison of EHN and DTBP indicates that, adding the same proportion, EHN is more effective to improve the ignition ability of dieseline than DTBP.