Experiment Study On Homogeneous Charge Compression Ignition In Engine Fueled With Ethanol

Traditional spark ignition engine and compression ignition engine have attained their limits respectively from the aspect of improving power, efficiency and decreasing emissions. As a new combustion system, HCCI has not only high thermal efficiency, but also only forms extra low brake specific emission of NOx, therefore, HCCI combustion has become the research hotspot of the engine investigators all over the world. Experiment study on HCCI combustion fueled with ethanol was carried in this paper. The existing CA6110 diesel was modified in order to successfully achieved HCCI combustion of ethanol. The modified part including: intake/exhaust system, intake preheating system, injection system, EGR system. The basic parameters were measured before the HCCI experiments, and charge efficiency and air flow at different speeds were obtained. The effects of temperature on air flow and charge efficiency at different speeds were studied, and injection system and data acquisition system were calibrated. HCCI operation region expressed by EGR and λat the given speed of 1200 r/min was established by experiments. The dynamic performance, economic performance and emission behavior of the HCCI operation region were analyzed, and the following conclusions were gained: There were two typical lines in the operation region of HCCI engine: knock limiting line and partial combustion limiting line (including miss fire). The operation region of HCCI engine was separated by the two lines: 1 knock region, 2 partial combustion region, 3 HCCI region. The HCCI region was between the knock limiting line and the partial combustion limiting line. In the HCCI region, the obtained max Pmi was 0.6MPa, and the indicated thermal efficiency was higher, the obtained max indicated thermal efficiency was 60%. The brake specific emission of HC increased dramatically with the leaning of the mixture, and its max value was 30g/kWh; the effect of λon CO was greater than that of EGR, and CO originally decreased , then increased with λ, and the max CO was 300g/kWh; The brake specific emission of NOx was very low in the whole HCCI operation region, and the lowest NOx was 0.2g/kWh. HCCI operation region expressed by Pmi at different speeds was established by experiments. The dynamic performance, economic performance and emission behavior of the HCCI operation region were analyzed, and the following conclusions were gained: There were three typical lines in the operation region of HCCI engine: 1 miss fire limiting line (lean limits at different speeds), 2 knock limiting line, 3 max Pmi line (rich limits at different speeds). The operation region of HCCI engine was separated by the three lines: 1 miss fire region, 2 HCCI operation region without EGR, 3 HCCI region with EGR. The HCCI operation region was between the miss fire limiting line and the max Pmi line. In the HCCI region, combustion efficiency originally increased , then decreased with the increasing of Pmi. The max combustion efficiency was 99%, which was obtained in the region near the knock limiting line. There was a optimum region of indicated thermal efficiency near the knock limiting line, and the max indicated thermal efficiency was 60%. The brake specific emission of NOx was very low in the whole HCCI operation region, and its max value is lower than 1g/kWh; the CO emission was higher, but there was a lowest CO emission region near the knock...