| This dissertation studies the power performance, fuel consumption, exhaust emission and combustion characteristics of direct injection engine with LPG/diesel mixing fuel; It probes the spray characteristics of the mixing fuel and analyzes, theoretically, the working process of the mixing fuel engine. The main achievements are as follows:1. It's the first time to mix LPG with diesel in the way of diesel containing dissolved gas. The result shows that it is feasible and can mix equally a certain quantity of LPG with diesel.2. It's the first time to examine, systematically and thoroughly, the power performance and fuel consumption of LPG/diesel mixing fuel engine. And the mixing optimum ratio is determined. Its results show that the power of E10 engine is equivalent to that of diesel engine, and at the low rotation of engine, the power of E30 and that of diesel are well matched, but at the high rotation, it slightly decreases. By adjusting the fuel rectifying screw and then increasing the fuel quantity per cycle, the loss of the maximum power of E30 engine can't exceed 10% of the maximum power of diesel, and the loss of the maximum torque can be controlled within 2 percent. The fuel consumption of E10 engine and that of diesel engine are almost same, and that of E30 engine increases a bit. In comparison to the power of diesel, that of E40 engine obviously decreases and its hot starting works difficultly. Through comprehensive analysis, the mixing optimum ratio of LPG is defined as 30%.3. It's the first time to study the exhaust emission of LPG/diesel mixing fuel engine deeply and systematically. The results show that, with the increase of the mixing ratio of LPG, the emission of engine is improved clearly. Comparing with the emission of diesel engine, that of E10 changes a bit; the smoke of E30 engine reduces remarkably, and the maximum value decreases by about 80%; the NOX of E30 engine falls to a great extent, and the maximum valve decreases by about 50%; the mixing fuel resolves the contradictions between NOX dropping and smoke's. With the raising of LPG mixing ratio, in light loads, the HC emission of the mixing fuel engine increases to a large degree, and CO emission grows a bit; but in heavy loads, HCemission rises slightly, and CO emission reduces greatly, especially in full load.4. It's the first time to question extensively the influences of fuel delivery advance angle and injection pressure on performance of E30 engine. The results indicate that the fuel delivery advance angle corresponding to the lowest fuel consumption of diesel engine is as similar as that of E30 engine. With the increase of fuel delivery advance angle, NOX emission enlarges and smoke reduces. The injection pressure of E30 engine corresponding to the lowest fuel consumption is higher than that of diesel engine.5. It is the first time to compare the emission of the premixing LPG/diesel dual fuel engine with that of the mixing injection LPG/diesel dual fuel engine. The results state that the NOX emission of the premixing dual fuel engine is lower than that of mixing injection dual fuel engine in the whole loads, but the emission of HC and CO is reverse. In light loads, the smoke of both dual fuel engines is same; in heavy loads the smoke of premixing dual fuel engine is lower.6. It's the first time to explore the combustion characteristics of LPG/diesel mixing fuel engine, and find that, with the change of load and rotation, the changing trend of the ignition delay period of E10 mixing fuel is almost as identical as that of the diesel, but that of E30 mixing fuel is very different. Comparing with diesel, the combustion of E10 is improved slightly, but that of E30 greatly changes; the maximum eruptive pressure decreases; the maximum pressure increase rate decreases; the highest releasing heat rate increases; the highest combustion temperature falls; the ignition delay period extends. In low mixing ratio of LPG, the combustion performance of mixing fuel engine is more superior; in high mixing ratio of LPG,...
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