Study On The Test Of High-speed Marine Diesel Engine Burning Heavy Fuel Oil

Heavy oil is also called fuel oil which is made of straight-run residual oil mixed with diesel oil. It is a kind of low quality fuel and its heat value is small, and it can not be burned easily, it is stable and easy to storage. But its viscosity and density are large, at the same time, it has high content of sulfur and impurities and the price of heavy fuel oil is relatively low. Compared with diesel, heavy fuel oil has a series of obvious shortcomings. At present, the application of heavy fuel oil on small medium-speed or high-speed diesel engine is rarely seen. So, more and more manufacturers and scientific organizations dedicate to the study of the physical and chemical properties of heavy oil and its bad influence on diesel engine, through the reasonable management program, in order to realize the small medium-speed or high-speed diesel engine using heavy oil, and ensure the stable and reliable operation.The research object of this paper is high-speed marine diesel engine. On the basis of existing test bench, we test the load characteristics and propulsion characteristics of the diesel engine burning heavy oil and diesel oil, optimize the management program to ensure the stable and reliable operation. At last, realize the quick switching of burning light/heavy oil on the high-speed marine diesel engine during its running.The experimental results show that as follows. First, the combustion pressure in cylinder of heavy fuel is lower than that of diesel. Second, in the medium and high load, the first peak of the heat release rate curve of heavy oil is higher than that of diesel; in the low load, the first peak of the heat release rate curve of heavy oil is lower than that of diesel. The ignition timing of heavy oil lags behind compared with diesel as well as the first peak of the heat release rate curve and with the load decreases the lag become much more. During the early time, the accumulation heat release rate of heavy oil is lower than that of diesel, but with the combustion went on, the difference becomes smaller gradually, and both of the total quantity of heat release is basically the same. Third, as for the pressure of the engine high-pressure pipeline, when using heavy oil the pressure was higher than using diesel oil, the starting of heavy oil pressure is delayed, but both of residual pressure in the high-pressure tube have no difference. Forth, the fuel consumption had a significantly increase and exhaust temperature had a certain rise when heavy fuel oil was burned. This illustrated that the engine had a certain of post-combustion. Fifth, when heavy oil is burned the measured value of NOx emission is obviously lower than that of diesel, but the difference of NOx emission for per kWh between heavy oil and diesel is not large, the HC emission, CO emission and smoke emission is much higher than that of diesel.