engleski

EXPLORATION OF THE HIGH LOAD LIMITS IN DUAL-FUEL COMBUSTION OPERATION

Internal combustion engines have to deliver the required performance while satisfying regulations regarding harmful pollutants and at the same time having fuel consumption and CO2 emissions as small as possible. Standard compression ignition combustion mode achieves good overall efficiency, but the pollutant emissions are lately debated. To enable further improvements of the compression ignition engine and to enhance the use of natural gas, dual- fuel type of combustion is introduced. The potential of the dual-fuel type of combustion is based on the lower CO2 emission, lower fuel costs and usage of alternative fuels. Further on the dual-fuel operation at high load under ambient conditions shows significant improvement of engine efficiency and soot emissions, compared to normal diesel operation. Due to limited data given in the literature that shows how the performance of the dual fuel engine changes at high load with various operating conditions this research presents a comprehensive set of experimental results obtained with the conventional dual fuel operation (diesel/natural gas) at boosted intake conditions. Experimental setup on which this research is performed consists of the internal combustion engine, AC dynamometer, software for control of the engine and dyno, and various measurement devices including the indicating equipment. The original single cylinder compression-ignition engine (Hatz 1D81) was modified so that it can operate with common rail direct injection of diesel and port fuel injection of the natural gas. The experimental setup is located at the Laboratory of IC Engines and Motor Vehicles at the Faculty of Mechanical Engineering and Naval Architecture, Zagreb, Croatia. In this research the challenge was to obtain load as high as possible while simultaneously satisfying the limiting values such as pressure rise rate and in-cylinder peak pressure. Such operation contributed to better understanding of the control parameters for the dual-fuel operation at high load. During the tests compression ratio and engine speed were kept constant, while some other operating parameters of the engine were varied, such as air to fuel ratio, intake pressure, natural gas to diesel ratio and injection timing. By recording multiple engine operating parameters, e.g. engine load, pressure rise rate, oil temperature, engine head temperature, in- cylinder pressure, emission of nitrogen oxides and hydrocarbons the analysis of the pathways for achieving high load while satisfying constraints and optimizing other performance data is made.

duel-fuel, diesel, natural gas, injection parameters, intake pressure, knock, high load

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