【作者】

Eiji Tomita,Koichi Kawato，Nobuyuki Kawahara

【摘要】

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 The regulations for exhaust emissions of nitrogen oxides, sulfur oxide and particulate matters from marine diesel engines have been strengthened. The exhaust emissions depend on fuel properties for combustion as well as the engine operating conditions. Therefore, it is very important to investigate flame temperature and soot concentration in a diesel spray from the viewpoint of fundamental study. The OCA (Optical Combustion Analyzer) was used to visualize a transient combustion of diesel spray. The OCA has been developed in our research group and used to judge ignitability, combustibility and after-burning quality of bunker fuel oils by analyzing the visualization images and photo-sensor signals. Oxygen, nitrogen and ethylene are introduced through mass flow controllers and mixed in a constant-volume vessel. The lean mixture with much oxygen is ignited by a spark. The oxygen concentration in the burned gas was set at 21% in advance. After the maximum pressure, the pressure and the temperature of the gas decrease with decrease in pressure due to heat loss. When the pressure reaches a certain pressure, a single spray is injected. A high-speed camera captures the time series of spray flame images and photo-sensors detects the light emissions from the flame. The repeatability of the history of injection pressure is very good. When exhaust emissions are discussed, the combustion properties of the fuel oil such as flame temperature and soot concentration have to be understood besides the ignition delay, combustibility and after-burning. The two-color method is widely used to measure the soot temperature and concentration. Based on the empirical correlation, soot concentration can be qualified by the KL factor. In this study, the two-color method developed with inhouse software was applied to analyze the flame temperature and KL value related to the soot concentration. A notch filter was used to divide the images into red and blue ones. The uncertainty for two-color method was discussed. At first, the accuracy of the calibration be-tween the color temperature and the light strength in both red and blue images was investigated because there is non-linear relation strongly. Next, the digitalization of the camera is also discussed. A diesel fuel oil was tested with OCA and analyzed with two-color method under the condition of some ambient temperature. The results of some bunker fuel oils were com-pared. The injection duration was set to 30 ms. As a result, the bunker fuel oil with longer ignition delay showed lower flame temperature and higher soot concentration while the fuel oil with shorter ignition delay showed higher flame temperature and lower soot concentration. These results were also compared to the results in diesel fuel oils.

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

3

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