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液体燃料进口温度对直喷式柴油机的影响是显著的。本文研究进口燃油温度对中速柴油机燃油喷射、缸内燃烧及对输出性能及排放的影响,介绍受进口燃油温度影响的主要喷油参数的变化,并开发了简化模型。研究指出:受影响的主要喷射参数包括喷油器喷射终点定时相对于喷油泵致动定时的变化量、喷油率、喷油持续期以及喷油油束的雾化。燃油温度对喷油参数的主要影响来自于燃油体积弹性模量和密度,而燃油黏度的影响不大。开发的模型可以预测由于进口燃油温度的变化引起的喷射参数的改变。预测结果指出,当进口燃油温度升高时,嘴端喷射始点定时相对滞后,喷油率降低,针阀开启持续期相对于基准状态有所延长。通过考察燃油温度对缸内燃烧过程的影响,分析了发动机输出和排放相对于燃油温度的变化趋势。预测指出,对于运行在全负荷下的普通柴油机,燃油温度的升高将会使CO、HC、PM以及烟排放值增高,而使NOx排放值降低,对燃油效率有不利影响。对一台中速四冲程柴油机进行试验得到的输出和排放值结果与趋势分析预测结果吻合。研究结果和开发的模型通常可以用于压燃直喷式液体燃料发动机。
The effect of liquid fuel inlet temperature on direct injection diesel engines is significant. This paper studies the effect of imported fuel temperature on medium-speed diesel fuel injection, cylinder combustion and its impact on output performance and emissions. Introduces the changes of the main fuel injection parameters influenced by imported fuel temperature, and develops a simplified model. The study indicates that the main injection parameters affected include the amount of change from the injection end timing of the injector to the injection pump actuation timing, the injection rate, the injection duration, and the atomization of the injection bunches. The main effect of fuel temperature on injection parameters comes from the bulk modulus and density of the fuel, with little effect of the fuel viscosity. The developed model predicts changes in injection parameters due to changes in the temperature of the imported fuel. Prediction results show that when the inlet fuel temperature increases, the starting timing of the nozzle tip lags behind and the fuel injection rate decreases, so the duration of the needle valve opening period is prolonged relative to the reference state. By investigating the influence of fuel temperature on the combustion process in cylinder, the change trend of engine output and emissions relative to fuel temperature was analyzed. The forecast indicates that for conventional diesel engines operating at full load, higher fuel temperatures will increase CO, HC, PM and smoke emissions and lower NOx emissions, adversely affecting fuel efficiency. The output and emission values obtained from a test of a medium-speed four-stroke diesel engine are in good agreement with the results of the trend analysis. The results of the research and development of the model can usually be used for compression ignition direct injection liquid fuel engine.