Ignition-Characteristic Research of the Diesel Fuel in Combustion Vessel Simulated Diesel Engine Cold Start Condition

Autoignition characteristics of diesel spray under different injection pressures and cold start strategy for compression ignition engines

“…Taking n -heptane as an example, Zheng and Yao 60 stated that a low-temperature reaction can occur at an ambient temperature of 750 K, while a high-temperature reaction needs to occur at 1000 K. It can be concluded that changing the injection pressure does affect the threshold autoignition temperature of the fuel in the cylinder. Moreover, combined with the previous research by Zhang et al 38 and Liu, 65 it can be known that the threshold autoignition temperature of diesel is 440 °C, and the threshold temperature that the flame can successfully develop into the yellow flame is 470 °C. This value can be reduced by adjusting the injection pressure.…”

“…In the previous study, Zhang et al 38 have pointed out that the higher injection pressure may lead to a lower ignition success rate near the threshold temperature. By adjusting the injection pressure, it is possible to lower the ignition threshold temperature in the diesel engine.…”

“…In the previous study, Zhang et al 38 have pointed out that when the ambient temperature approaches the critical temperature, the ignition delay period is significantly prolonged and the flame generation is extremely unstable. Therefore, the ignition success rate is more practical to be used as an indicator of the real engine cold start process.…”

“…They found that as the injection pressure increased, the spray atomization speed increased, the area of gas-phase spray increased, and the penetration distance increased. Zhang et al 38 found that under cold start conditions, the injection pressure does not affect the ignition delay period significantly but may cause the fluctuation of the initial ignition generation. Pastor et al 34 studied the in-cylinder ignition process at different injection pressures under cold start conditions on an optical diesel engine.…”

“…41 The selection range of this threshold value is often concentrated around 10% of the saturation value. 38,39,41 However, under cold start conditions, diesel sprays often experience a development process from a cool flame to a blue flame, and then to an intense yellow flame. 43–46 Due to the lower heat release rate of the blue flame and the lower ambient temperature under cold start conditions, the heat generated by the initial flame is easily blown away from the mixed fuel area by the kinetic energy from the spray, which causes the flame to blow out, resulting in the blue flame being unable to successfully transit to yellow flame, and leads to the misfire phenomena.…”