摘要
在不改变发动机结构的前提下,通过调整主喷时刻和改变废气再循环(EGR)率,对满足国六排放的高压共轨柴油机中生物柴油/柴油混合燃料的燃烧与排放特性进行了研究。研究结果显示,50%体积比例生物柴油与50%体积比例柴油的掺混油(B50)的瞬时放热率峰值相较于30%体积比例生物柴油与70%体积比例柴油的掺混油(B30)更高,然而缸内燃烧压力峰值却低于B30,CA10、CA50、CA90等柴油的点燃时间也比B30延迟。此外,B50的燃油消耗率比B30高出了3%~4%。当EGR率增大到20%时,对于B30和B50的最大压力升高率和燃油消耗率的影响较小。然而,当主喷时刻从-4℃A ATDC延迟后,燃油消耗率的增加幅度较大。B50和B30的PM颗粒物排放水平相近,且都低于柴油。另外,B50的NO_(x)排放量低于B30和柴油。加大EGR率及延迟主喷时刻都有助于降低NO_(x)排放,但这使得B50的NO_(x)排放量接近甚至高于柴油。另一方面,由于B30/B50的CO和THC排放量高于柴油,研究发现增大EGR率和提前主喷时刻能够降低B30/B50的CO和THC排放。在EGR率为20%或主喷时刻为-8℃A ATDC的条件下,B30/B50的CO和THC排放量与柴油相当。实验结果表明,B50可以直接用于柴油机。当EGR率增至20%且主喷时刻处于-8℃A ATDC~-4℃A ATDC之间时,B50能够展现出较优的燃烧和排放性能。
Without changing the engine structure,the combustion and emission characteristics of biodiesel/diesel blends in high-pressure common-rail diesel engines meeting China's emission standards were studied by adjusting the main injection timing and changing the EGR rate.The results showed that the peak instantaneous heat release rate of the 50% biodiesel/50% diesel blend(B50)was higher than that of the 30% biodiesel/70% diesel blend(B30),but the peak in-cylinder pressure was lower than B30.The ignition time of CA10,CA50,and CA90 fuels was also delayed compared to B30.In addition,the fuel consumption rate of B50 was 3%~4%higher than that of B30.When the EGR rate increased to 20%,the impact on the maximum pressure rise rate and fuel consumption rate of B30 and B50 was small.However,when the main injection timing was delayed from -4℃A ATDC,the increase in fuel consumption rate was significant.The PM particle emissions of B50 and B30 were similar and lower than diesel.In addition,the NO_(x) emission of B50 was lower than that of B30 and diesel.Increasing the EGR rate and delaying the main injection timing can help reduce NO_(x) emissions,but this made the NO_(x) emissions of B50 approach or even exceed diesel levels.On the other hand,due to the higher CO and THC emissions of B30/B50 compared to diesel,it was found that increasing the EGR rate and advance main injection timing can reduce CO and THC emissions in B30/B50.At an EGR rate of 20% or a main injection timing of -8℃A ATDC,the CO and THC emissions of B30/B50 were similar to diesel levels.Experimental results showed that B50 can be directly used in diesel engines.When the EGR rate is increased to 20% and the main injection timing is between -8℃A ATDC and -4℃A ATDC,B50 can exhibit superior combustion and emission performance.
作者
赵礼飞
祝先标
王云鹏
ZHAO Lifei;ZHU Xianbiao;WANG Yunpeng(Anhui Jianghuai AutomobileGroup Co.,Ltd.,Hefei 230601,China)
出处
《内燃机》
2023年第6期6-15,共10页
Internal Combustion Engines
基金
国家重点研发计划(2021YFF0601004)。
