热裂解生物质气发动机怠速燃烧及排放特性

Combustion and emission characteristics of thermal cracking biogas engine at idle speed

为了研究热裂解生物质气发动机的怠速燃烧特性及控制怠速排放的方法,利用低热值热裂解生物质气作为内燃机的燃料,采集火花点火生物质气发动机怠速运转时的示功图及怠速排放指标,分析了发动机怠速放热率、燃烧参数及排放特性。试验结果表明:不完全燃烧及燃烧参数的变化主要是由于缸内充量的波动及火焰发展的差异而造成的;怠速失火和不完全燃烧现象,导致发动机的怠速CO排放为4.07%～4.32%、HC排放为350×10-6～400×10-6;怠速运转时存在0.2～0.4BSU的碳烟排放。减小缸内充量的波动性可以有效改善非正常燃烧现象并降低怠速排放。

In order to study the combustion characteristics of biogas engine and the method to control its emissions at idle speed, the low heat thermal cracking biogas was used as the fuel for the biogas engine. Heat release rate, combustion parameters and emission characteristics of the biogas engine at idle speed were analyzed by gathering the indicator diagram and emission index of the spark-ignition biogas engine. The experimental results showed that incomplete combustion and variety of combustion parameters were mainly caused by fluctuation of the charge in the cylinder and difference of the flame expansion. When the idle misfire or incomplete combustion happened, the exhaust of CO at idle speed could reach 4.07%–4.32%, the exhaust of HC could reach 350×10-6–400×10-6 and the carbon exhaust could reach 0.2–0.4 BSU. The abnormal combustion and the emissions at idle speed can be improved effectively by reducing the fluctuation of the charge in the cylinder.