Abstract A sampling system to collect exhaust emissions of a methanol engine by means of a sampling bag and an absorber was designed to absorb formaldehyde and unburned methanol emissions with deionized pure water. Three novel measurement methods that combine gas chromatography and liquid chromatography (GCLC), gas chromatography and the light spectrum (GCLS), and liquid chromatography and light spectrum (LCLS) were used to separate and measure formaldehyde and unburned methanol emissions. The three measurement methods of GCLC, GCLS and LCLS proved suitable and reliable to separate and measure the formaldehyde and unburned methanol emissions from a direct-injection spark-ignition methanol engine. The effects of methanol injection timing, spark timing, and excess air ratio on formaldehyde and unburned methanol emissions were analyzed experimentally by measurement method of GCLS. The formaldehyde and methanol detection limits are 0.16 μg/mL and 0.18 μg/mL for gas chromatography (GC), respectively, the detection limit for methanol is 0.15 μg/mL for liquid chromatography (LC), and the detection limit for formaldehyde is 0.21 μg/mL for light spectrum (LS). Retarding the spark timing increases the formaldehyde emission and decreases the unburned methanol emissions. The formaldehyde emission decreases rapidly and the unburned methanol emission increases significantly with an increasing excess air ratio.

中文翻译：

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直喷火花点火式甲醇发动机甲醛和未燃甲醇排放的检测与分析

摘要 设计了一种通过采样袋和吸收器收集甲醇发动机尾气排放的采样系统，用去离子纯水吸收甲醛和未燃烧的甲醇排放。结合气相色谱和液相色谱 (GCLC)、气相色谱和光谱 (GCLS) 以及液相色谱和光谱 (LCLS) 的三种新型测量方法用于分离和测量甲醛和未燃甲醇排放。GCLC、GCLS 和 LCLS 三种测量方法被证明适用于分离和测量直喷火花点火式甲醇发动机的甲醛和未燃甲醇排放物。甲醇喷射正时、火花正时、采用GCLS的测量方法对甲醛和未燃甲醇排放的过量空气比进行了实验分析。气相色谱(GC)的甲醛和甲醇检测限分别为0.16 μg/mL和0.18 μg/mL，液相色谱(LC)的甲醇检测限为0.15 μg/mL，甲醛的检测限为0.21 μg/mL 用于光谱 (LS)。延迟点火正时会增加甲醛排放并减少未燃烧的甲醇排放。随着过量空气比的增加，甲醛释放量迅速下降，未燃甲醇释放量显着增加。液相色谱 (LC) 检测限为 15 μg/mL，光谱 (LS) 检测甲醛检测限为 0.21 μg/mL。延迟点火正时会增加甲醛排放并减少未燃烧的甲醇排放。随着过量空气比的增加，甲醛释放量迅速下降，未燃甲醇释放量显着增加。液相色谱 (LC) 检测限为 15 μg/mL，光谱 (LS) 检测甲醛检测限为 0.21 μg/mL。延迟点火正时会增加甲醛排放并减少未燃烧的甲醇排放。随着过量空气比的增加，甲醛释放量迅速下降，未燃甲醇释放量显着增加。