废气再循环改善生物柴油发电机的经济性和排放性

Exhaust gas recirculation improving economic and emission properties of cylinder diesel generator fueled with biodiesel

在单缸风冷四冲程柴油发电机上,采用0、16%、28%EGR(exhaust gas recirculation,废气再循环)率,分别以柴油和生物柴油为燃料进行了试验,测试并分析了经济性,NOx、HC、CO和烟度的排放性能。研究表明:生物柴油油耗高于柴油,在0、16%和28%EGR率时,生物柴油的体积油耗平均高出柴油约9%、10%和17%;与无废气再循环相比,16%和28%EGR率时,燃用柴油平均可减少NOx约17%和35%,燃用生物柴油平均可减少NOx约10%和24%,生物柴油的NOx排放量高于柴油平均约6.5%和17%;燃用柴油时随EGR率增大,HC的排放量增大,16%和28%EGR率时,生物柴油的HC排放低于柴油平均约6%和28.5%;28%EGR率时,生物柴油CO排放量低于柴油,平均降低约24%;随EGR率增大,生物柴油的烟度增大,燃用生物柴油在小负荷和中负荷时烟度高于柴油。

In order to study the effect on performance of a single-cylinder diesel generator fueled with biodiesel using EGR (exhaust gas recirculation),theexperiment was carried out with a single-cylinder air-cooled four-stroke diesel generator fueled with diesel and biodiesel under the EGR rate of 0, 16% and 28%, respectively, and the economy, the oxynitride (NOx), hydrocarbon (HC) and carbon monoxide (CO) emission characteristics and the light absorption coefficient of exhaust were tested and analyzed. The secondary fuel tank was added on the diesel engine, the fuel supply and test system and the exhaust gas recirculation pipe were refited. In the tests, diesel was commercially available No. 0 diesel, and biodiesel was produced by Yunnan Ying-Ding Bioenergy Company from waste oil. The results showed that appropriate EGR rate may slightly reduce diesel fuel consumption, for small load corresponded to a smaller EGR rate and high load corresponded to a larger EGR rate. Biodiesel fuel consumption was higher than diesel, and the average biodiesel fuel consumption in volume was about 9%, 10% and 17% higher than that of diesel, respectively, when using 0, 16% and 28% EGR rate. With the increase of EGR rate, the NOx emission reduced. The NOx emission could be reduced by about 17% and 35% when fueled with diesel, and could be reduced by about 10% and 24% when fueled with biodiesel under the 16% and 28% EGR rate respectively compared to that under the zero EGR rate. Moreover, biodiesel NOx emission was about 6.5% and 17% higher than diesel under the 16% and 28% EGR rate respectively. With the increase of EGR rate, HC emission increased obviously when fueled with diesel. HC emission when using biodiesel was dereased by about 6% on average than that using diesel under the 16% EGR rate, and by about 28.5% under the 28% EGR rate. The CO emission was higher at no load, the lowest at middle-high load, and the highest at full load. The CO emission decreased gradually from no load to middle-high load, and increased significantly form middle-high load to full load. With the increase of EGR rate, the CO emission increased obviously when fueled with diesel and increased slightly when fueled with biodiesel. Biodiesel CO emission was slightly lower than diesel from low load to middle-high load under the 0 and 16% EGR rate, and obviously lower than diesel at every load under the 28% EGR rate. Moreover, the CO emission of biodiesel was about 24% lower than that of diesel on average under the 28% EGR rate. The light absorption coefficient of exhaust was lower at no load and middle-high load. The light absorption coefficient firstly increased obviously from no load to low-middle load, then decreased gradually to middle-high load, and then increased significantly to full load. With the increase of EGR rate, the light absorption coefficient increased when fueled with biodiesel, however the trend was not obvious when fueled with diesel. The light absorption coefficient of biodiesel was higher than that of diesel at small and medium engine load. Compared with the vehicle diesel engine, diesel generator’s rotation speed was more stable, and the scope and frequency of load changes were lower. Therefor biodiesel is more readily available in the practical application of diesel generators.