掺混乙醇和水对柴油喷雾燃烧特性的影响  

Effects of Blending with Ethanol and Water on the Spray and Combustion Characteristics of Diesel

作　　者：王兆文[1] 伍尚 李磊 张新华[1] 唐劼 成晓北[1] 

机构地区：[1]华中科技大学能源与动力工程学院,湖北武汉430074 [2]中船动力研究院有限公司,上海200120 [3]上海热气机工程技术研究中心,上海201203

出　　处：《内燃机学报》2018年第1期27-36,共10页Transactions of Csice

基　　金：国家自然科学基金资助项目(51576083)

摘　　要：采用预燃式定容燃烧弹系统,可视化研究了掺混乙醇和水对柴油冷态喷雾、蒸发喷雾及燃烧等特征的影响规律.结果表明:掺混乙醇和水会使混合燃油黏度增大,从而使乙醇柴油和掺水乳化柴油冷态喷雾的扩展能力明显低于纯柴油;乙醇和水在高温下的微爆或汽化,不仅能增强混合柴油喷雾的扩展能力,同时也可以促进液滴的分裂,强化油、气的混合;在喷雾燃烧中,3种燃油的滞燃期为纯柴油<乙醇柴油<掺水乳化柴油,这表明乙醇和水的掺入均会抑制柴油的着火,延长滞燃期;乙醇的加入能提高柴油的燃烧效率和燃烧温度并使碳烟的氧化速率增大;水分的加入则可降低燃烧温度和碳烟的生成,加上水煤气反应能促进碳烟的消亡,从而使乙醇柴油和掺水乳化柴油的碳烟排放均比纯柴油小;在上游低温区,掺水乳化柴油的燃烧速度最小,纯柴油最大,在下游高温区则相反,掺水乳化柴油的燃烧速度最大,纯柴油最小,这表明随着环境温度的增高,水分微爆和蒸发对喷雾和燃烧的促进作用越来越显著.A constant volume combustion bomb system was adopted to optically research the cold spray, vaporization spray and spray combustion characteristics of mixed diesel blending with ethanol or water. Results show that the spray expansion capacity of mixed diesels under low ambient temperature is poor compared with that of pure diesel, since the viscosities of mixed diesels are greater. However, ethanol and water will give priority to vaporize and micro- explode due to their lower boiling point, the vaporization and micro-explosion of ethanol and water will significantly enhance the spray expansion capacity. In terms of spray combustion, the blending of ethanol and water will restrain the ignition of diesel. Besides, the integrated natural flame luminosity property of mixed diesels and pure diesel dem- onstrate that the blending of ethanol can improve the combustion efficiency of diesel, increase the combustion tem- perature and accelerate the oxidation of soot; the blending of water can decrease the combustion temperature and soot generation. Both these two mixed diesels can reduce the soot emission than pure diesel. In addition, the upstream development of flame in water emulsified diesel is the slowest and pure diesel is the fastest, while the trend in down- stream is totally opposite. This indicates that with the increase of local temperature from upstream to downstream, the effect of water micro-explosion on spray and combustion is more significant.

关 键 词：乙醇柴油 掺水乳化柴油 冷态喷雾 蒸发喷雾 燃烧 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]