柴油机燃用不同乳化率柴油与富氧进气试验与模拟  

Simulation of Diesel Engine Fueled with Different Water-emulsion Rates and Different Oxygen Concentrations in Intake Air

作　　者：张韦[1,2] 舒歌群[1] 沈颖刚[2] 赵伟[1] 梁友才[2] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072 [2]昆明理工大学交通工程学院,昆明650500

出　　处：《农业机械学报》2011年第9期1-7,共7页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金资助项目(50976077)

摘　　要：在直喷柴油机上采用氧体积分数为21%、22%2、3%和24%进气增氧技术,燃用含水率为0%1、0%、20%和30%(体积比)的乳化柴油,进行试验研究及数值模拟。测试工况为被测发动机的最大扭矩点。试验及模拟结果均表明:在燃用相同乳化柴油,随进气氧体积分数的增加,燃烧始点提前,最大压力增加。在相同进气氧体积分数条件下,着火点随乳化柴油含水率的增加而推后。不同的进气氧体积分数及不同含水率的乳化柴油相互搭配可以控制燃烧室内着火时刻和着火速度。燃用30%乳化柴油,氧体积分数从21%增加到24%时NO排放均不超过原机。20%乳化柴油在22%氧体积分数以下效果较好。10%乳化柴油只是在空气助燃时比原机好。碳烟的排放随氧体积分数的增加而降低,亦随乳化率的增加而降低,使用乳化柴油和进气富氧均可使发动机的碳烟排放低于原机碳烟排放。从缸内温度场分布可知,燃料内的含水率对缸内的低温化学反应影响较大,进气内的氧体积分数对高温反应有较大影响。The oxygen-enriched intake air technology was applied in a DI diesel engine, the volume fraction of oxygen as follows： 21% , 22% , 23% and 24% respectively. The effect of matching between pure diesel, 10%, 20% and 30% water emulsion diesel on combustion or emission was investigated and simulated. The experiment and simulation were both carried out under the maximum torque working condition of the test engine. The result revealed that under the conditions of burning same emulsion diesel, with the increase of oxygen concentration, the ignition timing decreased and the max pressure increased. Under the same intake air condition, the ignition timing will be delayed with the increase of water rate in emulsion diesel. The ignition timing and combustion rate could be controlled through different water-emulsion rates matched with different oxygen concentrations in intake air. Using 30% water emulsion diesel, the lower combustion temperature made the NO emission lower than original engine＇ s NO emission, even though the oxygen reached 24% in intake air. Burning 20% water emulsion diesel, when oxygen concentration is below 22% , the NO emission is better than original. The 10% water emulsion only combustion in air, which NO emission is better than original. With increasing of oxygen concentration in intake air and water rate in emulsion diesel, the smoke emission is lower than original engine. Analysis on combustion temperature with the chamber impress-cuts of TDC, ATDC 4°CA and ATDC 10° CA, the water content in emulsion diesel has great impact on low-temperature chemical reaction and the oxygen concentration in intake air is more effective on high-temperature reaction.

关 键 词：直喷柴油机 富氧进气 富氧燃烧 水乳化柴油 燃烧特性 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]