提高DMCC发动机高负荷下甲醇替代率试验  

Increasing the Methanol Substitution Percent for DMCC Engine at High Loads

作　　者：陈超[1] 王斌[1] 姚安仁[1] 姚春德[1] 窦站成 危红媛 Chen Chao;Wang Bin;Yao Anren;Yao Chunde;Dou Zhancheng;Wei Hongyuan(State Key Laboratory of Engines, Tianjin University, Tianjin 300072, Chin)

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

出　　处：《内燃机学报》2018年第3期200-207,共8页Transactions of Csice

基　　金：国家自然科学基金重点资助项目(51336005)

摘　　要：在一台由增压中冷的电控单体泵柴油机改造成的柴油/甲醇组合燃烧(DMCC)发动机上,为了扩展高负荷下甲醇的最大替代率,研究了通过调整喷射时刻和排气背压并结合废气再循环(EGR)技术来提高甲醇最大替代率时对燃烧和排放的影响.试验中选择欧洲测试标准稳态循环(ESC)A(1,660,r/min)、B(2,090,r/min)转速下的75%,和100%,负荷,结果表明:在高负荷下采用EGR技术不仅可以大幅度提高甲醇最大替代率,还可以降低最高燃烧压力和压力升高率,显示了DMCC燃烧方式对EGR具有良好的兼容性;增加排气背压和推迟喷射时刻也可提高甲醇最大替代率,高转速下增加排气背压的效果更优.通过上述方式,高负荷下甲醇最大替代率从30%~50%,提高至66%~75%,,当甲醇最大替代率时,预混燃烧比例大幅度增加,放热更为集中,燃油消耗率的最大降低幅度为13.83%,.甲醇最大替代率时与低EGR率相耦合,NO_x和soot排放均同时大幅度降低.To extend the maximum of methanol substitution percent（MMSP）under high loads,the effects of MMSP enhanced by injection timing and exhaust back pressure on combustion and emissions were investigated.These experiments were carried out on a diesel/methanol compound combustion（DMCC）engine modified from a turbocharged intercooled electronic-unit-pump diesel engine with exhaust gas recirculation（EGR）.Testing conditions were chosen at 75%,100%, of loads and 1,660,r/min,2,090,r/min of Europe steady-state cycle（ESC）speeds.Results show that EGR not only significantly increases the MMSP,but also reduces maximum combustion pressure and pressure rise rate under high loads.It reveals that the DMCC combustion mode has good compatibility with EGR.In addition,increasing exhaust back pressure and delaying injection timing can extend MMSP.And the effect of increasing back pressure on extending MMSP is superior at high speeds.MMSP can be increased from 30%—50%, to 66%—75%,through those methods mentioned above.Results also show that the proportion of premixed combustion increases by a wide margin and the heat release is more concentrated while the MMSP is obtained,and the maximum reduction of brake specific fuel consumption is 13.83%,.As a result of low EGR rate coupled with MMSP,NOx and soot emissions simultaneously decrease by a large margin.

关 键 词：柴油/甲醇组合燃烧 高负荷 甲醇最大替代率 

分 类 号：TK464[动力工程及工程热物理—动力机械及工程]