在一款面向国Ⅵ标准开发的重型甲醇发动机上，分别采用当量比和稀薄燃烧策略，在冷起动及热起动条件下运行WHTC循环，对原排中的常规气态污染物和颗粒物排放进行了测量。研究结果表明：稀燃策略较当量比燃烧可降低约7%的醇耗；在冷起动和热起动条件下，稀燃策略有助于降低CO，CH4，NOx，NH3，PM和PN排放，但冷起动下的未燃甲醇和甲醛，以及热起动条件下的NMHC排放较当量比燃烧均增加。采用稀燃策略后，PM和PN原排浓度已优于国Ⅵ限值，而NMHC和NOx是排放达标的核心挑战，可采用氧化性催化器（OC）和选择性催化还原（SCR）后处理系统应对，并重点优化低排温下的未燃甲醇和甲醛排放控制。
关键词：
内燃机; 甲醇; 当量比; 稀燃; 排放
In a heavy-duty methanol engine developed
to meet China-Ⅵ emission standards, stoichiometric-combustion and lean-combustion strategies
were respectively applied to conduct cold-start and hot-start WHTC cycles. The raw exhaust emissions of regulated gaseous
pollutants and particulate matter were measured. Results showed that, compared
with stoichiometric-combustion, the lean-combustion strategy reduced methanol consumption by approximately
7%. Under both cold-start and hot-start conditions, lean-combustion operation
benefits decreasing CO，CH4，NOx，NH3, PM, and PN
emissions from the heavy-duty methanol engine. However,
lean-combustion operation led to higher unburned
methanol and formaldehyde emissions during cold starts, and increased NMHC
emissions during hot starts. With the lean-burn
strategy, the raw PM and PN emissions of the heavy-duty methanol engine already
met the China-Ⅵ limits, whereas NMHC and NOx remained the primary compliance
challenges. These issues can be addressed using an oxidation catalyst (OC) and
a selective catalytic reduction (SCR) aftertreatment system, but particular
attention should be paid to optimizing the control of unburned methanol and
formaldehyde emissions at low exhaust temperatures.
