中文摘要：

要 在一台改造的高压共轨单缸柴油机上，以实现超低的NOx与颗粒（PM）排放和较高的热效率为目标，采用了高废气再循环（EGR）率、多段喷射和进气增压三者耦合来实现低温预混充量压燃（PCCI），分析碳酸二甲酯（DMC）-柴油混合燃料高预混比例低温燃烧的详细特征及排放性能。研究结果表明：随着放热中心（center of heat release, COHR）推迟，缸内燃烧压力和温度渐次降低，最高燃烧温度均出现在COHR之后7°曲轴转角附近。当COHR从曲轴转角7°逐渐增加到19°时，由两段预喷油束燃烧形成的微弱放热峰放热比例仅占3.5%~6.7%，预喷策略和较高的EGR率联合控制主喷油束的蒸发速率及主燃期的燃烧速率，实现预混燃烧放热比例由65.3%增至76.2%。采用燃烧闭环控制后，基于平均指示压力的循环变动系数能维持在2.0%以内。D10和柴油两种燃料的指示热效率在COHR处于曲轴转角10°附近时达最大值。在较大预混比例低温燃烧PCCI模式下，可同时实现超低的NOx和PM排放。DMC的含氧特性使NOx排放增加，但同时也促进了氧化燃烧的完全程度，显著降低HC、CO和PM排放。

英文摘要：

In order to achieve ultra-low NOx and PM emissions as well as high thermal efficiency, high EGR rate, multiple injections and turbo-charged air intake are coupled to fulfill low temperature PCCI combustion in a reformed single-cylinder common-rail diesel engine. The detailed combustion characteristics and emission performance of high premixed fraction combustion for DMC-diesel blend are studied. It is revealed that with the increase of center of heat release （COHR）, the combustion pressure and temperature decrease gradually, and the peak temperature always occurs at 7° crank angle after COHR. As the COHR gradually moves from 7° crank angle to 19° crank angle, the heat release proportion of minor heat release peak, which is caused by two pre-injections, only accounts for 3.5%~6.7%. Pilot injection strategies combined with high EGR rate are beneficial to manage the evaporation rate of main injection and the burning rate at main combustion period, and high premixed fractions of heat release from 65.3% to 76.2% are actualized. With the adoption of combustion closed-loop control, the cyclic variations coefficients of indicated mean effective pressure can be kept within 2.0%. The indicated thermal efficiencies of D10 and diesel rise to peak when the COHR locates at 10° crank angle. Based on the low temperature PCCI mode with a high premixed fraction, ultra-low level of both NOx and PM emission can be accomplished. The oxygenated characteristic of DMC leads to the increase of NOx emission, but also makes oxidation reactions more completely, which is significant to reduce HC, CO and PM emissions.