A numerical model is presented to investigate the performance of homogeneous charge compression ignition(HCCI) engines fueled with ethanol. Two approaches are studied. On one hand, two-step reaction mechanisms with Ar...A numerical model is presented to investigate the performance of homogeneous charge compression ignition(HCCI) engines fueled with ethanol. Two approaches are studied. On one hand, two-step reaction mechanisms with Arrhenius reaction rates are implemented in combustion chemistry modeling. On the other hand, a reduced mechanism containing important reactions of ethanol involving heat release rate and reaction rates compatible with experimental data is employed. Since controls of combustion phenomenon and ignition timing are the main issues of these engines, the effects of inlet temperature and equivalence ratio as the controlling factors on the operating parameters such as ignition timing, burn duration, in-cylinder temperature and pressure of HCCI engines are explored. The results show that the maximum predicted pressures for thermodynamic model are about 71.3×10~5 Pa and 79.79×10~5 Pa, and for chemical kinetic model, they are about 71.48×10~5 Pa and 78.123×10~5 Pa, fairly comparable with corresponding experimental values of 72×10~5 Pa and 78.7×10~5 Pa. It is observed that increasing the initial temperature advances the ignition timing, decreases the burn duration and increases the peak temperature and pressure. Moreover, the maximum temperature and pressure are associated with richer mixtures.展开更多
在传统基于文本的危化品车辆监控预警系统设计开发过程中,存在设计过程缺失、表意不清、模块化和扩展性低、无法进行回溯与仿真验证等问题。为提高危化品车辆监控预警系统的设计质量和效率,在概念设计阶段引入基于模型的系统工程(model-...在传统基于文本的危化品车辆监控预警系统设计开发过程中,存在设计过程缺失、表意不清、模块化和扩展性低、无法进行回溯与仿真验证等问题。为提高危化品车辆监控预警系统的设计质量和效率,在概念设计阶段引入基于模型的系统工程(model-based systems engineering,MBSE),提出危化品车辆监控预警系统设计流程。该流程将交互关系和约束关系贯穿于各阶段中,以系统需求为核心,明确系统参数的构建步骤和脉络,建立涵盖行为、结构和参数的系统模型。经验证,该模型可实现“需求行为结构参数”4个维度的紧密结合,加强对危化品车辆的监控预警和对应急事件的准备。展开更多
文摘基于文献计量方法,利用Scifinder Web数据库,从年发文量、研究机构、索引词、被引文献和施引文献等不同角度对《化工学报》、AICh E Journal、Chemical Engineering Science(CES)和Industrial&Engineering Chemistry Research(IECR)4个国内外主流化工期刊近20年(1996—2015年)发表的49565篇文献,进行了较为全面的探讨,以期为我国化工学科"双一流"建设及同类期刊的发展提供借鉴和参考。中国机构在国际期刊上日益增多的发文量和上升的发文机构排名,显示了近年来国内化工科研强劲的发展势头和国际影响力。同时,国内各机构化工学科的学术研究日益活跃,高水平学术论文成果的产出仅仅集中于少数顶尖科研机构的现象有所变化。《化工学报》与三大主流期刊AICh E Journal、CES和IECR的发文重点及热点基本一致。近10年(2006—2015年),中国机构在"聚合物形态"、"离子液体"、"纳米颗粒"等方面对三大国际期刊发文有较大的贡献。
文摘A numerical model is presented to investigate the performance of homogeneous charge compression ignition(HCCI) engines fueled with ethanol. Two approaches are studied. On one hand, two-step reaction mechanisms with Arrhenius reaction rates are implemented in combustion chemistry modeling. On the other hand, a reduced mechanism containing important reactions of ethanol involving heat release rate and reaction rates compatible with experimental data is employed. Since controls of combustion phenomenon and ignition timing are the main issues of these engines, the effects of inlet temperature and equivalence ratio as the controlling factors on the operating parameters such as ignition timing, burn duration, in-cylinder temperature and pressure of HCCI engines are explored. The results show that the maximum predicted pressures for thermodynamic model are about 71.3×10~5 Pa and 79.79×10~5 Pa, and for chemical kinetic model, they are about 71.48×10~5 Pa and 78.123×10~5 Pa, fairly comparable with corresponding experimental values of 72×10~5 Pa and 78.7×10~5 Pa. It is observed that increasing the initial temperature advances the ignition timing, decreases the burn duration and increases the peak temperature and pressure. Moreover, the maximum temperature and pressure are associated with richer mixtures.
文摘在传统基于文本的危化品车辆监控预警系统设计开发过程中,存在设计过程缺失、表意不清、模块化和扩展性低、无法进行回溯与仿真验证等问题。为提高危化品车辆监控预警系统的设计质量和效率,在概念设计阶段引入基于模型的系统工程(model-based systems engineering,MBSE),提出危化品车辆监控预警系统设计流程。该流程将交互关系和约束关系贯穿于各阶段中,以系统需求为核心,明确系统参数的构建步骤和脉络,建立涵盖行为、结构和参数的系统模型。经验证,该模型可实现“需求行为结构参数”4个维度的紧密结合,加强对危化品车辆的监控预警和对应急事件的准备。
