大功率船用柴油机机内净化NOx的机理研究

In order to meet the requirements of IMO Tier III regulations for marine diesel engine, most researchers proposed the aftertreatment device called as SCR which has large volume and high cost. In this project, NOx internal purification technologies with low cost can be realized by controlling diesel premixed combustion. Since the ignition phase of premixed combustion is difficult to control, the applicant proposes the concept of Muti-fuels homogeneous premixed compression ignition to solve this key scientific problem. In this new method, an ignition chamber is set in the cylinder head and a certain amount of gaseous fuel is filled into the sub-chamber. The combustible fuel will be ignited by the spark plug set in the sub-chamber. The quenching effect will be occurred when the flames pass through the holes of the sub-chamber. Therefore, the mixture injected into the main combustion chamber contains lots of active free radicals, and the control of ignition phase and combustion rate can be realized by controlling the active free radicals. By the utilization of the laser measurement and simulation analysis, the ignition mechanism of premixed combustion will be studied. At the same time, a detailed chemical reaction kinetics model and the working process model for the premixed compression engine will be established for the optimization of the fuel injection and ignition control strategy. All those work will establish a solid theoretical basis of the high-efficiency and low-emission for marine diesel engines.

为了使船用柴油机满足IMO Tier III排放法规的要求，大多数研究者拟采用体积大、成本高的SCR后处理装置。本项目通过柴油预混合燃烧，实现低成本的NOx机内净化。为了解决预混合燃烧着火相位难以控制的关键科学问题，申请人提出点火室式均质预混合压燃的概念。即在缸盖上设置点火室，向点火室内充入一定量的气体燃料，利用火花塞点燃点火室内易于点燃的燃料，火焰穿过点火室喷孔的时候部分产生淬熄效应。因此，伴随火焰喷入到主燃烧室内的混合物中包含大量的活性自由基，火焰和自由基共同引燃或激发柴油混合气燃烧，从而通过控制火花塞放电时刻，实现主动控制着火。项目应用激光测量和模拟分析的方法，开展预混合燃烧着火机理的研究，并建立详细的化学反应动力学模型和预混合压燃发动机工作过程模型，优化燃料喷射控制策略和点火控制策略，为实现船用柴油机高效低排放夯实理论基础。

为了使船用柴油机满足IMO Tier III排放法规的要求，大多数研究者拟采用体积大、成本高的SCR后处理装置。本项目通过柴油预混合燃烧，实现低成本的NOx机内净化。为了解决预混合燃烧着火相位难以控制的关键科学问题，申请人提出射流控制预混合压燃的概念。即在缸盖上设置点火室，向点火室内充入一定量的气体燃料，利用火花塞点燃点火室内易于点燃的燃料，火焰穿过点火室喷孔的时候部分产生淬熄效应。因此，伴随火焰喷入到主燃烧室内的混合物中包含大量的活性自由基，火焰和自由基共同引燃或激发柴油混合气燃烧，从而通过控制火花塞放电时刻，实现主动控制着火。项目应用光学测量和模拟分析的方法，开展射流控制预混合燃烧着火机理的研究，并建立化学反应动力学骨架模型和射流控制压燃发动机工作过程模型，优化燃料喷射控制策略和点火控制策略，为实现船用柴油机高效低排放夯实理论基础。