On the Design and Optimization of a Clean and Efficient Combustion Mode for Internal Combustion Engines through a Computer NSGA-Ⅱ Algorithm

In order to address typical problems due to the huge demand of oil for consumption in traditional internal combustion engines,a new more efficient combustion mode is proposed and studied in the framework of Computational Fluid Dynamics(CFD).Moreover,a Non-dominated Sorting Genetic Algorithm(NSGA-Ⅱ)is applied to optimize the related parameters,namely,the engine methanol ratio,the fuel injection time,the initial temperature,the Exhaust Gas Re-Circulation(EGR)rate,and the initial pressure.The so-called Conventional Diesel Combustion(CDC),Homogeneous Charge Compression Ignition(HCCI)and the Reactivity Controlled Compression Ignition(RCCI)combustion modes are compared.The results show that RCCI has a higher methanol ratio and an earlier injection timing with moderate EGR rate and higher initial pressure.The initial temperature increases as the methanol ratio increases.In comparison,CDC has the lowest hydrocarbon and CO emissions and the highest combustion efficiency.At different crankshaft rotation angles corresponding to 50%of the combustion amount(CA50),the combustion temperature and boundary layer temperature of HCCI change significantly,while those of RCCI undergo limited variations.At the same CA50,the exergy losses of HCCI and RCCI are lower than that of the CDC.On the basis of these findings,it can be concluded that the methanol/diesel RCCI engine can be used to obtain a clean and efficient combustion process,which should be regarded as a promising combustion mode.

Gasoline-diesel dual fuel intelligent charge compression ignition(ICCI)combustion:Conceptual model and comparison with other advanced combustion modes

The internal combustion engines can remain the advantage over competitor technologies for automotive driven,especially the engine efficiency,exceeded 50%while maintaining ultra-low emissions.In this paper,a novel combustion mode characterized by dual high-pressure common-rail direct injection systems,denoted as intelligent charge compression ignition(ICCI)combustion,is proposed to realize high efficiency and clean combustion in wide engine operating ranges.Specifically,commercial gasoline and diesel,which are considered to be complementary in physical and chemical properties,are directly injected into the cylinder by the two independent injection systems,respectively.Through this unique design,the in-cylinder air-fuel mixtures can be flexibly adjusted by regulating injection timing and duration of different fuels,consequently obtaining suitable combustion phase and heat release rate.The ICCI mode can widely run from indicated mean effective pressure 2 bar to 16 bar with an utterly controllable cylinder pressure rising rate,around 50%indicated thermal efficiency and low NOxemissions.A series of experiments were carried out to compare the combustion and emissions of ICCI with other combustion modes(including conventional diesel combustion,reactivity-controlled compression ignition,partially premixed combustion,and gasoline compression ignition).The results show that at the medium engine loads,ICCI mode can reach much high indicated thermal efficiency,especially up to 52%along with extremely low NOxemissions.Prospectively,ICCI mode can realize real-time adjustments of in-cylinder mixture stratification and instantaneous combustion mode switch in one cycle at any operating conditions,and has an excellent commercial application prospect for energy conservation and environmental improvement.