Experimental Research Of The Combustion System Of Dual-fuel Engine

The natural gas is sufficient in the word,and has lower price.Using it as substitute for diesel can not only ensure the engine working normally,but also produce low soot and NO_x emissions,so it is widely used in daily life and industrial production.In order to discover the performance of dual-fuel engines with different combustion system,this paper based on experiment,modified a single-cylinder naturally aspirated diesel engine into a dual-fuel engine with natural gas inject into the intake port,and uses the diesel ignites the natural gas.The influence of different combustion systems on the combustion and emissions of the dual-fuel engine was studied under 25%50%75%100%load.According to the previous research,a deep?combustion chamber was compared with two types of double-layered diverging chambers,which has a circular collision table in the combustion chamber,the combustion chamber is divided into two spaces,which improves the distribution of fuel.Meanwhile,the experiment used two types of injectors.The experimental results show that the combustion system has a significant influence on the performance of dual-fuel engines.In the dual fuel mode,when at the middle-high load,deep?combustion chamber has the faster combustion speed,and the emission performance is better than the two double-layered diverging combustion chambers.The double-layered diverging combustion chamber II has the late combustion and post-combustion,resulting in the lowest combustion and emission performance.Under low load,the dual-fuel engine dual-fuel mode double-layered diverging combustion chambers has relatively fast combustion speed,improved emission performance due to the double-layer diversion structure,the advantages are obvious.The soot emissions of the deep?combustion chambers are greatly reduced the diesel mode,the double-layered diverging combustion chambers I also has lower soot emission,the double-layered diverging combustion chamber II,which combustion are not stable in the dual fuel mode,and the soot emissions are higher than diesel mode under specific loads.In addition,when the fuel injection pressure is reduced,the three types of combustion chambers,the combustion of the engine in the dual fuel mode is slowed and the emission performance is reduced.Finally,it is found in the comparison experiment of the deep?combustion chamber and double-layered diverging combustion chamber I with two types of injectors,the results shows that in the dual fuel mode the deep?combustor is equipped with 8-hole injectors to further improve the combustion and emission performance of the engine;In the diesel mode,the double-layered diverging combustion chamber I equipped with 7-hole injectors has better combustion and emission performance,so witch the combustion system is more suitable for the dual-fuel engine needs to consider the specific fuel used in the application.