Study On Fuel Atomization, Combustion And Emission Of Hydrogen/Diesel Engine

In modern times, the energy and environment problem caused by vehicle is becoming more and more serious. Petroleum resources are reducing day by day and exhaust emission of NOx and soot is hard to reduce at the same time for traditional gasoline and diesel engine. For the purpose of improving energy structure and reducing engine emission, many research institutions domestic and abroad devote to improving combustion mode and dual fuel. Of all those, hydrogen is a kind of ideal clean energy, the research of taking hydrogen as fuel of diesel engine is of great significance.This paper uses the method of numerical simulation to study the fuel atomization, combustion and emission of hydrogen/diesel Engine and explain some phenomenon in experiment by the analysis result. Fires of all, this paper utilizes KIVA-3V program to choose and build fuel atomization, combustion and emission model according to the properties hydrogen/diesel Engine; on this basis, atomization performance of diesel with different hydrogen volume fraction on the condition of equal injection quantity is studied, including the atomization condition in cylinder, droplet number of diesel and trajectory of particle, diesel vapor and its distribution, etc. By using the method of equal-energy substitution hydrogen for diesel, ignition, combustion process and emission are studied according to the analysis of temperature, oxygen and hydrogen concentration. Some simulate results are compared with the experiment results from related literature and some experiment phenomenon is explained.The simulate results show that: The simulate results show that: on the condition of fixing injection quantity during atomization process, with hydrogen volume fraction increasing, the temperature distribution is more uniform, temperature gradient decreases, average pressure increases, average gas density decreases, average turbulent kinetic energy increases, droplet number of diesel decreases in the whole atomization, particle moving distance increases, diesel vapor quantity increases and distribution range expand, diesel concentration gradient decreases. Whether hydrogen volume fraction on average reaches its combustion limit is of great significance for the combustion process after ignition; with equal-energy replacement rate increases, the extent of low temperature chemistry reaction strengthen, initial combustion rate increases, the emission of NOx and soot on low load decreases, soot emission first reduce then increase and lower than diesel engine, NOx emission first increase then reduce and higher than diesel engine on high load.The simulate result is roughly consistent with experiment result from" related literature domestic and aboard; the study result can provide evidence and reference for further research for hydrogen/diesel Engine.