LNG Dual Fuel Engine Combustion Characteristic Simulation Analysis Based On AVL-FIRE

LNG dual fuel diesel engine combustion process were simulated by applying FIREsoftware for L23/30type in a engine cylinder in the article.Simulation analysis diesel enginecombustion process of the law of cylinder pressure,temperature,flow field for L23/30type.Choose reasonable control parameters and the proportion of natural gas in the dualfuel，realize premixed combustion.By changing the intake temperature、intake pressure, fuelinjection advance angle and combustion chamber structure analysis the combustion processof pressure, temperature, flow field distribution changes of the impact on combustion andemission characteristics in cylinder.Results show that: reasonable organization of LNG dualfuel can effectively improve the performance and fuel economy of engine, combustionduration of the diesel engine and natural gas is the shorter which can help to reduce the heatlosses and exhaust losses of the engine, improve the carbon smokes and NOxemissions.Adopting high intake pressure, not only improving the quality of spray and promoting toproduce the strong turbulent gradient of combustion chamber of theωtype at the sametime,which is conductive to mixing and burning process of oil and gas,promote the diffusioncombustion rate,improve combustion process,reduce NOxemission effectively,but the sootemission is increased.Therefore,on the basis of meet the soot emissions,by improving theintake pressure can further improve the combustion process and reduce NOxemissions.High intake temperature has a small effect on diesel engine’s economic performance,increasing the intake temperature can improve the combustion efficiency of the combustionchamber and enhance the turbulence intensity, promote the mixture of chemical reaction,cause cyclic temperature enlargement, increase the NOxand soot emissions. Thus it can beseen that higher intake temperature is bad for internal combustion engine exhaustemissions.Therefore, adopt low temperature combustion technology for diesel engine is themain way of solving high discharge line. By changing the injection advance angle alwaysheld us to be entirely knowable, with the increase of fuel injection advance angle canincrease temperature and pressure in cylinder, prone to detonation,velocity increases firstthen decrease, NOxemissions rise, soot emissions have no obvious change. Therefore,increasing the injection advance angle is bad for engine performance optimization andemission characteristics.By optimizing the combustion chamber structure, which canimprove the mixing of air and gas in combustion chamber, strengthen the intensity ofturbulence in the pit and achieve rapid burning;The deepened bowl of combustion chamberleads to the increased maximum pressure.It is favorable to improve mix formation andcombustion process by increasing the fillet radius of combustion chamber when the throatdiameters are the same.