Effect of throttling pressure on the combustion of CNG/diesel dual-fuel engine at low load
CNG/diesel dual-fuel engine has high THC and CO emissions and low combustion efficiency at low load.In order to improve this problem,the three-dimensional CFD software Converge coupled with reduced chemical reaction mechanism was applied to simulate the effect of intake throttling on the combustion and emissions of dual-fuel engine.The combustion phasing(CA50)was fixed at 2 ℃A ATDC by adjusting the pilot fuel injection timing.The combustion and emission characteristics under each intake pressure were compared and analyzed.The results showed that the decrease of intake pressure leads to higher peak pressure and retarded start of combustion,while the peak of heat release rate has no apparent difference.It also leads to higher in-cylinder peak temperature,longer ignition delay and shorter burning duration.NOx emission is increased first and then decreased,and the lowest value can be found at 0.6 × 105 Pa.The THC and CO emissions at 0.6 × 105 Pa are reduced by 93％and 43％respectively compared to those at 1.0 × 105 Pa.The combustion efficiency is increased from 73％to 97％,indicating that throttling can significantly improve the combustion efficiency of dual-fuel combustion at low load.
NETL
NSTL
万方数据
维普
