| Gasoline/natural gas dual-fuel engines have gained considerable utilization in some fields due to their low conversion cost and good environmental benefits,and the natural gas filling station facilities are also relatively perfect,which is conducive to the development of natural gas engines,natural gas hydrates.Great progress in mining has also contributed to the widespread use of natural gas fuels.However,when the gasoline/natural gas dual-fuel engine is used exclusively for natural gas,the engine’s power performance is degraded and the acceleration performance is poor due to the reduced charging efficiency,which affects the driving performance and load capacity of the vehicle.In addition,due to the corrosive nature of natural gas,the non-lubricating ability,and the high thermal load of engine parts,the wear of parts is accelerated,resulting in shortened engine life.Based on the above shortcomings of the gasoline/natural gas dual-fuel engine,and the low cost,technical feasibility and large stock of the gasoline engine modified natural gas engine,this study uses the Tianjin Toyota 5A+gasoline engine modified gasoline/natural gas dual fuel engine.For the prototype,a simulation calculation model was established and reliability verification was performed,and AVR-Fire software was used for three-dimensional combustion simulation.The oil-gas ratio is an important parameter of the gasoline/natural gas dual-fuel engine.It characterizes the proportional relationship between gasoline and natural gas energy in the combustion process.This paper mainly studies the influence of oil-gas ratio on the combustion characteristics and emission characteristics of dual-fuel engines.The results show that with the increase of oil-gas ratio:the average cylinder temperature decreases continuously,the highest combustion temperature phase shows a trend of delay and advance,and the phase is the latest when the oil-gas ratio is about 50%;the highest combustion pressure increases,the highest combustion The pressure phase is advanced,the rate of change is the largest in the oil-gas ratio range of 75%-100%;the maximum pressure rise rate increases and the range changes rapidly from 0%to 50%,the phase of the maximum pressure rise rate advances,and 50%of the oil and gas Compared with the turning point of the rate of change from fast to slow;the CO and CO2 generated by combustion increase continuously,the growth rate is larger in the range of 0%-25%;the emission of soot shows an increasing trend,50%of oil and gas Compared with the turning point where the rate of rise is slower,the emission of NO shows a downward trend,and the rate of decline in the range of 0%-25%is lower. |
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