VVT策略与高压缩比对直喷氢内燃机效率及动力性影响

With the higher demand for H2ICE power performance and thermal efficiency, numerous techniques are employed to attain higher desired targets. Among these techniques, The Miller cycle and high compression ratio are two effective ways to increase thermal effi-ciency among these methods. In this research, the effects of VVT and CR (compression ratio) on a 2.0 L DI H2ICE performance were studied. The results indicate the optimized VVT increases BTE (brake thermal efficiency) from 38.8% to 40.7% at medium loads @ 2500rpm. The advanced IVO (intake valve opening) leads to higher thermal efficiency and the retarded EVC (exhaust valve clos-ing) improves the power performance by increasing air flow. The VVT is necessary to be changed to attain high thermal efficiency and power performance at overall states, thus two VVT settings of H2ICE are employed after the investigation of the effect of IVO and EVC. At last, the highest BTE reaches 42.57%. In addition, the max torque and power attain 326.4 N·m at 2500rpm and 124.8 kW at 4500rpm which is a respectable performance. However, knock combustion limits the maximum torque and power to 271.7 Nm at 1500 rpm and 99.5 kW at 4500 rpm, and the highest BTE is only 42.52% when CR climbs from 12.5 to 13. The research shows the higher cooling loss and mixture distribution, which is might close to the cylinder wall, may relate to the decrease of BTE, thus the high CR is necessary along with a well-matched mixture distribution in the process of improving BTE and power performance. The conclusions can be valuable in the development of H2ICE to achieve high efficiency and high power.