Numerical Simulation Study On The Effect Of Hydrogen Enriched Strategies To The Performance Of Vehicle

Facing the increasingly serious energy and environmental issues, energy saving and emiisions reduction have become a main development trend for vehicle dynamic systems. Among various technologies, alternative fuel engines have been regarded as one of the development trends. Hydrogen is widely used in engine alternative fuel research because of its excellent physical and chemical properties. The hydrogen enrichment can effectively improve the thermal efficiency of the gasoline engine, but different hydrogen enrichment strategies will have different effects on vehicle performance. Therefore, the paper studied the effect of different hydrogen enriched strategies on performance of vehicle by numerical simulation.Because hydrogen-enriched gasoline engine is the power source of vehicle, the high accuracy of hydrogen-enriched gasoline engine model is important to the study of vehicle performance. Thus, a hydrogen-enriched gasoline engine fuel economy model was developed. It included a quasi-dimensional model to calculate the combustion behavior and a dynamic model to calculate the engine kinetic parameters. In the quasi-dimensional model, the two-zone thermodynamic differential equations were established base on the ideal gas equations and conservation equations of mass and energy for the burnt and unburnt zones, respectively. The heat release rate was determined by the turbulence entrainment model. The laminar flame speed correlation of hydrogen-gasoline blends was implemented in this model to characterize the variation of combustion properties after hydrogen addition. The numerical analysis code MATLAB was applied to solve the differential equations. Dynamic model was based on the data provided by quasi-dimensional model and engine mechanical loss model to calculate the engine kinetic parameters under different conditions. The predicting accuracy of the proposed model was evaluated through the comparison with experimental results under different hydrogen volume fractions, equivalence ratios, manifolds absolute pressures and engine speeds.The comparison results confirmed that the proposed model had a high accury and could provided the basic data for the simulation of vehicle.Finally, a vehicle model based on 1.6 L Elantra vehicle produced by Beijing Hyundai was established with CRUISE simulation software. In this model, the fuel economy model of hydrogen-enriched gasoline engines was implemented in vehicle model to study the effect of different hydrogen mixing interval on the fuel economy of vehicle under New European Driving Cycle(NEDC). The simulation results showed that the vehicle accumulated enery consumption was 27.01 MJ for the original gasoline engine-powered vehicle. When the hydrogen addition interval was in the low engine speed and small load condition which the engine speed was less than or equal to 2000 rpm and engine torque was less than or equal to 50 Nm, the hydrogen volume fraction in the intake was 3% and the vehicle accumulated enery consumption was 26.07 MJ. When the hydrogen addition interval was in the high engine speed and large load condition which the engine speed was greater than or equal to 2000 rpm and engine torque was greater than or equal to 60 Nm, the hydrogen volume fraction in the intake was 3% and the vehicle accumulated enery consumption was 26.76 MJ. Compared with the original engine, the energy saving of the second and third hydrogen-enriched strategies was 3.50% and 0.93%, respectively. Therefore, both of the second and third hydrogen addition strategies could save the energy of vehicle compared with original condition and the energy saving effect of hydrogen addition with high speed and large load was better than low speed and small load.