Effects of Air Fuel Ratio and Injection Timing on Performance for Four-Cylinder Direct Injection Hydrogen Fueled Engine

In this study, the influence air fuel ratio and injection timing on the engine performance of 4-cylinder direct injection hydrogen fueled engine was investigated. The effect of air fuel ratio (AFR) and engine speed on optimum injection timing is presented. The 4-cylinder direct injection hydrogen engine model was developed utilizing the GTPower commercial software. This model employed one dimensional gas dynamics to represent the flow and heat transfer in the components of engine model. Sequential pulse injectors are adopted to inject hydrogen gas fuel within the compression stroke. Injection timing was varied from 110 before top dead center (BTDC) until top dead center (TDC) timing. Engine speed was varied from 2000 rpm to 6000 rpm, while the equivalence ratio was varied from 0.2 to 1.0. The validation was performed with the existing previous experimental results. The negative effects of the interaction between ignition timing and injection duration was highlighted and clarified. The acquired results show that the air fuel ratio is strongly influence with optimum injection timing on the engine performance. It can be seen that the indicated efficiency increases with increases of AFR, power and torque increases with the decreases of AFR, indicated specific fuel consumption (ISFC) decreases with increases of AFR from rich conditions to lean. The injection timing of 60 BTDC was the overall optimum injection timing with a compromise.