Effects of injection mode on the mixture formation and combustion performance of the hydrogen internal combustion engine

For the hydrogen internal combustion engine with port fuel injection, H2 into intake port from injection system will expand, which will block the entry of air. Two types of injection modes, the dual injection with symmetric arrangement and that with spaced arrangement along the axis of intake port, were proposed to improve the blockage of intake port. And the effects of three types of injection modes (single pipe injection, two kinds of dual injection) and nozzle diameter on mixture formation and combustion performances were investigated. It is found that the mixture uniformity in cylinder is improved by using dual injection (especially the spaced dual injection). The combustion velocity is improved, especially when the equivalent ratio is 0.67. However the NOx emission increases. The uniformity coefficient of mixture is gradually decreasing, and the indicated power and indicated thermal efficiency are increasing first and then decreasing with the increase of nozzle diameter. The temperature in cylinder is highest by using the spaced dual injection, and the distribution of high temperature area also expands. Thus pre-ignition is more likely to occur. But the residual hydrogen mass in intake port reduces obviously after closing the intake valve, backfire can be restrained.