Development of a method for the estimation of the behavior of a CNG engine over the NEDC cycle and its application to quantify for the effect of hydrogen addition to methane operations

The so considered engine key points have hence been extensively studied by reproducing the engine performance at the test bench and by performing a detailed heat release analysis. Different composition of the hydrogen-methane blends have been considered up to a 25% by volume of hydrogen in the mixture and specific attention has been paid to the main combustion parameters and to their optimization. As a matter of fact, such a study would allow for detecting major trends in the engine design and control strategies to compensate for the poor behavior of some of the considered points. As an example, low load and speed operations assessed for the need of a better control of the engine parameters to diminish the cylinder-to-cylinder as well as the cycle-to-cycle variability.