Hydrogen and natural gas comparison in diesel HCCI engines -a review

Abstract

Abstract—Homogeneous charge compression ignition (HCCI) enginesuse a new mode of combustion. The new challenges in developing HCCI engines arethe difficultiesin: controlling the auto-ignition of the mixture and the heat release rate at high load operation, achieving a cold start, meeting emission standards and controlling knock. At low engine speeds, early auto-ignition can occur, possibly leading to knocking, while late auto-ignition at high engine speeds will make HCCI susceptible to misfire. Hydrogengreatly reduces emission levels but with reduced power. However, when it is combined with diesel in dual fuel mode, low NOx, CO and particulate matter emission levels are achieved while increasing engine efficiency by 13-16%. Numerical methods areused to predict HCCI engines’ performance, which is cost efficient compared toexperimentation alone. The multi-zone method promises better simulation results by combining detailed chemical kineticswith simplified 3Dmodellingso that turbulence and inhomogeneity in the mixture are considered; good agreement between simulations and experiments has been achieved. Specific strategies used in the experimental and numerical methods, and other issues associated withHCCI engines are discussed in this paper.