Simulation of hydrogen combustion in neon-oxygen compression ignition engine

Abstract

The elimination of nitrogen oxide (NOx) emissions for hydrogen combustion in the compression ignition (CI) engine is the primary concern, therefore replacing nitrogen with noble gas is one of the solutions to eliminate the NOx emission and improve the engine thermal efficiency. The current research trend focuses on oxygen-argon as the most suitable working. However, external heating for intake is required if operated in low compression ratio (CR) engines. Hence, neon is another option because the specific heat ratio is as high as other noble gasses, and the lower density of neon gas provides a higher temperature during compression. This paper aims to acknowledge neon-oxygen gas as the working gas for stabilization of the hydrogen ignition in the standard ambient intake condition. Besides, the optimum intake temperature and suitable CR were also determined from the analysis of the combustion properties. A computational analysis was performed using Converge CFD software with specific initial temperature and CR conditions base on Yanmar NF19SK engine parameters. The study showed that the minimum initial hydrogen temperature in the neon-oxygen atmosphere was lower than that of oxygen-argon. However, the initial minimum temperature needed for compression ratio 10:1 is 310 K, with the unstable ignition and potential of detonation. Considering the detonation phenomena, the most suitable initial temperature selected is at 380K For operation in ambient condition, pre-heating is still needed. Hence, increase the CR to 14 matched the objective to avoid pre-heating of intake. The neon-oxygen atmosphere is proved as the good working gas in CI engine hydrogen combustion when operated at a higher compression ratio and requires no modification. Analysis of the injection parameters and control of heat loss in the neon-oxygen atmosphere is needed in the future for hydrogen combustion strategies for this type of engine.