Effects of hydrogen blending ratio on combustion and emission characteristics of an ammonia/ hydrogen compound injection engine under different excess air coefficients

Currently, hydrogen and ammonia are the best green, zero-carbon energies worldwide. Applying ammonia and hydrogen to internal combustion engines is a top priority for achieving the dual-carbon goal for the automotive industry. However, both ammonia and hydrogen have disadvantages that make them unsuitable for use as fuels on their own. Hydrogen internal combustion engines can suffer from abnormal burning, such as premature ignition, backfiring, and detonation. At the same time, the difficulty of hydrogen storage, transportation, and refilling can also lead to the problem of high cost of use. Ammonia suffers from high ignition energy, poor flame-spreading speed, and inadequate burning stabilization. When used alone, it causes incomplete combustion of large amounts of ammonia. Therefore, our group uses the spray pattern of "hydrogen direct injection (HDI) plus ammonia port injection (API). " The influence of hydrogen blending ratio (HBR) on the combustion and emission characteristics of an ammonia/hydrogen compound injection engine with various excess air coefficients (l) is investigated. The blending ratios of hydrogen are 6.1 %, 16.8 %, 27.3 %, 37.7 %, 47.8 %, and 57.7 %, respectively. The experimental data suggests that the indicated mean effective pressure (IMEP) shows an incremental trend as the hydrogen blending ratio grows. Not only CA0-10 but also CA10-90 have been reduced. The whole combustion process is shortened. The temperature and pressure rise. When the ratio of hydrogen blending is higher than 27.3 %, the enhancement of the burning characteristics by hydrogen is not apparent. NOX emissions rise with the ratio of hydrogen blending. NH3 emissions tend to drop as the blending ratio of hydrogen rises. Combining the emission and combustion characteristics, the general engine performance is better when the l is 1.2 and the ratio of hydrogen blending is 27.3 %.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.