Effects of compression and mixing ratio on NH3/H2 fueled Si engine performance, combustion stability, and emission

Abstract

Carbon-free fuels for the worldwide decarbonization movement are ammonia and hydrogen. The experiment is conducted under WOT conditions with a constant ignition timing of 24°CA BTDC to evaluate performance, combustion stability, and emissions with varying CR (12 to 15), hydrogen energy fractions (5 to 21%), and engine speeds between 1500 and 1700 RPM. BP increased by 31.2% at 1700RPM and BTE increased by 39.0% at 1500RPM, despite a 9% decrease in volumetric efficiency at 1700RPM, from 5% hydrogen fraction at CR12 to 21% hydrogen fraction at CR15.The combustion process is sped up by the effect of hydrogen fraction and CR, causing the flame development and propagation period to shorten. NOx emission was increased significantly with hydrogen and CR, with an increase of 42.34% from 5% hydrogen at CR12 to 21% hydrogen at CR15 at 1700 RPM. Excessive NOx emissions are a drawback that can be successfully controlled by installing after treatment or exhaust gas recirculation technologies. Ammonia is another important key element used to reduce NOx emissions from vehicles because it is used in SCR. © 2022 The Authors