Experimental study on Miller cycle hydrogen-enriched ammonia engine by rich-burn strategy

In order to achieve climate goals as soon as possible, it is necessary to reshape the energy mix to replace fossil energy with carbon-neutral fuels as soon as possible. Ammonia is a good medium for energy storage, has a large industrial scale and a well-developed infrastructure. To address the problems of NOx emission and low exhaust energy of ammonia-hydrogen engines, this study proposes a rich burn strategy. Firstly, a commercial spark ignition (SI) internal combustion engine (ICE) was modified to achieve a dual fuel supply of ammonia and hydrogen. The engine was run at a steady state of 1500 rpm with the intake manifold absolute pressure (MAP) maintained at 60 kPa, and the ammonia and hydrogen supplies were adjusted to achieve different mixing ratios and excess air ratios. The experimental results showed that the rich burn strategy could significantly reduce the NOx emission and increase the exhaust temperature of the ammonia-hydrogen engine when the excess air co-efficient was below 0.8. The rich burn strategy can appropriately increase the engine power output, but it has some influence on the brake thermal efficiency (BTE).