NOx emission reduction in a hydrogen fueled internal combustion engine at 3000 rpm using exhaust gas recirculation

This paper describes five experiments conducted on a 2-l, 4-cylinder Ford ZETEC internal combustion engine (ICE) developed to operate on hydrogen fuel. The experiments were conducted to ascertain the effect exhaust gas recirculation (EGR) and a standard 3-way catalytic converter had on NOx emissions and engine performance. All the experiments were conducted at a constant engine speed of 3000 rpm and each experiment used a different fuel flow rate, ranging from 1.63 to 2.72 kg/h. These fuel flow rates correspond to a fuel equivalence ratio, Φ, ranging from 0.35 to 0.75 when the engine is operated without using EGR (i.e. using excess air for dilution). The experiments initially started with the engine operating using excess air. As the experiments proceed, the excess air was replaced with exhaust gas until the engine was operating at a stoichiometric air/fuel ratio. The results of these experiments demonstrated that using EGR is an effective means to lowering NOx emissions to less than 1 ppm while also increasing engine output torque.