Experimental Evaluation of SI Engine Operation Supplemented by Hydrogen Rich Gas from a Compact Plasma Boosted Reformer

It is well known that hydrogen addition to spark-ignited (SI) engines can reduce exhaust emissions and increase efficiency. Micro plasmatron fuel converters can be used for onboard generation of hydrogen-rich gas by partial oxidation of a wide range of fuels. These plasma boosted microreformers are compact, rugged, and provide rapid response. With hydrogen supplement to the main fuel, SI engines can run very lean resulting in a large reduction in nitrogen oxides (NOx) emissions relative to stoichiometric combustion without a catalytic converter. This paper presents experimental results of a microplasmatron fuel converter operating under variable oxygen to carbon ratios. Tests have also been carried out to evaluate the effect of the addition of a microplasmatron fuel converter generated hydrogen in a 1994 production 2.3L four-cylinder SI engine. The tests were performed with and without hydrogen-rich gas produced by the plasma boosted fuel converter with gasoline. Approximately two orders of magnitude reduction in NOx due to very lean operation was obtained under certain conditions. An advantage of onboard plasmaboosted generation of hydrogen is that it is used only when required and can be readily turned on and off. Substantial NOx reduction should also be obtainable by heavy exhaust gas recirculation (EGR) facilitated by use of hydrogen-rich gas with stoichiometric operation.