Extending the lean operation limit of a gasoline Wankel rotary engine using hydrogen enrichment

In this paper, an experimental investigation of the effect of hydrogen enrichment on a gasoline Wankel engine's Lean Operation Limit (LOL) was performed. A monorotor Wankel engine operating at 3000 rpm and wide open throttle was modified to run on gasoline and hydrogen blends. Excess air ratio varying from stoichiometric mixtures to the engine lean burn limit with 0%, 3% and 6% of hydrogen energy fractions in the intake were investigated. The experimental results proved that adding hydrogen to gasoline extends the original engine LOL while improving the engine stability. An increased thermal efficiency and reduced burn duration, brake specific energy consumption, and HC, CO and CO2 emissions were observed with hydrogen enrichment. Furthermore, the extension of the engine LOL with hydrogen addition could potentially control the NOx emissions of a gasoline Wankel engine to very low levels without using a three-way catalytic converter.