Comparison Between Lean-Burn and Stoichiometric Technologies for CNG Heavy-Duty Engines

Abstract

<div class="htmlview paragraph">Natural gas is a viable alternative fuel to obtain low exhaust emissions. A heavy duty DI Diesel engine was converted to Otto cycle natural gas operation. Two alternative solutions were compared:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">lean-burn technology;</div> </li> <li class="list-item"><div class="htmlview paragraph">stoichiometric feed with three-way catalyst and EGR.</div> </li> </ul> </div> <div class="htmlview paragraph">Power and efficiency were similar for the two above solutions, and exhaust temperature resulted similar to the diesel engine in both cases due to the diluted operation.</div> <div class="htmlview paragraph">The lean bum engine met EURO II ECE-R49 limits except for total hydrocarbons. Stoichiometric engine emissions resulted much lower than the limits. Particulate emissions were quite negligible for the two solutions.</div>