Abstract
A homogeneous-charge lean-burning spark-ignition gas-engine was studied as a diesel alternative. From the experimental results, it was shown that a deep-bowl combustion chamber may significantly suppress the cycle-to-cycle variations under a fuel-lean condition at a higher swirl ratio, thus achieving low NOx emissions at various engine loads by regulating mixture concentrations. Furthermore, the calculation of temperature distributions and NOx formation using a thermodynamic model based on the measured rates of heat release exhibited the availability of a homogeneous mixture for a low-NOx lean-burning gas-engine.