| An investigation was made to determine the effect of hydrogen enrichment (HLFG) on NOx and CO emissions, power, efficiency, and lean operating limit on a normally-aspirated landfill gas-fueled spark-ignition engine. In this investigation a 0.745 liter 2-cylinder Kawasaki engine was modified to operate with simulated landfill gas (60% CH4 and 40% CO2 by volume) containing hydrogen concentrations of 0, 30%, 40%, and 50% (by volume of the CH4 in the fuel). Empirical data was generated and compared with predictions from three existing semi-empirical engine models, using a first law-based finite heat release model to correlate measured pressure data and burn rate for each fuel mixture. Constant-rpm empirical results showed that engine-out NOx emissions could be lowered to the predicted future best available control technology targets for landfill gas to-energy projects of 0.20 g/kWh with 40% hydrogen enrichment, while retaining 95% of the baseline power and keeping CO emissions under 630 ppm. Of the three simulation models tested only "WAVE" software yielded good correlation with the experimental data for HLFG mixtures under the operating conditions in this study. In a cost comparison performed it was determined that only hydrogen enrichment with an in-stream autothermal fuel reformer has the potential to be more cost-effective than current strategies at reaching the NOx reduction target in IC engines. |
