Natural Gas (NG) is an excellent alternative fuel for spark ignition engines because of its high knock resistance. However, high methane (CH4) emissions from NG present a challenge as CH4 is one of the leading greenhouse gases that drive global warming. Blending NG with a fuel of higher flame velocity such as Hydrogen (H2) is desirable since it reduces the carbon intensity of the fuel and results in lower CH4 emissions and improved efficiency. This study investigates Natural Gas/Hydrogen (HNG) blends on a large-bore, two-stroke, spark ignition engine with H2 concentrations of 0, 10, 15, 25 and 30% by volume under lean burn conditions. The blends were tested at three different operating conditions i.e., 40, 60 and 70% of the rated load. The results indicated a decline in CH4 emissions with the addition of H2. The maximum reduction observed was 49% at the 40% load and 30% H2 concentration. Moreover, adding H2 led to improved combustion stability and thermal efficiency. The coefficient of variation (COV) indicated mean effective pressure (IMEP) reduced by 23% and indicated thermal efficiency (ITE) improved by 5.9%. The natural gas/hydrogen blends will be tested with varying spark timings and relative air-to-fuel ratios to further enhance the impact of H2 addition on engine performance, fuel efficiency, and combustion stability, along with CH4 emissions.
