Leakage Enhancement of Hydrogen Blends From Fittings, Stratification of Hydrogen Blends in Vertical Risers, and (if time allows) Other Recent Combustion Testing Results

1. Correctly assembled gas fittings inside buildings exhibit minimal or no leakage of natural gas and natural gas + 30% hydrogen blends, highlighting the importance of proper assembly and maintenance to ensure safety and reliability in hydrogen integration.
2. In gas appliances tests fueled with a 30% hydrogen-methane blend, we observed a significant decrease in methane slip but a simultaneous increase in hydrogen emissions from the combustion system. This requires further investigation.
3. In measuring the impact of hydrogen blending on the efficiency of conventional natural gas appliances, we observed an impact on the order of 1-3% up to 30% H2 by volume. The most significant change was with a condensing furnace, showing an increase in efficiency.