Inline Hydrogen Sensor Monitoring of a Tankless Water Heater Operating Up to 30% Hydrogen Blending.

Decarbonization of the buildings sector utilizing hydrogen has become a promising technical option to combat global warming. Therefore, blending hydrogen into natural gas infrastructures and providing low carbon fuels to appliances is being investigated worldwide. To facilitate the upcoming energy transition in building gas transmission, testing of existing appliances performance while operating on natural gas/hydrogen mixtures need to be conducted. In this study, various methane/hydrogen blends were supplied to a tankless water heater to study on the hydrogen impact on the water heater performances. The hydrogen percentage in the fuel mixture varied from 0% up to 30 vol%. In hydrogen blending efforts, it is of great interest for both gas utility companies and facility operators to be aware of the exact hydrogen percentage in the pipeline before or during combustion device operation. Moreover, there are also questions regarding hydrogen stratification and segregation after blending, due to the low density of hydrogen compared to the heavier hydrocarbons in natural gas infrastructures. Therefore, under this project, two inline gas sensors were installed in the residential pipeline to monitor the hydrogen contents and other fuel properties in real time, synchronized with the tankless water heater testing. This project demonstrates the feasibility for existing natural gas appliances operating on hydrogen-enriched fuels, with the gas contents being monitored using inexpensive sensors. This study provides the near future scope of gas utilities or gas consumers monitoring the gas contents in the pipeline with gas flowing into end use devices. The demonstrated example, using a varied-heating load tankless water heater with the highest gas input rate of 199,000 Btu/hr (58 kw) operating on natural gas/hydrogen blends, demonstrates the potential for domestic appliances carbon reduction using hydrogen. [ABSTRACT FROM AUTHOR]