Renewable hydrogen in gas grids, Effects on laminar burning velocities

H Krause; Eckart Sven
Hydrogen can be injected into the gas grid by using different power to gas methods, so the combustion influence of hydrogen is more and more of interest. Furthermore, the laminar burning velocity is one fundamental property of a reactive oxidizer-fuel mixtures, varying with pressure, initial composition and temperature. These values are important for validation of reaction mechanisms and the specific design of industrial burners. There are several experimental methods to measure laminar burning velocities, e.g. the stagnation flame method, the Bunsen flame method, the spherically expanding flame method and the flat flame burner method, which also includes the heat-flux burner method. The accuracy of the different methods could be strongly enhanced over the last ten years but there are still uncertainties of up to 25 % depending on method, boundary condition and fuel composition. Furthermore, for a lot of fuels, especially hydrogen containing fuel blends, there is a lack of experimental data. In this study, the heat-flux burner method was applied to measure the laminar burning velocities of hydrogen containing fuel blends. These fuel blends are of major interest since the hydrogen concentration in the gas grid system could in future rise to a significant value. For example, within the “power-to-gas” concept, some new technologies arise to use renewable energy to produce hydrogen and take it as “fuel”. So the change of the gas composition also changes the combustion properties, for example the burning velocity, heating value and ignition delay. Therefore, different hydrogen containing fuels were tested within a wide range of equivalence ratios between 0.7 and 1.6. Initial temperatures of 293 K up to 383 K were tested for atmospheric conditions. With these results the lack of data for hydrogen containing gases could be significantly closed and helps to validate reaction mechanisms for better simulation of internal combustion systems.
Thermal Engineering
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