Laminar burning velocities of low calorific and hydrogen containing fuel blends

Abstract

The laminar burning velocity is a fundamental property of a reactive fuel-oxidizer mixture, varying with composition, pressure and initial 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 velocity, e.g. the bunsen flame method, the spherically expanding flame method, the stagnation flame method and the flat flame burner method, which also includes the heat-flux burner method. The accuracy of the different methods could be enhanced over the last years but there are still uncertainties of up to 30 % depending on method, boundary condition and fuel composition. Furthermore, for a lot of fuels, especially fuel blends, there is a lack of data.In this study, the heat-flux burner method was applied to measure laminar burning velocities of low calorific fuels and hydrogen containing fuel blends. These fuel blends are of major interest since the hydrogen concentration in the gas grid system could in future 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”. On the other hand, the change of the gas composition also changes the combustion properties, for example burning velocity, heating value and ignition delay. Therefore, different low calorific fuels and hydrogen containing fuel are tested within a range of equivalence ratios from 0.7 to 1.4 for initial temperatures of 298 K up to 363 K for atmospheric conditions.