BACKGROUND
Ammonia (NH3) is a carbon-free energy carrier that offers significant advantages in terms of transport and storage compared to the more prominent hydrogen (H2). However, ammonia has a low reactivity and can therefore probably not be used in pure form in technical combustion systems. However, the reactivity can be significantly improved by mixing it with other fuels and if hydrogen is used as an additive, the combustion process remains carbon-free. Partial cracking is a promising strategy here: splitting NH3 produces H2 and N2. If only part of the ammonia is cracked, mixtures of NH3, H2 and N2 are produced and the energy required for partial cracking is correspondingly lower. It has already been shown that these mixtures have a considerably higher reactivity compared to conventional fuels such as natural gas. However, certain reaction pathways during the oxidation of ammonia lead to the formation of high quantities of nitrogen oxides (NOx). Available reaction mechanisms that can be used to predict emissions, among other things, show considerable differences. The research project is therefore focussing on determining basic experimental data that will contribute to a better understanding of the kinetic processes.
A laminar counterflow burner is often used for the investigations, on which so-called twin flames can be stabilised if the premixed fuel-air mixture is fed from both nozzles at the same speed. One of the advantages of this burner is the optical accessibility along the burner axis, which enables spatially resolved measurements through the reaction zone. Furthermore, a flat flame burner is used as a calibration burner or for analysing the exhaust gas composition directly behind the reaction zone.
