Investigations on the dependency of equivalence ratio on injector-type gas burners with porous media flame stabilization

In the recent years much attention has been paid on low NO x -burner concepts. Nowadays there is a tendency to emphasize different aspects additionally. More stress is put on criteria concerning the economical and manufactural point of view which means favourable production engineering characteristics. The size of modern residential gas appliances is about to decrease and a wide turn down ratio of the burner itself is becoming more important. Burner surface material, design and furthermore the question, how the gas/air mixture is provided, is of special interest in this context. The most simple and economical way may be the injector-type burner equiped with different kinds of burner surface material namely perforated sheet metal, ceramic fibre or ceramic foam. At Gaswarme-Institut Essen a modular burner prototype has been equiped with various porous media to investigate the possibilities of optimized injector geometries combined with these media. During the investigations a fuel lean premix injector burner for wall mounted appliances has been developed. It has to be pointed out that there is no need of water cooling although the burner operates in radiant mode.