Abstract
Systematic studies of a double-tier (double-stage) combustion device allowing an effective combustion process due to controlled fuel excess independently in the tiers have been reported. The investigations reported stress the attention on the relationship of the NOx and CO emissions to the air excess and demonstrate that there is an optimal range of air supply minimizing them. A mathematical model allows numerical studies on the novel combustion device and reveals the contributions of the combustion processes carried out in each tier to the gross performance of the combustion device.