Research on Combustion Processes Relevant to Burners in HVAC Systems. FinalReport, July 1 1991-July 31, 1994

摘要

An experimental investigation of the effects of using noncircular geometries forthe fuel nozzles, primary-air venturi inlets, and burner exit ports in the inshot burners of residential natural gas heating systems is presented. These burners generally produce partially-premixed laminar flames. For global characterization, primary-air entrainment and exhaust emission indices of NO, NOx, and CO were measured. For detailed flame structure, radial profiles of temperature and major species concentration were recorded. Shadowgraphy was used for flow visualization. Most of the experiments were performed in lab-scale combustion chambers. Some verification tests were conducted in a full-scale furnace. The results show that, generally, primary-air premixing and secondary-air entrainment increase, and the NOx emission decreases for noncircular cross-sections. However, CO emission can increase in some of these cases. Deeper examination of the flow and chemistry coupling mediated by noncircular shapes is warranted before clear design paths of applying noncircular shapes are recommended.