Experimental evaluation of burner cap design on energy efficiency in residential gas geysers

This research evaluates the thermal and combustion efficiencies of plate, circular, and swirl burners, with a particular focus on the influence of swirl angle on performance. The swirl burner achieved peak thermal and combustion efficiencies of 54.1 % and 75.2 %, respectively, at a 49° cap angle, where enhanced turbulence and improved air-fuel mixing minimized CO emissions to 0.0027 % corresponding to 27 ppm, dry basis, measured with a calibrated Testo 350 analyzer. This low CO concentration reflects optimized combustion under controlled laboratory conditions and is consistent with previously reported ranges for high-performance swirl burners. In comparison, the plate burner attained 48.97 % thermal and 47 % combustion efficiency, while the circular burner reached 46.81 % and 57 %, respectively. Other swirl angles, such as 41°, 45°, 53°, and 55°, produced lower efficiencies due to less favorable combustion dynamics or excessive airflow. These results demonstrate that geometric optimization of burner caps, particularly through swirl angle adjustment, can significantly enhance combustion efficiency, reduce emissions, and provide a practical pathway toward more energy-efficient and environmentally sustainable residential gas appliances.