Development of a lean premixed low-swirl burner for low NOx practical applications

Laboratory experiments have been performed to evaluate the performance of a premixed low-swirl burner (LSB) in configurations that simulate commercial heating appliances. Laser diagnostics were used to investigate changes in flame stabilization mechanism, flowfield, and flame stability when the LSB flame was confined within quartz cylinders of various diameters and end constrictions. The LSB adapted well to enclosures without generating flame oscillations and the stabilization mechanism remained unchanged. The feasibility of using the LSB as a low NOx commercial burner has also been verified in a laboratory test station that simulates the operation of a water heater. It was determined that the LSB can generate NOx emissions < 10 ppm (at 3% O-2) without significant effect on the thermal efficiency of the conventional system. Our study has demonstrated that the lean premixed LSB has commercial potential for use as a simple economical and versatile burner for many low emission gas appliances.