Numerical investigation on the influences of swirling flow to thermal efficiency enhancement of an LPG-energy saving burner

Abstract

This study investigated a swirling flow in household LPG burners and its effects on thermal efficiency enhancement. Modified from a typical energy-saving burner (EB), a newly invented swirling flame energy-saving burner (SEB) was built and tested both experimentally and numerically. Computational Fluid Dynamics (CFD) simulations were employed to investigate the flow inside the SEB with an inclined angle of 50 degrees and a swirl angle of 15 degrees as well as the flow inside the EB. The computational results were used to calculate the heat conversion efficiencies, which were then compared to the experimental values obtained from the water boiling test (DIN EN 203-2 standard). Additionally, the simulations provide data on the combustion temperature, the turbulence intensity, and the secondary air flow rate. This detailed information clearly confirms that the swirling flow does increase the maximum combustion temperature and the net heat flux into the vessel, directly enhancing the heat conversion efficiency and thus increasing the thermal efficiency. According to the simulations, the heat conversion efficiency of the SEB is around 3.44% greater than that of the EB, while the experiments show that the SEB gives approximately 2.75% higher thermal efficiency than that of the EB. The future expectation is that the heat conversion efficiency can be used to predict the increase in thermal efficiency. With this method, the commercial design of the energy-saving burner can be improved.