Experimental Study of Gaseous Flames Issuing from a Conically Stabilized Swirl Burner Using Prevaporized Partially Premixed Biodiesel and Diethyl Ether

This study investigates the effects of blends of diethyl ether, biodiesel, and Jet A-1 fuel on exhaust emissions and flame characteristics in a conical swirl burner. The tested fuels included pure Jet A-1 fuel (B0) and blends of diethyl ether and biodiesel (B5, B10, B5D40, and B10D40), where biodiesel was produced from used waste cooking oil via an ultrasound-assisted transesterification process. The fuel-air mixture was pre-vaporized at 300°C and burned in a cylindrical combustion chamber (diameter-to-length ratio of 3.75:12.5) using a screw burner (swirl number: 0.55) with a lean equivalence ratio (ϕ) of 0.80. Key parameters analyzed were exit temperature, CO, O 2 concentration, NO x emissions, blend ratio (BR), fuel flow rate, and local equivalence ratio (ϕ local ). As ϕ local approached stoichiometry (ϕ local = 1.0), chamber temperatures increased, while NO x and CO concentrations decreased. Conversely, when ϕ local neared the overall equivalence ratio (0.80), exit temperatures and NO x levels dropped but CO levels rose. Increasing the blend ratio, which raises the waste cooking oil methyl ester (WCOME) content, led to lower temperatures and higher CO emissions. All tests achieved stable flames, with the highest temperature of 1570 K using the B10 blend. Adding 40% diethyl ether to the blends notably reduced emissions and improved flame temperature, making this blend ratio ideal for better emission control and flame performance.