Experimental study on the electrospray and combustion characteristics of biodiesel-ethanol blends in a meso-scale combustor

The spray and combustion characteristics of biodiesel-ethanol blends were experimentally investigated by using electrospray atomization in a meso-scale combustor. Phase Doppler anemometry measurements were employed to obtain droplet size distribution. Optical measurements were carried out to quantify the electrospray structures. With the addition of ethanol, the spray angle increased and the droplet size decreased from 128 mu m to 12 mu m. The polydisperse spray of the biodiesel-ethanol blends with a low ethanol blending ratio yielded the bimodal distribution in droplet size due to Coulomb fission. Relative standard deviation of monodisperse droplets is below 15%. The combustion of the blends was performed in a meso-scale combustor with a 12 mm inner diameter. The flame can be stabilized near the mesh in the combustor without any external heating. It was found that the spray structures have a direct effect on the flame structures in spray combustion. 40% ethanol addition (BE40) has the best combustion performance compared to other blends. The results show that the flame of BE40 has a broader stabilization limit both in flow velocity and equivalence ratio. The reduction of the droplet size for the blends with high ethanol blending ratio results in the decrease of CO emission. (C) 2019 Elsevier Ltd. All rights reserved.