Effect of 2, 5-dimethylfuran concentration on micro-explosive combustion characteristics of biodiesel droplet

Abstract

Micro-explosive combustion is considered as an effective way to improve combustion efficiency in combustor. In this work, the micro-explosive combustion characteristics of biodiesel and DMF blended droplet are investigated using high-speed backlit image technique. The droplet is suspended at the intersection of two quartz fiber and ignited by a pair of electrodes. Flame temperature and soot concentration are measured using two-color pyrometry method. Moreover, two new parameters are proposed to analysis droplet micro-explosion, namely droplet instability and breakup index. The results shown that the instability of DMF25BD75, DMF50BD50 and DMF75BD25 droplets is mainly caused by bubbles coalescence, internal circulation of bubbles, micro-explosion and vapor jetting. The low-temperature flame region is mainly located near the droplet surface and flame edge. However, the soot concentration is highest in these two regions. The combustion of blended droplet includes a micro-explosive combustion stage and a stable combustion stage. Four modes of secondary atomization is determined according to droplet breakup index. When the DMF concentration is 50% and 75%, the burning rate is 9% and 37.5% higher than diesel, which is expected to realize rapid and high-efficient combustion.