Experimental study on evaporation and micro-explosion characteristics of biodiesel/n-propanol blended droplet

The evaporation and micro-explosion characteristics of biodiesel/n-propanol blended droplets at 573, 673 and 773 K ambient temperatures are studied using high-speed backlight imaging technique. The results show that the droplet evaporation is relatively stable at 573 K. However, micro-explosions occur at 673 and 773 K, the micro-explosion intensity increases with ambient temperature. The calculated superheat limit of n-propanol is 490 K. The blended droplet micro-explosion occurrence time is associated with the n-propanol concentration. The lower content of n-propanol, the earlier blended droplet micro-explosion occurs, and vice versa. The micro-explosion intensity and evaporation rate of the blended droplet first increase and then decrease as the n-propanol concentration increases. The micro-explosion delay time of the blended droplet first decreases and then increases with the increase of n-propanol concentration. Interestingly, the micro-explosion intensity, evaporation rate and micro-explosion delay time of droplet all reach the optimum value when the n-propanol concentration is 50%. Moreover, the oil membrane formation mechanisms of the soluble blended droplet with two different blended structures (n-propanol in biodiesel and biodiesel in n-propanol) are proposed. (C) 2020 Elsevier Ltd. All rights reserved.