An experimental study of evaporation characteristics of pure and blended biodiesel droplets at high temperatures

The evaporation characteristics of pure and blended biodiesel droplets have been investigated experimentally at different ambient temperatures under normal gravity and atmospheric pressure. The droplet suspended on the welding point of a thin K-type thermocouple method coupled with photographic technique is used to characterize simultaneously the histories of droplet temperature and size. The results indicate that pure and blended biodiesel droplet show the same two phase evaporation process as diesel. With the increase of biodiesel content, the maximum increment of squared droplet diameter and droplet temperature at the end of evaporation process increases. In addition, the transient heating phase th, equilibrium evaporation phase te, droplet lifetime tt increases with the increase of biodiesel content. With the increase of ambient temperature, the evaporation rate k of blends droplet increase, parameters of droplet temperature and time of evaporation phases of blended biodiesel droplet vary non-linearly with the ambient temperature. In addition, the decelerating effect of adding biodiesel to diesel on evaporation obviously weaken with the increase of ambient temperature.