The atomization characteristics play a key role in the highly efficient combustion of pyrolysis oil derived from waste tires. In this study, the fuel properties of tire pyrolysis oil (TPO) were initially studied, and then a high-speed camera and a phase Doppler particle analyzer were employed to characterize the atomization feature of TPO. The influence of pressure and nozzle orifice diameter on atomization characteristics such as spray angle, droplet velocity, and droplet size distribution was investigated. The results showed that TPO had a high calorific value of about 43.6 MJ/kg and a low viscosity of 3.84×10^–6 m²/s at 40 °C, which made it have the potential to be used as an alternative fuel. Higher pressure expanded the spray angle and extended the spray in both the axial and radial directions. With increasing pressure, spray angle and droplet velocity raised, and the increase in crushing effect of air reduced the Sauter mean diameter (SMD) of the droplets. To obtain proper atomization quality for combustion, the pressure is expected to be higher than 1.25 MPa. With increasing nozzle orifice diameter, droplet velocity increased, and the SMD of the droplets increased as well due to weakened crushing effect of the orifice. Therefore, the pressure must be increased to maintain the atomization quality when using a nozzle with a larger orifice. Due to the lower viscosity, the velocity and particle size distribution of TPO droplets after atomization were smaller than those of diesel droplets. The extremely small carbon black contained in TPO also contributed to the breaking of droplets and played a certain role in the size reduction of the oil droplets, but it may cause the risk of nozzle blockage. In summary, TPO showed great atomization characteristics for alternative fuel applications.

Graphical abstract

中文翻译：

---

废轮胎裂解油雾化特性

雾化特性对于废轮胎裂解油的高效燃烧起着关键作用。本研究首先研究了轮胎热解油（TPO）的燃料特性，然后采用高速相机和相位多普勒粒子分析仪表征了TPO的雾化特性。研究了压力和喷嘴孔直径对喷雾角度、液滴速度和液滴尺寸分布等雾化特性的影响。结果表明，TPO在40℃时具有约43.6 MJ/kg的高热值和3.84×10 ^–6  m ² /s的低粘度，这使得其具有作为替代燃料的潜力。较高的压力扩大了喷雾角度并在轴向和径向上扩展了喷雾。随着压力的增加，喷雾角度和液滴速度增大，空气破碎作用的增强使液滴的索特平均直径（ SMD ）减小。为了获得适当的燃烧雾化质量，压力预计高于1.25 MPa。随着喷嘴孔口直径的增加，液滴速度增加，由于孔口的破碎作用减弱，液滴的SMD也增加。因此，使用较大孔口的喷嘴时，必须提高压力以维持雾化质量。由于粘度较低，雾化后TPO液滴的速度和粒径分布均小于柴油液滴。TPO中含有的极细小的炭黑也有助于油滴的破碎，对油滴的尺寸减小起到了一定的作用，但可能会造成喷嘴堵塞的风险。总之，TPO 在替代燃料应用中表现出出色的雾化特性。

图形概要