915 MHz微波在沥青路面再生加热中的应用

Application of 915 MHz microwave in regenerative heating of asphalt pavement

摘要:

为验证915 MHz微波频率用于沥青路面再生加热的可行性,在分析微波加热机理的基础上,设计了喇叭天线参数并对其进行了优化,采用CST仿真软件,进行了915 MHz与2 450 MHz两种微波频率下单天线与阵列天线对沥青混合料的加热效果对比,同时对不同天线间距、加热高度、混合料厚度等对加热效果的影响因素进行了仿真分析。结果表明:915 MHz微波频率加热沥青混合料具有更好的均匀性与深度方向上更小的温度梯度；改变天线间距、加热高度和混合料厚度,会导致加热箱内微波相互干涉现象发生变化,进而对加热效果产生影响,当混合料厚度为250 mm,天线间距为70 mm×70 mm,加热高度为70 mm,此时加热效果最好,混合料温度均值最高,且离散系数最低,温度均匀性好,沥青老化现象较少。对于大型微波再生加热设备,由于其要求加热厚度大、产量高,采用915 MHz更为合适。

Abstract:

To verify the feasibility of 915 MHz microwave frequency for regenerative heating of asphalt pavement materials, on the basis of analyzing the microwave heating mechanism, the horn antenna parameters were designed and optimized, and the heating effect of single antenna and array antenna on asphalt mixture under two microwave frequencies of 915 MHz and 2 450 MHz was compared by using CST simulation software. The influencing factors such as antenna spacing, heating height, and mixture thickness on the heating effect were simulated. Results show that the asphalt mixture heated by 915 MHz microwave frequency had better uniformity and a smaller temperature gradient in the depth direction. The variation of the antenna spacing, heating height, and mixture thickness caused changes in the microwave interference phenomenon in the heating box, which in turn affected the heating effect. Under the conditions of mixture thickness 250 mm, antenna spacing 70 mm×70 mm, and heating height 70 mm, the heating effect was the best, the average temperature of the mixture was the highest, and the discrete coefficient was the lowest, with good temperature uniformity and less asphalt aging phenomenon. For large-scale microwave regenerative heating equipment, due to the requirements for large heating thickness and high output, 915 MHz is recommended.