基于最小能耗的沥青路面就地热再生加热机组优化控制

Optimization Control of Heating Equipment in Hot In-place Recycling of Asphalt Pavement Based on Minimizing Energy Consumption

原路面加热是沥青路面就地热再生的核心工艺环节,为探寻就地热再生加热机组运行速度及加热功率的合理组合,根据能量守恒定律建立了沥青路面就地热再生加热过程的传热模型,结合就地热再生原沥青路面加热特点,将传热模型转化为沿路面深度方向的一维传热,并依托沥青路面就地热再生实体工程,通过现场埋置温度传感器,监测加热机不同加热功率下路表及路表以下不同深度的温度,通过拟合传热方程,反演计算获得加热机组最大、最小功率的辐射热流密度。然后通过遗传优化算法结合传热模型,以加热过程最小化能耗为原则,寻找不同运行速度下加热机组的最优组合。结果表明:建立的传热模型能够较好地拟合就地热再生原路面加热的温度场;沥青路面加热时,热量的散失及温度传递的滞后性将会影响到加热机组热效率;按照最小化能耗的加热原则,3台加热机应先以最小功率进行加热,当需要提高加热机加热功率时,应优先增加第2台加热机的加热功率,然后是第1台,最后是第3台;由于加热机功率的限制,为满足沥青路面就地热再生加热温度要求,加热机运行速度应该小于等于3.2 m/min;推荐加热机组适宜的运行速度范围为2.4~3.1 m/min,在该范围内不仅能够满足加热过程的温度要求,还能最小化能量的消耗。

Original pavement heating is the core process in hot in-place recycling(HIR)of asphalt pavement.In order to explore a reasonable combination of running speed and heating power of HIR heating units,the heat transfer model for HIR process of asphalt pavement is established based on the law of conservation of energy.Combining with the heating characteristics of the original asphalt pavement,the heat transfer model is transformed into 1D heat transfer along the depth direction of the pavement.Relying on the HIR project of asphalt pavement,the temperature sensors are embedded on site to monitor the temperatures at different depths of road under different heating powers of the heating machine.The heat transfer equation is fitted,and the radiant heat flux densities of the maximum and minimum powers of the heating units are calculated by inversion calculation.Then,based on the principle of minimizing energy consumption during the heating process,the optimal combination of the heating units at different operating speeds is found by using optimized genetic algorithm and the heat transfer model.The result indicates that(1)The established heat transfer model can well fit the heating temperature field of the original asphalt pavement in HIR.(2)When heating the asphalt pavement,the heat loss and the hysteresis of temperature transfer will affect the thermal efficiency of the heating units.(3)According to the principle of minimizing energy consumption,3 heating units should work with the minimum power at first.When the heating power is expected to increase,the heating power of the second heating unit should be increased at first,then the first heating unit,and finally the third heating unit.(3)Due to the limitation of the power of the heating unit,the operating speed of the heating units should be less than or equal to 3.2 m/min to meet the temperature requirements of asphalt pavement in HIR.(4)It is recommended that the suitable operating speed range of the heating units is 2.4-3.1 m/min,which not only can meet the temperature requirements of the heating process,but also can minimize the energy consumption.