Heat Transfer Model and Numerical Simulation for Microwave Hot In-Place Recycling of Asphalt Pavements

To assess the temperature field when microwave heating is used to recycle asphalt mixtures, a two-dimensional mathematic model considering the heat absorbed and conducted by microwave internal heat-generation was developed based on a Fourier heat transfer model. The microwave internal heat-generation was modeled by approximating the radial field by a two dimensional planar surface with uniform dielectric properties throughout. The control volume based finite difference method (CV-BDM) was used to establish a discrete form of the energy conservation equations, and a numerical simulation was conducted. Results showed that non-linear heat transfer. For confirmation, an experiment was conducted using a microwave power system at 2.45GHz and recording the temperature variation as a function of surface location and heating time within samples of asphalt mixture. The data confirmed that this microwave heating method could both heat the mixture in a reasonable time and improve temperature uniformity.