The Study Of Asphalt’s Electric And Thermal Field Based On Microwave Heating And Its Control

Microwave has been widely used in industry as a new type of energy. Microwave heating rely on high-frequency alternating electromagnetic field in the material of polar molecules collide with strenuous exercise to generate heat. In this paper, based on the principle of microwave heating and its advantages, a further study has been down combined microwave heating and microwave hot in-place. The purpose of this study is to obtain the temperature field of asphalt surface and analyze the distribution of temperature field, optimized for heating asphalt heating chamber of pyramidal horn structure and build structures array pyramidal horn wall heating control system.Specific works are as follows:(1) Select pyramidal horn heating cavity, non-steady-state heat transfer model is established based on the Fourier heat transfer theory. The internal heat source intensity of asphalt mixture is calculate and discrete the solution region to obtain the heat conduction equation. By applying the variational principle, the corresponding boundary conditions and initial values are brought into the solution, The corresponding partial differential equations are transformed into the extreme value problem of the corresponding functional. By the superposition of each unit to get the solution of the functional region in the region on the temperature of the expression, and finally to solve the total temperature stiffness matrix.(2) Through asphalt mixed material heating experiments and finite element simulation methods to obtain the asphalt mixture temperature field test and finite element simulation of temperature field by selecting of a pyramidal horn antenna. Analysis of two kinds of methods to obtain the asphalt mixture temperature changes in the electric and magnetic fields, and fitting a 3D temperature field.(3) Three groups of asphalt mixture in the temperature field is obtained by heating simulation, and horn antenna structure is optimized through the establishment of the temperature rise rate criterion and uniform electric field criterion.(4) Collecting pavement pit groove and crack image by Camera, through the software of MATLAB developed the human-machine interface of asphalt pavement pit groove crack detection system. In order to decision which horn heating chamber need to work, a horn heating wall control system is designed and used for digital image processing of the collected pits and cracks and the information of its location. The control system with PLC as the core, solenoid valve as the control object, control panel with Siemens Smart700IE touch screen, and configuration write soft panel operation by WinCC flexible2008 tools.Through the above research, the following conclusions and results are obtained:(1) The total temperature stiffness matrix of the asphalt mixture is obtained by theoretical analysis.(2) Through the pyramidal horn heating cavity to heat the asphalt mixture experiment and finite element simulation, two kinds of methods’s temperature field distribution was the same, so finite element simulation is feasible.(3) Based on the simulation experiments and obtained consistent results, the temperature field obtained by the finite element simulation method, a horn length optimization size pyramidal horn antenna in the same aperture sizes is obtained by establish the temperature field temperature rise rate criterion and uniform temperature criterion of the pyramidal horn.(4) The array of pyramidal horn heating wall control system is built, the pyramidal horn heating cavity’s work is guided by the information of asphalt pavement’s pit groove and crack through digital image processing method. PLC is used to control the solenoid valve to determine pyramidal horn heating cavity extends and return to repair the asphalt pavement in the presence of defects.