| The hot in-place recycling as a fast,economical and environmentally friendly maintenance technology of asphalt pavement can be used to repair various flaws in the range of 5cm under asphalt pavement,which has been paid a great attention by highway maintenance industry.The metal fiber burner is the essential device of the process of hot in-place recycling,and it remains some problems,such as combustion instability and non-uniform heating.Through the analysis and study of the combustion radiation characteristics of the gas infrared radiation heater and got the method that improving the heating efficiency and radiation homogeneity of the heater.It can achieve the pavement repair effect of high efficiency and save energy.This thesis is based on the Project Study on heat transfer mechanism of the infrared continuous heating process of Asphalt Pavement Based on spectral analysis supported by NSFC.First,the thesis introduced the combustion principle of the porous medium,and analyzed the main factors which impact the radiation intensity of metal fiber heater.The paper has researched on the feature of infrared absorption of asphalt pavement and the optimum mesh temperature of the metal fiber burner is determined.Meanwhile,a rectangular heater with a heating power of 110kW/m~2 was selected as research object,calculated the amount of heater generated exhaust gas and average temperature of net.Then the paper based on the assumption of rectangular heater's metal fiber network structure established the micro model of the net,through Fluent software utilized numerical simulation to the process of combustion,and researched single and double porosity metal net models on the stability of metal fiber net surface during combustion.Secondly,through utilized Fluent software simulated flow field of the head of the heater,analyzed airflow in the head of heater and its homogeneity on the surface of metal net.At last,by means of establishing combustion test platform of metal fiber heater,the temperature distribution of the metal net surface during the combustion process of the heater was tested,and have finished structure design of splitter plate by the orthogonal test so as to improve the radiation homogeneity of the heater.The research results are as follows:Using the mismatched absorption theory can increase the penetration depth.The optimum surface temperature of the heater is calculated at 600~750?by selecting the appropriate radiation wavelength of metal mesh.The flue gas temperature and metal mesh temperature obtained by simulating the combustion state of the rectangular heater is consistent with the thermal calculation,and came to a conclusion that the combustion safety of double porosity metal fiber is higher than single porosity metal fiber.The trend of air distribution on the surface of metal fiber net which is obtained by numerical simulation for the flow field of the head of the rectangular heater is consistent with trend of surface temperature distribution of metal net by testing.It is concluded that the first grade splitter plate's structure is the main factor which is impacting the radiation uniformity of the metal fiber heater,and ascertained the structure of the first grade diffuser plate which can achieve uniform airflow distribution. |
PDF Full Text Request