Optimization Of High-power LED Lamp Heat Sink And Thermal Characteristics Analysis

High power LED (Light Emitting Diode) light has the character of energy conservation and environmental protection as the fourth generation light source, it is an environment friendly product. With an energy emergency and environmental pollu-tion, the LED will play more and more important role. At present, because of technology and heat dissipation problems of the high power LED lamp, which limit the LED lamp large-scale use, it will play a great significance to solve the problem of heat dissipation and the optimization of heat sink.First of all, finned heat sink is widely used for solving the problem of heat in the high power LED lamp, for the street lamp of LED, the way of natural convection has got the extensive application and research which are low cost, convenient maintenance, stable performance and etc advantages. In order to enhance the heat transfer of heat sink with straight fins of the high power LED lamps working under natural convection, structure optimization of this kind of heat sinks has been carried out.Based on a method of the minimum entropy generation, the influences of the important parameters on the heat transfer and fluid friction of the heat sink have been analyzed, such as the fin thickness and the numbers, the height of fin, total quality of the heat sink and wind speed. The results showed that the dimensionless entropy generation and the temperature entropy generation first increased, and then decreased with the increase of the number of the fins, and the entropy generation caused by temperature was about ten times of that by friction. In addition, under a given heat flux, there existed the best geometry parameters of heat sink fins that could minimize the entropy generation, and which could improve the whole performance of the heat sinks.Secondly, for the purpose of optimizing the straight fins heat sink, experimental researches and numerical simulation of this kind of heat sink have been carried out. Computational fluid dynamics (CFD) method is used to simulate the heat transfer performance of the heat sink, and the results show that both the average convection heat transfer coefficient and the heat resistance decrease with the increase of the number of fins. The height of the fins have the same effect on LED array thermal performance with the number of fins. When the heating power is increased, the horizontal air import volume is increased at the same time, both of them can lead to the decrease of the thermal resistance and the increase of the average convection heat transfer coefficient.Based on the field synergy principle, the decrease of the synergy angles are conducive to strengthen the heat sink thermal performance. Furthermore, the radiation play an important role in the whole heat transfer process of this type of LED under natural convection conditions, which not only increase heat transfer efficiency and weakens the thermal resistance, but also lower the LED junction temperature. So the radiation will be helpful to improve the heat transfer performance. In addition, according to the regression analysis method, the average Nusselt criterion correlations is derived. The calculated results of the simulation are also compared with the experimental data. The study suggest that the established mathematical model is able to predict the heat transfer characteristics of this type of heat sinkMoreover, the heat property test platform of array heat sink is setted up in the paper, the results of heat sink surface temperature are contrasted between numerical simulation and experiment test to verify the correctness of the numerical simulation,so it will be used in the next study of phase and will provide a good foundation and research method. It has certain guiding significance in the department of optimization the heat sink for saves time and cost.Finally, according to the front of the problem found in the experimental, in order to guarantee the high power LED lamp can be work in the normal environment temperature and demand different conditions, using the experimental method which make the high power LED lights can be used to control the temperature of heat accumulation. When power is changed, the "no phase change materials, paraffin wax phase change materials, paraffin wax and expanded graphite composite phase change materials are studied in order to compared high power LED lamp’s base plate surface temperature and heat sink’s surface temperature field changes in the three conditions. The comprehensive integration of high power LED lamp radiator research content and guiding direction.