The Enhancement Of Heat Dissipation Of High Power LED Lamp With Chimney Effect

High power LED street lights are widely used in the field of lighting because of the advantages of small volume, long service life and saving energy, but the small size due to that heat transfer problems become the key factors which hinder its development. Compare with forced convective, natural convection is more economic and stability. This paper proposes a radiator with stack effect and study its heat transfer by numerical simulation.Firstly, we propose the numerical model and the boundary condition, simulate for the experimental from other scholars and comparison, their similar results show that numerical simulation to solve these problems is feasible. Secondly, under the same heat source, quality, material we contrast the chimney effect and common flat fin radiator. For stack effect of monomer radiator fin, at first study the effect of the ratio of slot. Secondly, we study the effect of height with the same width. Lastly, we study the effect by fins’distribution density in the same plate. Due to the lighting equipment have inevitable inclined in the practical application, on the one hand this paper study the problem of rotation angles; On the other hand we compared stack effect fins with common flat fin radiator, study their inclined in two mutually vertical directions.Results show that the stack effect radiator can reduce the substrate temperature effectively. And then, we found that under larger heater there is a peak in variation temperature curves by different ratios of slot, but under the smaller heater substrate temperature curve is almost a straight line. The results of fin height variation show that when it increased from150mm to270mm, the radiator’s volume increased by80%, but just1.5℃temperature decrease. During we study the distribution density of stack effect fins, the results show that with it increases, at first the substrate temperature decrease rapidly, but it could rise slowly and even to initial level when step in critical density, on the other side, rectangular fins’substrate temperature decrease slowly and its critical peak move to large distribution density. Under the same condition of inclined, with the variation of rotation angles the radiator’s substrate temperature decrease9℃and Nu increases by15.96%. When we compare Stack effect radiator with rectangular finned radiator, in the x-y and Y-Z planes, in initial step the latter temperature change mildly, at the same time the former rise more fast than the latter and beyond it gradually. But, if the inclined reach a certain angle, substrate temperature of rectangular finned radiator increased sharply and soon surpass stack effect radiator. All of above shows that the set mode of radiator is one of the main factors influencing the performance of radiator, and with the structure of the stack effect can improve flow field effectively and enhance heat transfer.