Thermal Design Of LED Luminaires Based On Multi-physics Problem Analysis

Three LED lamps, which respectively are 28 W LED headlamp,18 W LED streetlamp, 12 W LED indoor lamp, were chosen as objects of study in this paper. Combined with ANSYS, EFD, and their different characteristics,Multi-physics theory was applied to design heat dissipation of the LED lamps and its drive circuit. The main contents of this paper are as follows:(1) A heat-sink with both vertical fins and horizontal fins was designed for the LED headlamp. Compared with traditional extruded heat sink, this structure could make full use of the wind taken in from the two sides of the car to achieve better cooling effect.(2) Design thought above was expanded then to design a new structure for LED street lamp, which combined the advantage of extruded heat-sink and pin-fin heat-sink. Results show that, compared with traditional extruded heat sink, the new structure made the highest temperature rise drop by 16.4℃ and the highest velocity rise by 1.29m/s. Optimization was processed then to parameters of radius, distribution and offset. And effect of wind speed and direction to heat dissipation was studied.(3) By using image processing and curve fitting technology, heat-sink with curved-shaped fins and inclined fins were designed for LED indoor lamp,which could achieve uniform distribution of the heat flow field. The result shows that, compared with traditional extruded heat sink, the curved-shaped one could make the highest temperature decreased, with more flow fluid moving faster, and that the inclined one, whose structure was more simple,could make the heat flow field become much more uniform-distributed. After that, orthogonal test was processed to study the angle of inclination of the fins.(4) Experiment contrast was processed to heat-sink with inclined fins, in which its cooling effect was validated. And simulation contrast experimentwas done, by using single field analysis and coupled field analysis,respectively, to indoor LED lamp of heat sink with inclined fins, validating advantage of coupled field analysis.(5) Application of heat pipe and micro-channel with nanofluids in the LED headlamp and street lamp was studied. These designs take the heat to the opening and dissipated it together, making the highest temperature rise decreased significantly.(6) After applying passive and active cooling methods to the three LED lamps and the simulation contrast, the final heat dissipation plan for the three LED lamps was accomplished according to the study all above.(7) Drive circuit and PCB plate for LED headlamp, street lamp, and indoor lamp, were designed based on HV9963, SD42527, CL6804,respectively. And the heat dissipation analysis and optimization for them were also accomplished.