| After experiencing the lighting methods of firelight,tungsten filament lamp and discharge lamp,the fourth generation lighting source-led was invented and used.LED lighting has many advantages,such as small occupied space,reduced power consumption,long service time,no radiation pollution,simple maintenance and so on.It is gradually replacing traditional lighting.At present,LED is widely used in indication,decoration,lighting and other fields.With the rapid development of LED lighting industry and the gradual miniaturization of equipment,the demand for lighting is increasing and the power of LED is increasing.Thermal design is one of the main contents of the reliability design of lighting devices,and the pulsating heat pipe with high heat transfer performance and arbitrary bending has a broad application prospect in the heat dissipation system of high-power LED lighting.Based on the above situation and requirements,this paper designs and makes an LED heat dissipation structure with excellent heat transfer performance,which is composed of pulsating heat pipe and gravity heat pipe,and tests and analyzes the heat dissipation structure by building an experimental system.The innovation of this paper lies in the following two points: firstly,the gravity heat pipe is installed on the back of the LED chip in the center of the temperature equalizing plate,which makes use of its efficient heat transfer performance,expands the heat source area,and makes the pulsating heat pipe and gravity heat pipe cooperate effectively in structure;Secondly,some sections of the pulsating heat pipe are in contact with the temperature equalizing plate and the gravity heat pipe at the same time,which effectively increases the evaporation section length and heat dissipation area of the pulsating heat pipe.The research method of this paper is to analyze the start-up characteristics,average temperature characteristics and heat transfer characteristics of pulsating heat pipe LED heat dissipation structure under different working conditions such as different heating power,whether pulsating heat pipe and gravity heat pipe cooperate and whether fins are installed.The main research work and results are as follows:(1)A high-power LED heat dissipation structure with pulsating heat pipe as the main body and gravity heat pipe as the collaborative heat dissipation is designed and manufactured.The liquid filling rate of pulsating heat pipe is 54.59% and the working medium is deionized water.Build the experimental system and use the control variable method,under different heating power(72W,96 W,120W,144 W,168W,192 W,216W,240W)the heat dissipation structure of pulsating heat pipe is experimentally studied.At the same time,comparative experiments are carried out under different experimental conditions,such as whether the pulsating heat pipe and gravity heat pipe cooperate,whether the condensing section of pulsating heat pipe is equipped with fins,etc.the experimental results show that the heat dissipation structure of pulsating heat pipe can still be guaranteed under the experimental condition of maximum heating power 240 W The working temperature of LED heat source is maintained below 80℃,which meets the heat dissipation demand of high-power LED lighting,and reflects the superior heat transfer performance of pulsating heat pipe LED heat dissipation structure.The experimental analysis shows that when the power is 216 W,the thermal resistance of the pulsating heat pipe heat dissipation structure is the smallest and the heat dissipation effect is the best.(2)According to the temperature variation curves of pulsating heat pipe and gravity heat pipe at the measuring points of evaporation section and condensation section,the heat dissipation performance of pulsating heat pipe led radiator structure under different heating power is analyzed and obtained.The influence of the above factors on the heat transfer characteristics of pulsating heat pipe is analyzed by using the temperature oscillation curves of evaporation section and condensation section under different conditions,such as whether the pulsating heat pipe cooperates with gravity heat pipe,whether the condensing section of pulsating heat pipe is equipped with fins,and different inclination angles of pulsating heat pipe radiator.The experimental results show that under the working conditions of cooperation between pulsating heat pipe and gravity heat pipe,installation of fan,installation of fin and 90° inclination of heat dissipation structure,the operation state of pulsating heat pipe radiator is the best,and the temperature of high-power LED heat source can be better controlled.(3)According to the problems encountered in the experiment and the measured data,the future prospect and next work direction plan of high-power LED radiator are made. |
