Experimental Study On LED Cooling Enhancement Based On Thermoelectric Cooling Coupled With Corona Wind

Recently,light-emitting diodes(LEDs)have received widespread attention due to their advantages such as high luminous efficiency,long endurance,and low power consumption.However,studies indicate that about 70%of the input electrical energy is finally converted into heat and wasted when the LED is working.The accumulation of heat leads to the increase of heat flux density per unit volume of the LED chip,and the working temperature continues to rise.An excessive high junction temperature will reduce the luminous intensity and luminous flux of the LED chip,thereby reducing its luminous efficiency and long-term reliability,and even cause damage to the device in severe cases.Therefore,the heat dissipation problem of the LED chip has become a major obstacle that limits its further promotion and application.Therefore,the discovery of an effective solution for LED cooling is urgently required.Thermoelectric cooling(TEC)is a widely used cooling technology.It has the advantages of fast cooling rate,no noise during operation,and easy to integrate with other electronic products.However,if the hot side of the thermoelectric cooler does not get good cooling,the heat dissipation efficiency will be reduced.Corona wind cooling(CWC)is a new cooling technology based on the principle of corona discharge.It has the advantages of simple structure,low power consumption,and flexible control.The main disadvantage is the limited corona wind velocity.In order to overcome the shortcomings of the two cooling technologies of TEC and CWC,solutions by combining thermoelectric cooling and corona wind have been proposed in the present work.Experiments are performed to optimize its working performance,and then it is used for the thermal management of high-power LED chips.A temperature-and-humidity controlling system and a heat dissipation performance test bench for the TEC and CWC coupling heat dissipation system were established,and the cooling performance optimization test was carried out.The influence of the structural parameters(discharge gap,electrode material,needle electrode arrangement)and operating parameters(ambient temperature,relative humidity,corona wind discharge power,thermoelectric cooling power)of the coupling system on the corona wind performance(onset voltage,volt-ampere characteristics,corona wind velocity)and the heat dissipation performance(hot side temperature,cold side temperature,junction temperature,total thermal resistance)is explored.The experimental results show that 5 mm discharge gap,pure tungsten needle electrode,and crossshaped needle electrode arrangement are the best structural parameters with the optimization goal of high corona wind velocity.After comprehensively considering the cooling performance and the power consumption,the 1 W corona discharge power and 1 W thermoelectric cooling power are regarded as the best operating parameters.In order to characterize the heat dissipation efficiency of the system,the energy efficiency ratio(Coefficient of Performance,COP)is used for evaluation.The temperature difference between the hot side and cold side become smaller,the COP value increases,and the system efficiency is improved after the corona wind system is combined with the thermoelectric cooling system.In order to verify the cooling effect of the coupling system on the LED chip,an LED optical characteristic test system was built,and the optimized thermoelectric cooling coupled with corona wind heat dissipation system was applied for the thermal management of the LED chip,and the optical performance of the LED under different working conditions was studied experimentally.The changes of the junction temperature,the luminous flux,the luminous intensity,and the chromaticity characteristics before and after cooling are compared.The results show that after applying the coupling heat dissipation system,the LED’s junction temperature can be kept within the ideal operating temperature range,and the attenuation of the luminous flux and the luminous intensity of the LED chip becomes slower.In the CIE1931 chromaticity diagram,the chromaticity coordinate shifts to the blue light,the shift of the chromaticity coordinate and the change of the color rendering index are within the range allowed by the regulations,and the chromaticity characteristics of the LED have been significantly improved.To evaluate the practical application value of the thermoelectric cooling coupled with corona wind heat dissipation system further,six widely used heat dissipation systems were designed and applied for cooling LED chips.According to the change of the LED’s junction temperature,the cooling rate and the cooling amplitude of the six heat dissipation systems can be calculated.Combined with the power consumption,volume,cost and noise level of each system as the evaluation index system.Principal component analysis is performed on the indicators,and the comprehensive scores and rankings of the six cooling systems are finally obtained using the data analysis software SPSS.The analysis results show that a total of two principal components are extracted from the six indicators,and the cumulative contribution rate exceeds 80%,which can provide a better explanation for the comprehensive capability of the cooling system.The main component score of the thermoelectric cooling coupled with corona wind system is 1.151,ranking first among the six cooling systems,indicating that the coupling system proposed in this paper has excellent comprehensive performance and wide application prospects.