Experimental Study On Light-Emitting Diode Cooling Enhancement Based On Corona Wind Coupled With Nanomaterials

Light-emitting diode(LED),which has the advantages of high efficiency and long service life,is now widely used in automotive lighting systems.However,the junction temperature of LED chips will continue to rise during the operation,resulting in its reduced working performance.Therefore,it is urgent to seek energy-saving and efficient cooling methods.Corona wind heat dissipation technology can enhance the heat dissipation of LED chips.However,the strength of corona wind intensity is the key factor to limit the promotion and application of corona wind heat dissipation technology.In view of the problem of the corona wind cooling technology used in LED chip heat dissipation,graphene and carbon nanotubes(CNTs)are used to strengthen the ‘needle-net' type of corona wind cooling systems,and the corona wind cooling systems modified by graphene and CNTs are designed respectively.A series of researches on LED heat dissipation strengthened by nanomaterials combined with corona wind were launched.The major research work is listed as follows:The apparent morphology and physicochemical properties of nanomaterials before and after corona discharge were compared and analyzed to verify the feasibility of nanomaterials in strengthening corona wind.(1)To explore the strengthening effect of nanomaterials on the corona wind cooling system,a corona wind performance test system and an LED thermal characteristic test system were established.The corona wind cooling systems were tested by the corona wind performance test system and the LED thermal characteristic test system.The effects of nanomaterials on the electrical performance(onset voltage,current-voltage characteristics,electrified field strength,current density)and heat dissipation performance(corona wind speed,energy conversion rate,LED junction temperature,total thermal resistance and average heat transfer coefficient)of the corona wind cooling system were investigated.The results showed that the nanomaterials can improve the electrical performance and heat dissipation performance of corona cooling system effectively.The better nanomaterials heat dissipation system consists of CNTs modified needle electrode mesh emitter and CNTs modified heat sink.(2)The optimized corona cooling system was applied to cool high-power LED chips to study the changes of the light output characteristics of LED chips under the action of corona wind.The LED photoelectric performance test system,LED luminous intensity and chromaticity characteristic test system were built.The LED photoelectric performance test system was applied to measure the luminous flux and junction temperature of LED chips under the different operating conditions,and the effect of the LED junction temperature on the LED luminous flux was explored.The effects of corona wind on the luminous intensity,related color temperature,color rendering index,H-V point of chromaticity coordinates and emission spectrum of LED chips were investigated by using the LED luminous intensity and chromaticity characteristic test system.The results showed that the nanomaterials-modified corona wind cooling system can improve the optical characteristic and chromaticity characteristic of the LED chip.When the discharge power of the corona wind cooling system is 3 W,the working junction temperature of the LED chip drops from 64 ? to 36 ?,the light flux output of the LED chip is stable around 1438.8 lm,and the maximum luminous intensity of the LED chip is 232 cd.Under the synergy of corona wind and nanomaterials,the related color temperature and color rendering index gradually increased,and the colorimetric coordinates distribution of LED chip was more concentrated.The change of the emission spectrum distribution also illustrates the corona wind cooling technology can effectively improve the shade of the LED chip performance.(3)To further explore the practicality and durability of corona wind technology enhanced by nanomaterials,a scanning electron microscope was applied to observe the SEM figures of nanomaterials-modified needles before and after the corona discharge,and the changes in the appearance of nanomaterials before and after corona discharge were analyzed.The Raman spectra of nanomaterials before and after corona discharge were obtained by Raman spectrometer.The peak fitting of Raman spectra of nanomaterials before and after corona discharge was performed to investigate the effect of corona discharge on the chemical heterogeneity and physical stability of nanomaterials.The results showed that the nanomaterials can prevent the corrosion of needle electrode by ozone oxidation material effectively.After corona discharge,graphene-modified needle electrodes apparent morphology and obvious changes have taken place in physical and chemical properties,and morphology of the CNTs-modified needle electrodes and physicochemical properties unchanged before and after corona discharge,CNTs enhanced corona wind cooling system is verified practicability of feasibility and durability.