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To enhance the heat dissipation of high-power light-emitting diodes (LEDs), corona wind based on corona discharge was promoted. In this paper, we aimed at reinforcing the intensity of corona wind by modifying the needle electrode with graphene solution. To explore the differences in the graphene-coated electrode and the original bare electrode on the electrical characteristics, the intensity of corona wind, and LED heat dissipation, a corona wind cooling system and a thermal test system were built for the experimental study. The results showed that the graphene-coated electrode system could produce corona wind at a lower voltage. In addition, the discharge current of the graphene-coated electrode system is higher than that of the bare electrode system under the same discharge voltage. The graphene-coated electrode system can induce a faster corona wind and the highest speed is about 3.4 m/s, showing that it is more efficient than the bare electrode system in corona wind production. Moreover, the temperature drop of LEDs for the graphene-coated system is greater, which means that the corona wind cooling system can reduce the junction temperature of the LED chips effectively. Ultimately, as the discharge power increases, the average convective heat transfer coefficient increases. Indeed, the result of this paper can be used for the wide variety of the graphene-coated corona wind generator application as a promising technology for the LED heat management. [ABSTRACT FROM AUTHOR]

Summary High voltage is an obstacle when applying electrohydrodynamics technology. Nanomaterials are good candidates for its extraordinary electrical properties and heat‐conducting characteristics. An originally designed ionic wind cooling system was secured with graphene using the dip‐coating method to study the cooling effect for the high‐power light‐emitting diodes. The experiment results indicated that the graphene on the needles' surface acted as new emitting electrode with a smaller curvature radius. The corona discharge current density increased, and the ionic wind inception voltage decreased, because of the high aspect ratios and the field emission characteristic of graphene. The maximum ionic wind volume velocity was improved by 41.3% when the discharge gap was 10 mm, which was attributed to the local electric field enhancement and the electron field emission effect that the graphene had. The best cooling performance was obtained when the needles and the heat sink were both coated with graphene. The junction temperature decreased 21%, and the luminous flux increased 5.6% at the discharge gap of 15 mm, taking the electrostatic screening effect into consideration. [ABSTRACT FROM AUTHOR]

Ionic wind technology is a right candidate for the thermal management of electronic devices. However, some highly-oxidizing substances are produced during corona discharge, which can destroy the electrode and shorten its service life. In the present work, nanomaterials were coated on the surfaces of needles, which act as emitting electrodes. The generation characteristics of ionic wind and the working durability of an ionic wind generator (IWG) were compared experimentally. The generator modified by nanomaterials was subsequently used to cool high-power LED chips, and the changes in the optical properties of the chips were studied. The results indicate that the electric field intensity and corona current increased after the application of the nanomaterials. The nanomaterials-decorated IWG performed better in operating durability than the original prototype. When the nanomaterials-decorated IWG was applied to cool LEDs, the case temperature at a discharge power of 3 W was reduced by 5.8 °C compared with the original generator. The luminous flux output increased by 28 lm and took less time to reach a stable working state. The ionic wind velocity and the energy conversion efficiency of the system were also greatly improved. This study provides a potential solution for the efficient thermal management of electronic devices. [ABSTRACT FROM AUTHOR]

• Formation of ionic wind and cooling enhancement mechanism was deeply explored. • Literatures published in the past few years were classified and discussed. • The ongoing challenges were highlighted and discussed. Corona discharge-produced ionic wind has drawn considerable attention as a potential candidate to solve the thermal problems that originate from heat accumulation in small-scale devices, as it has clear advantages over conventional cooling devices. The research and application cases of corona wind technology in the field of local heat transfer enhancement have been increasing in recent years. In this review, the formation process of corona wind and the mechanism of local heat dissipation enhancement are deeply investigated from the perspectives of physics, electricity, and thermodynamics. Related literature published in the past decade that has focused on the application of small-scale corona wind generators (CWGs) in local heat transfer enhancement is classified and discussed. Some important research conclusions are highlighted and used to guide the optimal design of a small-scale corona wind cooling system. The ongoing challenges of the power supply, adverse effects of byproducts, humidity, and electrode deterioration are discussed, and corresponding solutions are put forward. The use of corona wind cooling technology will present opportunities based on the research that has been conducted and its future development tendency. [ABSTRACT FROM AUTHOR]