Efficient cooling of light-emitting diode via plasma-activated aerosols

Spray cooling is an effective method for rapidly absorbing excess heat from high-temperature surfaces. The performance of this method can be further enhanced by applying a thin layer of two-dimensional materials to the heated surface, which increases surface wettability and promotes the rapid permeation of aerosols into the coating. However, the durability of these coatings over extended periods remains a challenge. In this study, we investigate the enhancement of spray cooling performance using plasma-activated aerosols generated by a nozzle-based nebulizer; plasma-activated water (prior to nebulization) is produced using an atmospheric pressure plasma. Compared to deionized aerosols, plasma-activated aerosols have lower surface tension, which facilitates rapid evaporation when deposited on the heated surface. Specifically, we observe up to a 23% reduction in surface temperature when the heated surface (initially at 100 degree Celsius) is sprayed at a nebulization rate of 0.33 g/min with plasma-activated aerosols (having an electrical conductivity of 1.1 mS/cm), as opposed to deionized aerosols. When applied to the cooling of LED bulbs, this technique increases the heat transfer coefficient by up to 45%, leading to a 30% increase in illuminance. Plasma-activated water is easy to produce, making it a feasible and significant improvement over deionized water for spray cooling. Importantly, this approach does not require modifications to the existing spray cooling systems, such as those involving surface coatings.