Highly efficient spray cooling enabled by acoustic microdroplet atomizer

Abstract

Droplets are ubiquitous in nature and play an essential role in spray cooling, which is a highly efficient cooling approach for high-power-density miniaturized electronic devices. However, conventional pressure-driven spray faces significant challenges in controlling microdroplet characteristics, particularly the droplet size and spray direction, both of which critically impact cooling performance. Herein, to conquer these challenges, we designed an acoustic microdroplet atomizer composed of a lead zirconate titanate (PZT) transducer and silicon inverted pyramid nozzles. This design enables precise control of droplet generation, overcoming the limitations of traditional spray methods. The acoustic atomization technology minimizes excess liquid accumulation while significantly enhancing thin liquid film evaporation. Compared to the conventional droplet generation techniques such as pressure-driven, injector-based, and piezoelectric spray, our acoustic atomizer achieves superior cooling performance. Notably, we demonstrate a high heat flux of ∼220 W/cm² with a 3.6-fold enhancement at a low flow rate of 24 mL/min, achieving significantly improved cooling efficiency. Finally, our acoustic atomizer provides precise control over droplet size, velocity, and flow rate by adjusting the number of nozzles and the PZT transducer's resonant frequency, elevating spray cooling performance. This novel acoustic atomization cooling technology holds great promise for practical applications, particularly in the thermal management of compact electronic components.