Spray cooling with a swinging fan nozzle: An experimental study on dynamic spray impingement and heat transfer

• Novel Swinging Spray Cooling (SSC) is proposed for thermal management. • A multi-view experimental setup is developed for spray and heat transfer analysis. • Swinging motion promotes liquid film spread to form a large coverage area. • SSC has a "thin-center, thick-edge" film distribution, achieving high HTC centrally. • The proposed method shows potential in tackling fast dynamic thermal challenges. Impinging sprays are well known to deliver superior cooling performance which can meet the demands of fast heat removal especially in large surface area of heat dissipation. Although various strategies such as surface modification and additive application have been extensively studied to enhance spray cooling performance, the potential benefits of motion control of nozzle in improving heat transfer remain largely unexplored. This study proposes a novel fan nozzle swinging spray cooling (SSC) method, which is different from the conventional fixed-angle inclination spray cooling (FISC) method. A multi-view experimental setup is designed to visualize the spray impingement and film evaporation. High-speed visualizations from top view and bottom view are used to study the spray impingement behavior and liquid film formation. Moreover, the film temperature change over time during film evaporation is measured by infrared thermography. Experimental results indicate that the swinging spray promotes film expansion and reduces liquid accumulation. SSC provides a larger liquid coverage area and thinner liquid film, which allows faster evaporation in comparison to FISC for the same liquid mass injected. Moreover, due to its unique evaporation mechanism, the heat transfer coefficient (HTC) of SSC is generally higher in the middle area of the liquid film and lower at the edge area. The local maximum HTC can reach up to 2062 W/(m²·K), which is 5.7 times that of FISC. In summary, the SSC method provides enhanced performance for spray cooling applications.