Heat transfer of drop burst impact on a flowing film

The key to spray cooling is the impact of coolant drops on a film flow on the cooling surface. In this work, we experimentally study the cooling effects of drop burst flows impacting a film flow cooling a substrate surface. A drop burst flow is a flow of drops dispensed in groups (bursts), and each group has a consistent number of drops (burst size n). The drop burst flows are formed by a continuous drop generator combined with a rotating disc with a special opening. A thin and sputter-coated silicon wafer is used as the hot substrate, and the sputter-coated gold film is used as an electrical heater. An infrared camera with high spatiotemporal resolution is used to record temperature change. The cooling enhancement is analyzed based on measured temperature fluctuation, average temperature, and heat transfer coefficient.