Efficient thermal management of high heat flux systems is critical in modern electronic and energy devices. Spray cooling, with its high heat removal capability and uniform surface cooling, is widely recognized as an effective technique. Extensive studies have explored spray cooling using water and other working fluids, focusing on droplet dynamics, surface wetting, and heat transfer enhancement. However, the influence of low-concentration alcohol additives on spray cooling performance and evaporation dynamics remains insufficiently understood. This work systematically investigates the non-monotonic heat-transfer behaviour by varying spray height, flow rate, and heat input individually, focusing on the effects of low-concentration ethanol additives (2%, 4%, and 5%). A single-nozzle spray cooling system is used to compare the thermal performance of pure water and ethanol–water mixtures. Experiments are conducted at a constant spray pressure of 0.2 MPa, with spray height (1.22–2.89 cm), flow rate (0.5–0.75 L/min), and heating power (200–260 W) varied. Surface temperature evolution is monitored, and the transient heat transfer coefficient is calculated to characterize cooling performance. Results show that small amounts of ethanol significantly alter droplet evaporation, liquid spreading, and surface wetting, leading to distinct cooling responses compared to pure water. These findings enhance the understanding of low-concentration alcohol additives in spray cooling and provide guidance for improving heat dissipation in high-heat-flux systems. Future work should explore the coupling effects of droplet dynamics, surface microstructures, and alternative working fluids to optimize spray cooling efficiency.
Khan et al. (Thu,) studied this question.