Experimental study of surface temperature non-uniformity and fluctuation in dense controllable droplet trains cooling

Understanding the characteristics of surface temperature uniformity and fluctuations in high heat flux cooling technology is crucial for achieving precise thermal management in high-power electronic devices. This study investigates the temperature non-uniformity (TNU) and temperature fluctuations (Delta Tb,tmax) in sparse and dense droplet train cooling, utilizing a self-designed droplet generator to achieve precise control over droplet flux and size. The droplet flux reached a maximum of N = 2,489,200 1/cm2s, and the minimum droplet diameter approached 150 mu m, nearly reaching spray cooling levels. Experimental results revealed that in the single-phase region, TNU does not exhibit a consistent decrease with increasing droplet train number, as interactions between adjacent droplet trains increase. Hot spots were observed in both the impact points and the liquid hump zones. In the nucleate boiling region, increased droplet train number improved temperature uniformity and reduced temperature fluctuations. Additionally, an adaptive arrangement of droplet trains, adjusted according to hot spot locations, enhanced cooling performance and critical heat flux (CHF), with the highest CHF reaching 923 W/cm2, compared to 860 W/cm2 for the standard configuration. This study demonstrates the significant potential of adaptive droplet train cooling in improving heat transfer uniformity, reducing thermal stress, and enhancing CHF in electronic cooling applications.