Design of a mini-channel heat sink for high-heat-flux electronic devices

• Countercurrent flow mini-channel heat sinks with different cavities are designed. • An evaluation criterion for comprehensive wall temperature uniformity is proposed. • Zigzag cavity yields lowest wall temperature and best wall temperature uniformity. • Average wall temperature is lower by 12.9 K than traditional mini-channel heat sink. • Best heat sink obtains comprehensive temperature uniformity factor of 0.32–0.48. High temperature and temperature nonuniformity cause thermal failure and thermal deformation for high-heat-flux electronic devices. To address this issue, a countercurrent flow mini-channel heat sink with cavity structures on the bottom wall is designed, as well as the width and height of the mini-channel are 1.25 mm and 0.5 mm, respectively. Also, a numerical investigation on the effects of the geometry (zigzag, square-wavy and wavy), height (0.1–0.9 mm) and length (2–15 mm) of cavity on wall temperature characteristic in such heat sink is carried out. The local and average heating wall temperatures, wall temperature uniformity factor, as well as a new comprehensive evaluation criterion by combining the temperature uniformity and energy consumption (i.e., comprehensive temperature uniformity factor, low value means good comprehensive performance) are used to assess wall temperature characteristic. The results show that the countercurrent flow mini-channel heat sink with zigzag cavities performs lowest wall temperature and best wall temperature uniformity as compared to those with other cavities. This mini-channel heat sink with cavity height of 0.9 mm and cavity length of 5 mm yields lowest average wall temperature, which is lower by 12.9 K on average than the traditional concurrent flow smooth mini-channel heat sink. However, this mini-channel heat sink with cavity height of 0.9 mm and cavity length of 3 mm achieves lowest comprehensive temperature uniformity factor (0.32–0.48), suggesting that this mini-channel heat sink performs best wall temperature uniformity as low energy consumption as possible.