Investigation of the thermal enhancement performance of circular and square mini-channel heat sinks with perforated and non-perforated twisted tape inserts

Rising heat generation from device miniaturization exposes the limitations of conventional cooling and motivates enhanced mini-channel heat sink (MCHS) designs. This study evaluates the thermal enhancement performance of circular and square MCHS fitted with perforated and non-perforated twisted tape inserts. The effects of four twist ratios (2.78–6.94) and Reynolds numbers ranging from 600 to 1500 are examined under a uniform heat flux of 50 W/cm 2 . The results reveal a strong dependence of heat transfer and flow characteristics on channel geometry, Reynolds number, and twisted tape insert configuration. Without inserts, the square MCHS delivers 29–32% higher heat transfer than the circular design due to greater heat-transfer area. However, the introduction of twisted tape inserts significantly enhances performance, particularly in the circular MCHS. At the lowest twist ratio (TTR = 2.78), the circular MCHS achieves up to 349% heat transfer enhancement over the plain channel and about 27% higher performance than the square MCHS, benefiting from smoother curvature and stronger, more uniform swirl. Increasing twist ratio (4.17–6.94) reduces swirl intensity and heat transfer for both geometries, though the circular MCHS consistently maintains a 4–17% advantage. The friction factor decreases with Reynolds number but increases sharply with inserts, resulting in penalties of up to 446% for circular and 378% for square MCHS at the lowest twist ratio. The performance evaluation criterion (PEC) identifies the circular MCHS as the more efficient design, achieving peak PEC values of 2.51 (perforated) and 2.43 (non-perforated) compared to a maximum of 1.69 in the square channel.