This study investigated the impact of different micro-rib arrangements on the flow and heat transfer performance of microchannel heat exchangers. Sixteen rib configurations were designed, and four optimized structures were analyzed through numerical simulations. Key parameters, including the velocity and temperature fields, pressure drop, friction coefficient, base temperature, and Nusselt number were evaluated against a smooth rectangular microchannel. The results reveal that the rib structures significantly increased the pressure loss and friction, with sharper profiles causing a higher resistance. Additionally, these induced throttling effects and generated horseshoe and wake vortices, thereby generating distinct flow patterns. The heat transfer was enhanced significantly, with a maximum base temperature reduction of 12.87 K and a 57.4% increase in the relative Nusselt number. Among the evaluated designs, the Type 1 microchannel achieved the best trade-off between pressure drop and heat transfer performance.

This study proposes a microchannel heat exchanger utilizing a symmetrical Tesla-valve structure to address the challenge of heat dissipation in high-performance electronic devices owing to increased integration and power density. By incorporating built-in diversion island designs, such as trapezoidal, crescent-shaped, and scallop-shaped protrusions, the disturbance of the fluid and mixing effects are enhanced. Numerical simulations are conducted using ANSYS FLUENT to assess the effects of various built-in diversion islands on the heat-transfer and flow characteristics of the microchannel and examine the effects of geometric parameters such as the arc angle and pitch. The results show that compared with conventional parallel straight tube microchannels, the three new structures significantly boost Nu and the performance-evaluation criterion (PEC). Among these, the PEC of the trapezium straight tube microchannel (TSTM) structure ranges from 1.04 to 1.20, showcasing superior overall performance. The optimization of the geometric parameters reveals that the TSTM structure with an arc angle of 18° and a pitch of 3.0 mm achieves the highest heat-transfer efficiency and best overall performance.