Influence of oblique angle variations on the thermo-hydraulic characteristics of the oblique fin heat sink with Al2O3 water nanofluid

The flow mixing through secondary flow is critical for improving the heat transfer of microchannel heat sinks. This study investigates oblique fin heat sinks (OFHSs) under forced convection conditions with Al2O3-water nanofluid under the Re 100-500. The study is referenced with a straight channel heat sink for benchmarking purposes. Five oblique angle configurations (15 degrees, 25 degrees, 35 degrees, 45 degrees, and 55 degrees) were investigated at the constant fin pitch and constant width ratio (primary width-to-secondary width ratio) of 2:1. The RNG k-epsilon model has been employed with enhanced thermofluidic effect and wall treatment. The findings revealed that secondary flow generation leads the thermal boundary layer to redevelop at each fin, resulting in continuous fluid flow development. Pressure drop increment has been noticed with oblique angles 15 degrees to 25 degrees, and the variation is almost insignificant among the 35 degrees, 45 degrees, and 55 degrees OFHS. The secondary flow rates were found to have a profound effect in all the cases. The 25 degrees degree shows a higher average convection coefficient among all the OFHSs. Also, the convection coefficient varied in the following order for both water and nanofluid: 15 degrees < 25 degrees > 35 degrees > 45 degrees > 55 degrees. The 25 degrees OFHS enables a more uniform water/nanofluids temperature to build up in the streamwise direction than the 35 degrees, 45 degrees, and 55 degrees OFHS. The thermofluidic analysis suggests that the proposed designs have superior heat convection performance than their flow resistance penalty. Therefore, the 25 degrees OFHS offers a promising option for further parametric research in the future.

Automated summary

This study investigates the performance of oblique fin heat sinks under forced convection conditions and finds that the generation of secondary flow has a significant impact on heat transfer and fluid flow. The 25 degrees OFHS shows higher convection coefficient and more uniform water/nanofluid temperature distribution among all the configurations. Therefore, the 25 degrees OFHS has great potential for further parametric research in the future.