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

Abstract

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°, 25°, 35°, 45°, and 55°) were investigated at the constant fin pitch and constant width ratio (primary width-to-secondary width ratio) of 2:1. The RNG k-ε 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° to 25°, and the variation is almost insignificant among the 35°, 45°, and 55° OFHS. The secondary flow rates were found to have a profound effect in all the cases. The 25° 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° < 25° > 35° > 45° > 55°. The 25° OFHS enables a more uniform water/nanofluids temperature to build up in the streamwise direction than the 35°, 45°, and 55° OFHS. The thermofluidic analysis suggests that the proposed designs have superior heat convection performance than their flow resistance penalty. Therefore, the 25° OFHS offers a promising option for further parametric research in the future.

Keywords:

• Al₂O₃-water nanofluids
• oblique angle
• oblique fin heat sink
• performance factor
• RNG k-ε model

Additional information

Funding

The Department of Science and Technology (SERB), India, supported this work (grant no. ECR/2016/000176).