Three-dimensional computational comparison of mini-pinned heat sinks using different nanofluids: Part two-energy and exergy characteristics

The energy and exergy characteristics of 3D-pinned heat sink (HS) designs have been computationally compared as the second part of a three-part investigation. Different pin profiles, such as circular, square, triangular, strip and elliptic pins, and without pin HS are conducted with three different types of nanofluids-Al2O3-water, SiO2-water, and CuO-water for laminar forced convection. The concentrations of nanofluids vary from 0 to 5vol% with different Reynolds numbers ranging between 100 and 1000. The finite volume method employing the SIMPLE algorithm for a computational solution is applied to solve the Navier-Stokes and energy equations. Four criterions studies are explained-energy efficiency, exergy loss, and exergy efficiency of HSs with pressure drop. The results showed that the highest energy and exergy efficiencies are nearly 76% and 57%, respectively, for elliptic-pinned HSs using pure water, while about 82% and 62% using 5vol% of SiO2-water nanofluids. Besides, the elliptic-pinned HSs have a favorable reduction in the exergy loss, nearly 17% using 5vol% of SiO2-water nanofluids. Subsequently, the elliptic-pinned HS is recommended to apply with pure water considering the development in pressure drop required. However, the elliptic-pinned HSs could be employed with 5vol% of SiO2-water nanofluids regardless of the development in pressure drop required for thermal energy dissipation applications with more exergy efficiency and reduction of exergy loss.