Using spiral channels for intensification of cooling process in an innovative liquid block operated with a biologically produced nanofluid: First and second law analyses

Abstract

The hydrothermal and irreversibility characteristics of an eco-friendly graphene-based nanofluid within a novel spiral heat sink are numerically investigated. The effects of heat sink material, nanoparticle weight fraction (φ), and Reynolds number (Re) are studied. Some comparisons are made between the spiral heat sink and two ordinary heat sinks, namely serpentine and base-plate heat sinks. The results indicate that the serpentine heat sink shows a somewhat better heat transfer ratio, but the corresponding pressure loss ratio is exceptionally high. The spiral heat sink is able to improve the heat transfer with reasonable pressure drop intensification and smaller irreversibility than the serpentine one. It is found that the main irreversibility occurs because of the temperature gradients, while the irreversibility caused by the friction is inconsequential. Higher particle concentration diminishes the temperature gradients and leads to smaller thermal irreversibility. For instance, at Re = 1000 and spiral heat sink made of copper, the thermal entropy generation of the nanofluid diminishes by 12.6 % when φ rises by 0.1 %. Furthermore, employing the copper heat sink yields a flatter temperature profile and declines the thermal entropy production, such that using the nickel leads to 41.4 % higher thermal entropy production than the copper at Re = 1000 and φ = 0.1 %.