Numerical analysis of the thermal performance of a nanofluid water-Al2O3 in a heat sink with rectangular microchannel

Abstract

The main objective of the work undertaken in this paper is to study the possibility of optimizing the flow structure and thermal performance of a heat exchanger numerically. For this purpose, the nanofluid water-Al2O3 is chosen as the cooling fluid, which is in forced convective and laminar flow in a two-dimensional rectangular microchannel. Then, as a first step, the impact of the chosen nanoparticles' concentration in the range was studied: (0 ⩽ Φ ⩽ 0, 04). The Nusselt number and the coefficient of friction were analyzed. The results show that the thermal performance has been remarkably improved (more than 40%). These results are mainly due to increased effective thermal conductivity and viscose coolant (nanofluid). In a second step, the impact of the solid diamond blocks' insertion in the initially laminar flow was analyzed. The inserts' presence strongly disturbed the flow and caused a modification of its structure (velocity field, temperature field, etc.). The results show that for the same concentration of corpuscles, the average Nusselt number and friction coefficient increase much more with the Reynolds number's rise compared to the case without inserts. The study has thus allowed us to show that a nanofluid of high concentration can best adopt as the cooling fluid of a heat sink, and such a heat sink with diamond inserts has the best thermohydrodynamic performance (more than 40% increase). The differential equations system's resolution governing the problem is ensured by a finite volume scheme associated with the SIMPLE algorithm (Semi Implicit Method for Pressure Linked Equation). The study performed with a Reynolds number chosen in a range corresponding to the laminar regime: (600 ⩽ Re ⩽ 1400). The concentration of the nanoparticles taken in the field: (0 ⩽ Φ ⩽ 0.04) corresponding to the validation range of formulas (7) and (9).