Influence of magnetic baffle and magnetic nanofluid on heat transfer in a wavy minichannel

Abstract

This study aims to numerically investigate the heat transfer and fluid flow analysis of magnetic nanofluid in the presence of external magnetic field. Recent studies have proved that corrugated channels have better heat thermal performance as compared to with the straight one. However, very few research has been done to investigate heat transfer characteristics in a wavy minichannel using magnetic nanofluid in the presence of external magnetic field at low Reynolds numbers. Laminar flow has a significant advantage of lesser power consumption as compared to turbulent flow. A water based 2 vol% Fe3O4 magnetic nanofluid is used as coolant in a two-dimensional minichannel with wavy surface as top wall. The fluid domain is tested against different combinations of Reynolds number varying from 150 to 210 and magnetic field strength varying from 1200 G to 3000 G with different configurations. The configurations include: The cases include: one source at 15 mm; two sources at 7.5 mm and 15 mm; one source at 25 mm; two sources at 25 mm and 32.5 mm; and four sources at 7.5 mm, 15 mm, 25 mm and 33.5 mm. Results show a significant average enhancement of 13 %, 29.6 %, 54.12 %, 78.35 % and 103.54 % in heat transfer when magnetic fields of 1200 G, 1500 G, 2000 G, 2500 G and 3000 G strength are applied, respectively in a wavy minichannel. These increments are 20 % more than the enhancement obtained in a plain mini channel. No work yet has been done to show the effect of position of magnets on heat transfer and pressure drop. Results show that the heat transfer is better when magnets are placed at more downstream location, however pressure drop is higher as compared to case when magnets are placed upstream. Also, the results show that pressure drop in wavy channel is less than plain channel at low magnetic fields for two cases, i.e., one source at x = 15 mm and two sources at x = 7.5 mm and 15 mm.