Effect of the magnetic field direction on forced convection heat transfer enhancements in ferrofluids^*

¹ Univ. Grenoble Alpes, G2Elab, 38000 Grenoble, France
² Univ. Grenoble Alpes, LEGI, 38000 Grenoble, France
³ Univ. Grenoble Alpes, LRP, 38000 Grenoble, France
⁴ SATIE, ENS Cachan – CNAM – Université de Cergy Pontoise – CNRS UMR 8029, 94230 Cachan, France

^a e-mail: Yvan.Avenas@g2elab.grenoble-inp.fr

Received: 31 January 2015
Revised: 3 June 2015
Accepted: 4 June 2015
Published online: 8 July 2015

Abstract

Applying a magnetic field on a ferrofluid flow induces a large increase of the convective heat transfer coefficient. In this paper, the thermal-hydraulic behaviors of two commercial ferrofluids are compared. The variations of both the pressure drop and the heat transfer coefficient due to the magnetic field are measured in the following conditions: square duct, laminar flow and uniform wall heat flux. The square section with two insulated walls allows for the characterization of the effect of the magnetic field direction. The experimental results show that the heat transfer is better enhanced when the magnetic field is perpendicular to the heat flux. In the best case, the local heat transfer coefficient increase is about 75%. On the contrary, another experimental setup shows no enhancement of thermal conductivity when the magnetic field is perpendicular to the heat flux.