Thermal performance of pin–fin heat sink subject in magnetic field inside rectangular channels

Abstract

Forced convective heat transfer and friction factor for air flowing inside rectangular horizontal duct over a set of pin–fins, is experimentally studied under uniform heat flux. Experiments are conducted with air subjected to a magnetic body force through a magnetic gradient field. Experiments are carried out for two different fin geometries. An experimental test loop equipped with the required measuring instruments is designed and constructed to assess the effects of magnetic field, mass flow rate, and applied heat flux on convection heat transfer process and pressure drop. The measurements of temperature, flow rate, applied voltage to the heater and pressure drop in the duct are recorded and manipulated to evaluate Nusselt number and friction factor. The obtained experimental results show that, both Nusselt number and pressure drop increases in case of using pin–fin in a staggered arrangement. Higher rates of heat transfer and pressure drop are obtained from the duct provided by a pin–fin set compared to flow in a plain duct under similar conditions. The turbulence structures are markedly elongated in the direction of the applied magnetic field when it is strong enough.The performance factor of the pin–fin inserts for both inline and staggered is evaluated. Comparison with the previous work shows good agreement. A correlation that best fits the experimental data is developed to predict the Nusselt number with presence of the magnetic field for pin–fin array inserts. The duct with staggered arrangement of fins produces a higher value of the heat transfer coefficient compared to in-line arrangement at all range of Reynolds number.