Improving Energy Efficiency of a Heat Exchanger Using Recovered Metal Chips During Forced Convection

Abstract

Among the methods used to enhance heat transfer, the insertion of porous media is prominent. Metallic foam is one of the most commonly used porous media in recent years; however, it presents a disadvantage due to its high cost. Therefore, the goal of this study is to utilize recovered metal chips from turning machines as an alternative in heat exchangers. To achieve this, we conducted a comparative experimental investigation on forced convection between two scenarios: an empty channel and a channel filled with the recovered metal chips. The investigation is divided into two main parts: a thermal analysis focusing on the enhancement of the heat transfer and improving energy efficiency, and a hydrodynamic analysis addressing the pressure losses in both cases. Experiments were conducted using an in situ test section. During experimentation, the water volumetric flow rates varied from 1.4 l/min to 4.2 l/min, with a heating power of 140 W. The used metal chips are made from hard steel. The results indicate that the insertion of metal chips made from hard steel in the channel increased the mean Nusselt number by an average factor of 3.97. However, the pressure drop in the channel filled with metal chips was four times greater compared to the empty channel.