Effect of Stainless Mesh Porosity on Heat Transfer in Circular Tube Heat Exchangers

Abstract

Heat exchangers were important devices used for heat transfer in various industries. Heat transfer enhancement in heat exchangers can be achieved using various methods. The porous media were placed across the flow inside the tubes of the heat exchanger. This method was used to enhance heat transfer. However, the selection of appropriate porous media must consider various factors, such as the type and porosity. Therefore, the objective of this research was to study the effect of stainless wire-mesh porosity on heat transfer in a circular tube heat exchanger with a porous triangular serrated insert. The SUS 304 stainless wire-mesh was used as porous media. The porosity (X) was examined in four levels: 0.55, 0.62, 0.77 and 0.77. The pitch ratios (PR = 2) and height ratios (HR = 0.40). The experimental have been conducted for the air flow in terms of Reynolds numbers (Re) ranging from 4,300 – 23,800. The experiment was conducted in the tube heat exchanger having a uniform heat fluxed wall. Experimental results indicate that a decrease in X leads to an increase in the Nusselt number (Nu) and the friction factor (f). This was because a larger volume of solid material enhances its heat storage capacity through conduction, resulting in increased heat transfer from the material to the fluid. The highest Nu and f were found at X=0.55, which were 2.75 and 23.85 times when compared with a smooth tube, respectively. In this research, the maximum thermal enhancement factor (TEF) of 1.28 was found at X=0.55. Experimental results also indicate that Nu increases as Re increases, while f decreases.