Thermo-hydraulic Analysis of Fluid Flowing Through Circular Pipe with Wire Mesh Inserts having Varying Mesh Porosity

Abstract

The experimental investigation was made to analysis the rate of heat transfer of fluid flowing through a heat exchanger with varying wire-mesh porosity inserts. The Nusselt number (Nu), friction factor (f), and overall heat transfer rate (Q) were evaluated using experiments. Three different wire mesh inserts of square, hexagonal and diamond porosity were examined. The SS 316 stainless wire mesh with a porosity of 9 pores per inch (PPI) were inserted normal to the flow field with a pitch distance of 5 cm for each shape of wire mesh. The experiments were conducted on test rig with air as a working fluid for turbulent flow regime having Reynolds number ranging from 6,000 to 16,000. Experiments were performed on computerized test rig with heated air flowed in one direction through inner pipe and counter flow cold water flowing through the outer concentric pipe. The circular inner pipe of 40 cm long having 4 cm inner diameter (Di), and 3 mm thick was used for experimentation. The experimental results showed that Nusselt number (Nu) increases with decrease in friction factor (f) with increase in Reynolds number (Re). Also, it is observed that the hexagonal porosity shape of wire mesh insert provides higher material contact and gain more energy absorption from hot air resulted in improvement in heat transfer coefficient as compared to diagonal and square porosity shapes of wire mesh inserts, under similar operating conditions. The friction factor and pressure drop for square porosity shape of wire mesh insert is higher as compared to hexagonal and diagonal porosity shapes of wire mesh inserts respectively. This is due to the fact that square porosity wire mesh provides more obstruction in the flow field compared with hexagonal and diagonal porosity shapes of wire mesh inserts. The hexagonal porosity shape of wire mesh insert provides better option for heat exchange applications.