Experimental study on effectiveness in segmental baffled shell and tube heat exchanger using Al2O3 nanofluid at variable concentrations

Abstract

Nanoparticles attracted many researchers because of their significant heat transfer enhancement properties in various applications. The nanoparticles have variable properties and a high specific surface (Cp) area, which enhance heat exchange between fluids and their particles at different volume concentrations. This article provides the outcomes of an experimental study on the overall heat transfer coefficient (Uo) and effectiveness ( ε) of the shell and tube heat exchanger (STHE) with a 25% baffle cut using Al2O3 nanofluid consisting of base fluid distilled water (DW) and Al2O3 nanoparticles at 0.05%, 0.1%, and 0.2% of volume concentrations. Using a two-step method and adding a weight fraction of 0.1% sodium dodecylbenzene sulfonate (SDBS) as a surface active agent to each volume concentration of nanofluid provides better stability. The thermophysical properties like density (ρ), thermal conductivity (k), and dynamic viscosity ( μ) of the Al2O3-DW nanofluid increased, but Cp of the same was reduced by increasing the volume fraction. Al2O3-DW nanofluid at different concentrations in parallel and counter flow variations of the STHE enhances the Uo and ε when compared with water. However, counterflow provides higher effectiveness. At 0.6 LPM of the nanofluid flow and hot fluid at T = 80°C temperature, the difference in the heat exchanger's effectiveness enhancement is 4.24% for parallel flow and 4.16% for counterflow at 0.2% concentration of Al2O3-DW nanofluid compared to water.