Experimental study on effectiveness in segmental baffled shell and tube heat exchanger using Al 2 O 3 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 (C_p) 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 (U_o) 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 C_p 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 U_o 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.