Numerical investigation of heat transfer enhancement for metal oxide nanofluid in elliptical tube heat exchanger

Abstract

Heat exchangers are an important system used for heat transference. These systems are present in many devices and utilities. These devices can be big such as in oil refineries, or small, such as in fridges and air-conditioners. However, there are several types of heat exchangers, each with their own benefit and advantage. In this study, two types of passive heat transfer solutions are used to numerically investigate the relationship between nanofluid particle diameter and fluid volume fraction concentration. The first is a double pipe with an elliptical cross-section that has a counter-fluid flow mechanic. This is then combined with another passive technique, which is the use of nanoparticles in combination with water, which creates nanofluids. ANSYS was used as a tool to numerically simulate the various scenarios using different nanoparticles. The boundary conditions and geometry, as well as the governing equations and the mesh of the heat exchanger are numerically simulated. The experiment was conducted under a laminar flow regime in an elliptical tube double pipe heat exchanger. The results of the simulation indicated that nanofluids such as silicon oxide, enhance heat transfer when compared to water. However, for the nanofluid characteristics itself, it was observed that as the diameter decreased and the concentration increased, the heat transfer values also improved. The ideal values identified in this research indicated that at 7 % volume fraction, and 15 nm particle size the results are most optimal. There is also an indication that as the Reynolds Number increased, the heat transfer enhancement values such as Nusselt Number and heat transfer coefficient also improve.