Augmentation of Heat Transfer Through Heat Exchanger With and Without Fins by Using Nano fluids

Abstract

This study was carried out to study the effect of silver and oxide zirconium – oil nanofluids on enhancement heat transfer in a heat exchanger with and without fins by changing flow direction. This study was done by changing the parallel flow configuration into counter flow configuration under laminar flow regime. The properties of nanofluids (density, viscosity, thermal conductivity and specific heat) are practically measured. The two types of nanofluids at 1%, 2%, 3%, 4% and 5% particle volume concentration were prepared by two step method. The nanofluid was applied in a heat exchanger with and without fins to enhance heat transfer. The measured results show that silver with oil nanofluid gives maximum heat transfer enhancement compared with oxide zirconium nanofluid used. The presence of Ag and ZrO2 nanoparticles attributes to the generation of strong nanoconvection current and better mixing. The effect of different parameters such as flow Reynolds number, nanofluid temperature, concentration and type of nanoparticle on heat transfer coefficient and pressure drop of the flow are studied. The obtained results show an increase in heat transfer coefficient to (Ag + oil) and (ZrO2 + oil) for heat exchanger with fins 38.5 % ,25.33% while without fins 22.41% and 16.25% respectively at concentration of 5%vol compared with base fluid (oil). The heat transfer coefficient and pressure drop is increased by using nanofluids (Ag + oil, ZrO2 + oil) instead of the base fluid (oil). The shear stress of nanofluids increases with an increase in concentration of nanoparticles for both parallel flow and counter flow. No much impact of changing flow direction on overall heat transfer coefficient .The precent work decided that the nanofluids behaviors are close to the typical Newtonian fluids through the relationship between viscosity and shear rate for ranging from (1% vol – 5% vol ). This article indicated that the thermal performance from nanofluids that contain metal nanoparticles show more enhancements compared to oxide nanofluids due to higher thermal conductivity for the silver. Moreover to performance index are used to present the corresponding flow and heat transfer technique.