Experimental Investigation of Laminar Convective Heat Transfer and Pressure Drop of Al2O3/Water Nanofluid in Circular Tube Fitted with Twisted Tape Insert

Year 2017, Volume: 4 Issue: 2, 73 - 86, 10.08.2017

LAITH JAAFER Al-saady , Fouad A. Saleh Bassim M. Maajel

Abstract

In the present study, convective heat transfer coefficient
and pressure drop of Al₂O₃/water nanofluid in laminar flow
regime under constant inlet temperature conditions inside a circular finned-tube
with a typical twisted tape was experimentally investigated. For this purpose,
Al₂O₃ nanoparticles of 20 nm size were synthesized,
characterized and dispersed in distilled water to formulate Al₂O₃/water
nanofluid containing 3 and 5% volume concentration of nanoparticles. The
thermophysical properties like thermal conductivity and viscosity of Al₂O₃
nanofluid is determined through experiments at different volume
concentrations and validated. Experiments are conducted in the Reynolds number
range of (678–2033) with tape of twist ratio (H/D = 1.85). The effect of
different volume concentrations on convective heat transfer coefficient and
friction factor was studied. The results emphasize that increasing of particle volume
concentration leads to enhance convective heat transfer coefficient.
Measurements show the average heat transfer coefficient enhanced about 21-51 %
with 5% volume concentration and increased about 19-38 % with 3% volume
concentration compared to distilled water. In addition, the average ratio of (f_nf/f_bf)
was about 2.3 for 5% volume concentration. Therefore, there is a significant
increase in friction factor for nanofluids. A generalized regression equation
is developed for the estimation of Nusselt number and friction factor valid for
nanofluid. 

Keywords

Typical twisted tape, Heat transfer

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