Heat transfer enhancements of low volume concentration Al2O3 nanofluid and with longitudinal strip inserts in a circular tube

Abstract In this work three-dimensional numerical study is presented that deals with thermo-hydrodynamic performance and entropy generation in recharging microchannel using water-based nanofluids. Four different water-based nanofluids (Al2O3, CuO, SiO2, and ZnO) are considered with volume concentration and nanoparticle diameter varied in the range of 1% to 5%, and 10 nm to 50 nm respectively to understand their effect on thermo-hydrodynamic performance and entropy generation. Constant wall heat flux of 100 W/cm2 is applied on the substrate bottom surface while coolant flows through recharging microchannel with Reynolds number Re = 100 to 500. It is revealed that among all the nanofluids under investigation, water/Al2O3 provides enhanced thermal performance with higher effectiveness parameter (η), and it also shows reduced entropy generation in recharging microchannel. With increasing volume concentration of water/Al2O3 nanofluid, heat transfer coefficient increases, effectiveness parameter increases, and entropy generation reduces. Water/Al2O3 nanofluid with smaller particle diameter shows enhanced heat transfer coefficient, and reduced entropy generation, whereas it shows decreased effectiveness parameter. This is attributed to increased pressure drop with decreasing particle diameter. This study suggest that optimized combination of particle diameter and volume concentration should be chosen for using nanofluid based coolants for high heat flux removal.

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Investigations on Convective Heat Transfer Enhancement in Circular Tube Radiator Using Al2O3 and CuO Nanofluids

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4039924 ◽

2018 ◽

Vol 10 (5) ◽

Cited By ~ 1

Author(s):

Sobin Alosious ◽

S. R. Sarath ◽

Anjan R. Nair ◽

K. Krishnakumar

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Reynolds Number ◽

Convective Heat Transfer ◽

Convective Heat ◽

Volume Concentration ◽

Circular Tube ◽

Convective Heat Transfer Coefficient ◽

Maximum Enhancement ◽

Study Results

In this study, forced convective heat transfer inside a circular tube automobile radiator is experimentally and numerically investigated. The investigation is carried out using Al2O3 and CuO nanofluids with water as their base fluid. A single radiator circular tube with the same dimensions is numerically modeled. Numerical model is validated using the experimental study results. In the experimental study, Al2O3 and CuO nanofluids of 0.05% volume concentrations (ϕ) were recirculated through the radiator for the Reynolds number (Re) between 260 and 1560. The numerical investigation is conducted for the nanoparticle volume concentration from 0% to 6.0% and 260 < Re < 1560. The investigation shows an enhancement of convective heat transfer coefficient (h) with the increase in nanoparticle volume concentration and with the Reynolds number. A maximum enhancement of 38% and 33% were found for Al2O3 and CuO nanofluids of ϕ = 1% and Re = 1560. For the same cooling load of the radiator, the pumping power can be reduced by 8% and 10%, when Al2O3 and CuO nanofluids (ϕ = 0.8%) were used. Enhancement in convective heat transfer can be utilized to reduce the radiator surface area required. However, the addition of nanofluid results in an enhancement of density (ρ) and viscosity (μ) along with a reduction in specific heat capacity (Cp). Hence, the selection of nanoparticle volume concentration should consider its effect on the thermophysical properties mentioned earlier. It is found that the preferred concentration is between 0.4% and 0.8% for both Al2O3 and CuO nanofluids. In our investigations, it is observed that the convective heat transfer performance of Al2O3 nanofluid is better than the CuO nanofluid.

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