Abstract
In the present study, the heat transfer characteristics, namely, heat transfer coefficient, Nusselt number, pressure drop, friction factor and performance evaluation criteria are evaluated for water, Al2O3 and Al2O3/Cu nanofluids. The effects of Reynolds number, volume fraction and composition of nanoparticles in hybrid nanofluid are analyzed for all heat transfer characteristics. The single particle and hybrid nanofluids are flowing through a plain straight tube which is symmetrically heated under uniform heat flux condition. The numerical model is validated for Nusselt number within 7.66% error and friction factor within 8.83% error with corresponding experimental results from the previous literature study. The thermophysical properties of hybrid nanofluid are superior to the single particle nanofluid and water. The heat transfer coefficient, Nusselt number and pressure drop show increasing trend with increase in the Reynolds number and volume fraction. The friction factor shows the parabolic trend, and the performance evaluation criteria shows small variations with change in Reynolds number. However, both friction factor and performance evaluation criteria have increased with increase in the volume fraction. The 2.0% Al2O3/Cu with equal composition of both nanoparticles (50/50%) have presented superior heat transfer characteristics among all working fluids. Further, the heat transfer characteristics of 2.0% Al2O3/Cu hybrid nanofluid are enhanced by changing the nanoparticle compositions. The performance evaluation criteria for 2.0% Al2O3, 2.0% Al2O3/Cu (50/50%), 2.0% Al2O3/Cu (75/25%) and 2.0% Al2O3/Cu (25/75%) are evaluated as 1.08, 1.11, 1.10 and 1.12, respectively.
Highlights
Published: 14 May 2021Currently, energy saving in thermal systems has grabbed considerable attention to reduce the heat losses and improve the heat transfer performance [1]
The comparison is presented for water/EG flow in the considered tube geometry under the constant heat flux of 7957 W/m2
The heat transfer coefficient, Nusselt number, pressure drop, friction factor and performance evaluation criteria are investigated for various Reynolds number, volume fractions and nanoparticle compositions of hybrid nanofluid
Summary
Published: 14 May 2021Currently, energy saving in thermal systems has grabbed considerable attention to reduce the heat losses and improve the heat transfer performance [1]. Numerous studies were reported on heat transfer applications of nanofluids in the thermal systems such as tubes. Firoozi et al have conducted a numerical study to investigate the heat transfer and flow characteristics of Al2 O3 /water nanofluid flowing through tubes incorporated with various dimple configurations [3]. Ledari et al have investigated the heat transfer and friction factor characteristics of oil based CuO and Fe3 O4 nanofluids flowing through the. Chaurasia and Sarviya have conducted experimental and numerical studies to analyze the thermal hydraulic and entropy generation performances of nanofluid flowing through helical screw insert tube with single and double strips [5]. Ying et al have concluded that Al2 O3 /water nanofluid with 0.063% mass concentration shows improvement in heat transfer coefficient and Nusselt number by 7.29% and 6.90%, respectively
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