Numerical investigation of laminar convective heat transfer for TiO2/water nanofluids using two-phase mixture model (Eulerian approach)

Kristiawan, Budi; Santoso, Budi; Juwana, Wibawa Endra; Ramadhan, Raden Mahesa; Riandana, Ivan

doi:10.1063/1.4968255

Cited by 12 publications

(12 citation statements)

References 9 publications

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“…The turbulent intensity of the flow increases following the increase in Re, leading to the enhancement of the convective heat transfer. These results are consistent with the those of the previous studies [3][4][5][6][7]9,10]. Figure 4 further shows that, for the STT, the pitch ratio y/W of 2.7 yields the highest Nu followed by those of 4.5 and 6.5.…”

Section: Resultssupporting

confidence: 92%

“…This software basically runs based on the finite volume method. This method is also applied to solve Equations (4)- (6), together with the k-ε renormalized group turbulence model. In addition, the standard-pressure and second-order upwind discretization methods are adopted in order to calculate both momentum and energy.…”

Section: Fluidmentioning

confidence: 99%

“…Numerous research studies have been performed on heat exchangers, to enhance the heat transfer, in order to achieve a higher heat exchange performance [1,2]. For this purpose, the following efforts have been reported in our previous works: a direct contact system for adsorption cycle [3][4][5], using nanofluid as the working fluid [6,7]; improvement of maldistribution inside the distributor of heat exchangers [8][9][10]; using inserts inside the tubes [11][12][13][14][15]. Based on the published reports, it is known that the investigations on passive heat transfer enhancement methods using various inserts do not consider the existing problems.…”

Section: Introductionmentioning

confidence: 99%

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Internal Flow in an Enhanced Tube Having Square-cut Twisted Tape Insert

et al. 2019

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In this study, a numerical simulation has been conducted in order to evaluate the thermal hydraulic performance of a turbulent single-phase flow inside an enhanced tube equipped with a square-cut twisted tape (STT) insert. The classical twisted tape (CTT) insert was also investigated for comparison. The k-ε renormalized group turbulence model has been utilized as the turbulent model. Various twist ratios (y/W) of 2.7, 4.5, and 6.5 were investigated for the Reynolds number range of 8000–18,000, with water as the working fluid. The numerical results indicated that, in comparison with the plain tube (PT), the tube equipped with the STT with the twist ratios of 2.7, 4.5, and 6.5 led to an increase in the values of the Nusselt number and friction factor in the inner tube by 45.4–80.7% and 2.0–3.3 times, respectively; in addition, the highest thermal performance of 1.23 has been obtained. The results further indicated that the tube equipped with the CTT of the same twist ratios improved the Nusselt number and friction factor in the inner tube by 40.3–74.4% and 1.7–3.0 times, respectively, in comparison with the PT; further, the maximum thermal performance of 1.18 was achieved.

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Section: Resultssupporting

confidence: 92%

Section: Fluidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal Flow in an Enhanced Tube Having Square-cut Twisted Tape Insert

et al. 2019

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“…However, unlike the radial velocity profiles which achieves nearly fully developed at x ≈ 0.5 m as shown in Figure 6, temperature distribution needs longer distance in axial direction to attain fully developed. This phenomena agrees with the experimental investigation in our experiments [24,27]. mentioned in Equation (7) can exhibit the temperature contours of the nanofluid domain.…”

Section: Temperature Contours Of Nanofluidssupporting

confidence: 92%

“…To verify the accuracy and the reliability of the numerical methods, pure water was applied prior to the nanofluids at both the laminar and turbulent flow. Computing the Nusselt number in this simulation was carried out based on the mean temperature as it demonstrated a better prediction of the Nusselt number than the centerline temperature as reported in a previous study [24]. The validation of this investigation was undertaken through a comparison with the established empirical correlations for laminar (Equations (12) and (13) and turbulent (Equations (14)-(16)) flow, as depicted in Figure 4a,b, respectively.…”

Section: Validation Of Numerical Resultsmentioning

confidence: 98%

Heat Transfer Enhancement of TiO2/Water Nanofluid at Laminar and Turbulent Flows: A Numerical Approach for Evaluating the Effect of Nanoparticle Loadings

et al. 2018

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Titania-based nanofluid flowing inside a circular tube under the boundary condition of a horizontal uniformly heated wall was investigated numerically for both laminar and turbulent flows. In this work, an innovative numerical method using an Eulerian approach for the two-phase mixture model was used to simulate the flow and convective heat transfer characteristics. The effect of nanoparticle loading and Reynolds number on the flow and heat transfer characteristics was observed. The Reynolds number was 500 and 1200 for laminar flow, while for turbulent flow, the Reynolds number was varied in the range from 4000 to 14,000. A comparison with the established empirical correlations was made. The results clearly showed at the laminar and turbulent flows that the existing nanoparticles provided a considerable enhancement in the convective heat transfer. For laminar flow, the numerical results found that the enhancement in the convective heat transfer coefficient of nanofluids were 4.63, 11.47, and 20.20% for nanoparticle loadings of 0.24, 0.60, and 1.18 vol.%, respectively. On the other hand, for turbulent flow, the corresponding heat transfer increases were 4.04, 10.33, and 21.87%.

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Evaluation of single-phase, discrete, mixture and combined model of discrete and mixture phases in predicting nanofluid heat transfer characteristics for laminar and turbulent flow regimes

Onyiriuka

Obanor

Mahdavi

et al. 2018

Advanced Powder Technology

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It is essential to investigate the appropriate model for simulating nanofluid flow for different flow regimes because, at present, most previous studies do not agree with each other. It was, therefore, the purpose of this study to present a Computational Fluids Dynamics (CFD) investigation of heat transfer coefficients of internal forced convective flow of nanofluids in a circular tube subject to constant wall heat flux boundary conditions. A complete threedimensional (3D) cylindrical geometry was used. Laminar and turbulent flow regimes were considered. Three two-phase models (mixture model, discrete phase model (DPM) and the combined model of discrete and mixture phases) and the single-phase homogeneous model (SPM) were considered with both constant and variable properties. For the turbulent flow regime, it was found that the DPM with variable properties closely predicted the local heat transfer coefficients with an average deviation of 9%, and the SPM deviated from the DPM model by 2%. It was also found that the mixture and the combined discrete and the mixture phase model gave unrealistic results. For laminar flow, the DPM model with variable properties predicted the heat transfer coefficients with an average deviation of 9%.

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Numerical investigation of laminar convective heat transfer for TiO2/water nanofluids using two-phase mixture model (Eulerian approach)

Cited by 12 publications

References 9 publications

Internal Flow in an Enhanced Tube Having Square-cut Twisted Tape Insert

Internal Flow in an Enhanced Tube Having Square-cut Twisted Tape Insert

Heat Transfer Enhancement of TiO2/Water Nanofluid at Laminar and Turbulent Flows: A Numerical Approach for Evaluating the Effect of Nanoparticle Loadings

Evaluation of single-phase, discrete, mixture and combined model of discrete and mixture phases in predicting nanofluid heat transfer characteristics for laminar and turbulent flow regimes

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