Experimental investigation of transient heat transfer coefficient in natural convection with Al2O3-nanofluids

Gavili, Anwar; Isfahani, Taghi Dallali

doi:10.1007/s00231-019-02752-5

Cited by 13 publications

(3 citation statements)

References 34 publications

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“…Besides, the additional references on these topics can be found in the books by Das et al (2007), Minkowycz et al (2013), Shenoy et al (2016) and Nield and Bejan (2017). On the other hand, a lot of experimental and theoretical work have been conducted to boost the thermal conductivity of the nanofluid, some examples can be found in Pak and Cho (1998), Ho et al (2010) and Gavili and Isfahani (2020).…”

Section: Introductionmentioning

confidence: 99%

Dufour and Soret effects on Al₂O₃-water nanofluid flow over a moving thin needle: Tiwari and Das model

Waini

Ishak

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2020

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Purpose This paper aims to examine the effect of Dufour and Soret diffusions on Al2O3-water nanofluid flow over a moving thin needle by using the Tiwari and Das model. Design/methodology/approach The governing equations are reduced to the similarity equations using similarity transformations. The resulting equations are programmed in Matlab software through the bvp4c solver to obtain their solutions. The features of the skin friction, heat transfer and mass transfer coefficients, as well as the velocity, temperature and concentration profiles for different values of the physical parameters, are analysed and discussed. Findings The non-uniqueness of the solutions is observed for a certain range of the physical parameters. The authors also notice that the bifurcation of the solutions occurs in which the needle moves toward the origin (λ < 0). It is discovered that the first branch solutions of the skin friction coefficient and the heat transfer coefficients increase, but the mass transfer coefficient decreases in the presence of nanoparticle. Additionally, the simultaneous effect of Dufour and Soret diffusions tends to enhance the heat transfer coefficient; however, dual behaviours are observed for the mass transfer coefficient. Further analysis shows that between the two solutions, only one of them is stable and thus physically reliable in the long run. Originality/value The problem of Al2O3-water nanofluid flow over a moving thin needle with Dufour and Soret effects are the important originality of the present study. Besides, the temporal stability of the dual solutions is examined for time.

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Section: Introductionmentioning

confidence: 99%

Dufour and Soret effects on Al₂O₃-water nanofluid flow over a moving thin needle: Tiwari and Das model

Waini

Ishak

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2020

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“…Nanofluid consists of single type of nanoparticles that are suspended in the base fluid. The utilizing of nanofluid in the heat transfer enhancement was considered by several researchers [10–15]. Studies have shown that a significant increment in the nanofluid heat transfer rate is attained when the hybrid nanoparticle is employed.…”

Section: Introductionmentioning

confidence: 99%

Unsteady hybrid nanofluid flow on a stagnation point of a permeable rigid surface

2020

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This study investigates the unsteady flow of Al2O3‐Cu/water hybrid nanofluid on a stagnation point of a permeable rigid surface. The similarity equations are obtained using similarity variables and then solved using the bvp4c solver. The outcomes show that dual solutions exist for the negative unsteadiness and some mass flux parameters. Besides, the heat transfer rate is intensified with the hybrid nanoparticles. Moreover, the increasing of the mass flux parameter tends to increase the heat transfer rate and the skin friction on the surface. Also, the reduction of the skin friction coefficient is observed, and a higher heat transfer rate is achieved for smaller values of the unsteadiness parameter. Finally, by a temporal stability analysis, it is found that the first solution is stable and reliable as time evolves.

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“…Nanofluid consists of a single type of nanoparticles that are suspended in the base fluid. The using of nanofluid in heat transfer enhancement was considered by several researchers, for example, Khanafer et al (2003), Oztop and Abu-Nada (2008), Tiwari and Das (2007), Mohebbi and Rashidi (2017), Gavili and Isfahani (2020) and Turkyilmazoglu (2020). Additionally, the studies of a nanofluid in a cavity were considered by Izadi et al (2018), and Alsabery et al (2019).…”

Section: Introductionmentioning

confidence: 99%

Hybrid nanofluid flow on a shrinking cylinder with prescribed surface heat flux

Waini

Ishak

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2020

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Purpose This study aims to investigate the flow impinging on a stagnation point of a shrinking cylinder subjected to prescribed surface heat flux in Al2O3-Cu/water hybrid nanofluid. Design/methodology/approach Using similarity variables, the similarity equations are obtained and then solved using bvp4c in MATLAB. The effects of several physical parameters on the skin friction and heat transfer rate, as well as the velocity and temperature profiles are analysed and discussed. Findings The outcomes show that dual solutions are possible for the shrinking case, in the range λc<λ<−1, where λc is the bifurcation point of the solutions. Meanwhile, the solution is unique for λ≥−1. Besides, the boundary layer is detached on the surface at λc, where the value of λc is affected by the hybrid nanoparticle φhnf and the curvature parameter γ. Moreover, the friction and the heat transfer on the surface increase with the rising values φhnf and γ. Finally, the temporal stability analysis shows that the first solution is stable in the long run, whereas the second solution is not. Originality/value The present work considers the problem of stagnation point flow impinging on a shrinking cylinder containing Al2O3-Cu/water hybrid nanofluid, with prescribed surface heat flux. This paper shows that two solutions are obtained for the shrinking case. Further analysis shows that only one of the solutions is stable as time evolves.

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Experimental investigation of transient heat transfer coefficient in natural convection with Al2O3-nanofluids

Cited by 13 publications

References 34 publications

Dufour and Soret effects on Al₂O₃-water nanofluid flow over a moving thin needle: Tiwari and Das model

Dufour and Soret effects on Al₂O₃-water nanofluid flow over a moving thin needle: Tiwari and Das model

Unsteady hybrid nanofluid flow on a stagnation point of a permeable rigid surface

Hybrid nanofluid flow on a shrinking cylinder with prescribed surface heat flux

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Experimental investigation of transient heat transfer coefficient in natural convection with Al2O3-nanofluids

Cited by 13 publications

References 34 publications

Dufour and Soret effects on Al2O3-water nanofluid flow over a moving thin needle: Tiwari and Das model

Dufour and Soret effects on Al2O3-water nanofluid flow over a moving thin needle: Tiwari and Das model

Unsteady hybrid nanofluid flow on a stagnation point of a permeable rigid surface

Hybrid nanofluid flow on a shrinking cylinder with prescribed surface heat flux

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Product

Resources

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Dufour and Soret effects on Al₂O₃-water nanofluid flow over a moving thin needle: Tiwari and Das model

Dufour and Soret effects on Al₂O₃-water nanofluid flow over a moving thin needle: Tiwari and Das model