Heat transfer and entropy generation analysis of nanofluids flow in an open cavity

Heat exchangers play an important role in different industrial processes; therefore, it is important to characterize these devices to improve their efficiency by guaranteeing the efficient use of energy. In this study, we carry out a numerical analysis of flow dynamics, heat transfer, and entropy generation inside a heat exchanger; an aqueous medium used for oil extraction flows through the exchanger. Hot water flows on the shell side; nanoparticles have been added to the water in order to improve heat transfer toward the cold aqueous medium flowing on the tube side. The aqueous medium must reach a certain temperature in order to obtain its oil extraction properties. The analysis is performed for different Richardson numbers (Ri = 0.1–10), nanofluid volume fractions (φ = 0.00–0.06), and heat exchanger heights (H = 0.6–1.0). Results are presented in terms of Nusselt number, total entropy generation, Bejan number, and performance evaluation criterion. Results showed that heat exchanger performance increases with the increase in Ri when Ri > 1 and when reducing H.

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“…The local Nusselt number on the outer surface on the tube side of the heat exchanger can be determined as [ 33 , 38 , 39 , 40 ]:

where η is the normal direction. The average Nusselt number on the outer surface on the tube side of the heat exchanger can be calculated as:

where A is the outer surface area.…”

Section: Conservation Equationsmentioning

confidence: 99%

Numerical Study of Nanofluid Irreversibilities in a Heat Exchanger Used with an Aqueous Medium

Ovando-Chacon¹,

Ovando-Chacón

León³

et al. 2020

Entropy

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“…A numerical analysis of entropy production in an open cavity with pulsating flow in a horizontal channel has been presented by Zamzari et al [19]. In a similar work, Mehrez et al [20] performed work on entropy generation of nanofluids flow in an open cavity. Other works related to the subject can be found in [21][22][23][24][25][26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Natural Convection and Irreversibility Evaluation in a Cubic Cavity with Partial Opening in Both Top and Bottom Sides

Öztop

Almeshaal

Kolsi

et al. 2019

Entropy

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A numerical study on natural convection in a cubical cavity with partial top and bottom openings is performed in this paper. One of the vertical walls of the cavity has higher temperature than that of the opposite one; the remaining walls are insulated perfectly. Three-dimensional simulations of governing equations have been performed using a finite volume technique. The results are presented for different parameters such as opening length and Rayleigh number. It is observed that heat transfer rate and fluid flow can be controlled via opening ratio size and Rayleigh number.

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“…In heat transfer processes different sources of irreversibility can be responsible for entropy generation: temperature gradients, viscous effect, magnetohydrodynamic effect, etc. Studies on entropy generation using nanofluids are mainly focused on differentially heated enclosures [21][22][23][24][25]. However, those related to horizontal and vertical channels are limited especially under mixed convection regime.…”

Section: Introductionmentioning

confidence: 99%

Mixed convection heat transfer and entropy generation analysis of copper–water nanofluid in a vertical channel with non-uniform heating

2019

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This paper reports results of a numerical investigation on mixed convection heat transfer and entropy generation for water-copper nanofluid within a vertical channel. The left wall is subjected to a heat flux density of sinusoidal variation, while the right one is cooled at uniform density. The Buongiorno model is employed to describe the nanofluid flow in order to take into account the thermophoresis effect and the Brownian motion. The governing equations are solved numerically using the finite volume method with the SIMPLE algorithm. The effects of pertinent parameters including the Richardson number (Ri), the heat flux ratio (R q) and the nanoparticles volume fraction (ϕ i) on the flow and thermal fields, as well as the entropy generation are analyzed for both non-uniform and uniform heating. The results show that the heat transfer rate and the various irreversibility modes are increased with the rise of Ri and R q and the reduction of ϕ i. It is also found that a sinusoidal heating is beneficial for the mean Nusselt number but, unfortunately, it is not favorable for the total entropy generation with augmentation rates of up to 7% and 14%, respectively. A map of the flow reversal occurrence is performed and reveals that the latter is strongly affected by the control parameters. In addition, a correlation is proposed to predict the onset of this phenomena with a maximum deviation of 5% compared to the numerical results.

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Heat transfer and entropy generation analysis of nanofluids flow in an open cavity

Cited by 51 publications

References 45 publications

Numerical Study of Nanofluid Irreversibilities in a Heat Exchanger Used with an Aqueous Medium

Numerical Study of Nanofluid Irreversibilities in a Heat Exchanger Used with an Aqueous Medium

Natural Convection and Irreversibility Evaluation in a Cubic Cavity with Partial Opening in Both Top and Bottom Sides

Mixed convection heat transfer and entropy generation analysis of copper–water nanofluid in a vertical channel with non-uniform heating

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