Advances of Nanofluids in Solar Collectors - A Review of Numerical Studies

The objective of this work is the mathematical modelling and the numerical simulation of the stationary, laminar, and natural convection, in a confined square cavity (H = L) filled with two fluids (a mixture of nanoparticles of aluminum oxide and Al2O3 water) in one partition and pure water in the other partition. A porous conductive wall of thickness w (w = L/e) and thermal conductivity Keff constitutes the exchange surface between these two partitions. The fluid movement is modeled by the Navier-Stokes equations in the two partitions, while the porous medium is modelled by the Darcy–Brinkman equation. Comsol Multiphysics software is used to solve the system of differential equations that is based on the finite element method. The results are discussed with particular attention to the mean and local Nusselt number (Nu), streamlines and isotherms. A parametric study for Rayleigh number Ra (102 to 106), volume fraction j (0% to 10%), and Darcy number Da (10-7 to 10-2) is performed. The obtained findings show that the increase in Ra, Da, and j intensifies the flow and improves the thermal exchange on the cold wall. For Da £ 10-5, Nu remains practically low and the natural convection is being dominated by conduction. For Da > 10-5, an increase in Nu is observed and the flows tend towards a purely convective situation. Furthermore, an increase in the heat transfer coefficients is observed with the raise of the porous layer permeability, volume fraction and Rayleigh number.

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“…This improvement is more significant in the case of Da = 10 -2 . These results agree well with the literature [41][42][43].…”

Section: Tablesupporting

confidence: 94%

Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

Douha

Draoui

Kaid³

et al. 2020

ARFMTS

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“…Publications on nano uids over the past decade review papers related to the heat transfer properties and application of nanofluids were published in 2019. The reviews include solar collector applications [20,21], a review of nanofluids in heat exchangers [22,23], review of nanofluids in heat pipes [24], radiator cooling [25], electronic cooling [5] and also a review on various thermophysical properties of nanofluids [26,27]. A list of some of the review papers published in 2019 is listed in Table 1.…”

Section: Number Of Publications Yearmentioning

confidence: 99%

An updated review of nanofluids in various heat transfer devices

Okonkwo

Wole‐Osho

Almanassra

et al. 2020

J Therm Anal Calorim

210

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The field of nanofluids has received interesting attention since the concept of dispersing nanoscaled particles into a fluid was first introduced in the later part of the twentieth century. This is evident from the increased number of studies related to nanofluids published annually. The increasing attention on nanofluids is primarily due to their enhanced thermophysical properties and their ability to be incorporated into a wide range of thermal applications ranging from enhancing the effectiveness of heat exchangers used in industries to solar energy harvesting for renewable energy production. Owing to the increasing number of studies relating to nanofluids, there is a need for a holistic review of the progress and steps taken in 2019 concerning their application in heat transfer devices. This review takes a retrospective look at the year 2019 by reviewing the progress made in the area of nanofluids preparation and the applications of nanofluids in various heat transfer devices such as solar collectors, heat exchangers, refrigeration systems, radiators, thermal storage systems and electronic cooling. This review aims to update readers on recent progress while also highlighting the challenges and future of nanofluids as the next-generation heat transfer fluids. Finally, a conclusion on the merits and demerits of nanofluids is presented along with recommendations for future studies that would mobilise the rapid commercialisation of nanofluids.

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“…The results obtained show a slight thermal enhancement due to the decrease in the thermal-conductivity of such conventional fluids. Some other studies resorted to increasing thermal-conductivity by adding nanoscale solid particles capable of excessively absorbing thermal-energy from hot walls [1][2][3]. In such contributions, researchers found enhanced thermal-transport over channels under the presence of aerobic or aqueous fluids.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Heat Transfer by Oil/Multi-Walled Carbon Nano-Tubes Nanofluid

Boursas¹,

Salmi²,

Lorenzini³

et al. 2021

ACSM

Self Cite

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The subject of the study is mainly based on thermal reinforcement by an oily fluid containing nanometer particles of carbon. The study is carried out by the presence of discontinuous bars in two different shapes, i.e. flat and V, inside a horizontal heat exchanger. The study relies on simulations in thermal and dynamic terms from the literature. The turbulence effect is diagnosed by applying the k-ε model, while the flow hydrothermal transport relationships are modeled based on the finite volume technique. Both the flow and heat-transfer aspects of all channel regions are studied and analyzed. The new heat-exchanger structure has been enhanced in the presence of these discontinuous bars by reducing the friction coefficient and eliminating stations with poor transfer of heat behind these deflectors.

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Advances of Nanofluids in Solar Collectors - A Review of Numerical Studies

Cited by 48 publications

References 84 publications

Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

Study of Laminar Naturel Convection in Partially Porous Cavity in the Presence of Nanofluids

An updated review of nanofluids in various heat transfer devices

Enhanced Heat Transfer by Oil/Multi-Walled Carbon Nano-Tubes Nanofluid

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