Natural convection analysis employing entropy generation and heatline visualization in a hollow L-shaped cavity filled with nanofluid using lattice Boltzmann method- experimental thermo-physical properties

Rahimi, Alireza; Kasaeipoor, Abbas; Malekshah, Emad Hasani; Amiri, Ali

doi:10.1016/j.physe.2017.10.004

Cited by 72 publications

(16 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To calculate the distribution functions, the lattice Boltzmann equation is solved. Two sets of distribution functions, one for velocity field and the other for the temperature field, are solved simultaneously (Rahimi et al, 2018a). After introducing Bhatnagar-Gross-Krook (BGK) approximation, the Boltzmann equation without external forces can be presented as follows (Bhatnagar et al, 1954):…”

Section: Lattice Boltzmann Methodsmentioning

confidence: 99%

Nanofluid flow and heat transfer due to natural convection in a semi-circle/ellipse annulus using modified lattice Boltzmann method

Xiong

Khosravi

Nabipour³

et al. 2019

HFF

View full text Add to dashboard Cite

Purpose This paper aims to numerically investigate the nanofluid flow, heat transfer and entropy generation during natural convection in an annulus. Design/methodology/approach The lattice Boltzmann method is used to simulate the velocity and temperature fields. Furthermore, some special modifications are applied to make the lattice Boltzmann method capable for simulation in the curved boundary conditions. The annulus is filled with CuO-water nanofluid. The dynamic viscosity of nanofluid is estimated using KLL (Koo-Kleinstreuer-Li) model, and the nanoparticle shape effect is taken account in calculating the thermal conductivity. On the other hand, the local/volumetric entropy generation is used to show the irreversibility under influence of different parameters. Findings The effect of considered governing parameters including Rayleigh number (103<Ra < 106); nanoparticle concentration (0<<0.04) and configuration of annulus on the flow structure; temperature field; and local and total entropy generation and heat transfer rate are presented. Originality/value The originality of this work is using of lattice Boltzmann method is simulation of natural convection in a curved configuration and using of Koo–Kleinstreuer–Li correlation for simulation of nanofluid.

show abstract

Section: Lattice Boltzmann Methodsmentioning

confidence: 99%

Nanofluid flow and heat transfer due to natural convection in a semi-circle/ellipse annulus using modified lattice Boltzmann method

Xiong

Khosravi

Nabipour³

et al. 2019

HFF

View full text Add to dashboard Cite

show abstract

“…The total generated entropy _ S g during the natural convection within the computational domain is defined as follows (Rahimi et al, 2018c:…”

Section: Entropy Generation Formulationmentioning

confidence: 99%

Study on fluid flow and heat transfer in fluid channel filled with KKL model-based nanofluid during natural convection using FVM

Rao

Shao

Rahimi

et al. 2019

HFF

Self Cite

View full text Add to dashboard Cite

Purpose A comprehensive study on the fluid flow and heat transfer in a nanofluid channel is carried out. The configuration of the channel is as like as quarter channel. The channel is filled with CuO–water nanofluid. Design/methodology/approach The Koo–Kleinstreuer–Li model is used to estimate the dynamic viscosity and consider the Brownian motion. On the other hand, the influence of nanoparticles’ shapes on the heat transfer rate is considered in the simulations. The channel is included with the injection pipes which are modeled as active bodies with constant temperature in the 2D simulations. Findings The Rayleigh number, nanoparticle concentration and the thermal arrangements of internal pipes are the governing parameters. The hydrothermal aspects of natural convection are investigation using different approaches such as average Nusselt number, total entropy generation, Bejan number, streamlines, temperature fields, local heat transfer irreversibility, local fluid friction irreversibility and heatlines. Originality/value The originality of this work is investigation of fluid flow, heat transfer, entropy generation and heatline visualization within a nanofluid-filled channel using a finite volume method.

show abstract

“…However, it should be noted that the PCM inside the container can fully complete its phase change on the day and remain in liquid form where the heat transfer of melted PCM is afterwards driven by free convection 33,34 . At this point, although various BCs can be possibly defined in the modelling step, 35‐38 appropriate modelling of natural convection in enclosures and specification of BCs become important as they can significantly affect the outcomes and should be suitable and realistic for the considered problem. Furthermore, it should be stressed out that the Nusselt number correlations for enclosures are available for isothermal BCs, while there is a lack of correlations for heat flux and convective BCs, which makes the solution of such problems more challenging.…”

Section: Introductionmentioning

confidence: 99%

Implications of boundary conditions on natural convective heat transfer of molten phase change material inside enclosures

Arıcı

Yıldız

Nižetić³

et al. 2020

Int J Energy Res

View full text Add to dashboard Cite

Summary Considering the significance of the appropriate selection of boundary conditions (BCs) in modelling step for practical engineering applications, this study presents a numerical work focusing on the impacts of BCs on the natural convection of molten phase change material (PCM) used for cooling of photovoltaics (PV). A rectangular enclosure loaded with liquid PCM (Pr = 41.22) is considered at an inclination angle of θ = 30° to simulate a PV‐PCM system. Heat flux is applied to the top wall, and impacts of two different BCs at the bottom wall, namely isothermal and convective BCs, on the flow and heat transfer characteristics are compared by taking six different Biot numbers (0.1 ≤ Bi ≤ 100) into account, while the reference case is considered as isothermal BC. Furthermore, the effects of various aspect ratios (AR = 1, 2 and 4) and Rayleigh numbers (Ra = 104, 105 and 106) are also included. The results revealed that Biot number has a significant effect on mean Nusselt number. Compared to the isothermal case, low Biot numbers (Bi < 10) significantly restrict convection motions inside the enclosure and result in remarkably different mean Nusselt numbers, while high Biot numbers give significantly similar results due to low thermal resistance outside the bottom wall. Moreover, the heat transfer enhancement by increasing AR and Ra is considerably high at high Biot numbers, while it is remarkably constricted at low Biot numbers. As a result of comprehensive analyses, it is deduced that utilization of isothermal BCs instead of convective BC for easiness of modelling can be a reasonable approach providing that Biot number is sufficiently large (Bi > 10). Although the inspiration of the present study is PV/PCM systems, the results can be generalized for any kind of fluids used in similar natural convection applications.

show abstract

Natural convection analysis employing entropy generation and heatline visualization in a hollow L-shaped cavity filled with nanofluid using lattice Boltzmann method- experimental thermo-physical properties

Cited by 72 publications

References 45 publications

Nanofluid flow and heat transfer due to natural convection in a semi-circle/ellipse annulus using modified lattice Boltzmann method

Nanofluid flow and heat transfer due to natural convection in a semi-circle/ellipse annulus using modified lattice Boltzmann method

Study on fluid flow and heat transfer in fluid channel filled with KKL model-based nanofluid during natural convection using FVM

Implications of boundary conditions on natural convective heat transfer of molten phase change material inside enclosures

Contact Info

Product

Resources

About