Wettability alterations and magnetic field effects on the nucleation of magnetic nanofluids: A molecular dynamics simulation

Taheri, M.; Mohammadpourfard, Mousa; Sadaghiani, Abdolali Khalili; Koşar, Ali

doi:10.1016/j.molliq.2018.03.075

Cited by 32 publications

(5 citation statements)

References 24 publications

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“…Another group of studies can be distinguished in the literature that has utilized active heat transfer enhancement techniques such as imposing magnetic and electric fields to the coolant fluid . Among these methods, using ferrofluid under the influence of an external magnetic field has been concentrated in recent years by many researchers …”

Section: Introductionmentioning

confidence: 99%

A magnetic vortex generator for simultaneous heat transfer enhancement and pressure drop reduction in a mini channel

Bezaatpour

Goharkhah

2020

Heat Trans

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An active vortex generator is proposed for heat transfer enhancement in heat sinks and heat exchangers and removal of highly concentrated heat fluxes. It is based on applying a uniform magnetic field of permanent magnets to a magnetic fluid (ferrofluid) flowing in a heated channel.Numerical simulations are carried out for a 2 Vol% ferrofluid at different Reynolds numbers (150-210) and magnetic field intensities (0-1400 G) to investigate the possibility of simultaneous heat transfer enhancement and pressure drop reduction by the proposed method. Comparisons are also made with the other conventional vortex generators. Results indicate that the external magnetic field acts as a vortex generator that changes the velocity distribution, improves the flow mixing, and thereby increases the convective heat transfer. Surprisingly, the heat transfer enhancement is accompanied by a decrease of the friction coefficient due to the flow separation and decrease of the flow contact with the surface. It is also concluded that increasing the magnetic field intensity, decreasing the flow rate, and adding a second identical magnetic vortex generator have favorable effects on both pressure drop and heat transfer. A maximum of 37.8% enhancement of heat transfer with a 29.18% reduction of pressure drop has been achieved at the optimum condition. K E Y W O R D S flow mixing, forced convection, heat transfer, magnetic field effect, magnetite ferrofluid, vortex generator

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Section: Introductionmentioning

confidence: 99%

A magnetic vortex generator for simultaneous heat transfer enhancement and pressure drop reduction in a mini channel

Bezaatpour

Goharkhah

2020

Heat Trans

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“…The features and advantages of molecular dynamics simulation make it an extremely efficient and flexible tool that can be used to measure thermal properties at the nanoscale and the atomic level [8][9][10]. For this reason, many researchers have utilized MD simulation to study the thermal properties of systems at the nanoscale such as nanofluids [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Effect of water/carbon interaction strength on interfacial thermal resistance and the surrounding molecular nanolayer of CNT and graphene flake

Jabbari

Rajabpour

Saedodin

2019

Journal of Molecular Liquids

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Heat transfer at the liquid/solid interface, especially at the nanoscale, has enormous importance in nanofluids. This study investigates liquid/solid interfacial thermal resistance and structure of the formed molecular nanolayer around a carbon-based nanoparticle. Employing non-equilibrium molecular dynamics simulation and thermal relaxation method, the nanofluid systems with different nanoparticle diameters and different surface wettability were investigated. Simulation results show that carbon nanotubes (CNTs) with a smaller diameter attract more value of the base fluid and lead to a reduced Kapitza resistance. It was found that the thickness of the nanolayer around the nanoparticle is independent of the water/carbon interaction strength. Also, the value of the Kapitza resistance decreases with increasing the interaction strength. Ultimately, a correlation was proposed for the thermal resistance of CNT/water and graphene/water nanofluids in terms of wettability intensity of nanoparticle surface.The proposed correlation in addition to fitting to simulation results can cover the physical conditions of the system.Corresponding authors: * Rajabpour@eng.ikiu.ac.ir † s_sadodin@semnan.ac.ir

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“…The viscosity of the water is reduced [50,51], so the diffusion process of solute is accelerated under the effect of the magnetic field, the range of motion of solute molecules is more extensive and more accessible, there are more opportunities for solute molecules to collide, the practical collision is increased, and the nucleation process is promoted. On the other hand, the presence of a magnetic field decreases the surface tension of the solution, and the free energy of the liquid-solid transition during crystallization decreases, which reduces the critical nucleation radius [52,53]. In summary of the above two reasons, the presence of a magnetic field can shorten the induction period time.…”

Section: Effect Of Magnetic Field On Induction Periodmentioning

confidence: 99%

Effects of Solubilizer and Magnetic Field during Crystallization Induction of Ammonium Bicarbonate in New Ammonia-Based Carbon Capture Process

et al. 2022

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As a chemical absorption method, the new ammonia carbon capture technology can capture CO2. Adding ethanol to ammonia can reduce the escape of ammonia to a certain extent and increase the absorption rate of CO2. The dissolution and crystallization of ethanol can realize the crystallization of ammonium bicarbonate and generate solid products. The induction of the crystallization process is influenced by many parameters, such as solution temperature, supersaturation, and solvating precipitant content. The basic nucleation theory is related to the critical size of nucleation. Accurate measurement of the induction period and investigating relevant factors can help to assess the nucleation kinetics. The effects of solubilizer content, temperature, and magnetic field on the induction period of the crystallization process of ammonium bicarbonate in the ethanol–H2O binary solvent mixture and determining the growth mechanism of the crystal surface by solid–liquid surface tension and surface entropy factor are investigated. The results indicate that under the same conditions of mixed solution temperature, the crystallization induction period becomes significantly longer, the solid–liquid surface tension increases, and the nucleation barrier becomes more significant and less likely to form nuclei as the content of solvating precipitants in the components increases. At the same solubilizer content, there is an inverse relationship between the solution temperature and the induction period, and the solid–liquid surface tension decreases. The magnetic field can significantly reduce the induction period of the solvate crystallization process. This gap tends to decrease with an increase in supersaturation; the shortening reduces from 96.9% to 84.0%. This decreasing trend becomes more and more evident with the rise of solvent content in the solution. The variation of surface entropy factor under the present experimental conditions ranges from 0.752 to 1.499. The growth mode of ammonium bicarbonate in the ethanol–H2O binary solvent mixture can be judged by the surface entropy factor as continuous growth.

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Wettability alterations and magnetic field effects on the nucleation of magnetic nanofluids: A molecular dynamics simulation

Cited by 32 publications

References 24 publications

A magnetic vortex generator for simultaneous heat transfer enhancement and pressure drop reduction in a mini channel

A magnetic vortex generator for simultaneous heat transfer enhancement and pressure drop reduction in a mini channel

Effect of water/carbon interaction strength on interfacial thermal resistance and the surrounding molecular nanolayer of CNT and graphene flake

Effects of Solubilizer and Magnetic Field during Crystallization Induction of Ammonium Bicarbonate in New Ammonia-Based Carbon Capture Process

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