Homogeneous and Multiphase Analysis of Nanofluids Containing Nonspherical MWCNT and GNP Nanoparticles Considering the Influence of Interfacial Layering

The practical implication of nanofluids is essentially dependent on their accurate modelling, particularly in comparison with the high cost of experimental investigations, yet the accuracy of different computational approaches to simulate nanofluids remains controversial to this day. Therefore, the present study is aimed at analysing the homogenous, multiphase Eulerian–Eulerian (volume of fluid, mixture, Eulerian) and Lagrangian–Eulerian approximation of nanofluids containing nonspherical nanoparticles. The heat transfer and pressure drop characteristics of the multiwalled carbon nanotubes (MWCNT)-based and multiwalled carbon nanotubes/graphene nanoplatelets (MWCNT/GNP)-based nanofluids are computed by incorporating the influence of several physical mechanisms, including interfacial nanolayering. The accuracy of tested computational approaches is evaluated by considering particle concentration and Reynolds number ranges of 0.075–0.25 wt% and 200–470, respectively. The results demonstrate that for all nanofluid combinations and operational conditions, the Lagrangian–Eulerian approximation provides the most accurate convective heat transfer coefficient values with a maximum deviation of 5.34% for 0.25 wt% of MWCNT–water nanofluid at the largest Reynolds number, while single-phase and Eulerian–Eulerian multiphase models accurately estimate the thermal fields of the diluted nanofluids at low Reynolds numbers, but overestimate the results for denser nanofluids at high Reynolds numbers.

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Analysis of Multiwalled Carbon Nanotubes Porosimetry And Their Thermal Conductivity with Ionic Liquid-Based Solvents

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences ◽

10.37934/arfmts.77.2.6375 ◽

2020 ◽

Vol 77 (2) ◽

pp. 63-75

Author(s):

Balaji Bakthavatchalam ◽

Khairul Habib ◽

R. Saidur ◽

Nagoor Basha Shaik ◽

Turnad Lenggo Ginta

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Carbon Nanotubes ◽

Ionic Liquid ◽

Multiwalled Carbon Nanotubes ◽

Experimental Investigations ◽

Step Method ◽

Multiwalled Carbon ◽

Heat Transfer Fluids ◽

The Impact

The suspension of nanoparticles with common heat transfer fluids like Ethylene glycol and water yields nanofluid exhibits superior thermal properties than their host fluids. Ionic liquids have the potential to demonstrate remarkable thermophysical properties (especially thermal conductivity) that ordinary nanofluids cannot achieve. On the other hand, the quantity and structure of nanoparticles porosity affects the nanofluid’s thermal conductivity considerably. Various investigations have revealed the improved thermophysical characteristicts of Multiwalled Carbon nanotubes (MWCNTs) nanofluids containing common solvents or base fluids. However, only limited studies are available on the impact of thermal conductivity in Ionic liquid-based nanofluids (Ionanofluids) owing to their high cost and viscosity. Ultrasonication technique is employed in preparing the three different Ionanofluids containing 0.5 Wt.% via the two-step method to achieve a greater stability and thermal conductivity without utilizing surfactants. Experimental investigations are performed to boost the thermal conductivity of MWCNT/Propylene glycol nanofluid using 1,3-dimethyl imidazolium dimethyl phosphate [Mmim][DMP], 1-ethyl-3-methyl imidazolium octyl sulfate [Emim][OSO4] and 1-ethyl-3-methyl imidazolium diethyl phosphate [Emim][DEP] at a temperature ranging from 295 K to 355 K. The acquired results illustrated that the thermal conductivity of MWCNT Ionanofluids incorporated with [Mmim][DMP], [Emim][OSO4] and [Emim][DEP] increased by 37.5%, 5% and 2% respectively. This unique class of Ionanofluids shows incredible capacity for use in high temperature applications as conventional heat transfer fluids.

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Numerical Simulation of the Performance of Applying Different Nanofluids in a Tube with a 90° Bend at the Center of the Tube

Journal of Nanomaterials ◽

10.1155/2021/8901541 ◽

2021 ◽

Vol 2021 ◽

pp. 1-19

Author(s):

Dinesh Kumar ◽

Gurpreet Singh Sokhal ◽

Nima Khalilpoor ◽

AlibekIssakhov ◽

Babak Mosavati

Keyword(s):

Heat Transfer ◽

Carbon Nanotubes ◽

Reynolds Number ◽

Heat Transfer Coefficient ◽

Aluminum Oxide ◽

Copper Oxide ◽

Transfer Coefficient ◽

Volume Concentration ◽

Multiwalled Carbon ◽

Flat Tube

This research manuscript addresses the study of the performance of a flat tube having a 90° bend under the flow of three different nanofluids such as copper oxide, multiwalled carbon nanotubes, and aluminum oxide/water nanofluids at different inlet fluid temperatures and Reynolds numbers. The performance of the flat tube is analyzed under the Reynolds number between 5000 and 11000 and a fluid inlet temperature range of 35°C–50°C. The results obtained in this study show that the heat transfer coefficient increases with the increase in volume concentration as well as Reynolds number. The maximum heat transfer coefficient is obtained using multiwalled carbon nanotubes followed by copper oxide and then aluminum oxide. This study also illustrates that the friction factor increases with the increase in volume concentration and decrease in Reynolds number. The results of the numerical study have been validated with the help of an experimental study. The study has proved that the use of nanofluids instead of the conventional fluid can lead to reducing the size of the tube for the same amount of heat transfer which can prove the reduction of the size in heat transfer equipment. Furthermore, it is also observed in this study that the presence of the 90° bend in the flat tube improved the heat transfer performance due to the increased turbulence at the bent section of the tube.

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