Thermal Performance Of Nanofluids Research Articles

Multi-objective optimization of nanofluid thermal performance in battery cold plates using computational fluid dynamics

Inspired by the tree root structure, this paper uses commercial CFD software to simulate and analyze the cold plate of three-dimensional battery, and focuses on the heat transfer problem of tree root sine pipe to improve the heat dissipation performance of LiFePO4 battery. Utilizing nanofluids as working fluids, the research explores the impact of channel geometry, discharge power, nanofluid type, volume fraction, initial temperature, and velocity on heat transfer characteristics. The results show that the heat transfer effect of sinusoidal pipeline is obviously improved compared with traditional pipeline. Among the tested nanofluids, a 5 % Cu-water mixture exhibited the highest heat transfer efficiency. Furthermore, higher initial nanofluid velocity and lower initial temperature led to reduced average cold plate temperatures. Response surface methodology and genetic algorithm were utilized to optimize the thermophysical properties and initial operating conditions of the nanofluid. The influencing factors, including initial temperature (288 K-298 K), initial velocity (0.05 m/s-0.25 m/s), and volume fraction (1 %-5 %), were analyzed with the objective of establishing a relationship between the average battery temperature and pressure drop. And the optimized solution identified an ideal combination of inlet velocity, temperature, and nanofluid volume fraction of 0.14 m/s, 288.00 K, and 4.41 %, respectively, maximizing heat dissipation while minimizing pressure loss.

Non-similar simulations of Ellis model based ternary hybrid nanofluid flow through porous media

The investigation of nanofluid flow through porous media is an emerging area of research in the optimization of thermal processing and numerous thermodynamic processes. The principal objective of these thermal applications is to examine the movement of ternary hybrid nanofluid across a stretched sheet oriented vertically. The flow being examined is represented mathematically in order to incorporate the influences of magnetic fields, thermal radiation, and viscous dissipation. The ternary hybrid nanofluid thermal performance can be enhanced and surpassed by adding nanoparticles to the base fluid. The non-Newtonian Ellis model takes into account the fluid movement through the porous media. Ferrous oxide ( Fe 3 O 4 ) , Zinc oxide ( ZnO ) , and Molybdenum disulfide ( Mo S 2 ) are regarded as nanoparticles, with ethylene glycol ( EG ) serving as the base fluid. To convert the governing equations into a dimensionless system, suitable non-similar transformations have been established. The local non-similarity (LNS) approach is used with the MATLAB built-in tool bvp4c up to the second truncation level. The physical impacts of dimensionless factors on the temperature and velocity profiles of the studied nanofluids are thoroughly investigated. When the magnetic and porosity parameters change, the velocity profile becomes smaller. The heat transmission rate declines when the assessments of the magnetic number and Eckert number increase. The skin friction coefficient experiences an increase as the estimates of magnetic properties and nanoparticle value rise. The current study holds various practical implications, encompassing Solar Thermal Energy Storage, Waste Heat Recovery, Advanced Cooling Technologies, Enhanced Geothermal Systems, and Enhanced Oil Recovery.

Thermal Performance of Nanofluid in Automobile Radiator

Thermal Performance of Nanofluid in Automobile Radiator

Stagnation Point Flow of CoF e 2 O 4 / Ti O 2 - H 2 O -Casson Nanofluid past a Slippery Stretching/Shrinking Cylindrical Surface in

Mounting temperatures in electronic devices during operation may damage sensitive internal components if too much thermal energy accumulates inside the system. The advent of an innovative ultrahigh-performance thermal management technology known as nanofluid has provided a veritable platform to improve the system performance and reliability by removing the high heat flux generated in the engineering and industrial devices. This paper examines the combined effects of Darcy–Forchheimer porous medium-resistant heating and viscous dissipation on stagnation point flow of a Casson nanofluid ( CoF e 2 O 4 - H 2 O and Ti O 2 - H 2 O ) towards a convectively heated slippery stretching/shrinking cylindrical surface in a porous medium. The governing nonlinear model equations are obtained, analysed, and tackled numerically via the shooting technique with the Runge–Kutta–Fehlberg integration scheme. A unique solution is obtained when the surface is stretching. For shrinking cylindrical surface, the model exhibits nonunique dual solutions for a defined range of parameter values, and a temporal stability analysis is conducted to ascertain the stable and physically achievable solution. The effects of emerging thermophysical parameters on the overall flow structure and thermal management such as velocity and temperature profiles, skin friction, and Nusselt number are quantitatively discussed through graphs and in tabular form. It is found that the thermal performance heat transfer enhancement capability of Ti O 2 - H 2 O is higher than that of CoF e 2 O 4 - H 2 O . Moreover, the nanofluid thermal performance is enhanced with nanoparticles volume fraction, Casson nanofluid parameter, and Biot number but lessened with porous medium permeability.

Sensible heat thermal energy storage performance of mono and blended nanofluids in a free convective-radiation inclined system

The photothermal conversion performance (PCP) of a nanofluid-based solar energy system is investigated numerically and experimentally. The impacts of particle size, volume concentration, nanoparticle type, base fluid type and collector inclination angle on the PCP are investigated. It is observed that using nanoparticles improves the ability to absorb solar energy. Temperature gain is 2.2, 3.2, 3.8, 4.2, and 9 times better than pure water for water-based Al, Al2O3, Au, Cu, and Graphite mono nanofluids, respectively. Interestingly, blended nanofluids containing the same nanoparticles significantly argument the optical properties, with useful heat enhancement ranging from 62.8 (mono) to 194 kJ/kg (hybrid). However, the collector's inclination angle, which ranges from 0 to 60°, has a negative impact on the PCP by reducing the solar radiation absorption of the nanofluids due to a decrease in the radiation penetrating the collector. Furthermore, as nanoparticle size increases, so does the thermal performance of the nanofluid. An experimental investigation is carried out for pure water and nanofluid at various wind speeds and solar irradiation levels ranging from 1 to 4 m/s and 200–1000 W/m2, respectively, to validate the numerical results.

Investigation of thermal stratification with velocity slip and variable viscosity on MHD flow of [formula omitted] nanofluid over disk

The thermal performance of nanofluids, which include a base fluid and three kinds of suspended nanosized particles, is unparalleled. In this work, we analyzed the impact of many parameters on coolant applications, including MHD stagnation point flow, ternary hybrid nanofluid, viscous dissipation, variable viscosity, thermal stratification, and velocity slip conditions. Researchers synthesized ternary hybrid nanoparticles by combining Al2O3), (Cu), (TiO2) and then investigated their behavior in the presence of a symmetrically stretched disc in H2O. Because of its implications for heat transmission, the study of flow across a stretched disc is crucial to the investigation of momentum and thermal boundary layers. Numerous sectors and areas of technology will greatly benefit from this study. Similarity transformation is used to convert the PDEs into an ODE system, which can then be numerically solved using the shooting technique and the RKF scheme. The acquired results show remarkable consistency with earlier findings in certain circumstances, with an estimated relative error of 0%. The temperature profile drops as the value of the magnetic parameter rises, whereas the velocity rises as a result of the rise in magnetic parameters. Nusselt number improvements of around 8.4% for nanofluids, 16.8% for hybrid nanofluids, and 38.05% for ternary hybrid nanofluids are seen when the strength of the parameter S is raised from 2.0 to 2.4 compared to regular fluids. For an accurate prediction of how Al2O3-Cu-TiO2/ H2O will flow and how it will heat up, physical factors must be included in the analysis.

Thermal performance of nanofluids in a sinusoidal channel with embedded porous region

Inclusion of porous structures in micro-channels enhances heat transfer rates in energy harvesting devices, which signifies as the working fluid becomes a nanofluid. The present study compares the thermal performance of CuO-water, TiO2-water and graphene-water nanofluids in a sinusoidal channel with a porous insert. The flow and heat transfer characteristics are simulated and the effects of volumetric fraction of nanofluids, Reynolds number ( Re), porous insert width, and its permeability on the flow and temperature fields are examined. The findings reveal that CuO-water nanofluid results in higher heat transfer rates than those of other nanofluids considered. Graphene-water nanofluid gives rise to lower performance than that of CuO-water nanofluid in terms of convection heat transfer despite the fact that graphene has higher thermal conductivity than CuO. In this case, a decrease in Nusselt number of as much as 6.34% is observed for CuO-water nanofluid among all the cases considered for the Reynolds number of 100. Increasing the permeability of the porous insert slightly enhances (∼0.24%) the average Nusselt number. The porous insert with a small width in the channel improves the heat transfer rates (2.25% increase in Nusselt number), i.e. the average Nusselt number reduces as the porous insert width increases.

On the thermal performance of nanofluid over a cylinder within a confined channel: The splitter effect

Implementing splitters in microchannels enhances fluid distribution, and nanofluids offer a promising approach to improving heat transfer efficiency. This study uses a home-written Lattice Boltzmann code to numerically investigate the integration of splitters and nanofluids in a copper-water-filled channel with varying Reynolds numbers (Re= 10 to 80) and volume fractions (0≤φ≤0.2) including a splitter at different positions and inclination angles under heat flux boundary condition. Results reveal that heat transfer augmentation occurs with an increase in flow and nanofluid usage compared to conventional fluids. The maximum Nusselt number (Nu) is achieved at a vertical position for all splitter plate locations showing a rise to more than 40% by increasing the φ to 0.1. The estimated Nusselt numbers obtained by the two correlation methods agree well with simulation results with a coefficient of determination (R2>0.9). These findings can be coupled with optimization techniques to determine the optimal conditions of splitters, improving heat transfer efficiency for some practical applications such as micro-heat sinks in electronic-cooling devices.

Unsteady mixed convective MHD boundary stagnation point nanofluid flow with multi-slip effects, variable wall temperature and porosity phenomenon

This research highlights the physical significance of nanoparticle in magnetohydrodynamics (MHD) stagnation point flow (SPF) over a stretchable surface with porosity effect and boundary slip phenomenon. The nanoliquid and its advanced thermal activity are shown extra auspicious results when the flow is considered over a permeable (porous) medium. In addition, the nanoparticles of radius size play an important role in the thermal performance of nanofluid. In this work, copper is accounted as a nanoparticle and water as a base fluid. Nanomanufacturing, surface engineering, coatings, nanofabrication and tribology are some of the important and special mechanical characteristics of nanoparticles [D. Guo, G. Xie and J. Luo, J. Phys. D, Appl. Phys. 47, 013001 (2014)]. The flow is electrically conducted in the presence of applied magnetic field. Mixed convection, Joule heating and viscous dissipation effects are accounted in the mathematical modeling. Appropriate similarity variables are used to convert the couple governing system of PDEs into ordinary ones and results are computed through bvp4c via shooting concept. From the obtained results, it is divulged that the velocity field increases against higher estimations of unsteady parameter, while it declines versus larger magnetic parameter and radius of nanoparticles. The engineering interest like skin friction and Nusselt number is mathematically calculated and results are computed in a tabular form, and their obtained outcomes show that the magnitude of skin friction rises against unsteadiness parameter and radius of nanoparticles. This study is an extended work of [Verma et al. Chem. Eng. J. Adv. 12, 100366 (2022)] with some extra flow assumptions like MHD, SPF, Joule heating, heat generation/absorption and viscous dissipation. Obtained results are compared with [Grubka and Bobba J. Heat Transf. 107, 248 (1985)], Verma et al. [Chem. Eng. J. Adv. 12, 100366 (2022)] and [Elbashbeshy and Emam Therm. Sci. 15, 477 (2011)] found 100% accuracy with them. The most important result of the conducted study is that the skin friction coefficient immensely augments subject to larger estimations of radius of nanoparticles when permeability of porosity is less.

Fractional analysis of radiative blood transport through a porous channel containing multishaped cobalt nanoparticles: An application to hemodynamics

AbstractIn this work, impacts of dispersing nonspherical shaped cobalt nanoparticles in the blood are analyzed for magnetohydrodynamic radiative transport of blood inside a vertical porous channel. An Oldroyd‐B model is used to feature flow characteristics of blood along with Fourier's principle of heat transmission for the mathematical modeling of the problem. A fractional system is constructed by employing the idea of the Caputo–Fabrizio derivative on subsequent differential equations. The Laplace transform method is adopted to solve the fractional flow and energy equations subject to generalized boundary conditions, which involve time‐dependent functions and , respectively. Instead of promoting the analytic velocity and energy expressions, Zakian's numerical algorithm is operated to achieve the reverse transformation purpose of Laplace domain functions. To certify the obtained solutions, two additional numerical algorithms named Stehfest's algorithm and Durbin's algorithm are inculcated in this study, and comparative illustrations are drawn. For the extensive investigation of shear stress and heat transfer phenomenon, numerical simulations for the coefficient of skin friction and Nusselt number are performed, and outcomes are communicated through various tables. The impacts of shape‐dependent viscosity and other significant parameters on flow patterns are investigated through graphs for multiple motion types of the left channel wall. Meanwhile, the thermal performance of nanofluid is examined for platelet, brick, cylinder, and blade shape nanoparticles, along with other thermal parameters. In addition, some recently reported results and flow profiles for Maxwell, second‐grade, and viscous fluids are deduced graphically as special cases of the current study.

Effects of Key Parameters on Nanofluid Thermal Performance in Heat Exchangers

AbstractNanofluids are utilized in cooling equipment such as heat exchangers and renewable energies such as solar cells as heat transfer fluid. The techniques for nanofluid stability enhancement and stability evaluations, such as zeta potential, electron microscopy, and photographic techniques for sedimentation, are reviewed as well as some recent achievements in nanofluid stabilization and research on the parameters affecting the thermal properties of nanofluids. Finally, the applications of nanofluids in cooling devices are described. Increased heat transfer, reduced heat transfer time and size of heat exchangers, and finally higher energy and heat efficiency could be the most significant achievements. The parameters affecting the thermal conductivity of nanofluids include concentration, temperature, particle fluid, type of base fluid, and nanoparticles.

Thermal performance of nanofluids in elliptical zigzag tube: a numerical approach

This work was aimed at evaluating the thermal performance of nanofluids in an elliptical zigzag tube. The particle diameter and volume fraction of nanofluids were quantitatively investigated using two passive heat transfer configurations. The governing equations of mass, momentum, and energy of nanofluids containing ZnO and SiO2 in water at volume fractions of 1–4%, nanoparticle diameters of 15, 35, and 55 nm, and Reynolds number ranging from 400 to 2000 were solved using ANSYS. The results generally indicate that the Nusselt number and heat transfer coefficient increased with increasing volume fraction as Reynolds number increases. SiO2 exhibits a better thermal performance than ZnO, wherein a 4% volume fraction of 15 nm nanoparticle renders a greater heat transfer coefficient of 1149 W/m2·K at Reynolds number = 2000. The heat transfer is essentially improved at smaller particle diameter and higher volume fraction. The zigzag curvature displays an important attribute to enhance the heat transfer over the straight tube, although the skin friction coefficient increases with an increasing angle at 45°.

Impacts of heater-cooler position and Lorentz force on heat transfer and entropy generation of hybrid nanofluid convection in quarter-circular cavity

PurposeThe study aims to assess the heater and cooler positional impacts systematically using four different quadrantal cavities filled with hybrid nanofluid, keeping the curved surface adiabatic under the orientated magnetic fields. Both heat transfer and entropy generation analyses are performed for a hybrid nanofluid flow in a quarter circular cavity considering different orientations of magnetic fields. The investigation is focused to assess the heater and cooler positional impacts systematically using four different quadrantal cavities (first to fourth quadrantal cavities), keeping the curved surface always adiabatic. The impacts of pertinent variables like Rayleigh number, Hartmann number and volumetric concentration of hybrid nanofluid on heat transfer characteristics are in consideration with the second law of thermodynamics. The analysis includes the thermal, viscous and magnetic aspects of entropy generation.Design/methodology/approachAfter validating against the experimental results, the present work explores numerically following the Galerkin weighted finite element technique. The solution is obtained through an iterative process satisfying the convergence limit of 10−8 and 10−10 for the maximum residuals and the mass defect, respectively.FindingsIt revealed that the mutual exchange of heater-cooler positions on the adjacent straight edges of the quadrant cavity does not have any impact on the flow direction. Although the magnitude of flow velocity enhances, the sidewall plays a decision-making role in the formation of a single circulation vortex. It also shows that thermal entropy production is the main cause behind thermodynamic irreversibility. The second or third quadrantal arrangement could have been opted as the best configuration of the heater-cooler position for achieving superior heat transfer. The Lorentz force plays a great role to moderate the heat transfer process. The maximum entropy generation is located, as expected, at the heating-cooling junction point.Research limitations/implicationsThere are plenty of prospects for extension of the present research concept numerically or experimentally, adopting three-dimensional analysis, working fluids, boundary conditions, etc. In fact, the study could be carried out for unsteady or turbulent fluid flow.Practical implicationsAs the position of the heated source and cold sink on the enclosure geometry can significantly alter the thermo-fluid phenomena, this kind of analysis is of utmost relevance for the further development of efficient heating/cooling arrangements and proper management of the devices subjected to magnetic field applications. This original contribution could be a potentially valuable source for future research and exploration pertaining to a thermal system or device, like heat exchangers, solar collectors, thermal storage, electronic cooling, food and drying technologies and others.Originality/valueIn the literature, an inadequate number of works have focused on a quadrantal cavity, mostly considering the first quadrant of the circle. However, during practical applications, it is possible that the cavity can take the shape of the other three quadrants too, and the corresponding knowledge on relative performance is still missing. Furthermore, the present investigation includes the existence of magnetic fields at various orientations. The impact analysis of this field-induced Lorentz force on the nanofluid thermal performance is another major contribution from the present work that would enrich the domain knowledge and could be useful for thermal system engineers.

Thermal performance of nanofluids based on tungsten disulphide nanosheets as heat transfer fluids in parabolic trough solar collectors

Nanofluids are considered as a new generation of heat transfer fluids since they exhibit thermophysical properties improvements compared with conventional heat transfer fluids. The high thermal conductivity of nanofluids and even the isobaric specific heat enhancements over conventional liquids make these colloidal suspensions very attractive in many research areas, including solar energy. In this work, nanofluids based on tungsten disulphide (WS 2 ) nanosheets have been prepared from the thermal oil currently used as heat transfer fluid in Concentrating Solar Power (CSP) plants. The high aspect ratio of WS 2 bidimensional nanostructures provides high long-term colloidal stability to the nanofluids and facilitates heat transport. Cetyltrimethylammonium bromide and polyethylene glycol have been used as surfactants to improve the exfoliation process and enhance the colloidal stability of the nanomaterial dispersions. Some properties such as density and viscosity of the base fluid have not been significantly altered by the presence of WS 2 nanosheets in the base fluid. However, studies on the thermal properties of nanofluids have shown promising results with increases in thermal conductivity of up to 33% and heat transfer coefficient by 21% over the base fluid. Furthermore, it has been estimated that the overall efficiency of the CSP system could be improved by 31% by replacing the conventional thermal fluid with 2D-WS 2 -based nanofluids. • The efficiency of PTC solar collectors is increased by 31% by using WS 2 nanofluids. • Nanofluids improved the heat transfer coefficient of the base fluid by 21%. • Thermal conductivity was enhanced by 33% in WS 2 -based nanofluids. • WS 2 nanofluids favours the elimination of selective coatings on the absorber tube.

Investigation on thermal performance of nanofluids in a microchannel with fan-shaped cavities and oval pin fins

In this paper, a combined structure of fan-shaped cavities and oval pin fins is designed for the rectangular microchannel heat sink with an aspect ratio of 2. Four structural parameters are investigated, including cavity height (hr), chord length (Ir), rib offset distance (S0) and rib height (Hf). Overall performance factor and total thermal resistance are used to reflect the microchannel performance. In the Reynolds number range of 132–531, the microchannel shows the best hydrothermal performance under hr of 0.05 mm, Ir of 0.2 mm, S0 of 0, and Hf of 0.1 mm. When the Reynolds number is 398, the overall performance factor of the microchannel with optimal parameter combination is 33% higher than that of a rectangular microchannel. Field synergy angle in the microchannel is calculated based on the field synergy principle. According to the KKL (Koo-Kleinstreuer-Li) model, the local thermal conductivity distribution of Al2O3 nanofluids is studied at different nanoparticle diameters. Moreover, the overall performance factors of the heat sink are investigated at several volume fractions of Al2O3 nanofluids. Under the Reynolds number of 132, the Nusselt number of 0.04 vol% nanofluid is 9.5% higher than the deionised water. Based on optimal structural parameters, compared with deionised water, Al2O3 nanofluid with a diameter of 10 nm and volume fraction of 0.04 further improve the overall performance factor of micro-channels by 5.8% and reduce the total thermal resistance by 2.9%.

Review on Thermal Performance of Nanofluids With and Without Magnetic Fields in Heat Exchange Devices

Addition of nanoparticles into a fluid can improve the heat transfer performance of the base fluid in heat exchangers. In this work, the preparation method and process of nanofluids are introduced, and thermal properties of nanofluids, such as thermal conductivity and viscosity, are discussed deeply. This paper summarizes various theoretical models of thermal conductivity and viscosity of nanofluids. A comprehensive literature survey on applications and limitations of nanofluids has been compiled. This paper also aims to review the natural and forced convective heat transfer characteristics of nanofluids with and without magnetic fields. The discussion for the natural convective heat transfer of nanofluids focuses on the heat transfer performance of non-conventional enclosures and electric heaters. The effects on heat transfer due to variations of heated walls are also investigated. Specific applications of nanofluids in a tube with trapezoidal ribs, double-tube heat exchangers, and plate heat exchangers have been reviewed and presented in a discussion about forced convective heat transfer. The previous results show that the inlet temperature of nanofluids obviously affects the heat transfer characteristics of double-tube heat exchangers, whereas a multi-walled carbon nanotube–water nanofluid shows significant advantages in plate heat exchangers. Finally, this paper studies natural convective heat transfer of magnetic fluids in a square cavity and forced convection heat transfer in a straight tube and a corrugated structure under the action of magnetic fields. It is found that the heat transfer performance of an Fe3O4–water nanofluid is enhanced when a magnetic field is applied to the corrugated plate heat exchangers, and the pressure drop can be reduced by around 10%. It is recommended that natural convection of magnetic fluids needs to be investigated experimentally in a real cavity and a corrugated channel under the influence of a magnetic field. In addition, studies of alternating magnetic field are recommended to reveal any improvements of thermal performance of magnetic fluids in heat exchange devices. This review puts forward an effective solution for improvement of the thermal performance of heat transfer equipment and serves as a basic reference for applications of nanofluids in heat transfer fields.

Performance Comparison of a Microchannel Heat Sink Using Different Nano-Liquid Metal Fluid Coolant: A Numerical Study

Abstract This article presents performance comparison between different liquid metal-based nanofluids termed as nano-liquid metal fluids in a microchannel heat sink to achieve ultimate cooling solutions without sacrificing the compact structure and heavy computing speed. The hydraulic and thermal performance of nanofluids having five different liquid metals (Ga, GaIn, EGaIn, GaSn, and EGaInSn) as base fluid and four different nanoparticles (carbon nanotube (CNT), Al2O3, Cu, and diamond) as solute are evaluated comparing with water-based nanofluids. Three-dimensional flow inside miniaturized channels are predicted using single-phase and two-phase numerical simulations. Numerical models are validated against data obtained from experimental studies from the literature. Three different grids are developed, and several element sizes were compared to obtain the grid independence. Upon evaluation, the study can point out that liquid metal-based nanofluids can generate much superior heat transport characteristics with more than 3.41 times higher heat transfer coefficient compared to conventional water-based nanofluids. GaIn–CNT combination exhibits the best thermal solution possible with a heat transfer coefficient increment of 2.68%, 17.19%, 22.16%, and 2.62% over CNT particle-based EGaIn, EGaInSn, Ga, GaSn liquid metal, respectively, for Re = 750. Considering hydraulic performance, performance evaluation criterion (PEC) has been introduced and Ga-based nanofluids are found to be most effective in this perspective. The effect on overall cooling effectiveness has also been carried out with a detailed particle concentration study. This study paves the pathway of using these extraordinary coolants in mini/microchannel heat sinks.

RETRACTED ARTICLE: Numerical assessment of the influence of helical baffle on the hydrothermal aspects of nanofluid turbulent forced convection inside a heat exchanger

This study is devoted to the numerical assessment of the influence of helical baffle on the hydrothermal aspects and irreversibility behavior of the turbulent forced convection flow of water-CuO nanofluid (NF) inside a hairpin heat exchanger with 100 mm length, 10 mm inner tube internal diameter, and 15 mm outer diameter internal diameter. The variations of the first-law and second-law performance metrics are investigated in terms of Reynolds number (Re = 5000–10,000), volume concentration of NF (varphi =0-4mathrm{%}) and baffle pitch (B = 25–100 mm). The results show that the NF Nusselt number grows with the rise of both the Re and varphi whereas it declines with the rise of B. In addition, the outcomes depicted that the rise of both Re and varphi results in the rise of pressure drop, while it declines with the increase of B. Moreover, it was found that the best thermal performance of NF is equal to 1.067, which belongs to the case B = 33.3 mm, varphi=2%, and Re = 10,000. Furthermore, it was shown that irreversibilities due to fluid friction and heat transfer augment with the rise of Re while the rise of B results in the decrease of frictional irreversibilities. Finally, the outcomes revealed that with the rise of B, the heat transfer irreversibilities first intensify and then diminish.

Hydrodynamic and heat transfer analysis of dissimilar shaped nanoparticles-based hybrid nanofluids in a rotating frame with convective boundary condition

Solar thermal systems have low efficiency due to the working fluid's weak thermophysical characteristics. Thermo-physical characteristics of base fluid depend on particle concentration, diameter, and shapes. To assess a nanofluid's thermal performance in a solar collector, it is important to first understand the thermophysical changes that occur when nanoparticles are introduced to the base fluid. The aim of this study is, therefore, to analyze the hydrodynamic and heat characteristics of two different water-based hybrid nanofluids (used as a solar energy absorber) with varied particle shapes in a porous medium. As the heat transfer surface is exposed to the surrounding environment, the convective boundary condition is employed. Additionally, the flow of nanoliquid between two plates (in parallel) is observed influenced by velocity slip, non-uniform heat source-sink, linear thermal radiation. To make two targeted hybrid nanofluids, graphene is added as a cylindrical particle to water to make a nanofluid, and then silver is added as a platelet particle to the graphene/water nanofluid. For the second hybrid nanofluid, CuO spherical shape particles are introduced to the graphene/water nanofluid. The entropy of the system is also assessed. The Tiwari-Das nanofluid model is used. The translated mathematical formulations are then solved numerically. The physical and graphical behavior of significant parameters is studied.

Thermal performance of nanofluids in rectangular microchannel with vortex generators: Application of electronic components cooling

In this study, the contributions of Au, Cu and Ag nanoparticles for enhancing the heat transfer in the rectangular microchannel heat sink with vortex generators are compared in this work. A two dimensional numerical method is used to simulate the forced convection of water-based suspensions of different nanoparticles in the microchannel heat sink submitted to a constant and uniform temperature (T= 303K) at the wall . The gouverning equations are solved numerically using code FLUENT based on CFD method. Comparisons with previously published work on the basis of special cases are performed and found to be in excellent agreement. The effect of volume fraction, Reynolds number and type of nanoparticles on the fluid flow and heat transfer processes within the microchannel are analyzed. In addition, an analysis of isothermals and streamlines based on the different nanofluid are developed and presented. It is shown that the different nanoparticles within different thermal conductivity values have substantial effects on the results. Finally, the local and average Nusselt number for various Reynolds numbers and volume fractions are presented.