Heat Transfer Properties Of Nanofluids Research Articles

Experimental studies on the effect of Al2O3 + water nanofluid concentrations on dimensionless heat transfer parameters in a cleanroom air handling unit

Nanofluid, a colloidal suspension of nonmetallic or metallic nanoparticles into conventional base fluid and used for heat transfer characteristics enhancement for many industrial applications. Cleanrooms are essential at various industries for controlling airborne contamination and environmental parameters. In this article, heat transfer properties of nanofluid (Al2O3 + water) at various nanoparticle concentrations (1%, 2%, and 3%) on a prototype cleanroom air handling chiller unit was investigated experimentally in laminar flow zone. Thermal conductivity ratio, Nusselt number, Peclet number, and pressure drop were obtained for above nanoparticle concentrations. Experimental investigations indicate the heat transfer properties improvement in a prototype cleanroom air handling chiller unit by using nanoparticle at base fluid. Experimental investigation on varying Al2O3 + water nanofluid concentrations in a cleanroom air handling chiller unit heat exchanger revealed a notable increase in heat transfer by reducing nanoparticle size from 50 to 10 nm and increasing concentration from 1% to 3% volume, resulting in a 17.70% rise in thermal conductivity ratio and a significant 9.23% increase in Nusselt number at higher Peclet numbers. However, this improvement in heat transfer was accompanied by a substantial 72.5% increase in pressure drops, particularly with increased Reynolds number and particle concentration. Manipulating nanoparticle characteristics resulted in substantial improvements in Nusselt number across a wide range of Reynolds numbers, with smaller particle sizes and higher volume concentrations yielding more significant heat transfer improvements. The novelty of this research lies in its investigation of the influence of variable Al2O3 + water nanofluid concentrations, encompassing different nanoparticle sizes, and volume concentrations, on dimensionless heat transfer parameters within a cleanroom air handling unit, offering valuable insights into optimizing heat transfer efficiency in a controlled and critical environment, addressing a significant research gap in the field.

Formulation of Graphene Nanoplatelets Water-Based Nanofluids using Polyvinylpyrrolidone (PVP) as Surfactant

Graphene nanoplatelets (GNP) have garnered significant interest owing to their remarkable mechanical properties, making them ideal materials for enhancing the heat transfer properties of nanofluids. However, the agglomeration of GNP in water-based nanofluids remains a significant challenge, limiting their practical applications. In this study, a comprehensive investigation into the formulation of water-based nanofluids using GNP is presented, with a focus on the incorporation of polyvinylpyrrolidone (PVP) as a surfactant to enhance their stability and dispersion. The nanofluid formulations were systematically prepared with varying concentrations of GNP and PVP to optimize their thermal properties. Additionally, the thermal conductivity and viscosity of the nanofluids were examined over a range of temperatures and concentrations. The results show that the formulation of GNP with 0.6 wt.% shows great potential as a nanofluid with 0.6611 W/mK and 1.22 mPa.s for thermal conductivity and viscosity, respectively. The findings also demonstrate that the incorporation of PVP significantly improves the stability and dispersion of GNP in water, leading to enhanced thermal conductivity and manageable viscosity. These findings contribute to the application of this nanofluid in various industries, specifically solar energy.

Effect of symmetrical and asymmetrical structures of transverse tube on heat transfer performance of nanofluids in a solar collector system

AbstractIn an effort to enhance the heat transfer performance of solar collectors, this paper proposed to replace the smooth tube with symmetrical and asymmetrical transversely corrugated tubes, and to couple with SiO2‐H2O nanofluids for heat transfer of solar collectors. Effects of nanofluids mass fraction (w = .0%, .1%, .3%, and .5%), Reynolds number (3000, 4000, 5000, 6000, and 7000), and groove radius (1.5, 2, and 2.5 mm) on the flow and heat transfer properties of nanofluids in solar collectors were studied. The comprehensive evaluation index was used to consider the heat transfer property and flow resistance of fluid flow at the same time. Results showed that with the augment of nanofluids mass fraction, Reynolds number, and groove radius, the heat transfer enhancement performance of the collector becomes better. Among them, when the Reynolds number is 4000, the asymmetric transversely corrugated tube with a nanofluids mass fraction of .5% and a groove depth of 2.5 mm has the best comprehensive flow and heat transfer performance, and the comprehensive evaluation index can reach 1.62. The study results in this paper are beneficial to the coupling of nanofluids and transversely corrugated tubes and their application in the domain of enhanced heat transfer of solar collectors.

The computational model of nanofluid considering heat transfer and entropy generation across a curved and flat surface

The entropy generation analysis for the nanofluid flowing over a stretching/shrinking curved region is performed in the existence of the cross-diffusion effect. The surface is also subjected to second-order velocity slip under the effect of mixed convection. The Joule heating that contributes significantly to the heat transfer properties of nanofluid is incorporated along with the heat source/sink. Furthermore, the flow is assumed to be governed by an exterior magnetic field that aids in gaining control over the flow speed. With these frameworks, the mathematical model that describes the flow with such characteristics and assumptions is framed using partial differential equations (PDEs). The bvp4c solver is used to numerically solve the system of non-linear ordinary differential equations (ODEs) that are created from these equations. The solutions of obtained through this technique are verified with the available articles and the comparison is tabulated. Meanwhile, the interpretation of the results of this study is delivered through graphs. The findings showed that the Bejan number was decreased by increasing Brinkman number values whereas it enhanced the entropy generation. Also, as the curvature parameter goes higher, the speed of the nanofluid flow diminishes. Furthermore, the increase in the Soret and Dufour effects have enhanced the thermal conduction and the mass transfer of the nanofluid.

Analysis of volume fraction of Casson Nanofluid flow over a flat moving plate with thermal radiation and nonuniform heat source/sink

We provide numerary analysis of Casson nanofluids flowing through porous materials on stretched magnetic surfaces. The behavior of non-Newtonian liquids is described by the Casson liquid model. Similarity transformations are used to create nonlinear partial differential equations and are solved using numerical methods. Nusselt Number,Skin Friction Coefficient, Temperature, Velocity results are collected. Graphs are used to show the effects of physical factors on the flow and heat transfer properties of nanofluids. These include the Kasson parameter, the porosity parameter, the magnetic parameter, the radiation parameter, and the Prandtl number. Results show that the temperature profile increases while the velocity field decreases with increasing Casson nanofluidic parameters. A decrease in the thickness of the pulse boundary layer and an increase in the thickness of the thermal boundary layer can be seen with increasing magnetic parameters alone.

NUMERICAL MODELLING OF A NON-LINEAR RADIATIVE NON-NEWTONIAN NANOFLUID FLOW WITH ARRHENIUS ACTIVATION ENERGY

This research has examined the flow properties of non-linear radiative nano non- Newtonian fluid flow via a stretched sheet, as well as the impact of Arrhenius activation energy is also inspected. The basic equations, which comprised time-dependent pivotal equations, were built using boundary layer approximations. As a numerical methodology, an explicit finite difference (EFD) technique was exerted. The fluid flow has been simulated employing FORTRAN in this case. A stability and convergence study has been performed to determine the accuracy of the numerical approach, and the system was determined to be converged at Pr≥ 0.062, and Le≥ 0.016. Here, non-dimensional outcomes based on various physical characteristics are considered. The effect of these numerous physical characteristics is explained and visually represented for a variety of flow fields. Furthermore, the examination of streamlines and isothermal lines has demonstrated enhanced visualization of the fluid flow. It has been revealed that non-linear pattern thermal radiation has a substantial impact on the heat transfer properties of nanofluid. Moreover, when non-linear radiation is addressed, the Lorentz force also has a significant impact on fluid flow. A great agreement has also served as a confirmation of the current effort. This sort of fluid has potential uses in mining, lubrication, and biomedical flow.

A review of uncertainties in the study of heat transfer properties of nanofluids

A review of uncertainties in the study of heat transfer properties of nanofluids

MHD electroosmotic peristaltic flow of Jeffrey nanofluid with slip conditions and chemical reaction

Nanofluid consideration has been magnified due to their exceptional heat transfer characteristics and prospective applications in engineering and medical sciences after the pioneering work of Choi. Since, majority fluids are non-Newtonian in nature. Therefore, considering Jeffrey fluid as a base fluid in current study enhance its role in applications. Moreover, geometric configuration of the channel is taken as asymmetric with tapering effects. Since, majority of human physiological systems and industrial machinery have complex geometry and. Therefore, tapering channel consideration cannot be ignored. High molecular weight of non-Newtonian liquids make no-slip condition inapplicable. Thus, slip effects are incorporated in the current analysis. The consider analysis is performed for peristaltic flow of Jeffrey Nano fluid through a tapered asymmetric channel in the presence of magnetic field. Main motivation for performing this study is to analyze the heat transfer properties of nanofluid for the treatment of multiple diseases like cancer. The resulting nonlinear equations are coupled and simplified through lubrication approach. Poisson-Boltzmann equations are linearized through Debye-Huckle linearization. Built-in command of NDSolve in MATHEMATICS is applied to compute the results. The results for velocity, pressure gradient, streamlines, temperature and concentration are discussed for involved parameters. The results indicate that velocity shows parabolic behavior near the center while mixed behavior is observed near the boundaries. It can also be noticed that tapering parameter (m) influence the velocity greatly. As increasing the tapering effect causes the geometry to expand resulting in decreased velocity near the center of the channel. During digestion of food, multiple chemical reactions are performed by enzymes, therefore, studying the impact of (γ) on temperature and concentration cannot be ignored. The outcome of the study shows decrease in temperature and concentration as energy is utilized in performing the digestion. The size of trapped bolus is found to be increasing as the values of Hartman number (M) and fluid parameter (λ1) are increased. Therefore, we can say that this study can provide basics to study physiological system with electroosmotic phenomenon. It also finds promising applications in drug delivery and food diagnostic etc.

COMBINED FREE AND FORCED CONVECTION OF NANOFLUIDS IN MINICHANNELS WITH DIFFERENT DIAMETERS

In this study, mixed convection heat transfer properties of nanofluids in minichannels were investigated by dispersing SiO2 nanopaticles into pure water. In the study, nanofluids prepared in three different volumetric ratios of 0.25%, 0.75%, and 1.25% were investigated experimentally under laminar conditions in circular horizontal minichannels with diameters of 1.21 mm, 1.5 mm, and 1.9 mm. For the minichannels with the diameters of 1.21 mm, 1.5 mm, and 1.9 mm, increasing the particle volume ratio from 0.25% to 1.25% provided a heat transfer enhancement compared to water by about 11-31%, 7-29%, and 9-27%, respectively. Increasing the minichannel diameter from 1.21 mm to 1.5 mm and from 1.5 mm to 1.9 mm caused an enhancement of the Nusselt number in the range of 6.9-13.9% and 3.39.3%, respectively. Summarizing the results, the natural convection/forced convection ratio and natural convection effect on total heat transfer increased at a constant Grashof number value when the volumetric ratio of nanoparticles increased. In contrast to the particle volumetric ratio, an increase in the minichannel diameter was found to reduce the natural convection/forced convection ratio and the natural convection effects on total heat transfer at a constant Grashof number value.

Preparation Methods and Challenges of Hybrid Nanofluids: A Review

The recent studies on nanotechnology have reported rapid development of nanofluids in various aspects due to the enhanced thermophysical and heat transfer properties of nanofluids. This paper reviews the preparation methods and some challenging issues of hybrid nanofluids during the Preparation of hybrid nanofluids. One-step and two-step are mainly the preparation methods of hybrid nanofluids. Compared to the one-step method, the two-step method is a widely used technique for preparing nanofluids due to its simplicity, whereas this technique has a complexity of achieving stability of hybrid nanofluids. On the contrary, the one-step is very flexible for achieving uniformity of nanofluids with comparatively high production cost. Some researchers followed various techniques such as surfactant addition, surface treatment, and pH modification for preparing a durable nanofluid. However, these methods also have their limitation, such as degrading the thermal attributes of hybrid nanofluids. So, future studies need to address these challenges along with the cost analysis during preparing the hybrid nanofluids.

Development in the Heat Transfer Properties of Nanofluid Due to the Interaction of Inclined Magnetic Field and Non-Uniform Heat Source

In the current scenario a new mathematical model is designed and examined for the unsteady course of nanofluid through permeable vertical surface due to the interaction of inclined magnetic field. Radiative heat transfer properties is included assuming the Cogley radiation, dissipative heat energy due to the conjunction o magnetic field i.e., Joule dissipation and the space and time-dependent heat source/sink amplifies the study as well. Depending upon todays need in various industries the implementation of nanofluid is vital. Therefore, present study involves the behavior of both metal and oxide nanoparticles in the base fluid kerosene. Involvement of transformation rules the problem is converted into nonlinear set of ODEs and further these are solved employing approximate analytical technique such as Variational Iteration Method (VIM). The characteristics of various flow parameters are analyzed via graphs and the numerical simulation along with the validation of the result is obtained through tables. The comparative study brings out the convergence criterion of the methodology adopted herein. However, the favorable results are; the fluid temperature augments with increasing nanoparticle volume fraction and suction enriches both the fluid velocity and temperature whereas injection retards it significantly.

Dynamic stability, sedimentation, and time-dependent heat transfer characteristics of TiO2 and CNT nanofluids

Nowadays, the stability and heat transfer properties of nanofluids have been extensively studied. However, for the practical application, the dynamic stability, sedimentation, and fouling characteristics are also important issues. Whether nanofluids can maintain stable heat transfer characteristics during intermittent operation in the system is also a worthwhile issue. In this paper, the dynamic stability, sedimentation, and fouling characteristics as well as the time-dependent heat transfer characteristics of TiO2 and CNT nanofluids are investigated sequentially. The results show that compared with static condition, the dispersion stability of nanofluids is much better, and the sedimentation and fouling on solid surface are much less in dynamic condition. For the nanofluids in this paper, the sedimentation and fouling on solid surface are loose and can easily washed out after slight flushing. Rough surfaces are easier to adsorb the nanoparticles sedimentation and form fouling, but it can be greatly removed using ultrasonication. Long-term shutdown reduces the convective heat transfer enhancement of nanofluids, but it can be well restored after the action of ultrasonication.

An experimental study on heat transfer performance and pressure drop of nanofluids using graphene and multi-walled carbon nanotubes based on diesel oil

The present study deals with the investigation of the heat transfer performance of nanofluids using diesel oil as base fluid and multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GNP) as nanoparticles with different concentrations and flow rates. These nanoparticles have been functionalized covalently with hexylamine (HA) and non-covalently with oleic acid (OA) to prepare nanofluids to include OA-MWCNT, HA-MWCNT, OA-GNP.HA-GNP and OA-MWCNT/GNP (1–1 Hybrid of each of nanoparticles) at 5 weight percentages include 0.05–0.5 wt%. An experimental setup designed and constructed and heat transfer performance of the above-mentioned nanofluids are investigated under laminar flow conditions at 4 flow rates. In order to utilize nanofluids in practical applications, the main purpose of this study is focused on investigating if the addition of nanoparticles can enhance the heat transfer performance of diesel oil.In addition, the pressure drop and performance index of nanofluids measured in a closed loop. The results revealed that heat transfer properties of nanofluids improved compared to the base oil. Also according to the results, by increasing the velocity of nanofluid, the convective heat transfer coefficient increases at all weight coefficient of nanoparticles and an increase in pressure drop for nanofluids than pure oil is not perceptible. The performance index of nanofluids, except for the two cases that are related to the hybrid of MWCNT and GNP, in other cases is more than one. Therefore, using nanofluids leads to an increase in the heat transfer coefficient more than increasing the pressure drop, and are suitable for use in the industrial units.

Influence of nanolubricant particles’ size on flank wear in hard turning

ABSTRACTThis paper presents the effects of cutting speed, nanoparticles’ size, and their concentration in water-based TiO2 nanofluid on the magnitude of tool flank wear and tool wear rate. The types of nanoparticles and base fluid, nanoparticle size, and nanoparticle concentration can affect the tribological and heat transfer properties of nanofluids, and thereupon, these parameters can affect the cutting forces and temperatures during the metal cutting process, thereby affecting tool wear and nanolubricant consumption. According to the achieved results, with an increase in the size of nanoparticles from 10 to 50 nm, the average decrease in cutting tool flank wear reduces from 46.2% to 34.8%.

Recent Progress and Challenges in Transformer Oil Nanofluid Development: A Review on Thermal and Electrical Properties

Transformer oil is refined electrical insulating oil, which is extremely stable at high temperatures and possesses excellent electrical insulating properties. These special types of oils are widely used in high voltage apparatus such as power transformers, high voltage capacitors and circuit breakers. Traditionally, mineral oils have been most commonly used as a coolant or as electrical insulation medium. However, the main concern related to mineral oil is overheating, overloading, short circuits that reduce the shelf life of the transformer unit and restrict its function as a reliable coolant. Moreover, other factors such as high electrical insulation requirements, safety and economic aspects need to be considered for the development of new insulating liquid material. Nanofluids have become the one of the alternatives for the existing products available in the market because of its high thermo-physical and good dielectric properties. This review focuses on the status of nanofluids, the effect of different nanoparticles to enhance the dielectric as well as its heat transfer properties of nanofluids. The thermo-physical properties of the newly developed transformer oil based nanofluids reported in comparison with different oils. Finally, future directions and challenges need to be addressed.

Experimental investigation of nanoparticles concentration, boiler temperature and flow rate on flow boiling of zinc bromide and acetone solution in a rectangular duct

Despite the increase in heat transfer properties of nano-fluids, they are not currently used in vapour absorption refrigeration systems (VARS), and there is little literature on the flow boiling behaviour of concentrated salt solutions with nano-particle suspension. A potential novel working fluid solution for a vapour absorption refrigeration unit capable of utilising very low grade waste heat is acetone and zinc bromide, and this fluid is investigated here as the salt solution with graphene nanoparticles in suspension in flow boiling similar to that found in VARS. Nanoparticle concentration, boiler temperature, and flow rate are investigated. The Rohsenow constant in the flow boiling correlation for the nanofluid acetone/ZnBr2 with graphene on a stainless steel surface is found to be 0.217. By increasing the particle concentration from 0 to 05 vol%, heat flux and heat transfer coefficient on the heated surface increase from 8638 W/m2 and 106 W/m2 K to 13164 W/m2 and 167 W/m2 K, respectively. The steady pressure of the system increases with increasing loading of the nanoparticles and consequently the saturation temperature increases. This is because of the increased vapour generation as a consequence of improved heat transfer properties. Heat transfer coefficient is linearly proportional to temperature difference between the fluid and wall (e.g. increases from 78 W/m2 K to 145 W/m2 K when the temperature difference increase from 102 K to 135 K) in the range tested and the heat flux correspondingly reflects a quadratic relationship with temperature difference. Increasing nanofluid flow rate reduces both the production of acetone in the condenser and the salt concentration in the strong solution reservoir. Regarding properties of the fluid, the density and the specific heat follow the simple mixture combination rule; the thermal conductivity of the nanofluid increases by 4.5% with increasing the loading the particles to 0.5 vol%, following reasonably well the correlation of Suganthi et al. (2014); the viscosity increases linearly with concentration of nanoparticles (e.g. increases from 3.22 m Pa s to 4.5 m Pa s by increasing the concentration from 0 to 0.5 vol%); the stability of the nano-salt-fluid is affected by the density of the base fluid. The nanofluid showing good stability for 4 h and during the circulation of the fluid in the rig. Over the range of temperatures tested, the salt solution demonstrates characteristics of nucleate boiling behaviour and offers significant improvement over the properties of the base fluid in terms of boiling effectiveness, indicating that it will provide improved operation in a VARS situation.

Cylindrical Couette flow and heat transfer properties of nanofluids; single-phase and two-phase analyses

A theoretical study is carried out to deliver the effects of the metallic nanoparticles on the hydrodynamic and thermal characteristics of a liquid confined in a cylindrical domain. Single-phase and two-phase models are applied, and the numerical results of two-phase model are compared with analytical results of single-phase model. In the two-phase model, the nanofluid inhomogeneity, Brownian motion and thermophoresis effects are taken into account. Contrary to what is usually assumed in literature, the nanofluid inhomogeneity is incorporated in the thermophysical properties of the nanofluid, i.e., the nanofluid thermophysical properties are considered variable with respect to the spatial variation of nanoparticles volume fraction throughout the domain. The results demonstrate that the nanofluid yields significant thermal improvement with a relatively lower rise in shear stress at the inner and outer surfaces of the cylindrical domain. However, compared with the results of two-phase model, the hydrodynamic and thermal impacts of nanoparticles evaluated by single-phase model are normally overestimated, depending on the ratio of thermophoretic and Brownian diffusions, the radius ratio of cylinders and the Brinkman number.

Numerical investigation of CuO-water nanofluid turbulent convective heat transfer in square cross-section duct under constant heat flux

Purpose – The purpose of this paper is to numerically investigate the convective heat transfer of water-based CuO nanofluids flowing through a square cross-section duct under constant heat flux in the turbulent flow regime. Design/methodology/approach – The numerical simulation is carried out at various Peclet numbers and particle concentrations (0.1, 0.2, 0.5, and 0.8 vol%). The finite volume formulation is used with the semi-implicit method for pressure-linked equations algorithm to solve the discretized equations derived from the partial nonlinear differential equations of the mathematical model. Findings – The heat transfer coefficients and Nusselt numbers of CuO-water nanofluids increase with increases in the Peclet number as well as particle volume concentration. Also, enhancement of the heat transfer coefficient is much greater than that of the effective thermal conductivity at the same nanoparticle concentration. Research limitations/implications – Simulation of nanofluids turbulent forced convection at very high Reynolds number is worth for further study. Practical implications – The heat transfer rates through non-circular ducts are smaller than the circular tubes. Nevertheless, the pressure drop of the non-circular duct is less than that of the circular tube. This study clearly presents that the nanoparticles suspended in water enhance the convective heat transfer coefficient, despite low volume fraction between 0.1 and 0.8 percent. Adding nanoparticles to conventional fluids may enhance heat transfer performance through the non-circular ducts, leading to extensive practical applications in industries for the non-circular ducts. Originality/value – Few papers have numerically studied convective heat transfer properties of nanofluids through non-circular ducts. The present numerical results show a good agreement with the published experimental data.

Investigation on convective heat transfer behaviour of kerosene-Al2O3 nanofluid

Turbulent convective heat transfer behaviour of kerosene-Al2O3 nanofluid is investigated experimentally in horizontal circular test section configuration in a closed loop test setup. The study intends to explore the potential use of kerosene-Al2O3 nanofluid for thrust chamber regenerative cooling in semi-cryogenic rocket engine due to its enhanced thermal properties. The effects of variation in particle size (13 nm, 50 nm), volume fraction (0.05%, 0.2%, 0.3%, and 0.5%) and Reynolds number (6000–38,000) on convective heat transfer performance and pressure drop are determined using the uniformly heated circular test section. Heat transfer performance of nanofluid is evaluated based on identical Reynolds number, Peclet number, velocity and constant pressure drop conditions. Detailed investigation of experimental data shows that in almost all the cases, heat transfer properties of nanofluid are significantly high compared to pure kerosene. Higher heat transfer coefficient is noticed for larger particle size nanofluid compared to smaller size though the measured thermal conductivity is higher for lower particle size nanofluid. A parameter to determine the total heat transfer performance of nanofluid is also defined, which again indicate the thermal advantages of nanofluid as a heat transfer fluid compared to the base fluid. The experiments also highlight the significant role of Prandtl number in convective heat transfer of nanofluids. A homogeneous fluid correlation which accurately predicts heat transfer coefficient and pressure drop for nanofluids is also presented.

Molecular dynamics simulation on flow behaviors of nanofluids confined in nanochannel

Nanofluids are new heat transfer liquids with remarkable heat transfer capability prepared by suspending nanoparticles in traditional heat transfer liquids (water, ethylene glycol and engine oil). The key reason for the enhanced heat transfer properties of nanofluids is not only their increased thermal conductivity but also the changed rheological behavior of base fluid due to the adding of nanoparticles. However, currently the investigation into influence of shear velocity on flow behaviors of nanofluids is still inadequate. In this paper molecular dynamics simulations are used to simulate flow behaviors of nanofluids confined in nanochannel under different shear velocities. Rotation and translation of nanoparticles and nonlinear velocity profiles of nanofluids are observed. The degree of nonlinearity, as well as the rotation and translation of nanoparticles, are enhanced with the shear velocity increasing. The existence of “solid-like” absorbed layers near the plates and around the nanoparticles is also demonstrated.