Effects Of Nanoparticle Volume Fraction Research Articles

Modeling and analysis of peristalsis of hybrid nanofluid with entropy generation

This investigation intends to explore the peristaltic transport of rotating fluid in a channel. The channel is considered symmetric with flexible walls, and porous medium fills the saturated space. In this analysis, hybrid nanofluid consisting of titanium oxides and copper particles is taken. Water is used as the base fluid. MHD and Hall effects are employed in this problem. Formulation of energy equation is based on radiation and non-uniform heat source or sink parameter. Convection conditions are utilized for the boundary. Thermodynamics second relation is employed for entropy generation. Maxwell–Garnetts model of thermal conductivity is employed. Numerical analysis is carried out using NDSolve of Mathematica. The effect of nanoparticle volume fraction, Taylor number, Hartman number, porosity and Hall parameters is analyzed for axial and secondary velocities, temperature, entropy generation and heat transfer rate. This study divulges that an enhancement in rotation parameter caused an increase in secondary velocity. Moreover, as volume fraction of nanoparticles enhances from 0.01 to 0.04, decay is noticed in fluid’s axial and secondary velocities. In this case, entropy also decreases. This study further disclosed that heat transfer rate gradually increases as we exceed the volume fraction of nanoparticles from 0.02 to 0.08. More pores also lead to an enhancement in fluid velocity, temperature and entropy.

Numerical simulation of melting behavior of nano-enhanced phase change material in differentially heated cavity

The melting and solidification process in enclosures filled with phase change materials has wide applications in metal casting, thermal energy storage, building insulation and battery thermal management. In the current study, the melting and heat transfer characteristics of Nano Enhanced Phase Change Material (NEPCM) are numerically investigated in a differentially heated square cavity. The NEPCM consists of ice as the phase change material (PCM) into which Single Walled Carbon Nano-tubes (SWCNT) particles of uniform size is dispersed. The left and right walls of the enclosed cavity are maintained at a constant wall temperature and considered as hot and cold walls and the remaining walls are treated as adiabatic and the simulation is performed using Ansys Fluent 19.2. The temperature difference between the hot and cold walls are varied and further investigations are performed by considering the effects of nanoparticle volume fraction on the melting behavior of NEPCM. The results are analyzed by plotting the stream function, melting interface temperature and velocity contours. The results indicate that the addition of SWCNT nanoparticles significantly influences the heat transfer characteristics and melting rate of phase change material. It is also found that the increase in nanoparticle volume fraction enhances the average melting and heat transfer rate of phase change material. The present results are validated and are in excellent agreement with the benchmark results available in literature.

Study of nanoparticle as a drug carrier through stenosed arteries using Bernstein polynomials

In this study, Bernstein polynomial approximation method is used to obtain the expressions of velocity, temperature, wall shear stress and stream function, to portray the transport characteristics of Newtonian gold-blood nanofluid flowing through stenosed artery in the presence of magnetic field. The impact of various flow parameters on velocity profile, wall shear stress and stream function is also investigated. The effect of nanoparticle volume fraction in the presence and absence of external magnetic field is studied. The results reveal that the temperature of the nanofluid and wall shearing stress are increased, whereas the velocity is decreased due to increase in the particle concentration in the presence of magnetic field.

SADI approach programming on GPU: convective heat transfer of nanofluids flow inside a wavy channel

In this study, the numerical simulation of convective heat transfer of nanofluids (Al2O3/water and CuO/water) inside a sinusoidal wavy channel is performed using the Graphics Processing Units (GPU). The governing equations including stream-function, vorticity transport, and energy are discretized using the fourth-order Spline Alternating-Direction Implicit (SADI) approach in combination with the curvilinear coordinates mapping. The final tridiagonal-matrices are solved by Parallel-Thomas-Algorithm (PTA) on GPU. A homogenous one-phase model is also applied to consider the effective characteristics of the nanofluids flow. In the first part of the results section, the effects of nanoparticle volume fraction, Reynolds number, and amplitude of the wavy wall on average Nusselt number and the skin friction coefficient of the channel are investigated. In the second part of the results section, the ability of GPU to accelerate the computation (or runtimes) is compared to the classic Thomas algorithm that runs on a Central Processing Unit (CPU). The results demonstrate that the speedup of PTA against CPU runtime for the finest grid is around 18.32×.

Inclusion of nanoparticles in PCM for heat release unit

The main motivation of the present work is to scrutinize the solidification of CuO-water within a heat release unit that has innovative fins. This compact structure along with limitation at the surface of the fins is simulated using Finite Element Method (FEM). Mixture of copper oxide and H2O is introduced as a working fluid. Moreover, the nanoparticle-enhanced phase change materials (NEPCM) shows a significant change in thermal behavior of nanofluid and pure PCM properties by considering the Brownian motion. The outcomes are depicted in the form of temperature, solid fraction and phase change front contours. The results are obtained to determine the variation of phase change by adding the nanoparticles in PCM for various time domains. Similarly, significant effects of nanoparticles volume fraction on the total energy and solid fraction are presented. Furthermore, it is found that the nanoparticles and radiation parameter with size of dp = 40 nm has the greatest heat transfer rate.

On Heat Transfer Performance of Cooling Systems Using Nanofluid for Electric Motor Applications.

This paper studies the fluid flow and heat transfer characteristics of nanofluids as advance coolants for the cooling system of electric motors. Investigations are carried out using numerical analysis for a cooling system with spiral channels. To solve the governing equations, computational fluid dynamics and 3D fluid motion analysis are used. The base fluid is water with a laminar flow. The fluid Reynolds number and turn-number of spiral channels are evaluation parameters. The effect of nanoparticles volume fraction in the base fluid on the heat transfer performance of the cooling system is studied. Increasing the volume fraction of nanoparticles leads to improving the heat transfer performance of the cooling system. On the other hand, a high-volume fraction of the nanofluid increases the pressure drop of the coolant fluid and increases the required pumping power. This paper aims at finding a trade-off between effective parameters by studying both fluid flow and heat transfer characteristics of the nanofluid.

Investigation of heat transfer of MHD Al2O3/water nanofluid in an enclosure with a semicircular wall and a heating obstacle

Lattice Boltzmann method (LBM) was used to simulate two-dimensional MHD Al2O3/water nanofluid flow and heat transfer in an enclosure with a semicircular wall and a triangular heating obstacle. The effects of nanoparticle volume fraction ([Formula: see text]), Rayleigh number [Formula: see text], Hartmann number [Formula: see text] and heating obstacle position (Cases 1–7) on flow pattern, temperature distribution and rate of heat transfer were investigated. The results show that with the enhancing Rayleigh number, the increasing nanoparticle volume fraction and the reducing Hartmann number, an enhancement in the average Nusselt number and the heat transfer appeared. The effect of Ha on the average Nu increases by increasing the Ra. It can also be found that the action of changing the heating obstacle position on the convection heat transfer is more important than that on the conduction heat transfer. The higher obstacle position in Cases 6 and 7 leads to the small value of the average Nusselt number. Moreover, the effect of Ha on average Nu in Case 1 at [Formula: see text] is more significant than other cases because the flow pattern in Case 1 is changed as increasing Ha.

Stagnation-Point Flow and Heat Transfer Over an Exponentially Stretching/Shrinking Sheet in Hybrid Nanofluid with Slip Velocity Effect: Stability Analysis

The effect of slip on stagnation point flow and heat transfer over an exponentially stretching/shrinking sheet filled with Copper-Alumina/water nanofluids is investigated numerically in this paper. The governing boundary layer equations are transformed into a set of ordinary differential equations using a similarity transformation and then solved numerically using the bvp4c function in Matlab. The effects of nanoparticle volume fraction, slip parameter and stretching/shrinking parameter on the flow pattern and heat transfer have been studied. It is found that dual solutions exist for hybrid nanofluid in the case of shrinking sheet. Furthermore, slip parameter and Copper nanoparticle acts in widening the range of solution. Hybrid nanofluids have the higher heat transfer rate compared to nanofluid and viscous fluid. A stability analysis showed that the first solution is linearly stable and physically realizable.

Pool Boiling Heat Transfer from Aluminum Alloy Circular Surface Using Al2O3 and CuO Water Based Nano-fluids

The present work aims to study the effect of nano-particles volume fraction of nano-fluid on the heat transfer during pool boiling with different values of heat flux. The concentration ratios by volume in demineralized water are taken as 0.02 %, 0.20 %, 0.40 %, 0.60, and 0.80 % for Al2O3 nano-particles and 0.02 %, 0.06 %, and 0.20 % for CuO nano-particles. Heat transfer coefficients for pool boiling were established experimentally for different values of volume fraction and heat flux. The heating element is made from an aluminum alloy (AL 6061) with a circular smooth surface of 100 mm diameter and 10 mm thickness. The nano-particles porous layer that builds up during boiling is observed by a scanning electron microscope of the heated surface before and after the boiling. The results demonstrate that the heat transfer rate depends on the concentration ratios and heat flux. Using nano-particles decreases the pool boiling heat transfer in comparison with demineralized water. Due to the deposition of nano-particles on the heated surface, lower heat transfer is obtained for a lower bubble departure compared with demineralized water for the small wall superheat.

Influence of inclined Lorentz forces through a porous media on squeezing Cu-H2o nanofluid in the presence of heat source/sink

PurposeThe purpose of this paper is to find the approximate solutions of unsteady squeezing nanofluid flow and heat transfer between two parallel plates in the presence of variable heat source, viscous dissipation and inclined magnetic field using collocation method (CM).Design/methodology/approachThe partial governing equations are reduced to nonlinear ordinary differential equations by using appropriate transformations and then are solved analytically by using the CM.FindingsIt is observed that the enhancing values of aligned angle of the magnetic causes a reduction in temperature distribution. It is also seen that the effect of nanoparticle volume fraction is significant on the temperature but negligible on the velocity profile.Originality/valueTo the best of the authors’ knowledge, no research has been carried out considering the combined effects of inclined Lorentz forces and variable heat source on squeezing flow and heat transfer of nanofluid between the infinite parallel plates.

MHD nanofluid heat transfer between a stretching sheet and a porous surface using neural network approach

Magnetohydrodynamic flow of nanofluids and heat transfer between two horizontal plates in a rotating system have been examined numerically. In order to do this, the group method of data handling (GMDH)-type neural networks is used to calculate Nusselt number formulation. Results indicate that GMDH-type NN in comparison with fourth-order Runge–Kutta integration scheme provides an effective means of efficiently recognizing the patterns in data and accurately predicting a performance. Single-phase model is used in this study. Similar solution is used in order to obtain ordinary differential equation. The effects of nanoparticle volume fraction, magnetic parameter, wall injection/suction parameter and Reynolds number on Nusselt number are studied by sensitivity analyses. The results show that Nusselt number is an increasing function of Reynolds number and volume fraction of nanoparticles but it is a decreasing function of magnetic parameter. Also, it can be found that wall injection/suction parameter has no significant effect on rate of heat transfer.

Measurements for stress sensing of composites using tailored piezospectroscopic coatings

Chromium-doped α-alumina is naturally photo-luminescent with spectral properties that are characterized by R-lines with two distinct peaks known as R1 and R2. When the material is subjected to stress, shifts in the R-lines occur, which is known as the piezospectroscopic (PS) effect. Recent work has shown that improved sensitivity of the technique can be achieved through a configuration of nanoparticles within a polymer matrix, which can be applied to a structure as a stress-sensing coating. This study demonstrates the capability of PS coatings in mechanical tests and investigates the effect of nanoparticle volume fraction on sensing performance. Here, measurements of spectral shifts that capture variation in stress of the coating during mechanical testing and in the region of substrate damage showed that stress contours are more noticeable on a soft laminate than hard laminate. It was found that the 20 % volume fraction PS coating showed the most distinct features of all the coatings tested with the highest signal-to-noise ratio and volume fraction of α-alumina. Post failure assessment of the PS coatings verified that the coatings were intact and peak shifts observed during mechanical testing were due to the stress in the substrate. The results suggest the ability to design and tailor the “sensing” capability of these nanoparticles and correlate the measured stress variations with the presence of stress and damage in underlying structures. This study is relevant to nondestructive evaluation in the aerospace industry, where monitoring signs of damage is of significance for testing of new materials, quality control in manufacturing and inspections during maintenance.

Heat transfer and entropy generation analysis of nanofluids thermocapillary convection around a bubble in a cavity

In view of the fact that thermocapillary convection is an important heat transfer mechanism in nucleate boiling, and nanofluids is used to be heat transfer medium extensively. The present paper reports the numerical investigation of nanofluids thermocapillary convection around a gas bubble in a cavity, and the effects of nanoparticles volume fraction and size on flow characteristics, heat transfer performance and entropy generation are studied. The results show that, with more nanoparticles add to base fluid can enhance the heat transfer performance of gas bubble thermocapillary convection, the convective intensity is reduced, and the local entropy generation decreases and its distribution becomes more uniform. However, with larger nanoparticles diameter the results are just the opposite, namely, the heat transfer performance is weakened, the convective intensity is enhanced and the total entropy generation increases and its distribution becomes more nonuniform. These findings are of significance for the heat transfer enhancement in nanofluid boiling heat transfer.

Numerical investigation of nanofluid convection heat transfer in a microchannel using two-phase lattice Boltzmann method

In this study, the laminar forced convection heat transfer of copper–water nanofluid in a 2D microchannel with one wall insulated and the other with constant heat flux is simulated numerically. In this paper, two-phase lattice Boltzmann method is used for simulation of the problem considering the intermolecular forces such as drag, buoyancy, Brownian, van der Waals and Born forces. The collision and streaming equations are used for both phases separately, and the effect of nanoparticles volume fraction on the velocity and temperature profiles is examined. It is observed that velocity decreases with increasing the nanoparticles volume fraction. Moreover, an increase in nanoparticles volume fraction raises the mean fluid temperature and increases the heat transfer rate. Further, the effect of an increase in nanoparticles volume fraction and their diameter changes on the Nusselt number variations in the microchannel is investigated. Also, the effect of considering viscous dissipation on the Nusselt number in different nanoparticle volume fractions is compared to the state without considering it. Finally, the effect of Reynolds number on Nusselt number is investigated.

Effects of nanoparticles volume fraction and magnetic field gradient on the mixed convection of a ferrofluid in the annulus between vertical concentric cylinders

In this paper, the thermomagnetic convection of magnetite-water ferrofluid is numerically investigated in the three-dimensional space between two vertical concentric cylinders under the influence of an external magnetic field. The main objective is to study the effect of volume fraction of the magnetic nanoparticles (0.01≤αp≤0.06) with the diameter of 10 nm and positive and negative gradients of the magnetic field (-5×105A/m2≤G≤5×105A/m2) on the hydrothermal behavior of the ferrofluid flow. For this purpose, the two-phase mixture model and the finite volume method are used to simulate the hydrodynamics and thermal behavior of the ferrofluid flow. The simulations are performed for a Reynolds number of 20, Grashof number of 10000, and outer to inner diameter ratio of 2.5. The numerical results indicate that the Kelvin force increases by increasing the volume fraction, decreasing the ferrofluid temperature and increasing the magnetic field gradient. In the presence of an external magnetic field with negative gradient, the skin friction coefficient on the inner wall is enhanced by increasing the volume fraction and the magnetic field gradient but on the outer wall, it decreases by increasing them. Besides, the Nusselt number increases with the increase in the volume fraction and the magnetic field gradient. In addition, positive gradient magnetic fields result in reducing the Nusselt number and friction coefficient on the inner wall, while they increase the friction coefficient on the outer wall.

Thermal hydraulic analysis of supercritical water reactor cooled by TiO2 nanofluid

ABSTRACT Heat transfer study of nanofluids as coolant in SCWRs core has been performed at Helwan University. A thermal hydraulic code has been produced to study the effect of TiO2 nanofluid water based as a coolant with comparison with pure water as a coolant. Various volume fractions of nanoparticles TiO2 (2, 6 and 10%) were used in order to investigate its effects on reactor thermalhydraulic characteristics. Based on Parameters of a SCW Canadian Deuterium Uranium nuclear reactor (CANDU), the fuel assembly was modeled to study the effect of nanoparticles volume fraction on thermos-physical properties of basic fluid and the temperature distribution of fuel, cladding surface and coolant in axial direction. The theoretical results showed that the density, viscosity and thermal conductivity of the coolant increases with the increase of nanoparticles volume fraction, contrasting to specific heat, which decreases with the increase in nanoparticles volume fraction.

Numerical Study of Heat Transfer and Entropy Generation of Nanofluids Buoyant-Thermocapillary Convection around a Gas Bubble

Buoyant-thermocapillary convection is an important heat transfer mechanism in nucleate boiling and nanofluids has been used as heat transfer medium extensively, so it is necessary to study the heat enhancement mechanism of nanofluids buoyant-thermocapillary convection around gas bubble. The present paper first reports the flow, heat transfer and entropy generation characteristics of nanofluids buoyant-thermocapillary convection around a gas bubble in a cavity, and the effects of nanoparticles volume fraction and size on buoyant-thermocapillary convection are discussed. The results show that, as nanoparticles volume fraction increases from 0 to 0.05, the convective intensity and entropy generation of buoyant-thermocapillary convection decreases gradually, and the average Nusselt number of bottom wall first increases and then decreases. As nanoparticles volume fraction is 0.02 the average Nusselt number is the largest and increased by 3.1% relative to that of pure fluid. As nanoparticles diameter increases from 20 nm to 80 nm, the temperature and flow fields indicate as the same structure, but the entropy generation increases gradually. The average Nusselt number of bottom wall increases slightly with nanoparticles diameter increasing, particularly, the average Nusselt number for nanoparticles diameter (dp) 80 nm is increased by 2.28% relative to that of dp = 20 nm.

A dissipative particle dynamics two-component nanofluid heat transfer model: Application to natural convection

The current paper presented a novel two-component dissipative particle dynamics (DPD) model to investigate heat transfer enhancement in natural convection using Al2O3-water nanofluid. This DPD model used two different types of particles to represent the base fluid particles and the nanoparticles. The energy and momentum interaction between nanofluid particles were incorporated within the new DPD model via modifying the DPD collisional heat flux and the friction parameter, respectively. The model was used to investigate the effect of nanoparticle volume fraction on heat transfer enhancement within the cavity. The study covered a wide range of nanoparticles (1% ≤ φ ≤ 7%) and three Rayleigh numbers were considered, which are Ra = 104, Ra = 5 × 104, and Ra = 105. In general, the DPD results reported a minor deterioration in heat transfer due to the presence of nanoparticles. By looking at the local distribution of enhancement along the hot wall of the cavity, it was found that, for high Rayleigh numbers, most parts of the hot wall experienced deterioration in heat transfer accompanied with some enhancements that were registered near the top wall of the cavity. Also, the results revealed that for the case of low Rayleigh numbers some enhancements were observed using low volume fraction of nanoparticles (φ ≤ 4%), however further increase in volume fraction of nanoparticles caused a deterioration in heat transfer.

Numerical Analysis of Heat and Mass Transfer Flow of Nanofluid over a Moving Wedge Using Spectral Quasilinearization Method

In this paper the problem of unsteady two-dimensional heat and mass transfer flow of nanofluid past a moving wedge is considered. The effects of nanoparticle volume fraction, viscous dissipation, chemical reaction, and convective boundary conditions are studied. The physical problem is modeled using partial differential equations. Using suitable similarity variables, the governing equations and their related boundary conditions are transformed into dimensionless forms of a system of coupled nonlinear ordinary differential equations. The resulting systems of equations are then solved numerically using spectral quasilinearization method (SQLM). The results reveal that the skin friction coefficient increases with increasing the values of nanoparticle volume fraction, unsteadiness and permeability parameters. The local Nusselt number reduces with increasing the value of nanoparticle volume fraction, Prandtl number and Eckert number. The local Sherwood number enhances with greater the value of nanoparticle volume fraction, unsteadiness, pressure gradient and chemical reaction parameters. Moreover, the method is checked against the previously published results and a very good agreement have been obtained.

Hydromagnetic pulsating flow of nanofluid between two parallel walls with porous medium

In this study, hydromagnetic pulsatile flow of a nanofluid between two parallel walls with thermal radiation is investigated. Water is considered as base fluid and Ag, CuO, Al2O3, TiO2 are considered as nanoparticles. Brinkman and Maxwell Garnetts models are considered. Perturbation technique is employed to obtain the solution of the governing system. The effects of nanoparticle volume fraction, magnetic parameter, Darcy number and thermal radiation on flow variables have been discussed in detail.