The electroosmotic peristaltic flow of modified hybrid nanofluid in presence of entropy generation has been presented in this thermal model. The Hall impact and thermal radiation with help of nonlinear relations has also been used to modify the analysis. The assumed flow is considered due to a non-uniform trapped channel. The properties of modified hybrid nanofluid model are focused with interaction of three distinct types of nanoparticles namely copper (, silver () and aluminum oxide ( The mathematical modeling and significances of entropy generation and Bejan number are identified. With certain flow assumptions, the governing equations are attained for optimized peristaltic electroosmotic problem. Widely used assumptions of long wave length and low Reynolds number reduced the governing equations in ordinary differential equations. The ND solver is flowed for the solution process. The physical significant of results is observed by assigning the numerical values to parameters. 相似文献
Heat transfer and flow characteristics of Cu/water nanofluids' flow in the serpentine microtubes are investigated experimentally. The serpentine microtubes are fabricated by bending a straight copper microtube with an inner diameter of 787 μm. Also, the Cu/water nanofluids are prepared using a novel one-step technique, namely electro-exploded wire. The effects of serpentine microtubes' geometrical parameters (pitch spacing, p, and straight section, l) and nanofluid concentration (weight fraction, φ) are examined. It is found that the heat transfer enhances by decreasing both the pitch spacing and the straight section of the serpentine microtube as well as increasing the weight fraction of the nanofluid. Also, the results show that the friction factor tends to increase in the same manner. A noticeable average enhancement in the thermal performance factor of 21.8% is obtained for a specific operating condition, i.e., the nanofluid at φ = 0.3% through the serpentine microtube with p = 9.6 mm and l = 10 mm. Finally, two correlations of Nusselt number and friction factor for the Cu/water nanofluids across the serpentine microtubes are proposed. 相似文献
A quasi-steady technique to simultaneously measure the local heat transfer coefficient and cooling effectiveness on surfaces involving film cooling situations is investigated. The method employs a composite slab consisting of a very thin laminate layer of low-thermal-conductivity material superposed upon a highly conductive metal substrate. The resulting heat transfer in the thin laminate is described by one-dimensional conduction. A very thin coating of thermochromic liquid crystals sprayed onto the surface of the laminate is used in conjunction with a computer image processing procedure to provide local surface temperature data. This information, combined with the substrate and mainstream gas temperatures, provides highly detailed (90 video pixels/cm2) local convection heat transfer distributions. The method is used to conduct flat-plate film cooling experiments consisting of a single row of discrete holes inclined at 35 to the mainstream flow. The local surface temperature is influenced by the combination of two interacting fluid streams at different temperatures. A numerical analysis was performed to assess the assumptions underlying the data reduction procedure. The experimental uncertainty of 7% in the heat transfer coefficient is comparable to prior studies. Furthermore, the uncertainty of 5% in the film cooling effectiveness, coupled with the negligible lateral conduction errors, indicates the present technique offers a unique capability for accurate measurement of the local film cooling effectiveness. 相似文献
An experimental study is performed to determine the pressure drop and performance characteristics of Al2O3/water and CuO/water nanofluids in a triangular duct under constant heat flux where the flow is laminar. The effects of adding nanoparticles to the base fluid on the pressure drop and friction factor are investigated at different Reynolds numbers. The results show that at a specified Reynolds number, using the nanofluids can lead to an increase in the pressure drop by 35%. It is also found that with increases in the Reynolds number, the rate of increase in the friction factor with the volume fraction of nanoparticles is reduced. Finally, the performance characteristics of the two nanofluids are investigated using the data of pressure drop and convective heat transfer coefficient. The results show that the use of Al2O3/water nanofluid with volume fractions of 1.5% and 2% is not helpful in the triangular duct. It is also concluded that at the same volume fraction of nanoparticles, using Al2O3 nanoparticles is more beneficial than CuO nanoparticles based on the performance index. 相似文献
More than 50% of oil is trapped in petroleum reservoirs after applying primary and secondary recovery methods for removal. Thus, to produce more crude oils from these reservoirs, different enhanced oil recovery (EOR) approaches should be performed. In this research, the effect of hydrophilic nanoparticles of SiO2 at 12 nm size, in (EOR) from carbonate reservoir is systematically investigated. Using this nanoparticle, we can increase viscosity of the injection fluid and then lower the mobility ratio between oil and nanofluid in carbonate reservoirs. To this end, a core flooding apparatus was used to determine the effectiveness and robustness of nanosilica for EOR from carbonate reservoirs. These experiments are applied on the reservoir carbonate core samples, which are saturated with brine and oil that was injected with nanoparticles of SiO2 at various concentrations. The output results depict that, with increasing nanoparticle concentration, the viscosity of the injection fluid increases and results in decreased mobility ratio between oil and nanofluid. The results confirm that using the nanoparticle increases the recovery. Also, increasing the nanoparticle concentration up to 0.6% increases the ultimate recovery (%OOIP), but a further increase to 1.0 does not have a significant effect. 相似文献
Although the compression ignition engines are a significant source of power, their detrimental emissions create considerable problems to the environment as well as to humans. The objective of the present experimental investigation is to examine the effects of the magnetic nanofluid fuels on combustion performance characteristics and exhaust emissions. In this regard, the Fe3O4 nanoparticles dispersed in the diesel fuel with the nanoparticle concentrations of 0.4 and 0.8 vol% were employed for combustion in a single-cylinder, direct-injection diesel engine. After a series of experiments, it was demonstrated that the nanoparticle additives, even at very low concentrations, have considerable influence in diesel engine characteristics. Furthermore, the results indicated that the nanofluid fuel with nanoparticle concentration of 0.4 vol% shows better combustion characteristics in comparison with that of 0.8 vol%. Based on the experimental results, NOx and SO2 emissions dramatically reduce, while CO emissions and smoke opacity noticeably increase with increasing the dosing level of nanoparticles. 相似文献
The purpose of this investigation is to theoretically shed some light on the effect of the unsteady electroosmotic flow (EOF) of an incompressible fractional second-grade fluid with low-dense mixtures of two spherical nanoparticles, copper, and titanium. The flow of the hybrid nanofluid takes place through a vertical micro-channel. A fractional Cattaneo model with heat conduction is considered. For the DC-operated micropump, the Lorentz force is responsible for the pressure difference through the microchannel. The Debye-Hükel approximation is utilized to linearize the charge density. The semi-analytical solutions for the velocity and heat equations are obtained with the Laplace and finite Fourier sine transforms and their numerical inverses. In addition to the analytical procedures, a numerical algorithm based on the finite difference method is introduced for the given domain. A comparison between the two solutions is presented. The variations of the velocity heat transfer against the enhancements in the pertinent parameters are thoroughly investigated graphically. It is noticed that the fractional-order parameter provides a crucial memory effect on the fluid and temperature fields. The present work has theoretical implications for biofluid-based microfluidic transport systems.
This article examines a mathematical model to analyze the rotating flow of three-dimensional water based nanofluid over a convectively heated exponentially stretching sheet in the presence of transverse magnetic field with additional effects of thermal radiation,Joule heating and viscous dissipation.Silver(Ag),copper(Cu),copper oxide(Cu O),aluminum oxide(Al_2O_3)and titanium dioxide(Ti O_2)have been taken under consideration as the nanoparticles and water(H_2O)as the base fluid.Using suitable similarity transformations,the governing partial differential equations(PDEs)of the modeled problem are transformed to the ordinary differential equations(ODEs).These ODEs are then solved numerically by applying the shooting method.For the particular situation,the results are compared with the available literature.The effects of different nanoparticles on the temperature distribution are also discussed graphically and numerically.It is witnessed that the skin friction coefficient is maximum for silver based nanofluid.Also,the velocity profile is found to diminish for the increasing values of the magnetic parameter. 相似文献