An experimental study on the rheological behavior of hybrid Tungsten oxide (WO3)-MWCNTs/engine oil Newtonian nanofluids

Marangoni convection in dissipative flow of nanofluid through porous space

In various machinery engines, the engine oil is utilized as a lubricant. Heat transportation rate and to saving the energy dissipated due to higher temperature are the basic goals of all thermal systems. Thus, current work is mainly focused to develop a model for the Marangoni flow of nanofluids (NFs) with viscous dissipation. The considered NFs are made of nanoparticles (NPs) i.e. [Formula: see text] and base fluid (BF) as Engine Oil (EO). Darcy Forchheimer (DF) law which leads to porous medium is implemented in the model to investigate the variations of NF velocity and temperature. The governing flow expressions are simplified through similarity variables. The obtained expressions are solved numerically via an effective technique known as the NDSolve algorithm. The consequences of pertinent variables on temperature, velocity and Nusselt number are designed through tables and graphs. The obtained results reveal that velocity rises for higher Marangoni number, Darcy Forchheimer (DF) parameter whereas it shows decaying behavior against nanoparticles volume fraction.

Novel electrosprayed enhanced microcapsules with different nanoparticles containing healing agents in a single multicore microcapsule

A novel method was employed to synthesize microcapsules containing both epoxy and hardener healing agents in a single microcapsule using a two-step electrospraying technique. Moreover, the sodium alginate microcapsule shell was enhanced with three types of nanoparticles, including MWCNT, nanoclay, and nanosilica. The surface morphology of fabricated microcapsules was examined using FESEM and AFM images. The TEM and elemental mapping images illustrated that the added nanoparticles into sodium alginate microcapsule shells were dispersed homogeneously. In addition, the mechanical properties of microcapsule shells were obtained using nanoindentation tests. Based on this research, the addition of nanoparticles increased the size and the roughness of microcapsules and improved the elastic modulus and the hardness of microcapsule's outer shells, significantly. For instance, the elastic modulus and the hardness of incorporated microcapsule shells with MWCNT increased by 85.5% and 91.3%, respectively, compared to neat sodium alginate multicore microcapsules, due to intrinsic high strength and high aspect ratio of MWCNT.

Analytical Study on Sodium Alginate Based Hybrid Nanofluid Flow through a Shrinking/Stretching Sheet with Radiation, Heat Source and Inclined Lorentz Force Effects

This study investigated the flow and heat transfer of sodium alginate-based hybrid nanofluids with a stretching/shrinking surface. The heat source/sink, Joule heating, inclined magnetic field, and thermal radiation influences are also examined in the designed model. The mixers of non-magnetic and magnetic nanoparticles are utilized, such as Cu and Fe3O4. The Casson fluid model is applied to determine the viscoplastic characteristics of sodium alginate (SA). The necessary governing SA-based hybrid nanofluid flow equations are solved analytically by hypergeometric function. SA-based hybrid nanofluid velocity, temperature, skin friction, and Nusselt number results are discussed in detail with various pertinent parameters, such as radiation, heat source/sink, inclined angle, magnetic field, Eckert number, and Casson parameters. It is noted that the dimensions of both Cu and Fe3O4 hybrid nanoparticles and Casson parameters are minimized by the momentum surface layer thickness. The magnetic field, radiation, heat source and Casson parameters serve to enhance the thermal boundary layer thickness. Finally, the current result was verified with previously published works.

Carbon-Based Nanofluids and Their Advances towards Heat Transfer Applications-A Review

Nanofluids have opened the doors towards the enhancement of many of today's existing thermal applications performance. This is because these advanced working fluids exhibit exceptional thermophysical properties, and thus making them excellent candidates for replacing conventional working fluids. On the other hand, nanomaterials of carbon-base were proven throughout the literature to have the highest thermal conductivity among all other types of nanoscaled materials. Therefore, when these materials are homogeneously dispersed in a base fluid, the resulting suspension will theoretically attain orders of magnitude higher effective thermal conductivity than its counterpart. Despite this fact, there are still some challenges that are associated with these types of fluids. The main obstacle is the dispersion stability of the nanomaterials, which can lead the attractive properties of the nanofluid to degrade with time, up to the point where they lose their effectiveness. For such reason, this work has been devoted towards providing a systematic review on nanofluids of carbon-base, precisely; carbon nanotubes, graphene, and nanodiamonds, and their employment in thermal systems commonly used in the energy sectors. Firstly, this work reviews the synthesis approaches of the carbon-based feedstock. Then, it explains the different nanofluids fabrication methods. The dispersion stability is also discussed in terms of measuring techniques, enhancement methods, and its effect on the suspension thermophysical properties. The study summarizes the development in the correlations used to predict the thermophysical properties of the dispersion. Furthermore, it assesses the influence of these advanced working fluids on parabolic trough solar collectors, nuclear reactor systems, and air conditioning and refrigeration systems. Lastly, the current gap in scientific knowledge is provided to set up future research directions.

Comparison of effects of nanofluid utilization (Al2O3, SiO2, TiO2) with reference water in automotive radiators on exergetic properties of diesel engines

In this study, nanofluids formed by using ethylene glycol and three kinds of nanoparticles such as Al2O3, SiO2, and TiO2 were added to the four-stroke internal combustion engine radiator and compared with the conventional coolant (pure water). This comparison is based on the exergy performances which are the main theme of the second law of thermodynamics. The tests were carried out at a fixed engine speed of 1800 rpm using diesel fuel, and the outputs were obtained from the test setup experimentally. A total of six nanofluid tests were performed on two different dispersions (0.2% and 0.4%). As a result of this study, the best exergy efficiency was obtained by using TiO2 particles with a 35.67% value. Increasing the percentage of nanoparticles in the fluid from 0.2 to 0.4 positively affected efficiency. Pure water generally lagged behind nanofluid performance in experimental parameters. Compared to conventional coolant (pure water), the lowest exhaust temperature value was measured by using an Al2O3/Ethylene Glycol mixture with a difference of 59 K. Also, by using Al2O3 nanoparticles as a coolant, 8.858 kW of exergy exhaust value was obtained. This is the best emission value measured in the experimental study. While calculating values close to each other in the use of other nanoparticles, the worst exergy exhaust results were obtained by using the conventional refrigerant. Consequently, in this paper, exergetic outputs such as exergetic efficiency, exergy destruction, exergy heat, exergy work, exergy total exhaust, and entropy production rate were calculated for pure water and each nanofluid.

Gas Turbine Intercoolers: Introducing Nanofluids—A Mini-Review

Coolant is one of the main factors affecting the overall thermal performance of the intercooler for the gas turbine intercooled cycle. The thermal conductivity of conventional coolants, such as water, is relatively low when compared to solid conducting materials, and therefore can hinder the progress towards achieving a compact and highly effective intercooler. Nanofluids are advanced types of working fluids that contain dispersed nanoparticles in conventional basefluids, and as such possess superior thermal conductivity compared to their counterparts. In this paper, a short review on the effect of different nanofluids on the thermal performance of gas turbines intercoolers is presented for the first time. Firstly, this work reviews the different designs of intercoolers used in gas turbines intercooled cycles. Then, it explains the different types of nanofluids and their fabrication processes. The effective parameters, such as physical stability, thermal conductivity, and viscosity are also highlighted and discussed. Furthermore, the level of enhancement in the performance of intercoolers utilizing nanofluids is demonstrated and evaluated. Lastly, the current challenges and future research directions in this field are provided.

Numerical investigation for rotating flow of MHD hybrid nanofluid with thermal radiation over a stretching sheet

This research investigates the heat and mass transfer in 3-D MHD radiative flow of water based hybrid nanofluid over an extending sheet by employing the strength of numerical computing based Lobatto IIIA method. Nanoparticles of aluminum oxide (Al₂O₃) and silver (Ag) are being used with water (H₂O) as base fluid. By considering the heat transfer phenomenon due to thermal radiation effects. The physical flow problem is then modeled into set of PDEs, which are then transmuted into equivalent set of nonlinear ODEs by utilizing the appropriate similarity transformations. The system of ODEs is solved by the computational strength of Lobatto IIIA method to get the various graphical and numerical results for analyzing the impact of various physical constraints on velocity and thermal profiles. Additionally, the heat transfers and skin friction analysis for the fluid flow dynamics is also investigated. The relative errors up to the accuracy level of 1e-15, established the worth and reliability of the computational technique. It is observed that heat transfer rate increases with the increase in magnetic effect, Biot number and rotation parameter.

Numerical treatment of radiative Nickel-Zinc ferrite-Ethylene glycol nanofluid flow past a curved surface with thermal stratification and slip conditions

The inadequate cooling capacity of the customary fluids forced the scientists to look for some alternatives that could fulfill the industry requirements. The inception of nanofluids has revolutionized the modern industry-oriented finished products. Nanofluids are the amalgamation of metallic nanoparticles and the usual fluids that possess a high heat transfer rate. Thus, meeting the cooling requirements of the engineering and industrial processes. Having such amazing traits of nanofluids in mind our aim here is to discuss the flow of nanofluid comprising Nickel–Zinc Ferrite and Ethylene glycol over a curved surface with heat transfer analysis. The heat equation contains nonlinear thermal radiation and heat generation/absorption effects. The envisioned mathematical model is supported by the slip and the thermal stratification boundary conditions. Apposite transformations are betrothed to obtain the system of ordinary differential equations from the governing system in curvilinear coordinates. A numerical solution is found by applying MATLAB build-in function bvp4c. The authentication of the proposed model is substantiated by comparing the results with published articles in limiting case. An excellent concurrence is seen in this case. The impacts of numerous physical parameters on Skin friction and Nusselt number and, on velocity and temperature are shown graphically. It is observed that heat generation/absorption has a significant impact on the heat transfer rate. It is also comprehended that velocity and temperature distributions have varied behaviors near and far away from the curve when the curvature is enhanced.

CFD study of heat transfer effect on nanofluid of Newtonian and non-Newtonian type under vibration

Nanofluids has significant effect on heat transfer enhancement for comparatively high Reynolds number than to low Reynolds number flow. Whereas, vibration effects reduces in significance as Reynolds number increases. This study combined these two method of heat transfer enhancement i.e. use of nanofluid flow through pipe under vibration. A grid independent CFD model used for the study was validated in various aspects such as it was validated for variation of local Nusselt number, isothermal vibrational flow and non-isoviscous viscosity model so that one could believe the results obtained from the model. A valid CFD simulations has been done to investigate the effect on heat transfer to fluid flowing from pipe subjected to a constant heat flux. Al2O3-water based nanofluid was used as Newtonian fluid as it exhibits Newtonian behavior at low concentration (∅ < 2%). In order to make it non-Newtonian in nature, mixture of Al2O3 nanoparticles and 0.5 wt% aqueous CMC solution was used. Temperature dependent viscosity and thermal conductivity relations were considered for nanofluid so that it can be effectively model as single phase fluid including factors like liquid layering, Brownian motion etc. Simulations were done for different Reynolds number, volume fraction and solid particle diameter and results were presented in the form of ratio of heat transfer coefficient of vibration flow to steady-state flow. At low Reynolds number flow, a significant increment was observed for non-Newtonian nanofluid and its effect increases for volume fraction and solid particle than that of Newtonian nanofluid for the range of simulation parameters used.