Effect of shot blasting on droplet contact angle of carbon aided phase change nanocomposites
TL;DR: In this article, the measurement of the contact angle of the nanocomposites made of phase change material (PCM) OM 08 and multi-wall carbon nanotubes (MWCNTs) with different volume sizes was performed.
Abstract: This experimental work deals with the measurement of the contact angle of the nanocomposites made of phase change material (PCM) OM 08 and multi-wall carbon nanotubes (MWCNTs) with different volume...
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TL;DR: The CAH analyses of colloidal suspensions at varying surfactant and particle concentrations reveal in-depth physical insight into contact line pinning, and a unique novel relationship is established between the contact angle and differential energy for distorting the instantaneous contact angle for a pinned sessile droplet.
Abstract: Even though there are quite large studies on wettability of aqueous surfactants and a few studies on effects of nanoparticles on wettability of colloids, to the best of authors’ knowledge, there is no study reported on the combined effect of surfactant and nanoparticles in altering the wettability. The present study, for the first time, reports an extensive experimental and theoretical study on the combined effect of surfactants and nanoparticles on the wettability of complex fluids such as nanocolloids on different substrates, ranging from hydrophilic with a predominantly polar surface energy component (silicon wafer and glass) to near hydrophobic range with a predominantly dispersive component of surface energy (aluminum and copper substrates). Systematically planned experiments are carried out to segregate the contributing effects of surfactants, particles, and combined particle and surfactants in modulating the wettability. The mechanisms and the governing parameters behind the interactions of nanocolloids alone and of surfactant capped nanocolloids with different surfaces are found to be grossly different. The article, for the first time, also analyzes the interplay of the nature of surfaces, surfactant and particle concentrations on contact angle, and contact angle hysteresis (CAH) of particle and surfactant impregnated colloidal suspensions. In the case of nanoparticle suspensions, the contact angle is observed to decrease for the hydrophobic system and increase for the hydrophilic systems considered. On the contrary, the combined particle and surfactant colloidal system shows a quasi-unique wetting behavior of decreasing contact angle with particle concentration on all substrates. Also interestingly, the combined particle surfactant system at all particle concentrations shows a wetting angle much lower than that of the only-surfactant case at the same surfactant concentration. Such counterintuitive observations have been explained based on the near-surface interactivity of the particle, fluid, and surfactant molecules based on effective slip length considerations. The CAH analyses of colloidal suspensions at varying surfactant and particle concentrations reveal in-depth physical insight into contact line pinning, and a unique novel relationship is established between the contact angle and differential energy for distorting the instantaneous contact angle for a pinned sessile droplet. A detailed theoretical analysis of the governing parameters influencing the wettability has been presented invoking the principles of DLVO (Derjaguin–Landau–Verwey–Overbeek), surface energy and interaction parameters influencing at the molecular scale, and the theoretical framework is found to support the experimental observations.
24 citations
TL;DR: In this paper , the performance of the low-capacity energy storage tank in different heat transfer fluid (HTF) conditions (at various flow rates) filled with spherical capsules containing nano-enhanced phase change material (nano-PCM) was investigated.
12 citations
TL;DR: In this paper , the effects of shot peening on the heat transfer, exergy analysis, and pressure drop in the heat exchanger were studied, and it was shown that nanofluids (0.15, 0.3, and 0.45%) can enhance the Nusselt number by 8.098, 16.81, and 26.98% compared with SG/H2O mixture.
7 citations
21 Sep 2022-Proceedings Of The Institution Of Mechanical Engineers, Part E: Journal Of Process Mechanical Engineering
TL;DR: In this article , a non-Fourier heat flux model was adopted to model the characteristics of hybrid nanofluid (copper/aluminum oxide-water) flow within an enclosure saturated with a porous medium.
Abstract: The current model manifests the characteristics of hybrid nanofluid (copper/aluminium oxide-water) flow within an enclosure saturated with a porous medium by adopting the non-Fourier heat flux model. In this model, the permeable enclosure is deemed to be heated by a four-sided corner heater. Besides the corners, the centre region of the upper and lower walls of the square enclosure is thermally insulated whereas the centre region of the left and right walls maintains an invariant temperature. The momentum and energy equations with boundary conditions are dimensionalized by using the appropriate non-similar quantities. The nondimensionalized governing equations along with the boundary conditions are solved by adopting the marker and cell technique. The present results are in good accordance with the earlier literature results which indicates that the adopted scheme is computationally significant. The pertinent parameters that arise from the flow field equations such as heat generation/absorption parameter, thermal relaxation parameter, Darcy number, Rayleigh number, length of constant/adiabatic temperature portion, and length of heat source position are visualized through streamlines and isotherms. Results indicate that the magnifications in the heat generation parameter have the propensity to amplify the local heat transfer rate. An amplification in the thermal relaxation parameter enhances the heat transfer rate. The impact of the cold and hot regions of the enclosure notably influences the fluid temperature within the enclosure. The strength of the streamlines is slightly lessened by enhancing the Darcy number. Natural convective hybrid nanofluid flow inside the porous cavity has a vital role in various engineering and industrial processes, for instance, extrusion of polymers and aerodynamic extrusion.
6 citations
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11,004 citations
"Effect of shot blasting on droplet ..." refers background in this paper
...The same can be affirmative by the Wenzel model (Figure 13(b)), the liquid fills the irregularities, which results in reduced contact angle [39,40]....
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TL;DR: In this article, the theory of the contact angle of pure liquids on solids, and of the determination of the surface free energy of solids was reviewed, and an algebraic expression for these properties in terms of measured contact angles was presented.
Abstract: The theory of the contact angle of pure liquids on solids, and of the determination of the surface free energy of solids, γs, is reviewed. The basis for the three components γLW s, γ⊕s, and γ⊖s is developed, and an algebraic expression for these properties in terms of measured contact angles is presented. The inadequacy of the 'two-liquid' methodology (which yields a parameter, 'γp') is demonstrated. Attention is given to contact angle hysteresis and to the film pressure, πe. Some recommendations are made with regard to contact angle measurements. A new treatment of hydrophilicity, and of the scale of hydrophobic/hydrophilic behavior, is proposed. It is shown that there are two kinds of hydrophilic behavior, one due to Lewis basicity (electron-donating or proton-accepting structures) and the other due to Lewis acidity (electron-accepting or proton-donating structures). The properties γ⊖ and γ⊕ are the quantitative measures of these types of behavior and they are structurally independent of each other. A t...
1,051 citations
"Effect of shot blasting on droplet ..." refers methods in this paper
...Different methods for measuring the contact angle of the nanocomposites/nanofluids were discussed elsewhere [15,16]....
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TL;DR: In this article, a 0.2-mm diameter cylindrical Ni-Cr wire under atmospheric pressure was used to investigate the CHF characteristics of nano-fluids, and the results showed that the CHFs of various nanofluids are significantly enhanced over that of pure water.
198 citations
"Effect of shot blasting on droplet ..." refers methods in this paper
...The contact angle made by the fluid droplet over different surfaces like a flat surface, wire [20,21], and tube [22] were calculated and reported....
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TL;DR: In this paper, temperature dependence of surface tension, interfacial tension and viscosity of a nanofluid is investigated for its applicability in droplet-based microfluidics.
Abstract: Interfacial tension and viscosity of a liquid play an important role in microfluidic systems. In this study, temperature dependence of surface tension, interfacial tension and viscosity of a nanofluid are investigated for its applicability in droplet-based microfluidics. Experimental results show that nanofluids having TiO2 nanoparticles of 15?nm diameter in deionized water exhibit substantially smaller surface tension and oil-based interfacial tension than those of the base fluid (i.e. deionized water). These surface and interfacial tensions of this nanofluid were found to decrease almost linearly with increasing temperature. The Brownian motion of nanoparticles in the base fluid was identified as a possible mechanism for reduced surface and interfacial tensions of the nanofluid. The measured effective viscosity of the nanofluid was found to be insignificantly higher than that of the base fluid and to decrease with increasing fluid temperature. The dependence on the temperature of the droplet formation at the T-junction of a microfluidic device is also studied and the nanofluid shows larger droplet size compared with its base fluid.
190 citations
TL;DR: Experimental measurements of the contact angle of nanofluid droplets cast on smooth glass and silicon substrates show that the contact Angle depends strongly on nanoparticle concentration, and smaller size nanoparticles lead to larger changes in contact angle at the same mass concentration.
Abstract: This paper investigates the change in contact angle of droplets of fluid containing dispersed nanoparticles (nanofluid) functionalized with thioglycolic acid molecules as a function of the concentration and size of nanoparticles, and the quality and composition of the substrate material. Bismuth telluride nanoparticles with an average size ranging from 2.5 to 10.4 nm and functionalized with thioglycolic acid groups were grown by a microemulsion method and dispersed in water. Experimental measurements of the contact angle of nanofluid droplets cast on smooth glass and silicon substrates show that the contact angle depends strongly on nanoparticle concentration. Moreover, smaller size nanoparticles lead to larger changes in contact angle at the same mass concentration. These findings contribute to understanding the role of functionalized nanoparticles in surface wettability.
176 citations
"Effect of shot blasting on droplet ..." refers background in this paper
...[24] studied the effect of volume concentration and size of functionalized nanomaterials in the nanofluids along with substrate material (smooth glass and silicon) substrates have a significant part in the variant of the droplet contact angle....
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...convection heat transfer; meanwhile, there is direct surface contact between the PCM and the heat transfer fluid [23,24]....
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