Experimental Investigation of Phase Change Phenomena in Nanofluids

2007 ◽  
Author(s):  
M. R. Madhusoodanan ◽  
V. Sajith ◽  
C. B. Sobhan
Keyword(s):  
Surface Tension ◽  
Base Fluid ◽  
Pure Water ◽  
Metal Oxide Nanoparticles ◽  
Capillary Rise ◽  
Functional Relation ◽  
Nano Particles ◽  
Oxide Nanoparticles ◽  
Surface Geometry ◽  
Rate Of Evaporation

Thermophysical properties of water like the thermal conductivity, viscosity and the surface tension are observed to change by the addition of nanoparticles. The nature of the variation of these properties with the addition of nanoparticles is a topic of increasing research interest. Rate of evaporation at a liquid surface is affected by various factors, among which the surface tension is the most predominant, and inversely affects the rate of evaporation. The introduction of nano particles into a base fluid obviously makes changes in surface geometry, which in turns alters the surface tension and hence the rate of evaporation. The present experimental study deals with the evaporation of nanofluids, obtained by suspending metal oxide nanoparticles in water. The rate of evaporation was determined by precise measurement of the rate of loss of weight of the nanofluid upon heating, keeping other parameters constant. Experiments with pure water and suspension of aluminum oxide nanoparticles showed that the rate of evaporation of the nanofluid is less compared to that of water, though a definite trend in the variation of the rate of evaporation with respect to the dosing level of nanoparticles was not found to exist. The surface tension is measured using the capillary rise method, which was observed to increase with nanoparticle addition without showing any clear functional relation with the nanoparticle dosing level. Distillation of nanofluids using standard apparatus also indicated a decrease in the evaporation rate with the addition of nanoparticles to the base fluid.

Micro-Structural Properties of Zinc Oxide Nano-Particles Synthesized by Bio-Polymeric Templates

2014 ◽  
Vol 906 ◽  
pp. 190-195
Author(s):  
Sujata Mandal ◽  
Dominic Savio ◽  
S.J. Selvaraj ◽  
S. Natarajan ◽  
Asit Baran Mandal
Keyword(s):  
Zinc Oxide ◽  
Zinc Oxide Nanoparticles ◽  
Metal Oxide Nanoparticles ◽  
Nano Particles ◽  
Oxide Nanoparticles ◽  
Electron Microscopic ◽  
Cellulose Fibres ◽  
Wurtzite Phase ◽  
Crystallite Sizes ◽  
Polymeric Templates

Zinc and iron oxide nanoparticles were synthesized using natural bio-polymeric templates viz. cellulose and sodium alginate. Cellulose fibres from different sources viz. filter-and blot-papers, were used as templates for this purpose. The synthesized Zinc oxide nanoparticles were characterized by X-ray diffraction (XRD), fourier transform infra-red spectra (FT-IR), UV-Visible spectrophotomer (UV-Vis) and scanning electron microscopic (SEM) studies. XRD studied confirmed the formation of highly crystalline hexagonal wurtzite phase of ZnO in all the synthesized nanoparticles. The average crystallite sizes of the nanoparticles obtained using different templates, were well below 50 nm. Characteristics of the zinc oxide nanoparticles obtained by template-based techniques were compared with those obtained by co-precipitation technique. Influence of various templates on the characteristics of metal oxide nanoparticles was studied.

scholarly journals Hydrophilicity Enhancement of Metal Oxide Nanoparticles Incorporated Polysulfone Ultrafiltration Membrane

2017 ◽  
Vol 20 (1) ◽  
Author(s):  
N. S. M. Sabri ◽  
H. Hasbullah ◽  
N. Said ◽  
N. Ibrahim ◽  
R. M. Kasmani ◽  
...  
Keyword(s):  
Contact Angle ◽  
Metal Oxide ◽  
Average Pore Size ◽  
Pure Water ◽  
Metal Oxide Nanoparticles ◽  
Water Flux ◽  
Oxide Nanoparticles ◽  
Phase Inversion Technique ◽  
Pure Water Flux ◽  
Bsa Rejection

Hydrophilicity property of membrane is a crucial feature in preventing fouling by most organic components including proteins. In this work, two different metal oxide nanoparticles were selected and their effects on hydrophilicity of polysulfone (PSf) flat sheet membrane for ultrafiltration were investigated. Addition of copper oxide (CuO) and iron oxide (Fe2O3) of 0.25 wt% concentration in N-methyl-2-pyrrolidone (NMP) were also compared to a neat PSf membrane. The membranes were prepared via dry-wet phase inversion technique with 18 wt% of PSf with 5 wt% polyvinylpyrrolidone (PVP). The physical and chemical properties of the prepared membranes were observed by contact angle measurements, porosity, average pore size and scanning electron microscope (SEM). The membranes permeation performance was also examined in term of pure water flux (PWF) and protein rejection by using bovine serum albumin (BSA) solution. Contact angle value of CuO/PSf obtained was 67.1° that was lower than the neat PSf membrane of 87.9° whereas 68.1° for Fe2O3/PSf indicating that metal oxides addition did enhance the membrane hydrophilicity with CuO was slightly better than Fe2O3. The reduction in contact angle ensured that the pure water flux through the membrane with metal oxide additive would improve as well. For CuO, the PWF increased to 159.3 Lm-2hr-1 from 81.3 Lm-2hr-1 of neat PSf, while Fe2O3 showed the PWF at 93.4 Lm-2hr-1. Morphological analyses displayed asymmetric membranes with narrow finger-like structure were formed in this study. A well-formed dense top layer indicated that the membrane would possess good BSA rejection property with 92% of rejection achieved by CuO/PSf membrane. The incorporation of nanoparticles with the membrane is proven to be an effective mean to increase the membrane hydrophilicity with improved water flux and BSA rejection.

scholarly journals Surface tension of aqueous binary mixtures under the supercooled conditions – Development of the measuring technique and preliminary data for water + lower alcohols

2018 ◽  
Vol 180 ◽  
pp. 02118 ◽  
Author(s):  
Václav Vinš ◽  
Jiří Hykl ◽  
Zbyněk Nikl ◽  
Miroslav Čenský ◽  
Jan Hrubý
Keyword(s):  
Surface Tension ◽  
Binary Mixtures ◽  
Capillary Tube ◽  
Pure Water ◽  
Capillary Rise ◽  
Solute Concentration ◽  
Liquid Column ◽  
Measuring Technique ◽  
Aqueous Mixtures ◽  
Experimental Apparatus

An experimental apparatus originally developed for the measurement of surface tension of supercooled water was modified such that it allows for measurement of binary aqueous mixtures. The measuring principle based on the capillary rise technique is similar to that employed in the previous measurements with pure water [J. Hrubý et al., J. Phys. Chem. Lett. 5 (2014) 425 and V. Vinš et al., J. Phys. Chem. B 119 (2015) 5567]. The temperature dependence of the surface tension is determined from the measured height of the liquid column elevated in a vertical capillary tube with an inner diameter of 0.32 mm. The aqueous liquid rises to a height of 60 mm to 95 mm depending on the solute concentration and the temperature. Preliminary tests performed with the binary mixtures of water with methanol, ethanol, and n-propanol at various concentrations and temperatures down to –28 °C approved functionality of the measuring technique. Some difficulties, such as influence of impurities on the liquid column elevation or formation of bubbles in the liquid column, were observed. The experimental apparatus is further being modified in order to obtain more accurate data for various aqueous mixtures.

Impact of metal oxide nanoparticles on unsteady stagnation point flow of the hybrid base fluid along a flat surface

Pramana ◽  
2021 ◽  
Vol 95 (1) ◽  
Author(s):  
Amit Kumar Pandey ◽  
Sohita Rajput ◽  
Krishnendu Bhattacharyya ◽  
Precious Sibanda
Keyword(s):  
Metal Oxide ◽  
Stagnation Point ◽  
Base Fluid ◽  
Flat Surface ◽  
Metal Oxide Nanoparticles ◽  
Stagnation Point Flow ◽  
Oxide Nanoparticles

scholarly journals Analysis of Platelet Shape Al2O3 and TiO2 on Heat Generative Hydromagnetic Nanofluids for the Base Fluid C2H6O2 in a Vertical Channel of Porous Medium

2021 ◽  
Vol 18 (14) ◽  
Author(s):  
Silpi HAZARIKA ◽  
Sahin AHMED ◽  
Ali J. CHAMKHA
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Porous Medium ◽  
Heat Generation ◽  
Base Fluid ◽  
Volume Fraction ◽  
Metal Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Nanoparticles Volume Fraction ◽  
Platelet Shape

An analytical investigation is performed on the unsteady hydromagnetic flow of nanoparticles Al2O3 and TiO2 in the EG base fluid through a saturated porous medium bounded by two vertical surfaces with heat generation and no-slip boundary conditions. The physics of initial and boundary conditions is designated with the flow model's non-linear partial differential equations. The analytical expressions of nanofluid velocity and temperature with the channel are derived, and Matlab Codes are used to plot the significant results for physical variables. From the physical point of view for nanofluid velocity and temperature results, the base fluid C2H6O2 has a higher viscosity and thermal conductivity than that of water. Physically, the platelet shape Al2O3 nanofluid has the highest velocity than TiO2 nanofluid. It is found that the velocity of nanofluid enhanced the porosity and nanoparticles volume fraction for Al2O3 - EG and TiO2 - EG base nanofluids. However, this trend is reversed for the effects of heat generation. Obtained results indicate that an increase in nanoparticles volume fraction raises the skin friction near the surface, but profiles gradually become linear, due to less frictional effects of nanoparticles. Moreover, due to higher values of nanoparticles volume fraction, the thermal conductivity is raised, and thus the thickness of the thermal boundary layer is declined. The results show that the method provides excellent approximations to the analytical solution of nonlinear system with high accuracy. Metal oxide nanoparticles have wide applications in various fields due to their small sizes, such as the pharmaceutical industry and biomedical engineering. HIGHLIGHTS Impact of platelet shape Al2O3 and TiO2 for base fluid C2H6O2 is studied In Couette and Poiseuille flow, nanoparticles play a vital role to enhance the heat transfer The infinite series solution has been used for solving the non-linear PDE’s The uses of Al2O3 and TiO2 in significant heat transfer applications is overviewed The physiochemical and structural features of metal oxide nanoparticles have diverse biomedical applications GRAPHICAL ABSTRACT

scholarly journals Ternary solution of sodium chloride, succinic acid and water – surface tension and its influence on cloud droplet activation

2008 ◽  
Vol 8 (2) ◽  
pp. 7189-7216 ◽  
Author(s):  
J. Vanhanen ◽  
A.-P. Hyvärinen ◽  
T. Anttila ◽  
Y. Viisanen ◽  
H. Lihavainen
Keyword(s):  
Surface Tension ◽  
Sodium Chloride ◽  
Succinic Acid ◽  
Pure Water ◽  
Capillary Rise ◽  
Cloud Droplet ◽  
Ternary Solution ◽  
Marine Aerosol ◽  
Cloud Models ◽  
Droplet Activation

Abstract. Surface tension of ternary solution of sodium chloride, succinic acid and water was measured as a function of both composition and temperature by using the capillary rise technique. Both sodium chloride and succinic acid are found in atmospheric aerosols, the former being main constituent of marine aerosol. Succinic acid was found to decrease the surface tension of water already at very low concentrations. Sodium chloride increased the surface tension linearly as a function of the concentration. Surface tensions of both binary solutions agreed well with the previous measurements. Succinic acid was found to lower the surface tension even if sodium chloride is present, indicating that succinic acid as a surface active compound tends to concentrate to the surface. An equation based on thermodynamical relations was fitted to the data. As a result, a surface tension parameterization of ternary solution was obtained over the whole concentration range. The parameterization can safely be used at temperatures from 10 to 30°C. These kinds of parameterizations are important for example in atmospheric nucleation models. To investigate the influence of surface tension on cloud droplet activation, the surface tension parameterization was included in an adiabatic air parcel model. Usually in cloud models the surface tension of pure water is used. Simulations were done for characteristic marine aerosol size distributions consisting of the considered ternary mixture. We found that by using the surface tension of pure water, the amount of activated particles is underestimated up to 8% if particles contain succinic acid and overestimated it up to 8% if particles contain only sodium chloride. The surface tension effect was found to increase with increasing updraft velocity.

scholarly journals Effect of Solvent Evaporation Time of Polysulfone Incorporated Copper Oxide Nanoparticles Incorporated Polysulfone Ultrafiltration Membrane on Protein Removal

2020 ◽  
Vol 24 (3) ◽  
Author(s):  
N. S. M. Sabri ◽  
H. Hasbullah ◽  
M. S. Tohid ◽  
N. Ibrahim ◽  
R. M. Kasmani ◽  
...  
Keyword(s):  
Copper Oxide ◽  
Pure Water ◽  
Metal Oxide Nanoparticles ◽  
Asymmetric Structure ◽  
Oxide Nanoparticles ◽  
Dense Layer ◽  
Evaporation Time ◽  
Water Permeation ◽  
Membrane Performance ◽  
Bsa Rejection

Polysulfone (PSf) membranes are becoming more popular in wastewater treatment recently, mostly due to its stability in chemical, thermal and mechanical properties. PSf membranes are hydrophobic, causing difficulty of water permeation. Incorporating metal oxide nanoparticles improving the membrane hydrophilicity, thus increasing membrane permeation and rejection. In this study, copper oxide nanoparticle (CuO NPs) incorporated PSf membranes were fabricated under different evaporation times of 3s, 6s, 8s, and 9s to investigate on membrane morphology and performance. The membrane morphologies were characterized by using scanning electron microscope (SEM) while the membrane performance was determined through pure water flux (PWF) and bovine serum albumin (BSA) rejection. When characterized by SEM, all membranes showed an asymmetric structure with thin and dense at the top while the bottom layer was thick and porous. It was discovered that as the evaporation time increased, the formation of the finger-like structure became narrower while dense layer became thicker. When tested with PWF, membranes with higher evaporation times showed less permeability, decreasing from 139.74 Lm-2h-1 to 89.89 Lm-2h-1. In terms of BSA rejection, increased in evaporation time caused the rejection rate to increase from 87.79% to 92.15%. This study proved that evaporation time is one of important parameters that influences the membrane performance significantly. 

scholarly journals Nano ZnO and its Perspective in Anti-Cancer Activities

2017 ◽  
Vol 16 (2) ◽  
pp. 41-52
Author(s):  
N Shobhaa ◽  
N Nandab ◽  
B M Nagabhushana
Keyword(s):  
Zinc Oxide ◽  
Metal Oxide ◽  
Zinc Oxide Nanoparticles ◽  
Metal Oxide Nanoparticles ◽  
Nano Particles ◽  
Oxide Nanoparticles ◽  
Zno Nps ◽  
Large Bandwidth ◽  
Anti Cancer ◽  
Potential Applications

Several methods are used to counter the deadly disease cancer. Zinc oxide nanoparticles (ZnO NPs) is one of the metal oxide nanoparticles which had been used in anti-cancer activities due to its large bandwidth and high exciting binding energy and it has potential applications like antibacterial, antifungal, anti-diabetic, anti-inflammatory, wound healing, antioxidant, optic properties and also which holds promise to treat cancer effectively. Studies have shown that Zinc metal oxide nano particles induce cytotoxicity in cancer cells. The mechanism for antitumor could work through apoptosis or the generation of reactive oxygen species or and necrosis, among other possibilities. This review is on some of the most significant antitumor results obtained with zinc oxide nanoparticles depending on their size, surface morphology, methods of preparation and also cytotoxicity result.

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