Influence Of Nanoparticle Concentration Research Articles

Thermal properties analysis and thermal cycling of HITEC molten salt with h-BN nanoparticles for CSP thermal energy storage applications.

Molten salts are the operational fluid for most concentrated solar power (CSP) systems, which has attracted more attention among the scientific community due to the augmentation of their properties with the doping of nanoparticles. Hexagonal boron nitride (h-BN) nanoparticles were dispersed in HITEC molten salt to create a novel nanofluid and evaluate the h-BN nanoparticles' influence on HITEC thermophysical properties. The influence of nanoparticle concentration (0.1, 0.5, and 1wt.%) of h-BN and HITEC was studied in this research. HITEC and nano-enhanced HITEC molten salt (NEHMS) were characterized using energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FT-IR). Specific heat capacity, latent heat, and melting temperature were assessed using differential scanning calorimetry (DSC). The maximum working temperature was evaluated with thermogravimetric analysis (TGA). The ideal nanoparticle concentration is 0.1 wt.% h-BN, which results in a 27% increase in heat capacity, a 72% increase in latent heat, and a 7% enhancement in thermal stability. The thermal cycling stability test proved the stability of the enhanced thermophysical properties. The material characterization revealed that the samples with improved thermophysical properties have a homogeneous dispersion of nanoparticles with minor nanoparticle agglomeration. The system advisor model (SAM) simulation comparison of the optimum sample with solar salt and HITEC salt revealed that using the optimum sample increases CSP plant efficiency by 0.4% and reduces power costs by 0.13¢/kWh.

Nanosecond-Laser-Induced Breakdown of Aqueous Colloidal Solutions of Dysprosium Nanoparticles: The Influence of Nanoparticle Concentration on the Breakdown Plasma and the Intensity of Physical and Chemical Processes

This paper studies the dynamics of the development of laser breakdown plasma in aqueous colloids of dysprosium nanoparticles by analyzing the time patterns of plasma images obtained using a high-speed streak camera. In addition, the distribution of plasma flashes in space and their luminosity were studied, and the amplitude of acoustic signals and the rate of generation of new chemical products were studied depending on the concentration of dysprosium nanoparticles in the colloid. Laser breakdown was initiated by pulsed radiation from a nanosecond Nd:YAG laser. It is shown that the size of the plasma flash, the speed of motion of the plasma–liquid interface, and the lifetime of the plasma flash decrease with an increasing concentration of nanoparticles in the colloid. In this case, the time delay between the beginning of the laser pulse and the moment the plasma flash reaches its maximum intensity increases with increasing concentrations of nanoparticles. Varying the laser fluence in the range from 67 J/cm2 to 134 J/cm2 does not lead to noticeable changes in these parameters, due to the transition of the breakdown plasma to the critical regime. For dysprosium nanoparticles during laser breakdown of colloids, a decrease in the yield of hydrogen peroxide and an increase in the rate of formation of hydroxyl radicals per water molecule, characteristic of nanoparticles of rare earth metals, are observed, which may be due to the participation of nanoparticles and hydrogen peroxide in reactions similar to the Fenton and Haber–Weiss reactions.

Influence of Nanoparticle Concentrations on Heat Transfer in Nano-Enhanced Phase Change Materials

Influence of Nanoparticle Concentrations on Heat Transfer in Nano-Enhanced Phase Change Materials

Influence of nanoparticle concentration in nanofluid MQL on cutting forces, tool wear, chip morphology when milling of Inconel 718

Influence of nanoparticle concentration in nanofluid MQL on cutting forces, tool wear, chip morphology when milling of Inconel 718

Influence of carbon-coated zero-valent iron-based nanoparticle concentration on continuous photosynthetic biogas upgrading

This study assessed the influence of carbon-coated zero-valent nanoparticle concentration (70, 140 and 280 mg L−1) on the performance of photosynthetic biogas upgrading in an indoor pilot scale plant composed of an algal-bacterial photobioreactor interconnected to an external biogas absorption column. In addition, the influence of nanoparticle concentration on the abiotic CO2 gas-liquid mass transfer in the biogas absorption column was also evaluated. Microalgae productivity was enhanced by > 100 % when nanoparticles were added to the cultivation broth, which also boosted nitrogen and phosphorus assimilation from centrate. The biomethane produced complied with most international standards only when nanoparticles were supplemented, achieving CO2 concentrations < 1 % (CO2 removal efficiencies > 98 %) and CH4 concentrations > 94 % in the treated biogas. Finally, this research consistently demonstrated that the improvement of biogas upgrading performance by the addition of nanoparticles was based on a photosynthesis enhancement or stimulation (which significantly increased the pH in the algal cultivation broth) rather than on an improved nanoparticle-mediated CO2 capture in the biogas absorption column.

Thermal management of electronic components based on hierarchical microchannels and nanofluids

In order to enhance the heat dissipation of electronic components, hierarchical microchannels and nanofluids were applied into the thermal management of electronic components in this paper. Two kinds of hierarchical microchannels (rectangular microchannels and circular microchannels) were considered, and three different channel equivalent diameters (microchannel-a, microchannel-b, microchannel-c) of microchannel were analyzed. In addition to above factors, influence of nanoparticle concentration on the pressure drop, cooling uniformity, thermal resistance, and heat transfer coefficient was studied. For rectangular microchannel, microchannel-a has the lowest cooling uniformity and microchannel-b has the highest heat transfer coefficient, but for circular microchannel, microchannel-b has the lowest cooling uniformity and microchannel-a has the highest heat transfer coefficient. The comprehensive performance index of the microchannel was also studied. It can be concluded that the rectangular microchannel has a lower comprehensive evaluation coefficient than the circular microchannel. The maximum PEC of rectangular microchannel is 1.08, and the circular microchannel can reach 1.26. However, the heat transfer capacity of the rectangular microchannel is stronger, and the thermal resistance is about 0.00005 smaller than that of the circular microchannel.

The Baffle Length Effects on the Natural Convection in Nanofluid-Filled Square Enclosure with Sinusoidal Temperature.

The proper process of applying heat to many technological devices is a significant challenge. There are many nanofluids of different sizes used inside the system. The current study combines this potential to improve convection effects, considering numerical simulations of natural convection using Cu/water nanofluids in a square enclosure with bottom blocks embedded in baffles. The enclosure consists of two vertical walls with isothermal boundary conditions; the left wall is the sinusoidal heat source, whereas the right wall is cooled. The investigations dealt with the influences of nanoparticle concentration, Rayleigh number, baffle length, and thermal conductivity ratioon isotherms, stream functions, and average Nusselt number. The results present that, when the Rayleigh number rises, the fluid flow velocity increases, and the heat transfer improves. Furthermore, the baffle length case (Lb = 0.3) provides higher heat transfer characteristics than other baffle height cases.

Heat transfer performance of an automotive radiator with MWCNT nanofluid cooling in a high operating temperature range

• An update review on nanofluids in an automotive radiator is presented. • Evaluation of the nanofluid stability using the UV–vis spectrophotometric method. • Thermophysical properties of MWCNT water/EG nanofluids are experimentally investigated. • Thermal performance of MWCNT nanofluids in a temperature range of 80–105 °C. • Observed agglomeration and sedimentation after experimental test in high temperature. This study investigates the heat transfer performance of multiwalled carbon nanotube nanoparticles (MWCNT) dispersed in a binary mixture of water-EG (ethylene glycol) at a volumetric ratio of 50:50 in an automotive radiator. The nanofluids were prepared using the two-step synthesis method at volumetric ratios of 0.025%, 0.05% and 0.1%. The UV–vis spectrophotometry method was used to evaluate the colloidal stability of the samples, reporting the absorbance-concentration relationship according to the Beer-Lambert law. Thermophysical properties such as thermal conductivity and viscosity were measured experimentally and compared with correlations in the literature. The influence of nanoparticle concentration as well as the coolant inlet temperature, of up to 105 °C, on the heat transfer rate and in the overall heat transfer coefficient were evaluated experimentally. The air velocity was maintained constant at 2 m/s and the coolant mass flow rate ranged between 0.09 kg/s and 0.11 kg/s. The maximum increases for the heat transfer rate and for the overall heat transfer coefficient were 4.6% and 4.4%, respectively. The results show that the increase in the concentration of nanoparticles can improve the performance in heat transfer, although the performance decrease for high nanofluid inlet temperatures in the radiator was significant. Finally, the stability of the nanofluids was reassessed after performing tests on the radiator, demonstrating high aggregation and sedimentation of nanoparticles.

Gold nanoparticles for power retention in electrochemical capacitors with KSCN-based aqueous electrolyte

The paper reports the performance of the electrochemical capacitor operating with a nanoparticle-modified electrolyte. 7 mol L −1 KSCN aqueous solution, known as the electrolyte exhibiting redox activity originating from pseudohalide anion (SCN − ), has been enriched by gold nanoparticles at nanomolar concentration. The cycle life, specific energy of the device and power retention have been improved. The influence of nanoparticles concentration on the electrochemical capacitor performance has also been verified. All the nanoparticle-modified electrolytes display very high conductivity (∼370 mS cm −1 ); it is confirmed that the high energy density is retained at the whole range of applied current densities: 13.7 Wh kg −1 (at 1 A g −1 ) and 12.1 Wh kg −1 (at 20 A g −1 ). • Nanoparticles in the electrolytic solution improve power of capacitor. • The concentration of nanoparticles does not play any significant role. • The redox activity of thiocyanate remains unaffected by the presence of gold nanoparticles. • The impact of the nanoparticles is observed for redox-active electrolytes only.

Influence of nanoparticle concentration on thermophysical properties and heat transfer performance of Al2O3 nanosuspension for refrigeration system

Different types of conventional heat transfer fluid have been synthesized according to different thermal application for energy conservation. The recent advancement in last two decades have been found by using nanofluid. The nanofluid are modified heat transfer fluid which uses the dispersed nanoparticles within the fluid to enhance the thermo physical properties. The experimentation in the paper shows the development of Al2O3 based nanofluid for the refrigeration application and the effect of nanoparticle concentration on different thermo physical properties of nanofluid. The base fluid in the experiment used are polyester oil (POE) and mineral oil (MO) which are commonly used as compressor lubrication oil in a refrigeration system. The synthesis of nanofluid was carried using two step method with different weight percentage concentration of 0.02%, 0.04%, 0.07% and 0.1%. The experiment followed for the determination of thermal conductivity, viscosity and specific heat. Use of Hamilton model for thermal conductivity and brinkman model for viscosity has utilized and compared against the experimental observation. The highest gain in the thermal conductivity by almost 57% noted in by using the 0.1 wt% of Al2O3 nanoparticles with mineral oil with slight increment in the viscosity. All the synthesized nanofluid were found to be stable as well as without agglomeration.

Techno-economic analysis of nitrogen-doped graphene/water nanofluid in various heat exchangers (A unified analysis)

Nitrogen-doped graphene (NDG)/water nanofluid is one of the emerging working fluids toward achieving high heating rates in heat transfer devices. In the present study, thermal performance improvement and techno-economic analysis of a double pipe, shell and tube, and plate heat exchangers are presented while incorporating NDG/water nanofluid as a working fluid. The variable properties of NDG nanofluid are incorporated and the influence of nanoparticle concentrations and mass flow rates on the device thermal performance and related costs are evaluated. The findings demonstrate that device heat transfer area and costs are adversely affected by using NDG/water nanofluid in all types of heat exchanging devices considered. An increase in heat transfer area is associated with the decrease of the specific heat capacity of the working fluid. The increase of heat transfer area can be as high as 58.5%, 45.1%, and 67.0% for double pipe, shell and tube, and plate heat exchangers, respectively. In addition, area increase becomes persistent with other types of nanoparticles used in the carrier fluid.

Experimental thermodynamic performance analysis of semi-transparent photovoltaic-thermal hybrid collectors using nanofluids

In this article, the experimental thermodynamic performance analysis of a semi-transparent photovoltaic-thermal hybrid collector (SPV-THC) using CuO, Al2O3, TiO2 based nanofluids and water is investigated and compared with conventional opaque photovoltaic panels. The SPV-THC consists of a polycrystalline silicon cell photovoltaic module with a serpentine tube configuration heat sink. The influence of nanoparticle concentration, mass flow rate of nanofluids, ambient factors such as solar irradiation and ambient temperature on thermodynamic performance of SPV-THC have been experimentally studied under the weather conditions in Coimbatore, India. The concentration of nanoparticles and mass flow rate of nanofluids were optimized to 0.2% (by volume) and 0.016 kg/s, respectively based on experimental trials. The experimental result shows that the electrical efficiency of SPV-THC using CuO, TiO2, Al2O3 based nanofluids and water has been improved by 11.2%, 9.1%, 7.3% and 5.9% respectively than the conventional opaque photovoltaic modules. Also, the thermal efficiencies of SPV-THC using CuO, TiO2 and Al2O3 nanofluids improved by 42.6%, 34.8% and 19.7% respectively than water.

Non-linear finite element modelling of light-to-heat energy conversion applied to solar nanofluids

Nanoparticles (NPs) exhibit remarkable photothermal conversion efficiency under optical illumination. This light-induced heating on NPs is interesting in many different applications, such as solar radiation absorption in nanofluids, which the present work focuses on. Consequently, mastering the temperature increase undergone by NPs and the surrounding media is extremely relevant today. As nanothermometry measurements of a single NP are hard to obtain, numerical simulations can contribute to better understand the physical phenomena involved in light-induced heating. In this vein, the current work presents theoretical and numerical formulations to predict the heating of optically excited NPs. Theoretically, a thermodynamic approach is conducted to obtain balance and constitutive equations. These equations are numerically discretised in the finite element method and implemented into a research code. The main novelty of the present work lies in developing, from a multiphysics perspective, a time domain formulation capable of modelling instantaneous dissipation that can be easily extended to account for more physical phenomena. Finally, the numerical model is validated by comparing analytical and numerical results, and maximum values of 0.0014 (%) of relative error between them are reached. Then some different analysis are performed for gold, silver and graphite NPs of 20 (nm) in diameter to characterise the temperature increase they produce in the surrounding medium (water) when optically excited at a wavelength of 400 (nm) and a laser intensity of 5 × 104(W/cm2) –silver NPs exhibiting the most significant temperature increase. The influence of NP concentration on the increase of temperature in nanofluids is numerically assessed as well by testing values of NP concentration up to a maximum of 0.052 (%), which considerably enhances temperature increase. In conclusion, the present numerical tool could be used to predict light-induced heating in NPs, which could complement and reduce the number of experiments for optimising the photothermal efficiency of solar nanofluids.

A Mie optimization model to determine optical properties of PCM based nanofluids for solar thermal applications of glazing window

Phase change material (PCM) filled in glazing windows keeps its temperature around the melting temperature during phase change, and stores energy in the day and releases energy in the night, which can reduce air-conditioning and heating energy consumption. The optical and thermal properties of phase change material can be improved by filling with nanoparticles to produce PCM based nanofluid, which is also fundamentally important in solar thermal applications of buildings. In the present work, two models to determine optical properties of PCM based nanofluids including Rayleigh and Mie optical scattering models were firstly investigated, in which PCM is paraffin wax and nanoparticle is TiO2. Then, the Mie optimization model was built and validated by transmittance spectrum measurement data of the paraffin nanofluid. And the influences of nanoparticle concentration and particle diameter on the optical properties of the paraffin nanofluid determined by the Mie optimization model were analyzed, including extinction and scattering characteristics. The results show that the calculation values of the Mie optimization model have a good match with the experimental transmission of the paraffin nanofluid. The larger the concentration of the nanoparticle concentration, the bigger the extinction coefficient and scattering coefficient of the paraffin nanofluid. When the nanoparticle concentration is constant, the larger the particle diameter is, the larger the scattering coefficient is doubled. When the diameter of the nanoparticles increases from 10 nm to 30 nm, the scattering coefficient of the paraffin nanofluid increases by 28.7 times.

Acoustically Forced Droplet Combustion of Liquid Fuel with Reactive Aluminum Nanoparticulates

ABSTRACTThis experimental study explores the effects of acoustic excitation on burning droplets of liquid ethanol loaded with reactive aluminum nanoparticles (nAl). Continuously fed fuel droplet combustion and flame extinction (blowout) experiments were conducted in the vicinity of a pressure node (or velocity antinode) created in a closed acoustic waveguide, with a range of applied resonant forcing frequencies, pressure or velocity perturbation amplitudes, and particle loading concentrations. Simultaneous phase-locked OH* chemiluminescence and visible images were taken to quantify the influence of nanoparticle concentration on burning rate constant (K) and flame-acoustic coupling dynamics. In the presence of velocity perturbations, nAl-laden droplets were observed to burn for longer periods of time than they burned in the absence of acoustics, likely resulting from suppression of particle agglomerate formation and expulsion. It was found that at higher forcing frequencies, there were relatively greater enhancements in K values of nAl-loaded droplets than for lower frequencies. Interestingly, while at higher forcing amplitudes, the burning rate constant increased for a given loading concentration, that increase tended to be reduced at higher loading concentrations. Phase-locked imaging demonstrated that the presence of nAl increased the Rayleigh index (G) as compared with neat fuels under the same forcing conditions. Higher amplitude excitation leading to extinction showed that the addition of nAl could significantly increase the mean extinction strain rate, in some cases by up to 44%.

Biodegradable Pickering emulsions of Lipiodol for liver trans-arterial chemo-embolization

Water-in-oil (W/O) Lipiodol emulsions remain the preferable choice for local delivery of chemotherapy in the treatment of hepatocellular carcinoma. However, their low stability severely hampers their efficiency. Here, remarkably stable W/O Lipiodol emulsion stabilized by biodegradable particles was developed thanks to Pickering technology. The addition of poly(lactide-co-glycolide) nanoparticles (NPs) into the aqueous-phase of the formulation led to W/O Pickering emulsion by a simple emulsification process through two connected syringes. Influence of nanoparticles concentration and water/oil ratio on emulsion stability and droplet size were studied. All formulated Pickering emulsions were W/O type, stable for at least one month and water droplets size could be tuned by controlling nanoparticle concentration from 24 µm at 25 mg/mL to 69 µm at 5 mg/mL. The potential of these emulsions to efficiently encapsulate chemotherapy was studied through the internalization of doxorubicin (DOX) into the aqueous phase with a water/oil ratio of 1/3 as recommended by the medical community. Loaded-doxorubicin was released from conventional emulsion within a few hours whereas doxorubicin from stable Pickering emulsion took up to 10 days to be completely released. In addition, in vitro cell viability evaluations performed on the components of the emulsion and the Pickering emulsion have shown no significant toxicity up to relatively high concentrations of NPs (3 mg/mL) on two different cell lines: HUVEC and HepG2. Statement of SignificanceWe present an original experimental research in the field of nanotechnology for biomedical applications. In particular, we have formulated, thanks to Pickering technology, a new therapeutic emulsion stabilized with biodegradable PLGA nanoparticles. As far as we know, this is the first therapeutic Pickering emulsion reported in the literature for hepatocellular carcinoma. Such a new emulsion allows to easily prepare a predictable and stable lipiodolized emulsion having all the required characteristics for optimum tumor uptake. As demonstrated throughout our manuscript, emulsions stabilized with these nanoparticles have the advantage of being biodegradable, biocompatible and less toxic compared to usual emulsions stabilized with synthetic surfactants.These findings demonstrate the plausibility of the use of Pickering emulsions for chemoembolization as a therapeutic agent in extended release formulations.

On the structural analysis of ordered B2 AlNi nanoparticles obtained using freezing simulations

Ordered B2 AlNi nanoparticles are less explored, both theoretically and experimentally compared to other ordered alloy nanoparticles. Hence, comprehensive structural analysis has been carried out for AlNi nanoparticles with B2 structure generated using freezing simulations. The structural analysis in ordered B2 AlxNi1-x alloy nanoparticles was carried out for four concentrations: x = 0.55, 0.50, 0.45, and 0.40. The final structures show a variety of defects such as vacancies, antisites, grain boundaries and antiphase boundaries. All the grain boundaries are twin grain boundaries with misorientation very close to ∑ = 3,<110>{112} symmetric tilt grain boundary. The {100} surfaces are Al-terminated as they have low surface energy. Finally, the influence of nanoparticle concentration on the structure was studied. Al segregates to the surface resulting in a depletion in the bulk volume. This segregation progressively decreases with increasing amount of Ni in the nanoparticle. As a result, AlNi antisites were observed at the surfaces of Al-rich nanoparticles. The {100} and {110} surfaces exhibit expansion which is not dependent on the concentration of nanoparticles. In contrast, the atoms in the bulk volume experience compression as the amount of Ni increases. The results show that structural control of ordered alloy nanoparticles that exhibit a wide range of phase stability can be achieved by varying concentration.

Fe2O3 and Gd2O3 nanoparticles loaded in mesoporous silica: insights into influence of NPs concentration and silica dimensionality.

Fine Fe2O3 and Gd2O3 magnetic nanoparticles (NPs) with sizes 7 nm and 10 nm embedded into mesoporous silica have been prepared using a wet-impregnation method. A comparative study of the reactant concentration along with the hosting matrix symmetry on mesostructuring and the magnetic properties of the nanocomposites have been investigated. Reactants with four different concentrations of Fe3+ and Gd3+ ions and silica matrices with two different kinds of symmetry (hexagonal and cubic) have been utilized for the study. The structural characterization of the samples has been carried out by the N2 adsorption/desorption method, high-energy X-ray diffraction (HE-XRD), TG/DTA, and high resolution transmission electron microscopy (HRTEM). The magnetic properties of the nanocomposites have been examined by means of SQUID magnetometry. It has been found that a range of different magnetic states (diamagnetic, paramagnetic, ferromagnetic, superparamagnetic) can be induced by the feasible tailoring of the particle concentration, the porous matrix symmetry and the composition. Furthermore, the existence of a “critical concentration limit” for embedding the particles within the body of the matrix has been confirmed. Exceeding the limit results in the expulsion of nanoparticles on the outer surface of the mesoporous matrix. Revelation of the relationships between particle concentration, matrix symmetry and magnetic properties of the particular composite reported in this study may facilitate the design and construction of advanced intelligent nanodevices.

Non-monotonicity in the influence of nanoparticle concentration on SAR in magnetic nanoparticle hyperthermia

Magnetic nanoparticle hyperthermia (MNH) has shown substantial promise as an alternative therapy for deep-tissue tumors or resistant bacterial films. However, while great progress has been made in understanding the physical mechanisms of thermal energy dissipation in MNH, the influence of interparticle magnetic interactions in concentrated solutions remains a substantial challenge limiting progress toward clinical adoption. We have developed a well-dispersed suspension of magnetite nanoparticles which can be varied smoothly with nanoparticle concentrations ranging from 0 to 900 mg/mL. This material serves as a well-controlled experimental model for exploring the role of nanoparticle concentration on heating. We have measured the specific absorption rate (SAR) of the nanoparticles as a function of nanoparticle concentrations up to 320 mg/mL (10% v/v) in applied field frequencies from 86 to 460 kHz. Our results clearly indicate that SAR is non-monotonic with a maximum at concentrations of approximately 1% v/v, in strong agreement with recent theory. In addition, they suggest that optimal concentration is dependent on applied field frequency, and that the exponential dependence of SAR on frequency varies smoothly with concentration. These results provide experimental support for current theoretical efforts and lend insight into new investigations, ultimately leading to better prediction and control of heating in MNH.

Numerical simulation of thermal efficiency of an innovative Al2O3 nanofluid solar thermal collector: Influence of nanoparticles concentration

Investigations on the potential thermal efficiency of an innovative nanofluid solar thermal collector have been performed using a commercial software (RadTherm ThermoAnalytics rel. 10.5). The Al2O3-nanofluid has been simulated as working fluid of the solar thermal collector, varying the nanoparticles concentration from 0%vol of Al2O3 nanoparticles (pure water) up to 3%vol of Al2O3 of nanoparticles. The numerical model has been validated with experimental data, obtained with a real prototype of the simulated solar thermal collector. Real thermal properties of the nanofluids at different concentrations have been used in the simulations. The boundary conditions used for the simulations have been those of real weather conditions. An increase in thermal efficiency (up to 7.54%) has been calculated using nanofluid with a volume fraction of 3% and the influence of nanoparticles concentration on the thermal performance of the solar collector has been pointed out.