Mass Fraction Of Nanoparticles Research Articles

Experimental study on the effect of different surfactants on the thermophysical properties of graphene filled nanofluids

In this study, the effects of different surfactants on the stability and thermophysical properties of graphene (GR) filled water (W) nanofluids were investigated in an experimental manner. Nanofluids filled by 0.05% mass fraction of GR nanoparticles with a surfactant concentration of 0.02%, 0.04%, 0.06%, 0.08%, and 0.1% were studied. The effects of surfactants on stability, viscosity, and thermophysical properties of prepared nanofluids were analyzed experimentally. The results show that the nonionic surfactants displayed best performance in terms of static stability, and the anionic surfactants stand in the second position. Further study reveals that thermal conductivity enhancement of nanofluids could reach 2.0% by filling only 0.05% mass fraction of GR and the heat transfer coefficient of nanofluids up to 27%.

Cooling performance of mini-channel heat sink with water-based nano-PCM emulsion-An experimental study

In this investigation, the cooling characteristics of mini-channel heat sink with the water-based nano-phase change material emulsions are examined experimentally. The n-eicosane nanoparticles and the pure water are considered as the as the phase change material and base fluid, respectively. The fluid flow and convection heat transfer in the mini channel heat sink are studied at different parameter ranges: the volumetric flow rate varied from Q˙ = 60 cm3 min−1 to 600 cm3 min−1, three values of the heat flux imposed on the bottom wall of the heat sinks including qh″ = 3.2 W cm−2, 3.95 W cm−2, and 4.78 W cm−2, and the mass fraction of n-eicosane nanoparticles varied from ωpcm = 0%–10%. The influences of these parameters on the friction factor, wall temperature, heat transfer effectiveness, Nusselt number, figure of merit, coefficient of performance, and thermal resistances are investigated. It is concluded that for the low volumetric flow rate and the heat fluxes of heat flux of 3.20 W cm−2, 3.95 W cm−2, and 4.78 W cm−2, using the n-eicosane nanoparticles with larger values of mass fraction is more proper to decrease the wall temperature. For low value of heat flux, the value of the convective heat transfer effectiveness is larger than unity for most values of Reynolds number. The maximum figure of merit index of 1.098 can be achieved at the Reynolds number of 1381, the heat flux of 4.78 W cm−2, and the mass fraction of 2%. The figure of merit index is decreased with boosting the mass fraction of n–eicosane particles. The figure of merit index is decreased about 44% with boosting the mass fraction of n–eicosane particles from 2% to 10% for the heat flux of 3.20 W cm−2. The usage of n-eicosane nanoparticles with the concentration of 2% results in the lower thermal resistances in comparison to the case of pure water. The difference between the thermal resistances for various mass fractions of n-eicosane nanoparticles decreases as the heat flux increases.

Modelling the viscosity of carbon-based nanomaterials dispersed in diesel oil: a machine learning approach

The viscosity of a nanofluid is one of its fundamental thermophysical properties, and it is an important consideration in heat transfer applications. Although the viscosity can be reliably obtained from experimental measurements, the development of models to predict the viscosity is a faster and more convenient approach. This study focuses on creating a machine learning model for the viscosity of different carbon nanomaterials dispersed in diesel oil. The nanomaterials considered here include multi-walled carbon nanotubes, graphene nanoplatelets, and their hybrid combinations. A support vector regression-based model was developed and validated using 120 experimental data points in the temperature range 5–100 °C. The model inputs are the nanoparticle mass fraction, the fluid temperature, and the viscosity of the diesel oil. The developed model yields very good predictive performance on the training and testing datasets. The correlation coefficient and the root mean square error were 99.98% and 0.0076 Pa s, respectively, for the training dataset, and 99.99% and 0.0026 Pa s for the testing dataset. These results indicate that the developed model is extremely accurate for predicting the viscosity of carbon-based nanomaterials in a diesel oil medium, and it was found to outclass all existing models. This model could therefore be extremely useful in the design of heat transfer applications.

Molecular dynamics simulation of thermal and phonon transport characteristics of nanocomposite phase change material

Nanomaterials have been widely used to prepare nanocomposite phase change material (NPCM) and enhance its thermal conductivity. However, most of the studies are mainly focused on the thermal transport properties and the microscopic mechanism is still not clear. In this paper, molecular dynamics (MD) method was adopted to study both the thermal and phonon transport behaviors of NPCM (CuO/paraffin) to deeply reveal the influence mechanism of nanomaterials on PCM. The results show that the nanoparticle can enhance PCM thermal conductivity, and the enhancement effect is strengthened with nanoparticle mass fraction and NPCM temperature increasing. After that, phonon density of states was calculated to investigate the phonon scattering phenomenon in NPCM. The results show that the phonon scattering is very small in nanoparticle; then with the distance to nanoparticle surface increasing, the phonon scattering quickly increases; however, there exists a nanolayer around the nanoparticle, where the phonon scattering almost keeps constant. The weaker phonon scattering, the higher thermal transport performance. So, the existence of nanolayer caused by nanoparticle reduces the phonon scattering and promotes the heat transfer, which contributes to the thermal conductivity enhancement of NPCM

ICMMS-2: Computational DFT Study of Gold Containing PVP/PEO/Gold Organometallic Polymer Nanocomposites

Polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) were used to prepare virgin and equimass fraction blend samples via an ordinary solution casting route. Polyblend was filled with a different mass fraction of green biosynthesized metallic gold nanoparticles (AuNP’s). The organometallic Nanocomposites were then studied using different characterization techniques. X-ray diffraction (XRD) investigation supports the formation of a face-centered cubic (FCC) structure of AuNP’s. FTIR spectral data reveals the persistence of the main vibrational groups in the polymeric matrix and suggests that the complexation process occurs via the carbonyl group. UV/Vis. is measurement used to estimate values of the optical energy gap and confirms the formation of AuNP’s in the nano-scale through observation of the surface plasmon resonance (SPR) peak at about 562 nm. Density functional theory (DFT) studies were employed to confirm the suggested mechanism of complexation between constituting polymers and to retrace structural changes within the polymeric matrices. Zeta sizer and transmission electron microscopy (TEM) reveals that AuNP’s were polydispersed with sizes ranging from 5-23.1 nm.

Experimental investigation of specific heat of aqueous graphene oxide Al2O3 hybrid nanofluid

The specific heat of aqueous graphene+Al2O3 (1:1) hybrid nanofluid was measured using the cooling method. The influence of nanoparticle mass fraction and temperature on the specific heat capacity of the hybrid nanofluids was investigated, the specific heat of the hybrid nanofluid was compared with that of aqueous graphene oxide nanofluid and Al2O3 nanofluid. A fitted formula of the specific heat of the hybrid nanofluid was proposed based on the experimental data. It indicates that the specific heat reduction ratio increases with increase of nanoparticle fraction and the maximum reduction ratio is 7% at 0.15 wt.% at 20?C. The mass fraction of nanoparticle affects the specific heat of hybrid nanofluid more significantly at lower temperature. Temperature impacts the specific heat more distinctly than the nanoparticle fraction. The specific heat increases with temperature and the maximum specific heat reduction ratio of the hybrid nanofluid diminishes from 7% at 20?C to 2% at 70?C at the mass fraction of 0.05%.

Construction of a durable superhydrophobic surface based on the oxygen inhibition layer of organosilicon resins

In this paper, we report a method to improve the adhesion of superhydrophobic coatings by using the unreacted groups on the surface of methyl vinyl silicone resin caused by oxygen polymerization inhibition during the UV curing process. The oxygen inhibition layer was used as a reactive site to bind unreacted vinyl groups of modified vinyl-SiO2 nanoparticles to the surface. Using a simple dip-coating method, the modified SiO2 nanoparticles were uniformly distributed on the surface of the oxygen inhibition layer. Through a double-curing system with the advantages of both thermal-condensation curing and UV curing, superhydrophobic coatings with good light transmittance (>80%) and water immersion resistance were prepared facilely and rapidly. Nano-SiO2 formed a relatively uniform hierarchical rough structure on the surface of the silicone coating, and there was a compact gap between the bulges, which greatly reduced the contact area between the water droplets and the surface, thus forming an “air cushion” consistent with the Cassie-Baxter model. When the mass fraction of the vinyl-SiO2 nanoparticles was 1.2wt%, the water contact angle was 154° and the rolling angle was below 5°.

Effects of heat sink structure on heat transfer performance cooled by semiconductor and nanofluids

On account of the low heat dissipation problem of common cooling systems, an experimental system with enhanced structures was set to improve the heat transfer of heat sink cooled by semiconductor and TiO2-water nano-fluids. The influences of structures (smooth surface, metal foam with PPI=30, cylindrical bulge (height: H=2 mm, staggered arrangement), cylindrical groove (depth: D′=2 mm, staggered arrangement)), nanoparticle mass fractions (ω=0.0–0.5 wt%), input power of the semiconductor (P=2 W, 4 W, 6 W), and Reynolds numbers (Re=414−1,119) on the flow and heat transfer properties of TiO2-water nanofluids were studied. The compositive thermal and hydraulic properties of the enhanced technologies were analyzed by thermal efficiency. Results indicated that the combination of semiconductor and metal foam shows the most excellent performance compared with other combinations and it can be enhanced by 48.1% at best. Nanofluids with ω=0.4 wt% display the best cooling capacity instead of the highest concentration. The cooling effect shows an increasing trend with the input power of the semiconductor.

Thermal Conductivity and Stability of Hydrocarbon-Based Nanofluids with Palladium Nanoparticles Dispersed by Modified Hyperbranched Polyglycerol.

Palladium nanoparticles, which were prepared by modified hyperbranched polyglycerol (mHPG) as stabilizers, can be dispersed well in nonpolar organic solvents and form highly stable nanofluids. The influences of three mHPG products modified with cyclohexanethiol (CSHPG), dodecanethiol (DSHPG), and octadecanethiol (OSHPG) on the preparation and stability of the palladium nanoparticles were investigated. The stability and thermal conductivity enhancement of the hydrocarbon-based nanofluids with Pd@mHPG (Pd@CSHPG, Pd@DSHPG, and Pd@OSHPG) compared to the corresponding base fluid were investigated at different temperatures. The average diameters of nanoparticles stabilized by CSHPG, DSHPG, and OSHPG are within 2.7–3.6 nm. The palladium nanoparticles could be dispersed well in the nonpolar base fluid such as decalin. The nanofluids with Pd@DSHPG and Pd@OSHPG could remain stable for up to 330 days at room temperature. The nanofluid with Pd@DSHPG or Pd@OSHPG could be stable for more than 24 h at 110 °C. The thermal conductivity of the nanofluids improved with increasing temperature and the mass fraction of nanoparticles compared to the corresponding base fluid. The long alkyl chain-modified HPG can give better protection for nanoparticles from agglomeration and assist metal nanoparticles in enhancing the thermal conductivity of nanofluids.

Enhanced cellular osteogenic differentiation on CoFe2O4/P(VDF-TrFE) nanocomposite coatings under static magnetic field

Cellular responses can be regulated and manipulated through combining stimuli-responsive biomaterial with external stimulus. In this present, the magneto-responsive CoFe2O4/P(VDF-TrFE) nanocomposite coatings were designed to understand cell behaviors of preosteoblasts, as well as get insight into the underlying mechanism of osteogenic differentiation under static magnetic field (SMF). CoFe2O4/P(VDF-TrFE) nanocomposite coatings with differential magnetic property (low, medium and high magnetization) were prepared by incorporation of different mass fraction of CoFe2O4 nanoparticles (6%, 13 %, 20 %) into P(VDF-TrFE) matrix. Cell experiments indicated that all nanocomposite coatings with the assistance of SMF could promote the cell attachment, proliferation and osteogenic differentiation of MC3T3-E1 cells. Among different nanocomposite coatings, low magnetization coating (6%) showed a higher ALP activity and gene expression of Runx2, Col-I, OCN. Molecular biology assays demonstrated that the combination of nanocomposite coatings and SMF could significantly up-regulate the expression level of α2β1 integrin and p-ERK. Whereas, the addition of inhibitor U0126 down-regulated sharply the expression level of p-ERK, which indicated that cellular osteogenic differentiation of MC3T3-E1 cells was governed through α2β1 integrin-mediated MEK/ERK signaling pathways during CoFe2O4/P(VDF-TrFE) nanocomposite coatings were combined with SMF. This work provided a promising strategy to enhance cellular osteogenic differentiation through a remote-control manner, which exhibited great potential in the application of bone tissue repair and regeneration.

Synthesis and Characterization of Molten Salt Nanofluids for Thermal Energy Storage Application in Concentrated Solar Power Plants-Mechanistic Understanding of Specific Heat Capacity Enhancement.

Molten salts mixed with nanoparticles have been shown as a promising candidate as the thermal energy storage (TES) material in concentrated solar power (CSP) plants. However, the conventional method used to prepare molten salt nanofluid suffers from a high material cost, intensive energy use, and laborious process. In this study, solar salt-Al2O3 nanofluids at three different concentrations are prepared by a one-step method in which the oxide nanoparticles are generated in the salt melt directly from precursors. The morphologies of the obtained nanomaterials are examined under scanning electron microscopy and the specific heat capacities are measured using the temperature history (T-history) method. A non-linear enhancement in the specific heat capacity of molten salt nanofluid is observed from the thermal characterization at a nanoparticle mass concentration of 0.5%, 1.0%, and 1.5%. In particular, a maximum enhancement of 38.7% in specific heat is found for the nanofluid sample prepared with a target nanoparticle mass fraction of 1.0%. Such an enhancement trend is attributed to the formation of secondary nanostructure between the alumina nanoparticles in the molten salt matrix following a locally-dispersed-parcel pattern. These findings provide new insights to understanding the enhanced energy storage capacity of molten salt nanofluids.

Study on the Anti-friction properties of Chemically Etched surface texture and its synergistic Anti-friction properties with nano-lubricating oil in sheet metal deep drawing process

In sheet metal deep drawing process, the sliding contact between mold and sheet metal will cause friction and wear between sheet metal and die, resulting in tensile breaking and die wear, which will not only shorten the service life of die seriously, but also lead to quality decline and the rising costs of the forming process. In this paper, an anti-friction method using chemically etched surface texture collocated with graphene nanoparticles added lubricating oil was proposed to reduce the COF between sheet metal and die during sheet metal deep drawing process. Several surface textures with different parameters were obtained by surface chemical etching treatment on the die. The surface texture was observed by Laser Confocal Microscope. The results show that the surface texture after corrosion consists of micron-scale convex and concave, in the process of friction, when the pressure is higher than 72 MPa, the concave in the surface texture forms a closed oil concave because of plastic deformation, lubricating oil provides static pressure bearing capacity in the closed oil concave, sheet metal was separated by the oil from die contact surface, which effectively reduced the COF. In addition, the anti-friction properties ware tested, which showed that when the mass fraction of graphene nanoparticles added is 0.3%, stable deposited film in the friction contact interface can be formed, and a good filling effect of the lubricating oil in the sealed oil concave can be guaranteed, which can preserve a better integrity of the surface texture.

The performance improvement of an indirect solar cooker using multi-walled carbon nanotube-oil nanofluid: An experimental study with thermodynamic analysis

In this study, the effects of the volumetric flow rate of the nanofluid (250 ml/min, 350 ml/min, 450 ml/min and 550 ml/min) and the mass fraction of the nanoparticles (0 wt%, 0.2 wt% and 0.5 wt%) on the energy and exergy efficiencies of an indirect solar cooker with multi-walled carbon nanotube-oil (MWCNT-oil) nanofluid are investigated. Moreover, the performance of the solar collector and cooking unit, as the two main parts of the indirect solar cooker, is analyzed from the energy and exergy viewpoints. The results reveal that while increasing the volumetric flow rate of the nanofluid enhances the energy and exergy efficiencies of the solar collector, those of the cooking unit are maximized at the flow rate of 250 ml/min. Furthermore, using the nanofluid with a higher nanoparticles mass fraction leads the energy and exergy efficiencies of the solar collector and cooking unit to increase. Based on the results, the overall energy efficiency of the nanofluid-based solar cooker with 0.5 wt% is 20.08%, and the relative improvement of the overall exergy efficiency of the nanofluid-based solar cookers with 0.2 wt% and 0.5 wt% compared to that of the cooker with thermal oil is 37.30% and 65.87% respectively.

Experimental investigation of heat transfer performance of a heat pipe combined with thermal energy storage materials of CuO-paraffin nanocomposites

As the phase change material (PCM), pure paraffin wax is mixed with CuO (high heat conduction) and Span-80 (as a dispersant) in this research. The CuO/paraffin nanocomposite PCMs is synthesized with mass fractions of 0.3%, 0.6%, 0.9% and 1.2% by a two-step method. Dispersion stability and nanoparticle morphology of CuO/paraffin nanocomposite PCMs are analyzed by using a spectrophotometer and a scanning electron microscopy. Thermal conductivity and phase change latent heat of CuO/paraffin nanocomposite PCMs are investigated by changing the nanoparticle mass fraction. In addition, this paper investigates heat transfer characteristics of the heat pipe-PCMs module and effects of fan power and heating power on the performance of the cooling module. Results show that the thermal conductivity of the PCMs increases by 24.4% when 1.2% CuO nanoparticles are added into the paraffin, whereas the latent heat of phase change decreases by 1.5%. Compared to without PCMs, the heat pipe with 1.2% CuO/paraffin composite at 10 V fan voltage shows 17.2% reduction of the evaporator temperature. In addition, it is found that both a high fan voltage and a high mass fraction of CuO nanoparticles can significantly improve the heat transfer characteristics of the evaporation.

Experimental investigation of nanoparticles distribution mechanisms and deposition patterns during nanofluid droplet evaporation

Droplet evaporation is fascinating, ubiquitous, and relevant for a wide spectrum of applications, such as printing, drug testing, coating, and biomedical diagnosis. In this paper, the effects of substrate temperature (30 °C, 47 °C, 64 °C, 81 °C) and 20 nm Al2O3 nanoparticles mass fraction (0.05%, 0.1%, 0.2%) on the nanoparticles distribution mechanisms and deposition patterns during the evaporation of Al2O3-H2O nanofluid droplet were experimentally investigated. An experimental device was designed and realized. The self-assembly and Marangoni forces were first highlighted and compared. Two coffee-ring and inner-ring patterns were then identified and analyzed. The evaporation process characteristics were finally determined and discussed.

Characterization of Hybrid-nano/Paraffin Organic Phase Change Material for Thermal Energy Storage Applications in Solar Thermal Systems

In this work, the experimental investigations were piloted to study the influence of hybrid nanoparticles containing SiO2 and CeO2 nanoparticles on thermo-physical characteristics of the paraffin-based phase change material (PCM). Initially, the hybrid nanoparticles were prepared by blending equal mass of SiO2 and CeO2 nanoparticles. The hybrid-nano/paraffin (HnP) samples were prepared by cautiously dispersing 0, 0.5, 1.0, and 2.0 percentage mass of hybrid nanoparticles inside the paraffin, respectively. The synthesized samples were examined under different instruments such as field emission scanning electron microscope (FESEM), Fourier transform infrared spectrometer (FTIR), differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and thermal properties analyzer to ascertain the influence of hybrid nanoparticles on thermo-physical characteristics of the prepared samples. The obtained experimental results proved that the hybrid nanoparticles were uniformly diffused in the paraffin matrix without affecting the chemical arrangement of paraffin molecules. Prominently, the relative thermal stability and relative thermal conductivity of the paraffin were synergistically enriched up to 115.49% and 165.56%, respectively, when dispersing hybrid nanoparticles within paraffin. Furthermore, the hybrid nanoparticles appropriately amended the melting and crystallization point of the paraffin to reduce its supercooling, and the maximum reduction in supercooling was ascertained as 35.81%. The comprehensive studies indicated that the paraffin diffused with SiO2 and CeO2 hybrid nanoparticles at 1.0 mass percentage would yield a better outcome compared to the next higher mass fractions without much diminishing the latent heat of paraffin. Hence, it is recommended to utilize the hybrid-nano/paraffin with 1.0 mass fraction of the aforementioned hybrid nanoparticles for effectively augmenting the thermal energy capacity of low-temperature solar thermal systems.

The Research of Conductivity and Dielectric Properties of ZnO/LDPE Composites with Different Particles Size

Nanocomposites exhibit a high dielectric strength, whereas microcomposites exhibit a high thermal conductivity. In this study, good insulating materials were developed on the basis of the synergetic effect of micro- and nanoparticles, which were used as inorganic fillers. With a double-melting blend, nano-ZnO/low density polyethylene (LDPE), micro-ZnO/LDPE, and micro-nano-ZnO/LDPE composites were prepared, according to the scanning electron microscope test, polarization microscope test, conductivity test, breakdown test, and dielectric spectrum test, the dielectric property of micro-nano-ZnO/LDPE was explored. The SEM test results showed that by adding a suitable proportion of ZnO particles, the inorganic particles could disperse uniformly without reuniting. The PLM test results showed that the micro- and nano-ZnO particles adding decreased the crystal size. The arrangement was regular and tight. The macroscopic results showed that the mass fraction of nanoparticles and microparticles were 3% and 2%, the samples conductivity was the lowest. The breakdown field strength of the nanocomposites increased. The breakdown field strength of nanocomposites with 1%, 3%, and 5% nanoparticle contents were 5%, 15%, and 10% higher than that of pure LDPE. The addition of inorganic particles resulted in new polarization modes: Ionic displacement polarization and interfacial polarization. The ZnO/LDPE composites exhibited a higher dielectric constant and dielectric loss factor than pure LDPE. However, with the increasing frequency, it took considerable time to attain interfacial polarization in the nanocomposite and micro-nanocomposite, thus decreasing the dielectric constant.

Investigation of Heat Transfer Characteristics of Al2O3-Water Nanofluids in an Electric Heater

Commonly, heat transfer performance of a nanofluid is enhanced by increasing the mass fraction of nanoparticles due to an improvement of the thermo-physical properties. However, increasing the number of nanoparticles in the base fluid will result in an increase of the nanofluid viscosity. This research aims to investigate natural convective heat transfer for an electric heater filled with various Al2O3-water nanofluids. The effects of various mass fractions of the nanofluid (0.1–2.0 wt.%) on the heating efficiency of the electric heater were analyzed over time, and results indicate that the electric heater with the 1.0% Al2O3-water nanofluid has the highest heating efficiency of the external environment.

Development of the ANN–KIM composed model to predict the nanofluid energetic thermal conductivity via various types of nano-powders dispersed in oil

Artificial neural network/kriging interpolation method optimization method which is evaluated concerned the hybrid nanofluid composed of iron oxide (Fe2O3) and aluminum oxide (Al2O3) nano-powders to improve the thermal properties of 10w40 engine oil at different amounts of volume fraction and temperature. An input-target dataset contains 30 input-target pairs. The proposed model is examined at non-trained inputs throughout the investigated intervals beside the first derivatives of the thermal conductivity with respect to temperature and nanoparticle mass fraction. It can be seen that the obtained results have suitable smoothness and continuity. Accordingly, the kriging method shows the acceptable outcomes through the experimental prediction of Al2O3/Fe2O3 nanoparticles dispersed in 10w40 engine oil.

Thermal-hydraulic analysis of Al2O3 nanofluid as a coolant in Canadian supercritical water reactor by porous media approach

In this study, thermal-hydraulic analysis of Canadian Supercritical Water Reactor (Canadian SCWR) with nanofluid coolant has been done by porous media approach. In the applied analysis the derived conservation equations of mass, momentum and energy for coolant and conduction heat transfer equation for fuel and clad were discretised by finite volume method and solved numerically using C# program. Nanofluid coolant with various concentration of Al2O3 (Alumina) nanoparticle (up to 40% mass fraction) was selected for this study. Since in Canadian SCWR coolant and moderator are separated, higher mass fraction of nanofluid can be applied in this concept. The achieved results show that by increasing Al2O3 mass fraction, coolant heat transfer coefficient and average coolant temperature grow up in the middle of the core and pressure drop will be raised. Average clad and fuel temperature in the core was calculated. The results show that by using Alumina nanofluid with 40% nanoparticle mass fraction, maximum clad wall and fuel temperatures decrease about 20 °C and 30 °C respectively.