Mass Concentration Of Nanoparticles Research Articles

Complex Formation Behavior of Silica Nanoparticles and Xanthan

AbstractPolyion complex formation between negatively charged polysaccharide, xanthan, and positively charged silica nanoparticles, Ludox CL is investigated in an acetate buffer at pH 5.0. Appreciable precipitate is found in the composition range cx/cSiNP from 0.056 to 0.58, where cx and cSiNP are the mass concentrations of xanthan and silica nanoparticles, respectively. The sign change of the ζ potential for the mixed solutions is observed in the cx/cSiNP range. Significantly high scattering intensity is detected for the mixed solutions in a wider cx/cSiNP range, clearly showing the complex formation. The scattering profile measured by the small‐angle X‐ray scattering reveals that silica nanoparticles are packed loosely in the complex both when xanthan forms double helix and single chain conformations.

Tribological Performance of Different Concentrations of Al2O3 Nanofluids on Minimum Quantity Lubrication Milling

Nanofluid minimum quantity lubrication (NMQL) is a green processing technology. Cottonseed oil is suitable as base oil because of excellent lubrication performance, low freezing temperature, and high yield. Al2O3 nanoparticles improve not only the heat transfer capacity but also the lubrication performance. The physical and chemical properties of nanofluid change when Al2O3 nanoparticles are added. However, the effects of the concentration of nanofluid on lubrication performance remain unknown. Furthermore, the mechanisms of interaction between Al2O3 nanoparticles and cottonseed oil are unclear. In this research, nanofluid is prepared by adding different mass concentrations of Al2O3 nanoparticles (0, 0.2%, 0.5%, 1%, 1.5%, and 2% wt) to cottonseed oil during minimum quantity lubrication (MQL) milling 45 steel. The tribological properties of nanofluid with different concentrations at the tool/workpiece interface are studied through macro-evaluation parameters (milling force, specific energy) and micro-evaluation parameters (surface roughness, micro morphology, contact angle). The result show that the specific energy is at the minimum (114 J/mm3), and the roughness value is the lowest (1.63 μm) when the concentration is 0.5 wt%. The surfaces of the chip and workpiece are the smoothest, and the contact angle is the lowest, indicating that the tribological properties are the best under 0.5 wt%. This research investigates the intercoupling mechanisms of Al2O3 nanoparticles and cottonseed base oil, and acquires the optimal Al2O3 nanofluid concentration to receive satisfactory tribological properties.

Investigation of the stability of nanofluids based on water and carbon nanoparticles synthesized by the electric arc method

In this work, arc discharge synthesis was carried out by sputtering electrodes of various compositions in a helium medium, as a result of which two types of materials containing carbon globules and graphene flakes were obtained. The synthesized materials were characterized with transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. The effect of the type and concentration of carbon nanoparticles and the type of surfactants on the stability of water-based nanofluids was studied with optical spectroscopy. For carbon globules and water, the mass concentrations of nanoparticles and sodium dodecyl sulfate were determined to obtain a nanofluid based on them stable for 1 month, which are 0.02% and 1%, respectively. It was shown that the use of neonol AF 9-12 at a concentration of 2% didn’t lead to the stabilization of carbon globules with a mass concentration of 0.02% in water. For graphene flakes, the mass concentrations of nanoparticles and stabilizers to obtain a water-based nanofluid stable for 1 month were: 0.02% graphene flakes and 1% SDS, as well as 0.02% graphene flakes and 2% neonol AF 9-12, respectively.

Spray characteristics of fuel with cerium oxide nanoparticles

Combining experiment and simulation, spray characteristics of CeO2 nano-fuels and diesel including penetration distance, cone angle, and Sauter mean diameter (SMD) were investigated at various working conditions to reveal the effect of nanoparticles on the fuel spray. The correlation degree between spray characteristics and injection pressure, ambient pressure, and mass concentration of nanoparticles was assessed using the grey relationship analysis. Due to stronger axial diffusion and relatively weaker radial diffusion, nano-fuels showed a longer spray penetration, a smaller cone angle, and a larger SMD than diesel. The difference in spray characteristics between nano-fuel and diesel widened along with an increase in mass concentration. Additionally, the kinetic energy of spray, air resistance, and entrainment were susceptible to injection and ambient pressures. In general, higher injection pressure increased spray penetration and cone angle while reduced SMD. Oppositely, higher ambient pressure decreased the spray penetration while increased the cone angle and SMD. Among the three factors, the injection pressure had the greatest effect on spray characteristics, followed by ambient pressure and then mass concentration.

Thermophysical Properties of Vegetable Oil-Based Hybrid Nanofluids Containing Al2O3-TiO2 Nanoparticles as Insulation Oil for Power Transformers.

The massive demand in the electrical power sector has resulted in a large demand for reliable, cost efficient, and environmentally friendly insulation oil to reduce the dependency on mineral oil. The hybridization of nanoparticles in vegetable oil is a novel method to enhance the thermal properties of vegetable oil. This study focuses on the experimental investigation of the thermophysical properties of coconut oil, soybean oil, and palm oil-based hybrid nanofluids suspended with Al2O3-TiO2 nanoparticles at a mass concentration of 0.2, 0.4, and 0.6%. The ratio between Al2O3 and TiO2 nanoparticles was maintained constant at 50:50. The main purpose of the study is to evaluate the thermal conductivity, dynamic viscosity, and density of different vegetable base oils suspended with Al2O3-TiO2 in the temperature range of 30 to 60 °C. The influence of temperature on the augmentation of thermophysical properties for different vegetable oil-based hybrid nanofluids is investigated experimentally. The experimental results for thermal conductivity for the three types of base fluids show that the effect of nanoparticle mass concentration in thermal conductivity enhancement is less significant for temperatures more than 50 °C. The palm oil with a 0.6% Al2O3-TiO2 nanoparticle concentration exhibited the highest thermal conductivity with a 27.5% thermal conductivity enhancement relative to the base oil. The effect of nanofluid temperature on density and viscosity augmentation is more distinct compared with the impact of Al2O3-TiO2 nanoparticles concentrations. Among all three types of hybrid nanofluids, palm oil based nanofluids were found to have superior thermophysical properties compared with coconut oil and soybean oil, with the highest thermal conductivity of 0.628 W/m·k and lowest viscosity of 17.772 mPa·s.

Heat transfer and pressure drop characteristics of ZnO/DIW based nanofluids in small diameter compact channels: An experimental study

This experimental study is focused on heat transfer performance and pressure drop characteristics of ZnO/DIW-based nanofluids (NFs) in horizontal mini tubes of different (1.0–2.0 mm) diameters. Different mass concentrations (0.012–0.048 wt %) of nanoparticles (NPs) were tested with varying fluid flow rates (12–24 ml/min) of NFs. The thermal conductivity (TC) and viscosity (VC) of stable NFs were tested at 20–60 ᵒC, at a fixed temperature (40 °C), and concentration of NPs (0.048 wt%) the maximum rise was 18.27% and 20.31%, respectively. The local and average heat transfer coefficients (HTCs) and the pressure gradient were noticed to be directly proportional to volume flow rate of NFs and the mass concentration of NPs. However, an inverse trend was noticed with the test section's diameter. At 0.048 wt % of NPs and 24.0 ml/min flow rate of NFs, the maximum rise in local and average HTCs and pressure gradient was 17.11–11.61% and 13.05–9.79%, and 29.19–12.25%, respectively, in a tube's diameter of 1.0–2.0 mm. The friction factor increased with NP's loading while the same reduced with the fluid flow rate. The corresponding maximum change in the friction factor was 28.85–12.72% for the tubes with 1.0–2.0 mm diameters, respectively, at a 12.0 ml/min flow rate of NFs. The comparison of experimental findings for the HTCs, pressure gradients and friction factors with the standard Shah and Darcy's correlations showed that the observations are in good agreement with the predicted ones.

A Simple Model to Estimate the Number of Metal Engineered Nanoparticles in Samples Using Inductively Coupled Plasma Optical Emission Spectrometry.

Accurate determination of the size and the number of nanoparticles plays an important role in many different environmental studies of nanomaterials, such as fate, toxicity, and occurrence in general. This work presents an accurate model that estimates the number of nanoparticles from the mass and molar concentration of gold nanoparticles (AuNPs) in water. Citrate-capped AuNPs were synthesized and characterized using transmission electron microscopy (TEM) and ultraviolet–visible spectroscopy (UV-vis). A mimic of environmental matrices was achieved by spiking sediments with AuNPs, extracted with leachate, and separated from the bulk matrix using centrifuge and phase transfer separation techniques. The quantification of AuNPs’ molar concentration on the extracted residues was achieved by inductively coupled plasma optical emission spectroscopy (ICP-OES). The molar concentrations, an average diameter of 27 nm, and the colloidal suspension volumes of AuNPs enable the calculation of the number of nanoparticles in separated residues. The plot of the number of AuNPs against the mass of AuNPs yielded a simple linear model that was used to estimate the number of nanoparticles in the sample using ICP-OES. According to the authors’ knowledge, this is the first adaptation of the gravimetric method to ICP-OES for estimating the number of nanoparticles after separation with phase transfer.

The effect of hybrid nanofluid CuO-TiO2 on radiator performance

This study aims to improve the performance of the vehicle's cooling system called the radiator, which is part of increasing energy efficiency. Research has been done to investigate the convective heat transfer of hybrid nanofluid, using CuO and TiO2 nanoparticles and water-ethylene glycol (RC) as base fluids on a radiator. The mass concentration of the hybrid nanoparticles varied from 0.25 %, 0.30 %, and 0.35 %. For the preparation of the hybrid nanofluid through a two-step method, by mixing dry samples of CuO and TiO2 nanoparticles (50:50) and then the mixture of radiator coolant, RC (60 % water and 40 % ethylene glycol). The fluid flow varies from 20 liters per minute to 28 liters per minute. Temperature variations range from 70 °C to 90 °C by using controlled heating. Four thermocouples measure the inlet and outlet hot fluid flow and the airflow before and after the radiator. The experiment showed that the overall heat transfer coefficient increases remarkably with the increase of the hybrid nanoparticle concentration under various flow rate values. The maximum overall heat transfer coefficient increases by about 83 % compared to pure radiator coolant under 0.35 % mass concentration at a flow rate of 22 liters per minute and a temperature of 70 °C. It has also been found that the heat transfer rate is highly dependent on the radiator's mass fraction and flow rate. Increasing the mass concentration shows maximum enhancement in heat transfer rate. Inlet temperature also enhances the heat transfer rate, but its effect is small compared to nanofluid's mass concentration and flow rate. This study reveals that hybrid nanofluids can be suitable as a working fluid, especially in small-scale heat transfer devices.

Combined effect of electric field and nanofluid on bubble behaviors and heat transfer in flow boiling of minichannels

In this work, electric field and nanofluid are coupled to enhance flow boiling heat transfer in minichannel. Pin electrodes are adopted to create non-uniform electric field. The effects of nanoparticle mass concentration, surfactant type and mass concentration under electric field on nanofluid flow boiling heat transfer are studied. Image analysis technique is used to quantify boiling bubble behaviors. The results demonstrate that without electric field, bubbles for nanofluid flow boiling are smaller and more discrete than R141b. Under electric field, bubble size reduces and the number of bubbles increases, which reveals synergy effect of electric field and nanofluid on bubble behaviors is effective. Besides, electric forces mitigate bubble coalescence and delay transition from bubbly to slug flow. Maximum heat transfer coefficient of nanofluid is 80% higher than R141b. Under electric field, boiling heat transfer of nanofluid modified by anionic surfactant (SDBS) is better than cationic (CTAB) and nonionic (Span80) surfactant. • Electric field and nanofluid were devised to enhance flow boiling of minichannel. • Bubble behaviors and flow pattern transition in nanofluid flow boiling under electric field was discussed. • Synergy effects of electric field and nanofluids on enhancing flow boiling heat transfer was discussed. • Maximum heat transfer enhancement ratio of 1.8 for nanofluid and electric field is obtained.

Computational analysis of heat transfer augmentation and thermodynamic irreversibility of hybrid nanofluids in a tube fitted with classical and elliptical‑cut twisted tape inserts

This work investigates heat transfer and entropy generation of a turbulent flow of an Al2O3–Cu/water hybrid nanofluid in a plain tube (PT) with classical (TPT) and elliptical‑cut twisted tape (TECT) inserts. The heat transfer and pressure drop are investigated numerically at Re (7000–15,000), mass concentration (1–4%), and the inlet temperature of the fluid (300 K). Further, the total entropy generation and Bejan number are examined at Re = 7000 and a mass concentration of 4%. The obtained results indicate that heat transfer can be intensified when inserting classical and elliptical‑cut twisted tape. In addition, an increase in the thermal conductivity of the fluid may cause a slight increase in the heat transfer coefficient. Moreover, heat transfer and thermal performance factors increase when the mass concentration of nanoparticles increases. The Nusselt numbers for TECT and TPT are 1.7 and 1.57 times higher than those for PT, respectively. The Nusselt number and thermal performance factor of hybrid nanofluid are greatest at roughly 195 and 1.9, respectively, showing 3.9% and 7.73% improvement compared to CuO/water nanofluid at Re = 7000. The analysis of the generation of entropy is expressed as a function of thermal and frictional contributions. The results indicate the existence of a minimum entropy generation for each type of tubes for Al2O3–Cu/water hybrid nanofluid. Total entropy generation analysis demonstrates that thermal entropy generation dominates at high heat flux. Moreover, increasing the nanoparticles decreases the generation of total entropy, which is ascribed to the thermal conductivity increment. In addition, the rate of total entropy generation declines as the vortex flow increases.

Dynamic viscosity and surface tension of propylene glycol containing TiO2 nanoparticles

Adding nanoparticles with high thermal conductivity into the work fluid is one of the most significant ways to enhance heat transfer. In this article, the influences of nanoparticle mass concentration (0.5–10.0 wt.%) and temperature (5–25 °C) were investigated on the viscosity of TiO2-propylene glycol nanofluid. At the same time, eight kinds of mass concentrations (0.5–10.0 wt.%) were used to investigate the changing regularity on the surface tension of nanofluid; Accordingly, the modified correlations including nanoparticle concentration were proposed respectively. The experimental results show that the viscosity of the nanofluid increases with the increase in particle concentration. Within the concentration of 10.0 wt.%, the viscosity increases by about 7.0% for every 1.0 wt.%. While the viscosity decreases with the increase in the temperature. The surface tension of the mixture increases slowly with the increase in particle concentration. Within 2.0 wt.%, the surface tension of nanofluid increases by less than 1.0% for every 0.5 wt.%, when the concentration of nanofluid exceeds 2.0 wt.%, surface tension raises less than 1.0% per 2.0 wt.%.

Production of lightweight Zn–ZrB2 nanocomposite coatings for mechanical, microstructure and corrosion-resistance improvement of carbon steel in acidic medium

Lightweighting has been a concept in most industries. Manufacturing engineering components with low density is currently seen as a way to achieve better efficiency and handling. Hence, low-density ZrB2 ceramic particles were incorporated in the matrix of Zn to produce lightweight Zn–ZrB2 nanocomposite coatings. After preliminary runs of the experiment, coated samples were developed varying the mass concentration of ZrB2 nanoparticles between 7 g/L and 13 g/L at cell voltages of 0.3 and 0.5 V, and at a constant temperature of 45 °C. The Corrosion rate was examined in 0.5 M H2SO4 solution in accordance with ASTM standard using the potentiodynamic polarization technique, while the Brinell hardness technique was used to determine the hardness of samples. A Pin-on-disc tribometer was used to determine the coefficient of friction (COF) of the samples. The microstructures of the coatings were investigated using OPM, SEM and XRD. The result of the potentiodynamic polarization test indicated that there was an enhancement in corrosion resistance by the coating with a reduction in corrosion rate from 12.345 mm/year to 0.8587 mm/year, indicating significant protection of the carbon steel's active sites and passivating effect of the coating. The hardness value was also observed to have increased from 137.9 kgf/mm2 for the uncoated steel to 245.8 kgf/mm2 for the coated steel, which shows that the coating provided a strengthening mechanism for the steel surface. Moreso, the uncoated steel exhibited higher COF compared to the entire coated samples. The SEM and OPM images revealed that the coated samples exhibited refined surface morphology. The refined SEM morphology of the coatings was attributed to the dispersion and dissolution of nanoparticles. The XRD also indicated that the coatings possessed chemical and microstructural homogeneity, good quality texture and high stability.

Microfluidic Study of the Effect of Nanosuspensions on Enhanced Oil Recovery.

The essential advantages of microfluidic studies are the excellent visualization of the processes of oil displacement from the porous medium model, simple cleaning, and the possibility of the repeated use of the microfluidic chip. The present article deals with the process of oil displacement by suspension flooding using a microfluidic chip, simulating a porous medium, and the suspensions of silicon dioxide nanoparticles (22 nm). The mass concentration of nanoparticles in suspensions ranged from 0.1 to 2 wt%. Five mass concentrations (0.125 wt%, 0.25 wt%, 0.5 wt%, 1 wt% and 2 wt%) were considered. The article presents the experimental photographs of the oil displacement process by water and SiO2 suspension. It is shown that, with the increasing concentration of nanoparticles, the oil recovery factor increases. A significant effect is observed at 0.5 wt% concentration of nanoparticles. It is shown that the increase in oil recovery during flooding by SiO2 suspension with the maximum concentration was 16%.

Thermal management of photovoltaic panel with nano-enhanced phase change material at different inclinations.

Photovoltaic (PV) panel, coupled with phase change material (PCM), has attracted broad attention for the panel's thermal management. Despite the higher energy storage capability of PCMs, the main disadvantage is their low thermal conductivity which is compensated to an extent with the nano-enhanced PCMs (NEPCMs). In this study, numerical simulations are carried out to compare the heat transfer phenomena and thermal response of PV-NEPCM with simple PV-PCM for various tilt angles. CuO nanoparticles with mass concentrations of 1%, 3% and 5% are selected for NEPCM. The thermal performance of PV-NEPCM at inclinations of 0°, 15°, 30° and 45 [Formula: see text] is compared with a simple PV-PCM system to know the effect of mass concentration of nanoparticles and inclination. The average temperature of PV, liquid fraction and thermal energy stored in PCM, the pattern of isotherms and streamlines and performance of PV are compared for PV-PCM and PV-NEPCM systems. Results show that the loading of nanoparticles increases the heat transfer rate to PCM in all the configurations. It has also been shown that at lower inclinations, the use of NEPCM is more effective due to the presence of conduction heat transfer. At higher tilt angles, heat transfer from the PV module takes place by natural convection. By using NEPCM, the maximum decrease in PV temperature of 1.26 [Formula: see text] and maximum improvement in the liquid fraction of 8.25% are achieved when [Formula: see text] with 5% mass concentration of nanoparticles compared to simple PCM. Enhancement of thermal energy stored in PCM increases upon adding nanoparticles, and the highest improvement is obtained for [Formula: see text] Maximum enhancement of efficiency of PV module is found to be 1.75% for [Formula: see text] inclination on adding nanoparticles of 5% mass concentration.

КЛИНИКО-ФУНКЦИОНАЛЬНАЯ, КЛЕТОЧНО-МОЛЕКУЛЯРНАЯ ХАРАКТЕРИСТИКА ПРОФЕССИОНАЛЬНОЙ ХРОНИЧЕСКОЙ ОБСТРУКТИВНОЙ БОЛЕЗНИ ЛЕГКИХ В ЗАВИСИМОСТИ ОТ СОСТАВА НЕНАМЕРЕННЫХ НАНОЧАСТИЦ

Introduction. Occupational chronic obstructive pulmonary disease (OCOPD) is characterized by steadily progressive persistent bronchial obstruction and emphysema, which leads to disability and reduced life expectancy of patients. Industrial aerosols are one of the main occupational health risks. According to Federal State Statistics Service, 4.5% of all workers are exposed to aerosols of predominantly fibrogenic action, 7.7% – to a chemical factor. At present, the determination of the physicochemical properties of nanoparticles and the study of their effect on the phenotype of occupational bronchopulmonary pathology are still insufficiently studied. Aim of the research. To identify clinical, functional, cellular and molecular features of the phenotype of occupational chronic obstructive pulmonary disease under exposure to aerosols with unintentional nanoparticles of various compositions. Materials and methods. A single-center cohort study was performed. Patients with OCOPD (GOLD 2011-2021 criteria) who worked under conditions of exposure to aerosols containing unintentional nanoparticles were included (n = 70). Comparison group – COPD due to tobacco smoking (n = 70), control – conditionally healthy (n = 70). The groups are comparable in terms of demographic indicators, duration of the disease. Nanoparticles in the air of the working area were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and scanning electron microscopy. At the workplaces, in 36 persons, the mass concentration of metal nanoparticles was the highest, in 34 persons – that of silica nanoparticles. Spirography, body plethysmography, assessment of the diffusing capacity of the lungs (DLco/Va) for carbon monoxide (DLco/Va), cytological examination of induced sputum were performed. Markers of cellular inflammation and fibrosis were studied: interleukin-1β (IL1-β), interleukin-5 (IL-5), C-reactive protein (CRP), fibroblast growth factor-2 (FGF-2), transforming growth factor-β1 (TGF-β1), procollagen type 3 N-terminal propeptide (PIIINP), matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-9 (MMP-9), soluble vascular cell adhesion molecule-1 (sVCAM 1) and distribution subpopulations of blood monocytes by flow cytometry. Correlations were determined by the method of linear regression. Results. The clinical and functional peculiar characteristics of COPD when exposed to aerosols with metal nanoparticles are: the greatest severity of dyspnea according to mMRC scale 2.35 ± 0.120 points, dry cough with paroxysms 75.0%, low quality of life 70.8 ± 5.68 points, ventilation function of the lungs with the greatest severity of bronchial obstruction (Raw 0.66 kPa s/l, FEV1 36%) and static pulmonary hyperinflation (functional residual capacity (FRC) 192%, residual volume of the lungs (PRV) 187%), maximum pulmonary hypertension (37 mm Hg), the lowest values of DLco 36%. The cellular and molecular composition in OCOPD from exposure to metal nanoparticles is characterized by: eosinophilic type of inflammation 47.2%, the highest level of classical monocytes 95.4%, high expression of CCR5 21.56%, elevated serum concentrations of PIIINP 156.7 ± 15.23 ng/mL, IL-5 2.1 ± 0.42 pg/mL and MMP-9 346.2 ± 31.74 pg/mL. In COPD due to expose to industrial aerosols containing silica nanoparticles, the disease is characterized by the least severity of dyspnea mMRC 1.64 ± 0.118 points, the presence of a pronounced dry cough 61.7%, a significant decrease in DLco/Va (47%) with the least severity of bronchial obstruction (Raw 0.51 kPa s/l, FEV1 56%) and pulmonary hyperinflation. The cellular and molecular features of COPD from exposure to silica nanoparticles include: paucigranulocytic type of inflammation 44.1%, the lar¬gest proportion of non-classical CD14DimCD16+ monocytes – 21.1%, a significant level of CCR2 expression 11.10%, elevated serum concentrations of PIIINP 92, 1 ± 9.32ng/mL, FGF-2 16.1 ± 3.51pg/mL and sVCAM-1 46.1 ± 9.15 pg/mL. Reliable correlations between the mass concentrations of metal nanoparticles and classical monocytes (B = 1.6), silicon nanoparticles and nonclassical monocytes (B = 1.2) were determined. At the same time, classic monocytes were significant predictors of DLco (B = –1.7), functional residual lung capacity (B = 1.3), mean pulmonary artery pressure (B = –1.6), inflammation with eosinophilia (B = 1.2), non-classical monocytes – DLco (B = –1.4), paucigranulocytic inflammation (B = 1.3), p < 0.015. In the linear regression model, the mass concentration of metal nanoparticles is associated with the N-terminal propeptide of type 3 procollagen, interleukin-5, and matrix metalloproteinase-9. Serum PIIINP concentrations were associated with carbon monoxide diffusing capacity (DLco), IL-5 – with eosinophilic airway inflammation, and MMP-9 – with residual volume of lungs/total lung capacity (RV/TLC) ratio. The mass concentration of silica nanoparticles was associated with PIIINP, FGF-2 and sVCAM-1. In turn, the N-terminal propeptide of procollagen type 3 was associated with DLco, mean pulmonary artery pressure (MPAP); fibroblast growth factor-2 – with DLco, and sVCAM-1 – with MPAP (p < 0.01). Conclusion. Under conditions of exposure to industrial aerosol, various phenotypes of chronic obstructive pulmonary disease are formed depending on the composition of unintentional nanoparticles.

The investigation of the average diameter of the SiO2 nanoparticles effect on the oil displacing efficiency from the pore in the rock formation using nanosuspension as a displacing agent

The numerical investigation of the nanofluid flow, which displaced the oil, in a microchannel was carried out. The effect of the average diameter of the SiO2 nanoparticles on the oil displacing efficiency by nanofluids for different sizes of microchannel at various Reynolds numbers was studied. A T-shaped microchannel with a vertical channel, called a pore channel, which imitated the pore in the rock formation was considered as a computational domain. The main flow channel width and height were 200 µm. The width and height of the pore channel were varied in the range from 100 µm to 800 µm. The Reynolds number varied from 0.1 to 100. The oil recovery coefficient, which is defined as the ratio of the displacing volume of oil from the pore to the volume of the pore was considered as the main studied characteristic. The nanofluid is considered a single-phase fluid with experimentally obtained properties. The mass concentration of SiO2 nanoparticles was 0.5%. The average diameters of nanoparticles were 5 nm, 18 nm, and 50 nm. It was found, that the oil recovery coefficient increased with a decrease in the average diameter of nanoparticles. It was obtained that the nanofluid can enhance the oil recovery several times compared to pure water.

PEG 400-Based phase change materials Nano-Enhanced with Alumina: An experimental approach

This article depicts several novel experimental data on thermophysical properties of Al2O3/PEG 400 nanoparticle enhanced fluids. Both temperature variation and nanoparticle mass concentration are investigated as main factors for influencing the viscosity and heat capacity of studied nanofluids. Different approaches were used in this study to compare the data and to outline the theoretical interpretation of our experimental data.Rheological experiments at two temperatures, 288.15 K and 298.15 K show a Newtonian behavior for PEG 400 and the fluids with Al2O3 nanoparticles, while the increase in viscosity is up to 32 %, depending on the mass concentration of nanoparticles. The experimental work involved also several heating–cooling cycles and it was noticed that viscosity decreases while temperature increase and a small hysteresis (up to 10 %) was noticed for higher loadings of nanoparticles. Viscosity data analysis involved a comparison with well-known correlations as well as a VFT analysis followed by a 3D analysis of all experimental data. Specific heat for most of the nanofluids increase both with nanoparticle mass concentration and temperature; exception is the 5 %wt alumina–PEG 400. The goodness of theoretical correlations for viscosity are discussed and new correlations for viscosity and specific heat are proposed.

Hydrogen Containing Nanofluids in the Spark Engine’s Cylinder Head Cooling System

The article is devoted to the following issues: boiling of fluid in the cooling jacket of the engine cylinder head; agents that influenced the thermal conductivity coefficient of nanofluids; behavior of nanoparticles and devices with nanoparticles in the engine’s cylinder head cooling system. The permissible temperature level of internal combustion engines is ensured by intensification of heat transfer in cooling systems due to the change of coolants with “light” and “heavy” nanoparticles. It was established that the introduction of “light” nanoparticles of aluminum oxide Al2O3 Al2O3 into the water in a mass concentration of 0.75% led to an increase in its thermal conductivity coefficient by 60% compared to the base fluid at a coolant temperature of 90 °C, which corresponds to the operating temperature of the engine cooling systems. At the indicated temperature, the base fluid has a thermal conductivity coefficient of 0.545 Wm2×°C W/(m °C), for nanofluid with Al2O3 particles its value was 0.872 Wm2×°C. At the same time, a positive change in the parameters of the nanofluid in the engine cooling system was noted: the average movement speed increased from 0.2 to 2.0 m/s; the average temperature is in the range of 60–90 °C; heat flux density 2 × 102–2 × 106 Wm2; heat transfer coefficient 150–1000 Wm2×°C. Growth of the thermal conductivity coefficient of the cooling nanofluid was achieved. This increase is determined by the change in the mass concentration of aluminum oxide nanoparticles in the base fluid. This will make it possible to create coolants with such thermophysical characteristics that are required to ensure intensive heat transfer in cooling systems of engines with various capacities.

Numerical Simulation of Enhancement of Superficial Tumor Laser Hyperthermia with Silicon Nanoparticles

Biodegradable and low-toxic silicon nanoparticles (SiNPs) have potential in different biomedical applications. Previous experimental studies revealed the efficiency of some types of SiNPs in tumor hyperthermia. To analyse the feasibility of employing SiNPs produced by the laser ablation of silicon nanowire arrays in water and ethanol as agents for laser tumor hyperthermia, we numerically simulated effects of heating a millimeter-size nodal basal-cell carcinoma with embedded nanoparticles by continuous-wave laser radiation at 633 nm. Based on scanning electron microscopy data for the synthesized SiNPs size distributions, we used Mie theory to calculate their optical properties and carried out Monte Carlo simulations of light absorption inside the tumor, with and without the embedded nanoparticles, followed by an evaluation of local temperature increase based on the bioheat transfer equation. Given the same mass concentration, SiNPs obtained by the laser ablation of silicon nanowires in ethanol (eSiNPs) are characterized by smaller absorption and scattering coefficients compared to those synthesized in water (wSiNPs). In contrast, wSiNPs embedded in the tumor provide a lower overall temperature increase than eSiNPs due to the effect of shielding the laser irradiation by the highly absorbing wSiNPs-containing region at the top of the tumor. Effective tumor hyperthermia (temperature increase above 42 °C) can be performed with eSiNPs at nanoparticle mass concentrations of 3 mg/mL and higher, provided that the neighboring healthy tissues remain underheated at the applied irradiation power. The use of a laser beam with the diameter fitting the size of the tumor allows to obtain a higher temperature contrast between the tumor and surrounding normal tissues compared to the case when the beam diameter exceeds the tumor size at the comparable power.

Experience in registration of evaporation of liquid drops on a substrate by the capacitive method

This paper presents the results of an experimental study of the dynamics of evaporation of nanofluid droplets based on distilled water with a mass concentration of SiO2 nanoparticles of 0.1%, 0.5%, and 7% lying on a metal surface. The drop height was changed over time using original equipment, which is based on an integrated approach to the combined use of capacitive and optical recording methods. The experimental results show that the change in the height of nanofluid droplets with concentrations of 0.1%, 0.5%, and 7% is linear over the main part of the evaporation time interval. A deviation from the linear law is observed at the final stage, at the time interval of complete evaporation. The time for complete evaporation of droplets of nanofluids with a concentration of 0.1% increases by 20%, for droplets with a concentration of 0.5%, it increased by 28% in comparison with the evaporation of droplets of the base liquid. The particle concentration of 7% does not lead to an increase in the evaporation time of droplets in comparison with the evaporation of low concentration droplets. Before the formation of a jelly-like residue of nanoparticles, the evaporation rate of droplets with a particle concentration of 7% is comparable to the evaporation rate of droplets with a concentration of 0.1%.