Al2O3 Water-based Nanofluids Research Articles

Effects of nanoparticle size on surface dynamics and thermal performance in film boiling of Al[formula omitted]O[formula omitted] water-based nanofluids

This study investigates the impact of nanoparticle diameter on film boiling in Al2O3 water-based nanofluids along a vertical cylinder, focusing on nanoparticle sizes of 5 nm, 10 nm, 30 nm, and 50 nm. Using a Continuous-Species-Transfer method within a Computational Multi-Fluid Dynamics framework, the behavior of nanoparticles in both liquid and vapor states is simulated, considering Brownian motion and thermophoretic effects. A 2D axisymmetric analysis reveals how nanoparticle sizes influence temperature gradients, nanoparticle concentration patterns, thermophysical properties, and the Nusselt number to assess heat transfer efficiency. Findings indicate that during film boiling, smaller nanoparticles exhibit higher concentrations on the heated wall over time. Additionally, nanofluids with smaller particles demonstrate higher thermal conductivity and viscosity near the heated wall, along with lower surface tension. Interestingly, nanofluids with 30 nm and 50 nm nanoparticles perform closely, indicating a size threshold beyond which further reductions do not significantly enhance boiling heat transfer. In contrast, nanofluids containing 5 nm and 10 nm nanoparticles exhibit markedly superior thermal removal efficiency, underscoring the critical role of nanoparticle size in optimizing film boiling performance.

Enhanced Stability, Superior Anti-Corrosive, and Tribological Performance of Al2O3 Water-based Nanofluid Lubricants with Tannic Acid and Carboxymethyl Cellulose over SDBS as Surfactant

In this research work, the stability, tribological, and corrosion properties of a water-based Al2O3 nanofluid (0.5 wt%) formulated with tannin acid (TA) and carboxymethyl cellulose (CMC) as dispersants or surfactants were investigated. For comparative purposes, sodium dodecylbenzene sulfonate (SDBS) was also incorporated. The stability of the nanofluid was assessed through zeta potential measurements and photo-capturing, revealing the effectiveness of TA and CMC in preventing nanoparticle agglomeration. Tribological properties were examined using a pin-on-disk apparatus, highlighting the tribofilm of Al2O3 that enhanced lubricating properties of the nanofluid by the SEM, resulting in reduced friction and wear of the contacting surfaces. Sample with the addition of both TA and CMC exhibited the best tribological performance, with a ~ 20% reduction in the friction coefficient and a 59% improvement in wear rate compared to neat nanofluid without TA and CMC. Additionally, the corrosion resistance of the nanofluids were evaluated via weight loss and electrochemical impedance spectroscopy. The nanofluid sample containing both TA and CMC exhibited the lowest corrosion rate, with 97.6% improvement compared to sample without them. This study provides valuable insights into the potential applications of TA and CMC-based Al2O3 nanofluids as effective and environmentally friendly solutions for coolant or lubrication in cutting processes.

Effects of Varying Volume Fractions of SiO2 and Al2O3 on the Performance of Concentrated Photovoltaic System

Highly concentrated triple-junction solar cells (HCTJSCs) are cells that have diverse applications for power generation. Their electrical efficiency is almost 45%, which may be increased to 50% by the end of the year 2030. Despite their overwhelming ability to generate power, their efficiency is lower when utilized in a concentrated manner, which introduces a high-temperature surge, leading to a sudden drop in output power. In this study, the efficiency of a 10 mm × 10 mm multijunction solar cell (MJSC) was increased to almost 42% under the climatic conditions in Lahore, Pakistan. Active cooling was selected, where SiO2–water- and Al2O3–water-based nanofluids with varying volume fractions, ranging from 5% to 15% by volume, were used with a 0.001 kg/s mass flow rate. In addition, two- and three-layer microchannel heat sinks (MCHSs) with squared microchannels were designed to perform thermal management. Regarding the concentration ratio, 1500 suns were considered for 15 August at noon, with 805 W/m2 and 110 W/m2 direct and indirect radiation, respectively. A complete model including a triple-junction solar cell and allied assemblies was modeled in Solidworks software, followed by temperature profile generation in steady-state thermal analyses (SSTA). Thereafter, a coupling of SSTA and Ansys Fluent was made, in combination with the thermal management of the entire model, where the temperature of the TJSC was found to be 991 °C without active cooling, resulting in a decrease in electrical output. At 0.001 kg/s, the optimum average surface temperature (44.5 °C), electrical efficiency (41.97%), and temperature uniformity (16.47 °C) were achieved in the of MJSC with SiO2–water nanofluid with three layers of MCHS at a 15% volume fraction. Furthermore, the average outlet temperature of the Al2O3–water nanofluid at all volume fractions was high, between 29.53 °C and 31.83 °C, using the two-layer configuration. For the three-layer arrangement, the input and output temperatures of the working fluid were found to be the same at 25 °C.

A comprehensive statistical approach for determining the effect of two non-ionic surfactants on thermal conductivity and density of Al2O3–water-based nanofluids

The purpose of this study was to evaluate the effect of surfactants on the density and thermal conductivity values of water, as well as to separately evaluate the variations in these values due to particle–surfactant interaction. To this end, Al2O3–water-based nanofluids with different particle volume concentrations (0.3–1.1%) were prepared, as were Tween 80 and Tergitol NP-10 surfactants at different weight ratios (0.2–0.8%). Density and thermal conductivity of obtained nanofluids were then measured at temperatures ranging from 298 to 338 K. Statistical evaluation was carried out to determine the effects of surfactant type, temperature, particle concentration, and surfactant concentration on density and thermal conductivity. Additionally, the sedimentation method, zeta potential, and particle size analysis were utilized to estimate the stability of nanofluids. Results showed that when base fluid (water and surfactant) density was determined, the use of surfactants had no additional impact on the density of the nanofluids. The highest observed improvement in thermal conductivity was 7.5%, obtained using 0.2 wt% Tween 80 and 1.1 vol% Al2O3 at 338 K. Although particle concentration was the most influential factor and surfactant type was not statistically significant for density ratio, the thermal conductivity ratio was affected by other factors in addition to particle concentration.

Experimental investigation for stability and surface properties of TiO2 and Al2O3 water-based nanofluids

Experimental investigation for stability and surface properties of TiO2 and Al2O3 water-based nanofluids

Performance analysis of solar parabolic collector using Al2O3 nanofluids

The present study has been carried out to examine the performance analysis of parabolic solar collector using Al2O3 water-based nanofluids, Al2O3-ethylene glycol-based nanofluids, with different nanoparticle volume concentrations such as 2%, 4% and 6%. Experiments are conducted to determine thermophysical properties such as thermal conductivity, specific heat, density, viscosity using a KD2 prothermal properties analyser, a differential scanning calorimeter, electronic weighing balance, a capillary viscometer, respectively, and the obtained results are compared with solutions of theoretical models. Afterwards, these nanofluids are used in parabolic collector to study its performance for getting high thermal efficiency.

Turbulent heat transfer and nanofluid flow in an annular cylinder with sudden reduction

Turbulent heat and fluid flow of a nanofluid in an annulus with sudden area reduction are numerically and experimentally studied. Two different nanofluids are considered. Nanoparticles made of aluminum oxide (Al2O3) and titanium oxide (TiO2) with volume concentrations varying from 0.005 to 0.02 have been examined. Reynolds number and heat flux varied from 10,000 to 40,000 and 1000 to 6000 W m−2, respectively. Area reduction ratios from 1 to 2 were studied in this research. For turbulence modeling, the SST k–ω model in a 3D domain was utilized. In order to validate the numerical results, Al2O3–water-based nanofluid was tested, and a great agreement was observed. It was noted that the maximum thermal performance enhancement was about 194.7% in an annular channel with an area reduction ratio of 2 compared with a straight pipe using water. The heat transfer enhancement is attributed to the downstream flow separation and recirculation region. It was noted that rising the volume concentration of the nanoparticles improves the heat transfer coefficient; this enhancement was about 26.9% (Al2O3) and 5.5% (TiO2). Also, the influence of the Reynolds number on the surface heat transfer coefficient augmentation is quantitatively reported in this paper. The maximum pressure drop was about 7.5% for Al2O3 and 5.9% for TiO2 nanofluid, compared with pure water at a reduction ratio of 2 at the highest Re value considered here.

Preparation and characterization of PVDF-filled MWCNT hollow fiber mixed matrix membranes for gas absorption by Al2O3 nanofluid absorbent via gas–liquid membrane contactor

Porous polyvinylidene fluoride (PVDF)-filled MWCNT hollow fiber mixed matrix membranes were fabricated and applied for carbon dioxide absorption in a gas–liquid membrane contactor with Al2O3 water-based nanofluid absorbent. The formation of MWCNTs’ nanotubes was verified through Transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FESEM) images while the resultant membranes were characterized for their morphology, gas permeation rate, pore size, porosity, surface hydrophilicity and wettability resistance. Upon the incorporation of MWCNT into the matrix, the formation of finger-like pores was facilitated and surface roughness increased. Gas permeation test results showed increasing the surface porosity and reducing the pore size. The surface contact angle also was improved from 83°±1.5 for the unfilled membrane to 103°±1.5 for the membrane containing 5wt% CNT. CO2 absorption flux also was enhanced considerably. For instance, the flux of the membrane containing 5wt% CNT as the best performing membrane at a liquid velocity of 2.5m/s and Al2O3 water-based nanofluid as absorbent was 3.85×10−3mol/m2s which was approximately 200% higher than that of the plain membrane at the same operating conditions. A long-term absorption test also revealed non-wetting tendencies of the membranes as well as the unclogged membrane pores by the nanomaterials existed in the nanofluid absorbent. Therefore, it could be hypothesized that the improved membrane structure and synthesized nanofluid absorbent considering their superior performance to several commercial and in-house made membranes can be suitable alternatives to the current polymeric membranes and commercial used absorbents, respectively.

Magnetohydrodynamic three-dimensional boundary layer flow and heat transfer of water-driven copper and alumina nanoparticles induced by convective conditions

This work examines the magnetohydrodynamic (MHD) three-dimensional (3D) flow comprising Cu and Al2O3 water-based nanofluids. The effects of heat and mass transfer with the effects of nanoparticles are carried out in the existence of thermal radiation and convective heat and mass transfer boundary conditions. By applying the proper similarity transformations the partial differential equations describing velocity, temperature and nanoparticle volume fraction (NVF) are transformed to a system of nonlinear ordinary differential equations (NODE). An optimal homotopy analysis technique is applied to evaluate the analytical solutions. The influences of pertinent parameters on the velocity, temperature and NVF are displayed in graphical and tabular forms. Calculations of Nusselt number, skin friction coefficients and the local Sherwood number are evaluated via tables. An excellent comparison has also been made with the previously-published literature.

Impact of nano-particles shapes on Al2O3-water nano-fluid flow due to a stretching cylinder

PurposeThe purpose of this study is to theoretically probe the shape impacts of nano-particle on boundary layer flow of nano-fluid toward a stretching cylinder with heat-transmission effects. The base fluid used for this study is pure water, and aluminum oxide nano-particles are suspended in it. Four different shapes of nano-particle, namely, cylindrical, brick, platelets and blades, are considered to carry out the study.Design/methodology/approachThe problem is modelled mathematically and the nonlinear system of equations is attained by using appropriate transmutations. The solution of transmuted equations is achieved by utilizing a shooting technique with Fourth-Fifth order Runge–Kutta Fehlberg scheme. Numerically attained results are elucidated through graphs and tables which are further compared under limiting cases with existing literature to check the validity of the results.FindingsIt is observed that fluid velocity and temperature of cylindrical shaped water nano-fluids are more than the nano-fluid having brick-shaped nano-particles. Moreover, it is seen that the nano-fluids suspended with platelets-shaped nano-particles have higher velocity and temperature than the nano-fluids containing blade-shaped nano-particles. The curvature parameter and nano-particles volume fraction have increasing effects on flow velocity and temperature of nano-fluids containing all types of nano-particle shapes.Originality/valueNumerous authors have examined the impacts of nano-particle shapes on characteristics of heat transfer and fluid flow. However, to the best of the authors’ knowledge, the shape impacts of nano-particles on boundary layer flow of nano-fluid toward a stretching cylinder with heat-transmission effects have not been discussed. So, to fulfill this gap, the present paper explicates the impacts of various nano-particle shapes on Al2O3–water-based nano-fluid flow past a stretching cylinder with heat-transfer effects.

Three-dimensional modelling of natural convection and entropy generation in a vertical cylinder under heterogeneous heat flux using nanofluids

PurposeThis study aims to investigate a three-dimensional computational modelling of free convection of Al2O3 water-based nanofluid in a cylindrical cavity under heterogeneous heat fluxes that can be used as a thermal storage tank.Design/methodology/approachEffects of different heat flux boundary conditions on heat transfer and entropy generation were examined and the optimal configuration was identified. The simulation results for nanoparticle (NP) volume fractions up to 4 per cent, and Rayleigh numbers of 104, 105 and 106 were presented.FindingsThe results showed that for low Ra (104) the heat transfer and entropy generation patterns were symmetric, whereas with increasing the Rayleigh number these patterns became asymmetric and more complex. Therefore, despite the symmetric boundary conditions imposed on the periphery of the enclosure (uniform in Ɵ), it was necessary to simulate the problem as three-dimensional instead of two-dimensional. The simulation results showed that by selecting the optimal values of heat flux distribution and NP volume fraction for these systems the energy consumption can be reduced, and consequently, the energy efficiency can be ameliorated.Originality/valueThe results of the present study can be used for the design of energy devices such as thermal storage tanks, as both first and second laws of thermodynamics have been considered. Using the optimal design will reduce energy consumption.

Power generation and electric charge density with temperature effect of alumina nanofluids using dimensional analysis

The present study was conducted in two parts. The first section was to prepare Al2O3 water-based nanofluids for the thermal-electrochemistry experiment through a two-step synthesis assisted by a microemulsion ultrasound technique. Moreover, 0.5–2.5 wt-percent concentration (wt%) nanofluids were added into a battery cell with copper (Cu) and aluminum (Al) electrodes for an reduction-oxidation (Redox) reaction to investigate the generating power capacity between 20 °C and 40 °C. The second part derived the empirical formula of electric charge density for alumina nanofluids as electrolyte using micro-power generation experiment and dimensional analysis between functional relationships and experimental parameters. The results revealed that the mixtures of Al2O3 nanofluid and emulsifying agent at a concentration of 2.5 wt% and 40 °C had the highest electric charge density based on the thermodynamic activity and chemical potential of the electrolytes. The empirical formula validated and estimated the electric charge density for alumina nanofluids with an emulsifier at between 20 °C and 40 °C and between 0.5 wt% and 2.5 wt%. However, the error rates for the calculated and measured values were high due to unstable power outputs at low temperatures. The error rate was below 5%. The formula presented here was an approximate estimation model which took the emulsifier into account.

Boundary layer flow of nanofluids to analyse the heat absorption/generation over a stretching sheet with variable suction/injection in the presence of viscous dissipation

ABSTRACT In this investigation, the heat and mass transfer characteristics in boundary layer flow about a stretching sheet in a porous medium filled with TiO2 – water and Al2O3 – water-based nanofluids, in the presence of internal heat generation or absorption and viscous dissipation with variable suction or injection effects is numerically studied. The similarity transformations are used to transform the governing boundary layer equations for momentum, energy and species transfer into a set of non-linear ordinary differential equations which are solved numerically by Keller-box method. The obtained numerical results are validated against results computed by using MATLAB bvp4c routine, and excellent agreement is observed. The impact of various pertinent parameters on velocity, temperature and concentration as well as the friction factor coefficient, local heat and mass transfer rates are derived and discussed through graphs and tables for TiO2 and Al2O3 water-based nanofluids. The present study reveals that an increase in Eckert number (Ec) and heat generation/absorption parameter (Q) significantly decreases local heat transfer rate.

Two-Phase Analysis of A Helical Microchannel Heat Sink Using Nanofluids

A three-dimensional helical microchannel heat sink (HMCHS) model is developed to investigate the heat transfer characteristics using Al2O3–water-based nanofluid. The two-phase mixture model with modified effective thermal conductivity and viscosity equations is employed for solving the problem numerically. The model developed is validated by comparing the results of Nusselt number with available experimental and numerical data for a wide range of Reynolds number. The detailed results of the thermal field are reported for the effects of helix radius (0.15–0.30 mm), pitch (0.5–2.0 mm), number of turns (7–10), and aspect ratio (1.5–3.0). The analysis presents a unique fundamental insight into the complex secondary flow pattern in the channel due to curvature effects.

EFFECT OF SCREEN MESH WICK AND AL2O3 NANOFLUID CONCENTRATION ON CIRCULAR HEAT PIPE PERFORMANCE

ABSTRACTIn this paper the experimental study of the behavior of screen wick and nanofluid toimprove the performance of a circular heat pipe. Pure water and Al2O3-water basednanofluid are used as working fluids. An experimental setup is designed andconstructed to study the heat pipe performance under different operating conditions.The effect of filling ratio, volume fraction of nano-particle in the base fluid, screenmesh as a wick and heat input rate on the thermal resistance is investigated. Totalthermal resistance of the heat pipe for pure water and Al2O3-water based nanofluid isalso predicted. An experimental correlation is obtained to predict the influence ofPrandtl number and dimensionless heat transfer rate, Kq on thermal resistance.Thermal resistance decreases with increasing Al2O3-water based nanofluidcompared to that of pure water. The experimental data is compared to the availabledata from previous work. The range of operating parameter are filling ratio 40% to100%, nanofluid concentration from 0.0% to 2.0%, and heat rate from 8 to 32 watt.The agreement is found to be fairly good.

Effects of Temperature and Particle Size on the Thermal Property Measurements of Al2O3−Water Nanofluids

An experimental investigation was conducted on the effective thermal conductivity and viscosity of Al2O3 water-based nanofluids. The thermal conductivity was determined using the transient hot wire...