Alumina Nanofluids Research Articles

On the magnetohydrodynamic natural convective alumina nanofluidic transport inside a triangular enclosure fitted with fins

Natural convective transport inside a triangular enclosure is introduced in several engineering, industrial, and technological applications including wideband antenna designing, solar power, electronic cooling devices, attic designing, coatings, etc. Fins are well appreciated in various engineering applications starting from electric transformers, gas turbines, heat exchangers, semiconductor devices, automobile radiators, air-cooled engines, hydrogen fuel cells, etc. Nanofluids do have superior heat transport capabilities due to their improved thermal conductivity compared to other conventional coolants. With such motivation, this investigation explores the magnetized alumina nanofluid flow enclosed within the triangular cavity and circular cylinder. The inner hot cylinder includes several rectangular fins having different lengths. The inclined walls are kept cold, whereas the lower surface is uniformly heated. Accurate similarity variables are employed to renovate the dimensional flow profiles into their non-dimensional form. Later, those leading dimensionless equations interact with Galerkin finite element scheme to acquire the desired solutions. The present model is verified with existing literature followed by grid test, comparison test, and experimental work. The whole investigation enlightens how different lengths of the fins affect the hydrothermal behavior inside the enclosure. For this purpose, various velocities, streamlines, isotherms, Nusselt number plots are presented for the flow factors like Rayleigh number (104≤Ra≤106), Hartmann number (0≤Ha≤60), and nanoparticle concentrations (0.00≤φ≤0.04). The investigation reveals that velocities, temperature, isotherms are increased for AR=0.4, while such effects are comparatively lower for AR=1.2. Heat transport is enhanced for nanoparticle concentration and Rayleigh numbers, but numerically high heat transport magnitude is perceived for AR=0.4.

A semi-analytical passive strategy to examine a magnetized heterogeneous mixture having sodium alginate liquid with alumina and copper nanomaterials near a convectively heated surface of a stretching curved geometry

In this article, the authors have analyzed a steady and incompressible two-dimensional flow of sodium alginate (SA)-based viscous ternary nanofluid including copper and alumina nanoparticles near a stretchable curved surface. A uniform magnetic field is exerted on the nanofluid flow along the radial direction. Furthermore, an appropriate convective heating process and zero wall mass flux are adopted in this study as boundary conditions. The chemical reaction, variable internal heating, thermophoresis, Brownian motion, and Arrhenius activation energy impacts are assumed. A robust semi-analytical method abbreviated as HAM (i.e., homotopy analysis method) is chosen in this analysis to get accurate solutions for the modeled problem. Additionally, HAM results are compared extensively with an outstanding tabular/graphical agreement and consistency. The impressions of the embedded factors on the velocity profile, the temperature variation, the concentration distribution, the skin friction factor, and Nusselt's number of sodium alginate-based copper nanofluid, alumina nanofluid, and copper-alumina hybrid nanofluid are deliberated comprehensively. The results showed that the velocity distribution of SA-based nanofluid and hybrid nanofluid decreases as the nanoparticles' volume fraction and magnetic factor increase, whereas the temperature distribution of SA-based nanofluid and hybrid nanofluid improves as the nanoparticles' volume fraction escalates. The rising solid volume fraction and magnetic factor increase the strength of the surface drag force of SA-based copper nanofluid and alumina nanofluid. The increasing nanoparticles' volume fraction and internal heat source parameter upsurge the heat transfer rate of SA-based copper nanofluid and alumina nanofluid. It is also revealed that the hybrid nanofluid is highly affected by the involved physical factors as compared to the case of monotype nanofluids.

Impact of Irregular Heat Sink/Source on the Wall Jet Flow and Heat Transfer in a Porous Medium Induced by a Nanofluid with Slip and Buoyancy Effects

In many industries, extremely high-performance cooling is a crucial requirement. However, the fundamental challenge to developing energy-efficient heat transfer fluids required for cooling is insufficient thermal conductivity. In this case, the utilization of nanofluid is effective to overcome these challenges. The current study aims to examine the two-dimensional (2D) stretching wall jet heat transfer fluid flow induced by a water-based alumina nanofluid embedded in a porous medium with buoyancy force. In addition, irregular heat sink/source and slip effects are assessed. The leading partial differential equations are changed into ordinary differential equations by incorporating similarity variables, then these equations are computationally or numerically worked out via the boundary-value problem of fourth-order (bvp4c) technique. The pertinent factors influencing the symmetry of the hydrothermal performance including friction factor, velocity, and temperature profiles, are illustrated using tables and graphs. The symmetrical outcomes reveal that the velocity declines in the presence of nanoparticles, whereas the temperature uplifts both assisting and opposing flows. Moreover, the friction factor augments due to porosity while the heat transfer rate declines.

A forced convection of water aluminum oxide nanofluid flow and heat transfer study for a three dimensional annular with inner rotated cylinder

The article examines a water alumina nanofluid and heat transfer through the three-dimensional annular. The annular is constructed by the two concentric cylinders in which the inner cylinder can rotate along the tangential direction at a constant speed. A slip boundary condition will be imposed to vanish the viscous effect in the vicinity of the outer cylinder wall. Moreover, the rotating cylinder is kept at a hot temperature, and the outer one is at a cold temperature. A three-dimensional incompressible Navier Stokes and energy equations were carried in cylindrical coordinates. The simulation was observed using the emerging computational tool of COMSOL Multiphysics 5.6, which implements Least Square Galerkin's scheme of finite element method. The parametric study will be done by altering the speed of rotation of the inner cylinder from 1 to 4, volume fraction from 0.001 to 0.9, and the aspect ratio from 0.4 to 0.6 for a fixed Reynolds number of 35,000. The results will be displayed with graphs and tables for average values of the Nusselt number, the percentage change in the temperature, and the skin friction at the middle plan. It was found that the average Nusselt number at the middle of the annular increases before the volume fraction of 0.2 and then decreases for all values of the volume fraction for a fixed rotation of the inner cylinder. The average percentage change relative to the inner cylinder's hot temperature decreases with the volume fraction increase for the fixed rotation. Also, it was found that the quantity of nanoparticles in the domain is improving the average skin friction in the middle of the channel, and it can be reduced by improving the rotation of the inner cylinder by about 10–23% strictly depending upon the aspect ratio for a particular case.

Manyetik Alan Altinda Nanoakişkanlarin Akiş Karakteristiklerinin İncelenmesi

The existence/application of an externally induced magnetic field, like in satellite cooling applications, causes a decrement in heat transfer when used with nanofluids. This study investigates the flow characteristics and velocity profile of distilled water, alumina nanofluid, and cobalt ferrite ferrofluid in a horizontal cylindrical heat pipe flowing in a laminar regime and being exposed to an external magnetic field. All of the simulations were performed with ANSYS Fluent MHD module, for a concentration of 2%, Reynolds number of 10, and Hartmann numbers of 25, 50, and 150. The velocity profiles, pressure drops, and flow characteristics are examined by varying the magnetic field intensity while keeping all other parameters constant. It is concluded that an external magnetic field causes a deterioration in the velocity profiles of the nanofluid, especially in cobalt ferrite, while it does not have a significant effect on water. When the magnitude of the magnetic field is increased by 2 times, it is seen that the velocity of the fluid decreases by 6% and increasing the magnetic field from 0 to 50 Tesla causes a deceleration rate of 9%, which leads to the conclusion that application of a magnetic field for the first time has a more significant slowing effect when comparing it to increasing the magnetic field. In addition, when a magnetic field of 50 Tesla is considered, the maximum velocity of alumina is lower than that of water by 5.10%, and the maximum velocity of cobalt ferrite is lower by 28.57%.

Thermophysical analysis of Al2O3/CuO nanofluid in water/EG basefluid for hybrid louvered heat exchanger

In this research, main objective is to study the effect of heat transfer in a hybrid radiator (wavy and rectangular louvered) tube on the thermophysical properties of Aluminium oxide and copper oxide-based nanofluids. ANSYS Fluent has been used in the simulation and the SST-K-ε model is used since the flow condition is turbulent. The study presents a thorough comparison in physical properties of nanofluids with variable volume concentrations between 0.05 and 0.30 per cent. An increase in Nusselt number of 174% was established with CuO-based nanofluid compared to a 162% increase with Al2O3-based nanofluid. For a CuO-based nanofluid at a volume concentration of 3% and a mass flow rate of 6 l/min, convective heat transfer of 37021.41 W/mK is recorded, a 142% increase over the base fluid. Increasing mass flow and volume concentration reduces the friction factor. As volume concentration increases, heat transfer capacity increases and reaches a maximum of 8.93% higher than base fluid at a flow rate of 6 l/min.

MHD mixed convective stagnation point flow of nanofluid past a permeable stretching sheet with nanoparticles aggregation and thermal stratification

Using a thermally stratified water-based nanofluid and a permeable stretching sheet as a simulation environment, this research examines the impact of nanoparticle aggregation on MHD mixed convective stagnation point flow. Nanoparticle aggregation is studied using two modified models: the Krieger–Dougherty and the Maxwell–Bruggeman. The present problem's governing equations were transformed into a solvable mathematical model utilizing legitimate similarity transformations, and numerical solutions were then achieved using shooting with Runge–Kutta Fehlberg (RKF) technique in Mathematica. Equilibrium point flow toward permeable stretching surface is important for the extrusion process because it produces required heat and mass transfer patterns and identifies and clarifies fragmented flow phenomena using diagrams. Nanoparticle volume fraction was shown to have an impact on the solutions' existence range, as well. Alumina and copper nanofluids have better heat transfer properties than regular fluids. The skin friction coefficients and Nusselt number, velocity, temperature profiles for many values of the different parameters were obtained. In addition, the solutions were shown in graphs and tables, and they were explained in detail. A comparison of the current study's results with previous results for a specific instance is undertaken to verify the findings, and excellent agreement between them is observed.

Al2O3–H2O nanofluids for cooling PEM fuel cells: A critical assessment

Polymer electrolyte membrane (PEM) fuel cells are promising eco-friendly and sustainable power generation technology. Thermal management of these cells is one of the main challenges facing their commercialization. Alumina nanofluids, in addition to others, have been proposed to overcome excess heat generated within the PEM fuel cell stacks. However, most the previous studies investigated the hydrothermal performance of the nanofluids as a function of Reynolds number (Re). It is evident that all parameters must be kept constants except one to examine its effect on the performance. To this end, choosing Re as a parameter (independent variable) is problematic as it is a function not only of nanofluid's velocity, but also its density and viscosity. In this study, a well-validated CFD model has been built to simulate the hydrothermal performance of alumina nanofluids of different volumetric concentrations (0%, 0.05%, 0.1% and 0.2%) as functions of Re (170 < Re < 530), flow rate (20 ml/min ≤ Vf ≤ 50 ml/min), and pumping power (0.025 mW < Pp < 0.3 mW). This study shows a maximum reduction of 7.9% in the thermal effectiveness and a maximum increase of 6% in the pumping power when using the nanofluids instead of water. This deterioration in the hydrothermal performance is due to the reduction in the effective specific heat capacity and increase in viscosity of the nanofluids. Also, it is concluded that it is incorrect to use Re as an independent variable in analysing the hydrothermal performance of nanofluids because of the dependency of Re on some of the thermophysical properties of the nanofluids, which are functions of the concentration. Adopting such analysing procedure leads to false conclusions.

Performance and exergy analysis of solar-operated vacuum fan and external condenser integrated double-slope solar still using various nanofluids.

Productivity, distillate exergy, and energy efficiency of the conventional passive single-basin double-slope solar still is minimum, due to low evaporation and condensation rate. This research article attempts to increase the production rate, distillate exergy, and energy efficiency of the single-basin glasswool-insulated double-slope solar still by attaching novel solar-operated vacuum fan, external condenser and adding 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid. Inclusion of vacuum fan and external condenser enhances the production rate in the modified solar still. It is evident that as the vacuum fan exhales the vapour in the basin, the temperature of water in the basin and transparent glass are reduced significantly and so the vaporization amount increases considerably. It makes that a large amount of vapour is extracted by the vacuum fan and allowed to pass though the condenser, and therefore, the entire condensate of the solar still is increased significantly. To attain a comparative study, conventional and modified double-slope solar still of identical dimensions were developed utilizing aluminium and an experimental investigation carried out during the peak of summer. The inclusion of solar-operated vacuum fan and external condenser in the modified glasswool insulated double-slope solar still enhances the maximum energy efficiency, exergy efficiency, and cumulative production by 28.37%, 78.60%, and 64.29% due to enhancement in the evaporation rate of liquid in the solar still basin. Also, the addition of 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid in the conventional double-slope solar still possess the maximum increase in the energy efficiency and exergy efficiency by 20.96%, 18.01%, 10.76% and 52.53%, 38.52%, 30.35% as compared to conventional solar still without nanofluid. It is primarily due to increase in the thermal conductivity and radiative property of nanofluid. The result also signifies that the addition of 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid in the modified double-slope solar still possess the maximum enhancement in the energy efficiency and exergy efficiency by 21.33%, 19.36%, 17.03% and 50.11%, 36.82%, 23.75% as compared to modified solar still without nanofluid. Combined effect of using solar-operated vacuum fan, water cooled condenser, and 0.1% volume concentration of copper oxide, aluminium oxide, and zinc oxide nanofluid in the double-slope solar still enhances the maximum production rate and cumulative production by 59.26%, 55.56%, 51.85% and 96.43%, 82.14%, 75% as compared to conventional double-slope solar still. Among the three different nanofluids, the copper oxide nanofluid produced the highest cumulative production, energy efficiency, and exergy efficiency.

The Forced Convection Analysis of Water Alumina Nanofluid Flow through a 3D Annulus with Rotating Cylinders via κ−ε Turbulence Model

We investigated the dynamics of nanofluid and heat transfer in a three-dimensional circular annular using the κ−ε turbulence model and energy equations. The pipe contained two concentric and rotating cylinders with a constant speed in the tangential direction. A heat flux boundary condition was executed at the inner cylinder of the annular. The pipe was settled vertically, and water alumina nanofluid was allowed to enter, with the initial velocity depending on the Reynolds number, ranging from 30,000 to 60,000. The volume fraction of the solid particles was tested from 0.001 to 0.1. The speed of the rotation of the cylinders was tested in the range from 0.5 to 3.5. The simulations were developed using COMSOL Multiphysics 5.6, adopting the finite element procedure for governing equations. The results were validated using the mesh independent study and the average Nusselt number correlations. We found that the average Nusselt number in the middle of the channel decreases linearly with the increase in the volume fraction of the water alumina nanofluid. The novelty of the present work is that various correlations between the average Nusselt number and volume fraction were determined by fixing the Reynolds number and the rotation of the inner cylinder. We also found that fixing the Reynolds number and the volume fraction improves the average Nusselt number at the outlet linearly. In addition, it was stated that the increase in the total mass of the nanofluid would decrease the average temperature at the outer cylinder of the annular. Moreover, the maximum average improvement percentage in the average Nusselt number, which is about 21%, was observed when the inner cylinder rotation was changed from 1.5 to 2.5 m/s.

High Speed Grinding of EN31 Steel with Alumina Nanofluid Coolant

Grinding is a choice for obtaining high surface quality and closer dimensional tolerance. For meeting this objective economically, the material removal rate (MRR) must be sacrificed to certain extent. The MRR could be increased by either increase in wheel speed, depth of cut, and feed rate. An increase in MRR increases the surface temperature leading to thermal defects on surfaces. Improving the MRR without compromising the surface quality is a challenging objective. Many investigations are progressing for machining various materials under different cooling environments to meet such challenges. This experimental novel aim is to investigate the performance of Al2O3 nanofluid in high-speed grinding of EN31 steel under flood cooling method for reduction of surface roughness and cutting zone temperature. Taguchi’s full factorial design was employed for experimental investigation. The factors such as feed, depth of cut and cutting fluid environment were considered for analysing the responses of cutting zone temperature and surface roughness. The thermal analysis on the work piece was carried out with experimental values by the finite element analysis method. The nanofluids outperform in terms of reduction of surface roughness and downsizing cutting zone temperature. The proposed nanofluid-based grinding significantly reduced the surface roughness and cutting zone temperature.

Thermal management of power electronics using nanofluids and nucleate boiling heat transfer technique

Nucleate boiling is an efficient solution for thermal management of power electronics where high-intensity heat flux needs to be transferred in a compact space. Both micro surfaces and nanofluids are used in literature to enhance the performance of nucleate pool boiling heat transfer systems; however, the effect of nanofluids over the microporous surface still needs to explore in several phase change heat transfer applications. The study’s objective is to examine the performance of nanofluid over microporous surfaces in Nucleate Boiling Heat transfer (NBHT) and performs a comparative analysis with plain and micro-porous surfaces. The study analyzed three ceramic (Alumina) nanofluids for nucleate pool boiling heat transfer (NBHT) over plain and microporous surfaces. The literature reported enhanced performance of nanofluids over the plane surface is verified in the study before proceeding to the detailed analysis over the microporous surface. Three different concentrations of 0.005%, 0.0005%, and 0.00005% were tested for the nanofluid. For plane surface, the critical heat flux (CHF) has been increased to 1035 [kW/m2] for Alumina from 783 [kW/m2] for deionized water, with the average increase in heat transfer coefficient (HTC) being 46.5%. The maximum CHF has been reported for micro-porous surfaces with a value of 1110 kW/m2. Out of the tested surfaces and fluids combination, the micro-porous surfaces with deionized water have been concluded as the most efficient surface with the highest heat transfer capacity for thermal management of high-power electronics and other high heat flux applications.

Analytical study of fluid flow and thermal characteristics of flow in micro channel heat sinks with working fluid as water and alumina & water nanofluid

The electronic industry is looking at microchannel based MEMS technology to resolve the issue of increasing heat dissipation from electronic circuits. Micro-channels play an important role in development of small scale fluid flow devices. The internal flow configuration represents a convenient geometry for heat transfer between fluids used in chemical processing, environmental control, and energy conversion technologies. In order to fabricate such micro devices effectively, it is extremely important to understand the fundamental mechanisms involved in fluid flow and heat transfer characteristics in microchannels. This paper presents an analytical study of flow mechanism in microchannels, with a focus on effect of geometric dimensions and flow rate on the various flow parameters of a Rectangular microchannel. An attempt is also made to determine optimum microchannel dimensions based on the analysis. Basic flow equations are used for modelling the flow and determining various parameters. Further, the study analyses the effect of using Alumina & Water nanofluid on flow and thermal characteristics as compared to using water alone. The results observed show a deeper and wider microchannel would keep the pressure drop across the microchannel lower. Also using nanofluid as working fluid would result in lower pressure drop.

A novel nanofluid cooling system for modular lithium-ion battery thermal management based on wavy/stair channels

An innovative liquid cooling system that contains stair and wavy channels by alumina nanofluid with copper sheath is numerically analyzed to improve the battery thermal management system's temperature distribution and cooling capacity during discharge/charge processes. The effects of the charge/discharge current rate, alumina nanofluid coolant, inflow velocity, ambient/fluid inflow temperature, stair channel, interfacing regions between adjacent LIBs, and the contact regions between LIBs and wavy channel shell on the thermal efficiency of the battery module was investigated. Based on the outcomes, it is concluded that the addition of coolant alumina nanofluid with a 2% volume fraction notably reduces the highest temperature and temperature non-uniformity across the battery module. Simulation results illustrated that by using a 2% volume fraction of Alumina nanofluid, the peak temperature and temperature difference for the discharge process decreased 1.2 °C and 0.4 °C, compared to DI water, respectively. In addition, increasing the coolant inlet velocity led to a decrease in maximum temperature and temperature difference. Different ambient/fluid inflow temperatures of the battery module are evaluated to simulate different weather climates. An innovative design using the stair channel cooling is finally developed for the LIB thermal management system. Comparing the two stair and straight channels, it is accomplished that the temperature non-uniformity for the stair-type channel is almost reduced by 0.19 °C and 0.22 °C for the discharge and charge processes, respectively.

Optimization the performance of photovoltaic panels using aluminum-oxide nanofluid as cooling fluid at different concentrations and one-pass flow system

The photovoltaic panel's efficiency will drop when the surface temperature rises, that will also have an adverse effect on the panel's performance and lifespan. Therefore, the cooling of the photovoltaic panel will increase the electrical efficiency. In this experimental study, monocrystalline solar panels are cooled using water or aluminum-oxide nanofluid at various concentrations (1 wt %, 2 wt %, and 3 wt %). The experiments were conducted at different flow rates of cooling fluid ranging from (0.8–1.6) L/min. The results are compared to the photovoltaic panel that was used without cooling. The most significant decrease in photovoltaic surface temperature was achieved using a nanofluid at a concentration of 3 wt%. In comparison to an uncooled panel, the surface temperature at this concentration decreased by 23.14%. For the same nanofluid concentration of 3 wt%, the panel efficiency increased to 20.2% in turbulent flow as compared to 15% in laminar flow. The greatest increase in output power was also seen with nanofluid at a 3 wt% concentration. At cooling by nanofluid with this concentration, the output power improved by 13% as compared to uncooled panel. The greatest increase in cooling fluid temperature was produced by the use of turbulent flow of nanofluid with a concentration of 3 wt%. This temperature rise was 9.9 ° C for the same concentration of turbulent flow as compared to 7.9 ° C for laminar flow. Nanofluids, on the other hand, will be extremely effective at storing and using the heat extracted from a thermal Photovoltaic as passive energy, which may be used for a variety of purposes.

Numerical Analysis of Pool Boiling of Nanofluids for High Heat Dissipation Applications

Thermal management using nanofluids has gained popularity in recent times owing to their superior thermophysical properties enabling higher heat dissipation levels in electronic components. Boiling process or latent heat component greatly enhances the heat transfer and considering the complexity of boiling phenomenon and the high cost of nanofluids, there is an excellent scope for numerical studies in this area. In the present study, an Eulerian multiphase model is developed to ascertain the pool boiling characteristics of Alumina nanofluid at atmospheric pressure using a flat plate heater. The previous experimental study conducted by the authors is used as a reference and for validation of the numerical model. The pool boiling curves for 0.5%, 1%, and 2% Alumina nanofluids with water as base fluid are obtained through numerical simulations employing the heat flux partitioning (HFP) model. A significant enhancement in the pool boiling heat flux is reported and compared with the available literature on alumina nanofluids. The theoretical correlations for nucleate pool boiling, namely, the Rohsenow correlation and the Kandlikar correlation, were found to under-predict heat flux compared to numerical results. The significance of critical heat flux (CHF), or the onset of boiling crisis in pool boiling, is detailed and a methodology for numerically determining the same is developed. The CHF enhancement of up to 120% over the base fluid reported in the present study is found to be consistent with the experimental results.

Novel usage of the curved rectangular fin on the heat transfer of a double-pipe heat exchanger with a nanofluid

The convection heat transfer in a countercurrent double-tube heat exchanger with various fins in a turbulent flow is investigated. The suitable heating or cooling process of fluids is the effective use of the double-pipe heat exchanger. We use water-aluminum oxide nanofluid and water-titanium dioxide at four concentrations (0.4%, 2%, 4%, 6%) as the cold fluid in the inner tube and water as the hot fluid in the annular space. The single-phase model for nanofluid modeling and the standard k-ε model with scalable wall function for simulating the turbulent flow is utilized. To better examine this novel geometry, its performance is compared with simple and rectangular-finned geometries. The results show that the water aluminum oxide nanofluid has a better convection heat transfer coefficient than water titanium dioxide and pure water. Raising the nanofluid concentration from 0.4% to 6% increases the convection heat transfer coefficient by 12%. Heat exchangers with a rectangular and curved fin have 81% and 85% better efficiency than the heat exchanger without a fin. The novel geometry causes a smaller pressure drop despite its higher convection heat transfer coefficient. Also, it is shown that with raising the Reynolds number and nanofluid concentration, the pressure drop increases.

Applicability of Nanoparticle Flooding Process in a Carbonate Rock of Kurdistan Region: Experimental Investigation of Interfacial Tension and Wettability

Enhanced oil recovery (EOR) has long proven to be a good method to mobilize the residual oil that is by passed and capillary trapped by secondary recovery methods. Chemical EOR methods enhance the microscopic and macroscopic efficiency, and ultimately the overall oil recovery is improved. However, the adsorption rate of the surfactant, low resistance to high temperature and salinity are some of the factors that would turn chemical flooding impractical and uneconomic in many cases. Lately, the application of nanotechnology in enhanced oil recovery has showcased some good and prolific results in terms of incremental oil recovery. In this study, the applicability of Nanoparticle flooding in carbonate rocks of Pilaspi formation was probed through a series of tests such as thin section analysis, x-ray diffraction, x-ray fluorescence, interfacial tension and contact angle measurements. The results showed that the composition of the carbonate rocks is predominantly calcite (CaCO3) with minor traces of quartz and dolomite. From the interfacial tension (IFT) measurements, it was figured out that the silica and alumina Nanofluids lowered the IFT by 27% and 42% with the light oil, and 43% and 49% with the heavy oil, respectively. The contact angle measurements revealed that the Alumina Nano-fluid at 0.25 wt. % reduced the contact angle on the surface of the light and heavy oil aged thin sections from 169◦ and 115◦ to nearly 119◦ and 78◦. On the other hand, the silica nanoparticle at 0.25 wt. % reduced the contact angles on both thin section types to around 129◦ and 80◦, respectively.

Preliminary CFD investigation for secondary coolant in molten salt reactor with alumina nanofluid considering FLiBe and FLiNaK as base fluid through a double pipe heat exchanger

This work analyzes a computational fluid dynamics (CFD) methodology based on ANSYS to investigate the 3 % and 4 % volume fraction alumina (Al2O3) nanofluids with base fluids FLiBe (LiF(67)-BeF2(33) (mol%)) and FLiNaK (LiF(46.5)-NaF(11.5)-KF(42) (mol%) through a double pipe heat exchanger. The purpose of the paper is to choose better candidates as secondary coolants in molten salt reactors for better thermodynamics performances and heat transfer characteristics. Six secondary coolants with and without nanofluids and fuel salt as primary coolants are driven through the inner and outer pipe. Later overall heat transfer coefficient, outlet temperatures and pressure drops of the fluids, and LMTD are calculated. Thus, this work eventually recommends the best candidate as a secondary coolant by CFD methodology using ANSYS-FLUENT 18.1. J. Bangladesh Acad. Sci. 46(1); 45-55: June 2022

Numerical investigation of heat transfer in helical tubes modified with aluminum oxide nanofluid and modeling of data obtained by artificial neural network

The purpose of this study is to investigate the computational fluid dynamics to find the effects of Reynolds number, different volume fractions of aluminum oxide nanofluid and different heat fluxes in heat transfer performance (Nusselt number) in a helical tube. This simulation was investigated at Reynolds number range 2000 and 10,000 and volumetric fraction range 1% and 4% of aluminum oxide nanofluid and constant heat fluxes of 4000–6000 W/m2. The single-phase model was used to model the nanofluid and the feasible k-ε model was used to simulate the turbulent flow. Then, perceptron artificial neural networks with the Levenberg–Marquardt algorithm were used to predict the Nusselt number such that input parameters include Reynolds number, nanoparticle volume fraction and output or target was considered Nusselt number for the network. The results show that with increasing the volume fraction of aluminum oxide nanofluid and Reynolds number, the Nusselt number increases by about 20.35%. Also, by increasing the constant heat flux from 4000–6000 W/m2, the Nusselt number increases by 18.75%. The results of the artificial neural network show that the topology 2-10-1 is very successful in predicting the Nusselt number so that the minimum mean squared error for the data allocated to the training and validation sections were 0.024449627 and 0.117025052, respectively, which are obtained under optimal epochs 19 and 9. The value of the correlation coefficient obtained in predicting the Nusselt number is 0.944416302.