Titania Nanofluids Research Articles

Particle swarm optimization based numerical study for pressure, flow, and heat transfer over a rotating disk with temperature dependent nanofluid properties

In the era of nanotechnology and advanced manufacturing, many industrial applications involve the flow control over the rotating disk. Rotating machineries, computer storage devices, dynamic filtration processes, gas turbine engines, bio inspired electro-catalysis processes are a few of them. Considering the wide applications of flow over rotating permeable disks, this paper presents the investigation of flow, temperature and pressure characteristics of water-based titanium oxide nanofluid with temperature dependent properties. The quadratic Boussinesq approximation is considered to incorporate the density variations due to temperature change. The numerical computation is carried out using metaheuristic based hybrid shooting technique. Temperature dependent dynamic viscosity and thermal conductivity models for nanofluid are considered and the numerical results for velocity components, pressure and temperature distributions are investigated. The investigation unveiled reduction in skin friction and heat transfer rate with increasing value of quadratic convection parameter. The suction parameter is found to be very significant in terms of increasing heat transfer rates. An 80% increase in local Nusselt number is observed for a small change in suction parameter from −1 to −1.5.

Improving the cooling performance of photovoltaic panels by using two passes circulation of titanium dioxide nanofluid

The major goal of this study is to achieve the cooling effect of a photovoltaic panel by employing titanium dioxide nanofluid as a cooling fluid in two passes circulation to lower the panel surface temperature, improve the performance of the photovoltaic/thermal system, and increase efficiency. Photovoltaic technology is constantly losing efficiency due to the high temperature of the PV panel's upper surface, which results in lower output power and lower overall efficiency. Five photovoltaics panels were utilized in this investigation to compare the three concentrations of Titanium Oxide nanofluid (1 wt%,2 wt%,3 wt%), as well as cooling by water and an uncooled penal. The output powers were (44.5, 44, 43.2, 42.6, and 39.5 W) when the three concentrations of Titanium Oxide nanofluid (3 wt%, 2 wt%, and 1 wt%) were used, then water cooled and uncooled, respectively. Cooling by nanofluid at concentration (3 wt%) had the highest efficiency (19.23%). Depending on the concentrations, there is a variation in temperature between the cooling fluids' output and inlet. For the three concentrations of Titanium Oxide nanofluid (3 wt%, 2 wt%, and 1 wt%), and water, the results were (7.3, 7.8, 8.3, 8.6 °C). When the surface temperatures of the solar panels were compared to the uncooled photovoltaic panels, it was discovered that the cooling system reduced the surface temperatures by 19.0%. All of the results were obtained at 30° tilt angles with fluid rotating in two passes. The high concentration of nanofluids produced the best results, resulting in a benefit of greater heat extraction.

Experimental studies of different operating parameters on the photovoltaic thermal system using a flattened geometrical structure.

The efficiency of the photovoltaic (PV) cell reduces with an increase in solar irradiation. The reduction in the efficiency of the photovoltaic (PV) cell can be attributed to the increase in cell temperature. A novel design of a thermal absorber fabricated by a flat spiral tube is used to remove heat and decrease the cell temperature, thus forming the photovoltaic thermal system (PVTS). Water and titanium oxide (TiO2) nanofluid (NF) with a concentration ratio of 0.1% are used as the working fluid in the PVTS. The study has been carried out for the mass flow rates (mf) of 0.05, 0.066, and 0.083kg/s. The reduction in the cell temperature is obtained to be 5.7 and 11.2°C due to the cooling effect of water and TiO2 NF, respectively. The percentage increase in electrical efficiency is 2.93 and 5.28% by cooling using water and TiO2 NF, respectively. The hourly variation of the performance of the PVTS shows that TiO2 NF at 0.083kg/s shows the highest photovoltaic thermal efficiency of 69.2% and thermal and electrical efficiency of 56.45 and 12.75%, respectively. The best coefficient of energy for TiO2 NF is 1.27 for a mf of 0.083kg/s.

Experimental study of the effect of filled bed type on the performance of a cross-flow cooling tower with the approach of using water-based nanofluids (MWCNTs and TiO2)

This study aimed to experimentally investigate the effects of filled beds on the performance of a cross-flow cooling tower (CFCT) with the approach of using nanofluids. Multi-walled carbon nanotubes (MWCNTs) and titanium dioxide (TiO2) nanofluids and 6 kinds of filled beds in two classes of splashes and films were used. To select the best bed using TiO2/water and MWCNTs/water nanofluids with a concentration of 0.05 wt%, the effect of these beds on the thermal performance of CFCT was evaluated, and the results were compared with each other and with pure water. The effects of nanofluid type and flow ratio (L/G) on CFCT performance factors, including cooling range, effectiveness, Merkel number, and evaporation rate, were investigated. The nanofluids were prepared by the two-step method and gum arabic was used as a surfactant to improve their stability. The results showed that, using nanofluids instead of water as the operating fluid generally improves the thermal performance of CFCT. It was found that the appropriate bed for water and nanofluid was bed 5 and bed 3, respectively. As well as, the use of a suitable filled bed at low flow ratio had a much greater effect on improving the performance of the tower. For example, at the same concentration of MWCNTs/water nanofluid using bed 3, the increase in tower effectiveness compared to pure water was about 28% at L/G=0.4 , while it was only 7% at L/G=2 . In addition, the parameters of cooling range, effectiveness, and Merkel number were increased by 28%, 85%, and 131%, respectively, when bed 3 was used compared to the bedless condition, indicating the importance of a suitable bed when using nanofluids.

Electroosmotically modulated peristaltic propulsion of TiO2/10W40 nanofluid in curved microchannel

The present investigation emphasizes the fluid flow analysis and the heat transfer characteristics of 10 W40-based titanium dioxide nanofluid subject to electroosmotic forces and the peristaltic propulsion in a curved microchannel. The Carreau fluid model is employed to predict the shear-thinning behavior of nanofluid. The effect of Brownian and thermophoretic movements of the nanoparticles and the thermophysical attributes are included in the problem with the modified Buongiorno model. The uniqueness here is the inclusion of variable thermophoretic and diffusion parameters in the Buongiorno model. Moreover, the non-Newtonian fluid model is used with experimentally fitted values of the parameters for the considered fluid. The resulting system of equations is highly nonlinear and coupled and therefore executed numerically through the built-in package in Maple 17. The results of the said investigation indicate that for maintaining a larger temperature difference, buoyancy forces are strengthened and fluid motion is facilitated. However, the magnitude of the Nusselt number drops for the larger temperature difference. It is also revealed that the temperature of the nanofluid drops for a larger curvature parameter which physically corresponds to a less curved channel. Further, the electroosmotic flow parameters have a progressive impact on the velocity and the convective heat transfer process.

Experimental study on spray cooling heat transfer enhancement using MWCNT and TiO2 hybrid nanofluid

In the present study, two nanofluids namely Multi-walled carbon nanotubes and Titanium dioxide dispersed in distilled water, have been used with three different concentrations; 0.1%, 0.2%, and 0.3% by volume, to investigate heat transfer enhancement in spray cooling applications. A square copper specimen of 10 mm2 has been spray cooled with a volumetric flux of 2.5 cm3/cm2s using a 0.4 mm diameter pressure nozzle. The results revealed that the average heat transfer coefficient and corresponding critical heat flux enhanced significantly at 0.2 vol% for both nanofluids in contrast to distilled water. The results showed an improvement of 21.9% and 26.3% in heat transfer coefficient for Multi-walled carbon nanotubes and Titanium dioxide nanofluid, respectively. The effect of hybrid nanofluid in various concentrations has also been investigated on heat transfer performance. The results obtained showed a maximum value of 425 W/cm2 for critical heat flux and 4.42 W/cm2K for heat transfer coefficient, with a heat transfer coefficient improvement of nearly 40.31% in comparison to distilled water. This results in an enhancement ratio of 1.6 for critical heat flux and 1.4 for heat transfer coefficient. In contrast to single nanoparticle nanofluid, the hybrid nanofluid indicated a moderate improvement in heat transfer coefficient of 11.7% and 7.8% for Multi-walled carbon nanotube and Titanium dioxide nanofluids, respectively. It has been observed that heat transfer performance was first enhanced and then declined as the volume fraction increased from 0.1% to 0.3% for all the nanofluids.

Surveying the hybrid of radiation and magnetic parameters on Maxwell liquid with TiO2 nanotube influence of different blades

AbstractIn this paper, the impacts of Maxwell nanoliquid transmission, rectangular with titanium oxide nanoparticles are explored over the triangular, chamfer blades. The innovation of this paper is the use of the number of chamfers, rectangular, and triangular blades at the top and bottom of a stretched plate to study physical nanofluid parameters such as temperature and the effects of magnetism. Also, by determining the appropriate height and length for the blades, we achieve the best optimization of temperature and velocity of nanofluid between the plate and the blades, which improves heat transfer and with a more and better effect of magnetic effects. The finite element method is utilized for the calculated differential equations. In this paper, by utilizing the reaction surface strategy, we optimized the titanium oxide nanofluid velocity and temperature, and magnetic parameter passing from the extending sheet. On average, the titanium oxide nanoparticle velocity around the two rectangular blades at the beginning of the sheet is 73.09% higher than triangular blades and 66.98% higher than chamfer blades. Based on the outcomes got from the titanium oxide nanofluid speed charts and the warm exchange cantors and magnetic impacts within the Design‐Expert computer program, the most excellent optimization occurred for TiO2 nanofluid speed and TiO2 nanofluid temperature and TiO2 magnetic parameter with u = 0.523, T = 3.25, and H = 2.671.

Performance of a PV Module Using Water Based Titanium Oxide Nano Fluid Coated Fins

Performance of a PV Module Using Water Based Titanium Oxide Nano Fluid Coated Fins

Review: Observation on CFD Analysis of ZnO and TiO2 Nanofluid with Oil and Ethylene Glycol in Square and Helical Coil Heat Exchanger

Abstract: Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide the excellent thermal performance in helical coil heat exchangers. Research studies on heat transfer enhancement have gained serious momentum during recent years and have been proposed many techniques by different research groups [1]. A fluid with higher thermal conductivity has been developed to increase the efficiency of heat exchangers. The dispersion of 1-100nm sized solid nanoparticles in the traditional heat transfer fluids, termed as nanofluids, exhibit substantial higher convective heat transfer than that of traditional heat transfer fluids. Nanofluid is a heat transfer fluid which is the combination of nanoparticles and base fluid that can improve the performance of heat exchanger systems. In this present paper the efforts are made to understand that how to compare the heat transfer rate in Copper helically coiled tube and squared coiled tube heat exchanger using Zinc Oxide and Titanium Dioxide Nano fluid by studying research papers of various authors. Keywords: Helical Coil, Nano-fluid, Heat Exchanger, CFD, Pressure Drop, Temperature Distribution.

Augmentation of Heat Transfer in Shell and Coil Type Heat Exchanger Using Nano Fluid

The heat transfer efficiency of most thermal devices can be enhanced by increasing it. Some process sectors, such as power plants and automobiles, require heat transfer enhancement in either heating, cooling, or evaporation on equipment such as air conditioning, radiators, freezers, and condensers. The approaches that are accessible can be divided into two categories: passive and active techniques. The goal of the study was to use passive strategies to improve heat transmission in a twin pipe heat exchanger. Water and titanium dioxide nano-fluid are examples of nanofluid.

Non-Newtonian nanofluids flow analysis at the ingress section in process intensified system

The flow of Bingham nanofluids at the ingress section functioning as non-Newtonian nanofluids in cylindrical concentric rollers have been studied. This analysis could be advantageous for chemical processing industries and thermal processing intensified systems. The silver(Ag), copper(Cu), Aluminum oxide(Al2O3) and Titanium dioxide(TiO2) nanofluids through water adjoining with Bingham fluid, which are refered as Bingham nanofluids with the yield value Bnf = 10. The investigative study had been carried out with the supposition that the cylindrical roller twain are revolving, with two different flow region space K = 0.3 and 0.8, in the selfsame along with the reverse directions including diverse angular velocity. Theoretically, this intensified system can be considered as an aircraft turbojet engine model. The continuity, momentum and energy equations were derived through the finite difference method. These equations were solved to find the pressure along the radial direction and to obtain velocity components such as axial, radial, tangential and thermal conductivity. Numerous non-Newtonian flow parameters, various concentrations with algebraic considerations were computed and results were obtained for the same. The major purpose of the present investigation is to identify the advancement of the velocities, pressure and thermal conductivity in the ingress section of considered processing intensified systems.

Effect of nanoparticle on rheological properties of surfactant-based nanofluid for effective carbon utilization: capturing and storage prospects.

Previous studies have shown insufficient dispersion and thermal stability of nanofluids for high-temperature carbon capture and storage applications. Compared to the other NPs, TiO2 nanofluids exhibit superior stability due to their high zeta potential. In previous studies, TiO2 nanofluids have shown superior performance in heat transfer and cooling applications along with importing the stability of other nanofluids like SiO2 in form of nanocomposites. Therefore, in this study, a nanofluid formulation consisting of titania nanofluid in a base solution of ethylene glycol (EG) with different co-stabilizers such as surfactants was synthesized for better dispersion stability, enhanced electrical, and rheological properties especially for the use in high-temperature industrial applications which include carbon capture and storage along with enhanced oil recovery. The formulated nanofluid was investigated for stability using dynamic light scattering (DLS) study and electrical conductivity. Additionally, the formulated nanofluid was also examined for thermal stability at high temperatures using an electrical conductivity study followed by rheological measurements at 30 and 90 °C. At a high temperature, the shear-thinning behavior of EG was found highly affected by shear rate; however, this deformation was controlled using TiO2 nanoparticles (NPs). Furthermore, the role of surfactant was also investigated on dispersion stability, electrical conductivity followed by viscosity results, and it was found that the nanofluid is superior in presence of anionic surfactant sodium dodecyl sulfate (SDS) as compared to nonionic surfactant Triton X-100 (TX-100). The inclusion of ionic surfactant provides a charged layer of micelles surrounding the core of a NP and it produced additional surface potential. Consequently, it increases the repulsive force between two adjacent NPs and renders a greater stability to nanofluid while nonionic surfactant allowed monomers to adsorb on the surface of NP via hydrophobic interaction and enhances the short-range interparticle repulsion, to stabilize nanofluid. This makes titania nanofluid suitable for widespread high-temperature applications where conventional nanofluids face limitations. Finally, the application of the synthesized titania nanofluids was explored for the capture and transport of CO2 where the inclusion of the anionic surfactant was found to increase the CO2 capturing ability of titania nanofluids by 140-220% (over the conventional nanofluid) while also showing superior retention at both investigated temperatures. Thus, the study promotes the role of novel surfactant-treated titania nanofluids for carbon removal and storage and recommends their applications involving carbonated fluid injection (CFI) to carbon utilization in oilfield applications.

Efficient degradation of tetracycline by RGO@black titanium dioxide nanofluid via enhanced catalysis and photothermal conversion

The applications of photocatalytic pollutant degradation have remained limited due to the low efficiency of solar energy utilization. In this study, a photothermal catalyst consisting of reduced graphene oxide @ black TiO2 (RGO@BT) nanofluid with effective full-spectrum (from ultraviolet to infrared light) absorption was synthesized by a typical two-step method of high temperature calcination and hydrothermal method. Moreover, the photothermal catalytic performance of the RGO@BT nanofluid on tetracycline was verified. Compared with individual processes (i.e, photocatalysis and thermocatalysis), the photothermal catalytic process significantly enhanced tetracycline degradation under simulated global standard spectrum sunlight (AM 1.5G, 1000 W m−2). The maximum photothermal conversion efficiency reached 91.8%, which resulted in 94.7% tetracycline degradation (40 mg L−1) after 120 min of treatment with 200 mg L−1 RGO@BT nanofluid. Holes, OH, and O2− were found to be the main active species during the photothermal catalytic process. Moreover, heat was spontaneously converted from light energy without the use of any external energy source. The elevated system temperature facilitated the tetracycline degradation based on the Arrhenius behavior. These findings provide insights into the improvement of photocatalytic efficiency in organic contaminant degradation via solar energy-efficient photothermal conversion materials.

Effects of temperature and concentration on thermophysical properties of TiO2-MWCNTs-doped graphene nanofluids

This paper presents to investigate the effects of temperature and concentration on thermophysical properties of titanium dioxide (TiO2) nanofluids containing multi-walled carbon nanotubes (MWCNTs)-doped graphene. In this present study, the ethylene glycol-based hybrids TiO2-MWCNTs and MWCNTs-doped 10 wt per cent graphene nanofluids were prepared five concentrations (0.02 to 0.10 per cent) using a two-step, direct-mixing methods. The effect of the temperature, concentration and type of nanofluid and its interaction with TiO2-MWCNTs and MWCNTs' thermal conductivity and viscosity has been studied using a central composite design technique. The significance of the analytical, statistical model being developed is validated using variance analysis. Twenty-four experiments were conducted to develop second-order polynomial equations for target outputs. Based on the results obtained, the predicted values were insensible in agreement with the experimental data. More than 85 per cent of thermal conductivity and viscosity variations of nanofluids can be predicted by models that convey the applied model’s precision. The expected optimised value shown in the optimisation plot is 0.6035 W/°C for thermal conductivity and 14.673 mPa/s for viscosity. The desirable parameters such as temperature, concentration and nanofluid type are 30 °C, 0.06 per cent and TiO2-MWCNT, respectively. The validation with the experimental result indicates that the model can reasonably predict the optimal experimental conditions. Viscosity decreases due to an increase in temperature and concentration. It demonstrates the effect of concentration and temperature on viscosity.

Pengaruh Penambahan Surfaktan Gum Arabic Terhadap Sifat Fisik dan Stabilitas Fluida Nano Titania (TiO2)

This study aims to examine the physical properties of titania (TiO2) by adding arabic gum surfactants to obtain stable nanofluid. Nano titania fluid preparation was carried out by dispersing titania nanoparticles and arabic gum in a homogenizer for 3 hours with particle variations in fraction volume and arabic gum surfactant concentration. The study was carried out by varying the volume of the particle fraction at 0.1%; 0.2%; 0.3%; 0.4% and 0.5% and arabic gum surfactant concentrations at 1%; 2%; 3%; 4%; and 5%. Measurements are also made at a temperature variation of 30 OC; 40 OC; and 50 OC. Measurement of physical properties is carried out by measuring the properties of electrical conductivity, density, viscosity, and stability of titania nanofluid. The measurement results indicate that the higher the concentration of surfactant and the volume fraction of particles, the electrical conductivity, density, and viscosity of nano titania fluid is increasing. Increased temperature will reduce the viscosity of titania nanofluid.

Heat‐transfer and hydrodynamic performance investigation of graphene‐titanium dioxide composite nanofluid in micro‐heat exchangers

AbstractNanofluids have made a breakthrough contribution toward maximizing the efficiency of heat exchangers. Consequently, graphene nanofluids have attracted significant attention, as they yield the best heat‐transfer enhancement among all nanofluids; however, graphene is highly expensive, and further studies on hybrid graphene nanofluids are required to optimize costs. Research has been performed on the performance of pure graphene nanofluids, though little has been conducted on hybrid graphene nanofluids. Therefore, we investigated the hydrodynamic and convective heat‐transfer performance of graphene‐titanium dioxide composite (GTNC) nanofluid in a micro‐heat exchanger, and compared the results with the performance of pure graphene and pure titanium dioxide nanofluids under similar conditions. Herein, we report the synthesis of GTNC using our novel green micro‐synthesis technique and the preparation of graphene, titanium dioxide, and GTNC nanofluids using a two‐step method at three concentrations (0.02~0.08 wt%) using a surfactant. Furthermore, the stability and thermo‐physical properties of nanofluids were investigated, and nanofluids were studied for their effect on the performance of a counter‐current laminar flow micro‐heat exchanger at different flow rates (Re = 750‐1460). Findings show that thermal conductivity enhancement of GTNC nanofluid and pure graphene nanofluid at the highest mass fraction (0.08%) was 25.8% and 31.6%, respectively, while the maximum enhancement of convective heat‐transfer coefficient was 64.6% and 87%, respectively. These results indicate that hybrid GTNC nanofluid showed proximate thermal performance and stability level to graphene nanofluid with 50% less graphene content, which improves the economics of the process.

Radiation absorption on MHD convective flow of nanofluids through vertically travelling absorbent plate

An exploration of the unsteady MHD boundary layer flow over a moving vertical porous surface with nanofluids under the influence of a uniform transverse magnetic field and heat radiation absorption effects has been brought out. Two different kinds of water-based nanofluids comprising of Al 2 O 3 and TiO 2 are adopted into deliberation. The governing equations for the flow are solved by making use of the Laplace transform method, and the solutions are displayed in closed form. The velocity, temperature, concentration, the shear stress, the rate of heat and mass transportations near the surface has been described graphically for numerous values of the relevant parameters. The velocity and temperature enhances with increasing radiation absorption parameter. It is also observed that an increase of volume fraction of nanoparticles leads to the enhancement of the temperature on central line of the flow. Nusselt number might be tracked down to be elevated for alumina than titanium dioxide nanofluid. The present investigation originated applications in aerospace engineering as well as industrial many mechanisms.

Natural Convection Enhancement in the Annuli Between Two Homocentric Cylinders by Using Ethylene Glycol / Water Based Titania Nanofluid

The natural convection heat tranfer in annulate region confined between two homocentric cylinders were numerically studied in the present work. The annulus was filled by ethylene glycol / water based Titania nanofluid. Both internal and external cylinders are presereved at an isothermal hot and cold temperatures respectively, whereas, the upper and lower walls are adiabatic. The numerical solution is obtained by applying the finite volume method along with the SIMPLER, and TDMA algorithms. In the current study, the solid volumetric fraction is varied as (0 % ? ? ? 3 %), the volume ratios of EG to water are varied as (0:100 %, 40 : 60 %, 100:0 %), while both the Rayleigh number and radii ratio are considered fixed at (Ra = 104 and ? = 2). The obtained results indicated that, the average Nusselt number increases as the solid volumetric fraction and the volume ratio of ethylene glycol in the base fluid increase. Moreover, the velocity profiles reach their maximum value in the half region adjacent the internal hot wall when TiO2 – water nanofluid is used. Also, the temperature profiles decrease along the radial distance for all considered values of volume ratios of EG to water.

Employing response surface methodology and neural network to accurately model thermal conductivity of TiO2–water nanofluid using experimental data

In this research, the thermal conductivity of the H2O–titania nanofluid is modeled versus the particle concentration and temperature via the Artificial Neural Network (ANN) and Response Surface Methodology (RSM). The experimental data include six particle concentrations and five temperatures from 30 to 70 °C. The thermal conductivity augments by the increment in nanoparticle concentration and temperature, such that the maximum thermal conductivity increment happens at the highest temperature and nanoparticle concentration (i.e., T = 70 °C and φ = 1%). It is observed that the impact of temperature on the thermal conductivity is more noticeable than the influence of particle concentration, however, the thermal conductivity demonstrates a more non-linear trend versus nanoparticle volume fraction compared with the temperature. The best structure of the neural network has 2 hidden layers with 2 and 4 neurons, respectively in the 1st and 2nd hidden layers. The results show that the prediction precision of the ANN correlation is better than that of the RSM correlation.

Entropy generation in electromagnetohydrodynamic water based three Nano fluids via porous asymmetric microchannel

Nanofluids are of immense importance to the researchers as they have significant uses industrially due to their high heat transfer rates. This new model is employed to examine the electroosmotic flow of magnetohydrodynamic nanofluids through an asymmetric microfluidic channel. Microchannel flow is driven by the electroosmosis and peristalsis mechanisms. Nanoparticles (copper, alumina and titania) with water as a base fluid have been considered. The effects of Joule heating, mixed convection, permeability of the porous medium and dissipation of energy are considered. Besides, velocity slip conditions are also encountered at the walls. Electroosmotic phenomenon is modeled through Poisson equation and Nernst–Planck equation. Debye–Hückel approximation is considered to obtain Boltzmann distribution of electric potential across electric double layer. The emerging non-linear mathematical model is solved numerically by the built-in scheme of working software. The table is inserted for numerical values of heat transfer rate at the upper wall for three different type of water-based metallic nanofluid. To verify the accuracy of results, the comparison of solutions is also shown. Entropy generation in terms of Bejan number under different parameters is also investigated. The influence of physical factors on the characteristics of heat transfer has been pointed out. Water-based copper and titania nanofluids have relatively higher temperature and heat transfer rate when compared to the alumina-water nanofluid. Porosity decays the temperature throughout the microchannel. Moreover, temperature is strongly increased for higher values of the Joule heating parameter γ, in presence of Cu-water nanofluid. The current analysis is related to bio-inspired electrokinetic nanofluidic micropump models and incipient nanomedicine technologies.