Recent progress on flat plate solar collectors equipped with nanofluid and turbulator: state of the art

This paper reviews the impacts of employing inserts, nanofluids, and their combinations on the thermal performance of flat plate solar collectors. The present work outlines the new studies on this specific kind of solar collector. In particular, the influential factors upon operation of flat plate solar collectors with nanofluids are investigated. These include the type of nanoparticle, kind of base fluid, volume fraction of nanoparticles, and thermal efficiency. According to the reports, most of the employed nanofluids in the flat plate solar collectors include Al2O3, CuO, and TiO2. Moreover, 62.34%, 16.88%, and 11.26% of the utilized nanofluids have volume fractions between 0 and 0.5%, 0.5 and 1%, and 1 and 2%, respectively. The twisted tape is the most widely employed of various inserts, with a share of about one-third. Furthermore, the highest achieved flat plate solar collectors' thermal efficiency with turbulator is about 86.5%. The review is closed with a discussion about the recent analyses on the simultaneous use of nanofluids and various inserts in flat plate solar collectors. According to the review of works containing nanofluid and turbulator, it has been determined that the maximum efficiency of about 84.85% can be obtained from a flat plate solar collector. It has also been observed that very few works have been done on the combination of two methods of employing nanofluid and turbulator in the flat plate solar collector, and more detailed work can still be done, using more diverse nanofluids (both single and hybrid types) and turbulators with more efficient geometries.

Dynamics of chemically reactive Carreau nanomaterial flow along a stretching Riga plate with active bio-mixers and Arrhenius catalysts

Nanomaterial flow has fascinated the concern of scientists across the globe due to its innovative applications in various manufacturing, industrial, and engineering domains. Bearing aforementioned uses in mind, the focal point of this study is to examine the Carreau nanofluid flow configured by the Riga surface with Arrhenius catalysts. Microorganisms are also suspended in nanofluid to strengthen the density of the regular fluid. Time-dependent coupled partial differential equations that represent the flow dynamics are modified into dimensionless patterns via appropriate non-dimensional variables, and handled through an explicit finite difference approach with stability appraisal. The performances of multiple flow variables are examined graphically and numerically. Representation of 3D surface and contour plots for heat transportation and entropy generation are also epitomized. The findings express that the modified Hartmann number strengthens the motion of nanomaterial. Reverse outcomes for heat transport rate and entropy are seen for the radiation variable. Concentration diminishes for chemical reaction variable. Activation energy enhances the concentration of nanomaterial, whereas reduction happens in the movement of microbes for bio-Lewis number. Greater Brinkman variable heightens the entropy.

Effervescent tablet-assisted deep eutectic solvent based on magnetic nanofluid for liquid phase microextraction of tyrosine kinase inhibitors in plasma samples by high-performance liquid chromatography

BACKGROUND

Tyrosine kinase inhibitors (TKIs) are efficient anti-cancer drugs. The analysis of TKIs in the treatment of cancer is important to achieve the highest anti-cancer effects with minimal toxicities. Herein, we report an efficient effervescent tablet-assisted deep eutectic solvent based on nanofluid (ETA-DES-NF) combined with HPLC-UV for the determination of three anti-cancer drugs (erlotinib, imatinib, and nilotinib) in human plasma samples.

METHODS

In this method, a magnetic nanofluid composed of deep eutectic solvent (DES) and Fe3O4@SiO2 nanoparticles was used as an extraction solvent. The deep eutectic solvent acted as a carrier and stabilizer for Fe3O4@SiO2 nanoparticles. A tablet was used in the nanofluid for dispersion. The effervescent tablet was implemented to generate in situ CO2 and provide the effective dispersion of the sorbent into the sample solution for diminishing the extraction time and improving the extraction efficiency. Moreover, the magnetic nanofluid enhanced phase separation efficiency without centrifugation to collect the organic solvent.

RESULTS

The synthesized nanofluid was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The impact of main parameters, including the type and volume of DES, the composition of the tablet, the composition of the nanofluid and the composition of eluent, were optimized. According to the optimized conditions, the limits of detection (LODs) and the limits of quantitation (LOQs) were from 0.5-0.8 to 1.5-2.4 μg L-1 for imatinib, erlotinib, and nilotinib, respectively. The intra-day and inter-day relative standard deviations (RSD% n = 5) were determined to be 3.1-5% and 6.4-7.5%, respectively.

CONCLUSIONS

The developed method displayed high sensitivity, low consumption of solvent, low cost, simplicity, high recoveries, short extraction time, and good repeatability for determination of three anti-cancer drugs in human plasma samples.

Heat and mass transfer by stirring nanofluids with the presence of renewable solar rays, Joule heating, and entropy procreation

Renewable solar radiation is the foremost energy source because of its accessibility, natural replication, and sustainability in an environmentally safe manner. Here, researchers intended to inspect the heat and mass transfer via nanofluid transported on an inclined permeable expanded sheet in the presence of solar thermal radiation without any barrier. Mainly, the formation of non-recovery energy called entropy and Joule heating are also weighed. The guiding non-linear partial differential equations were transformed into systems of non-linear higher-order ordinary differential equations by felicitous similarity transformation. They are solved by the prevalent technique called the Homotopy Analysis Method, which is executed by the BVPh2.0 package in Mathematica 12.1 software. Comparisons with preceding published articles confirm the method's validity and accent its admirable uniformity. Afterward, the magnetic field interaction delays the mobility of nanofluid while increasing the magnitude of local skin friction and temperature distribution. By intensifying the thermal radiation parameter and Eckert number, the temperature and entropy production escalated. Furthermore, the heat transfer by convective surpasses that of conductive owing to the particles' Brownian motion. Thermophoresis established surplus tiny-particles concentration. Heat transfer from solar radiation in moving nanofluids has been applicable for cooking, heating water, and producing electricity.

Insight into the enhancement effect of amino functionalized carbon nanotubes on the H2S removal performance of nanofluid system

By constructing nanofluid system, trace functionalized nanoparticles can significantly enhance the absorption performance of basic liquid. In this work, amino functionalized carbon nanotubes (ACNTs) and carbon nanotubes (CNTs) were introduced into alkaline deep eutectic solvents to build nanofluid systems and used for the dynamic absorption of H2S. The experiment results showed that the introduction of nanoparticles can significantly enhance the H2S removal performance of original liquid. When performing H2S removal experiments, the optimal mass concentrations of ACNTs versus CNTs were 0.05 % and 0.01 %, respectively. The characterization showed that the surface morphology and structure of the nanoparticles unchanged significantly during the absorption-regeneration process. A double mixed gradientless gas-liquid reactor was used to explore the gas-liquid absorption kinetics characteristics of the nanofluid system. It was found that the gas-liquid mass transfer rate increased significantly after the addition of nanoparticles. The highest total mass transfer coefficient of the nanofluid system of ACNTs was increased to more than 400 % of the value before the addition of nanoparticles. The analysis showed that the shuttle effect and hydrodynamic effect of nanoparticles play important role in the process of enhancing gas-liquid absorption, and the amino functionalization enhanced the shuttle effect of nanoparticles significantly.

Heat transfer study and optimization of nanofluid triangular cavity with a pentagonal barrier by finite element approach and RSM

Nowadays, several engineering applications and academic investigations have demonstrated the significance of heat transfers in general and mixed convection heat transfer (MCHT) in particular in cavities containing obstacles. This study's main goal is to analyze the MCHT of a nanofluid in a triangular cavity with a pentagonal barrier using magneto hydrodynamics (MHD). The cavity's-oriented walls are continuous cold temperature, whereas the bottom wall of the triangle and all pentagonal obstacle walls are kept at a constant high temperature. For solving governing equations, we utilized the Galerkin's finite element approach. Four dimensionless factors, Richardson number (0.01 ≤ Ri ≤ 5), Reynolds number (10 ≤ Re ≤ 50), Buoyancy ratio (0.01 ≤ Br ≤ 10) and Hartmann number (0 ≤ Ha ≤20) are examined for their effects on streamlines, isotherms, concentration, velocity, and the Nusselt number. Also, with the help of Taguchi method and Response Surface Method (RSM) the optimization of the studied dimensionless parameters has been done. The optimum values of Ri, Re, Ha and Br are obtained 4.95, 30.49,18.35 and 0.05 respectively. Ultimately, a correlation has been extracted for obtaining the optimum average Nusselt number (Nu) in mentioned cavity.

A critical review of concentrating and nanofluid-based hybrid PV/T systems utilizing beam splitting technique: Progress, challenges, and way forward

The utilization of nanofluids and concentrating techniques in solar photovoltaic/thermal (PV/T) systems, to enhance the overall system performance, have been analysed explicitly in the last few years. More recently, nanofluid-based optical filters were integrated with photovoltaic (PV) systems for the effective utilization of solar spectrum, i.e. below and beyond the band-gap of PV cells. Therefore, to quantify the recent progress of spectral beam splitting-based hybrid PV/T systems (BSPV/T), a systematic review has been presented therein. The study highlights the technological and scientific advancement in BSPV/T in last two decades. Linear Fresnel mirror-based BSPV/T showed significant enhancement in the overall performance of hybrid PV/T system. Recently developed nanoparticle-laden BSPV/T system shows significant improvement in overall thermal efficiency of BSPV/T system, thanks to decoupling of thermal system and PV cell. Further, economic analysis, carbon footprint, and environmental assessment of BSPV/T are also discussed briefly. At the last, the authors have made an effort to identify the challenges, limitations, and prospective paths for future research in BSPV/T systems.

Advances of nanofluid in food processing: Preparation, thermophysical properties, and applications

Nanofluids (NFs) are homogenous mixes of solid nanoparticles as well as base fluid in which the size of the solid nanoparticles (NPs) is smaller than 100 nm. These solid NPs are intended to enhance the thermophysical characteristics and heat transmission attributes of the base fluid. The thermophysical characteristics of nanofluids are influenced by their density, viscosity, thermal conductivity and specific heat. These colloidal solutions of nanofluids include condensed nanomaterials such as nanoparticles, nanotubes, nanofibers, nanowires, nanosheets, and nanorods. The effectiveness of NF is significantly influenced by temperature, shape, size, type, as well as the concentration of NPs or the thermal characteristics of the base fluid. Compared to oxide NPs, metal NPs have superior thermal conductivity. Many of these investigations revealed that hybrid NFs had enhanced thermal conductivity than traditional ones. Thermal conductivity values are reduced by the formation of clusters in nanofluid. When compared to spherically formed nanoparticles, cylindrically shaped nanoparticles produced superior outcomes. In food industries, NFs could be used in various unit operations where heat needs to be transported from a heating or cooling medium to food product using a heat exchanger, as in freezing, pasteurization, refrigeration, drying, thawing, sterilization, and evaporation. The objective of this review is to analyze the recent developments in the research of nanofluids including innovative production methods, stability assessment, enhancement approaches, and thermophysical properties of nanofluids.

Recent advancements in flat plate solar collector using phase change materials and nanofluid: a review

Solar energy has emerged as one of the most promising sources of renewable energy to replace the current energy market. Flat plate solar collectors (FPSC) not only are one of the easiest collectors to produce and work with but also are cheap and economical. Due to this, extensive research has been done on FPSC to improve its efficiency and reliability. Some of the methods include using nanofluids to improve the heat transfer process, phase change materials to increase and maintain stable temperatures, or integrating the collector with additional components. This review article focuses on analyzing the recent improvements in FPSC, with a particular emphasis on the achieved efficiencies and temperatures in the studies. Additionally, it is aimed at updating the information in the current field, providing a comprehensive overview of the advancements in FPSC technology. Furthermore, the article explores the combined effects of nanofluids and phase change materials in photovoltaic/thermal (PVT) collectors, considering the resulting temperature enhancements. By critically evaluating the efficiency improvements and temperatures achieved through these approaches, this article is aimed at providing valuable insights into the state-of-the-art of FPSC and their potential for advancing solar energy utilization.

Analysis of the Time-Dependent magnetohydrodynamic Newtonian fluid flow over a rotating sphere with thermal radiation and chemical reaction

This article presents the magnetohydrodynamic (MHD) flow of a nanoliquid due to a rotating sphere at a stagnation point. The flow is considered to be influenced by the magnetic field, dissipative, thermally radiative, and chemically reactive. Also, the thermophoretic and Brownian motion influences are taken into consideration. Some restrictions in the present analysis are taken: like there is no-slip and convective conditions, joule heating, Hall effects and buoyancy-driven. The solution of the present analysis is derived through the homotopy analysis method (HAM). The significance of several physical parameters on velocities, thermal and concentration profiles are shown with the help of Figures. Also, the significance of different physical factors on skin frictions, local Nusselt number and Sherwood number are demonstrated with the help of Tables. The outcomes show that the Nusselt number is lower for the larger Brownian motion parameter, Eckert number, and thermophoretic parameter, while the increment in the thermal radiation parameter augmented the Nusselt number. It is established that the increasing rotation, magnetic and positive constant parameters have increased the velocity profiles along the x-direction while reducing the velocity profiles along the z-direction of the nanoliquid flow. The increasing positive constant parameter reduces the thermal graph of the nanoliquid flow. Furthermore, the intensifying Eckert number, thermophoresis, Brownian motion, and thermal radiation factor have escalated the thermal profiles of the nanoliquid flow.

Evaluation of AGM and FEM method for thermal radiation on nanofluid flow between two tubes in nearness of magnetism field

The nanofluid flow through two orbicular cylinders is explored utilizing the overall Koo-Kleinstreuer-Li (KKL) model within the nearness of a magnetic field. The impact of thermal radiation is considered in the energy equation. The novelty of this study is examining convective heat transfer for nanofluid flow between two flat tubes with the Akbari-Ganji method and Finite Element Techniques to examine the heat flux field by implies of 2D forms of temperature and velocity at unprecedented Reynolds numbers. The approaches for solving ODEs are AGM and FEM. Semi-analytical methods are assessed for specific parameters of aspect ratio, Hartmann number, Eckert number, and Reynolds quantity with various values. Adding Ha, Ec, and G causes the temperature gradient to grow, while adding the Reynolds number causes it to decrease. As the Lorentz forces increase, the velocity decreases; nevertheless, as the Reynolds number rises, the velocity decreases. With the reduction of the fluid's dynamic viscosity, the temperature will decrease, which will decrease the thermal trend along the vertical length of the pipes.

Performance study on a solar concentrator system for water distillation using different water nanofluids

The rapid growth in the world-population urges the need for potable water in various regions, especially in hot and dry regions. The main challenge in the productivity of potable water is the cost and availability of water sources. Thus, it is crucial to develop effective methods to overcome this global need. Utilizing solar power is proven to be a promising path to implementing thermal solar radiation in solar distillation applications. This work investigates the effectiveness of using concentrated solar power to irradiate heat exchange to evaporate water in a receiver, which will be collected as pure water in a condenser later. The thermal performance of the proposed model and its productivity are tested experimentally by using tap water only, and the test was repeated twice using two nanofluids namely, (aluminium oxide (Al2O3) and zinc oxide (ZnO)). The results showed that using (Al2O3) has a superior influence on the productivity of the solar unit, where the productivity is increased by 43.53% and 21.89% when compared to tap water and zinc oxide (ZnO) nanofluid respectively. The thermal efficiency of the solar unit was also increased by 9.91% (maximum) when using (aluminium oxide (Al2O3) as a working fluid compared to tap water. The model has simple components and is easy to install with a compact size, which can be developed be utilized in urban and desert areas.

A review of different twisted tape configurations used in heat exchanger and their impact on thermal performance of the system

Heat transfer in water with the help of solar energy is an effective way to harness renewable energy and reduce reliance on non-renewable sources of energy. The utilization of turbulent promoters is an efficient solution to ameliorate the performance of heat exchangers (HE). The current work summarizes the experimental and numerical behaviour of HE reported in the literature, including the thermal examinations of HT and fluid flow characteristics with various turbulent promoters and tube arrangements. This article reviews multiple studies in which different twisted tape (TT) geometry enhances the HT rate in various HE tubes. The current work also compares the thermal performance (η) of TT configurations in HE tubes using correlations developed by different investigators. Maximum heat transfer and minimum friction factor concerning fluid utilized in the system may also produce the optimal form for twisted tapes.

Examination of bio convection with nanoparticles containing microorganisms under the influence of magnetism fields on vertical sheets by five-order Runge-Kutta method

In this paper, we analyzed vertical bio convection in nanofluids containing microorganisms. The novelty of this article is the numerical and analytical investigation of magnetic flow, radiation heat transfer, and viscous dissipation on bio convective fluid flow using the Five-order Runge-Kutta technique. Utilizing similitude parameters, determined ODE (ordinary differential equation) equations from partial differential equations for continuity, momentum, energy, and nanofluid concentration. Five-order Runge-Kutta was then used to solve the equations. The results show that it has a more significant influence on and then and. In addition, it exerts a force on neighboring particles, which causes them to shift from a hot zone to a great region. The density of microorganisms inside a part rises as it grows; when Le rises and Ha remains the same, x(ξ) falls, and When Ha rises, and Le remains the same, x(ξ) fall.

A design of neuro-computational approach for double-diffusive natural convection nanofluid flow

The artificial intelligence based neural networking with Back Propagated Levenberg-Marquardt method (NN-BPLMM) is developed to explore the modeling of double-diffusive free convection nanofluid flow considering suction/injection, Brownian motion and thermophoresis effects past an inclined permeable sheet implanted in a porous medium. By applying suitable transformations, the PDEs presenting the proposed problem are transformed into ordinary ones. A reference dataset of NN-BPLMM is fabricated for multiple influential variants of the model representing scenarios by applying Lobatto III-A numerical technique. The reference data is trained through testing, training and validation operations to optimize and compare the approximated solution with desired (standard) results. The reliability, steadiness, capability and robustness of NN-BPLMM is authenticated through MSE based fitness curves, error through histograms, regression illustrations and absolute errors. The investigations suggest that the temperature enhances with the upsurge in thermophoresis impact during suction and decays for injection, whereas increasing Brownian effect decreases the temperature in the presence of wall suction and reverse behavior is seen for injection. The best measures of performance in form of mean square errors are attained as 7.1058 × 10 - 10 , 2.9262 × 10 - 10 , 1.1652 × 10 - 08 , 1.5657 × 10 - 10 and 5.5652 × 10 - 10 against 969, 824, 467, 277 and 650 iterations. The comparative study signifies the authenticity of proposed solver with the absolute errors about 10^-7 to 10^-3 for all influential parameters results.

Thermohydraulic performance investigation of a heat exchanger with combined effect of ribbed insert and Therminol55/MXene+ Al2O3 nanofluid: A numerical two-phase approach

MXene-based nanofluids are novel trends with improved dispersion stability and thermophysical characteristics over previously established nanofluids. In the present work, the thermohydraulic characteristics of a double pipe heat exchanger (DPHEX) with a Therminol55(TH55)/MXene + Al₂O₃ nanofluid and various geometrically shaped (triangular, rectangular) ribbed twisted tape (TT) inserts are numerically investigated using the ANSYS Fluent interface. A counter flow arrangement with three different types of inserts (RRTT, TRTT, TT) and TH55/MXene + Al₂O₃ nanofluid at 0.20 wt% are studied inside the heat exchanger. Adding ribbed inserts to the conventional TT insert enhances the turbulence intensity by creating extra vortices. The thermal boundary layer grows thinner due to increased axial and radial velocity. Due to the substantial flow obstruction, adding ribs increases the overall pressure drop between the inlet and outlet. The maximum increase in Nu is 11.04 % using nanofluid instead of water, whereas the combination of insert and nanofluid exhibited up to 105 % enhancement for rectangular-ribbed TT compared to the plain tube. Nevertheless, the pressure decrease is found to be maximum in rectangular-ribbed TT because of significant flow disruption. This was likewise true with triangular-ribbed TT and TT insert. According to the PEC assessment, the RRTT insert had a maximum PEC value of 1.67 greater than TRTT and traditional TT for both TH55 and nanofluid flowing inside the tube. To summarize, the combination of TH55/MXene + Al₂O₃ RRTT insert may be a promising choice for improving heat exchanger performance in a new generation efficient thermal system.

Experimental study of thermal characteristics of ZrO2/EG nanofluid for application of heat transfer

In thermal management system, nanofluids will act as robust elements in future for coolants. Nanofluids have remarkable potential during the heat transfer increase reported by researchers from all over the world. Nanofluids have attracted many researchers, and there have been tremendous advances because of the high thermal characteristics and possible applications in certain areas such as the transport sector, aerospace, medical regions, and microelectronics. This current study reports on the thermal characteristics of nanofluid based on ZrO₂/EG. The nanoparticles are characterized by XRD and SEM techniques. Nanofluid was prepared by a two-step method in ethylene glycol (EG) using ultra sonication. The thermal conductivity of ZrO₂/EG nanofluid was investigated experimentally at various volume concentrations (0.02-0.1vol. %) and temperature range between 35 and 55 °C. The enhancement in thermal conductivity was observed to be 26.2% at 0.1 vol. % which exhibits superior performance as compared to base fluid (EG). The results of the experiment were compared with the three most often utilized model in the literature. The behavior of ZrO₂/water-based nanofluid thermal conductivity, viscosity, and stability in various concentrations was studied.

The use of a hybrid photovoltaic/thermal (PV/T) collector system as a sustainable energy-harvest instrument in urban technology

A solar cell is a converter that uses semiconductor material to convert photon energy packets. The electrons located in the material's crystalline structure can escape from the bonds between their atoms and generate electricity. Photovoltaic (PV) solar cells can work via diffuse radiation and have the highest efficiency among other types of solar cell generation. Photovoltaic Thermal Collector (PVT)-based active cooling technology makes it possible to increase the efficiency of PV solar cells and to generate thermal energy at the same time through the direct conversion of solar radiation. Therefore, this study modeled various riser configurations on PVT collectors to cool PV solar cells using water heat transfer fluids and nanofluids: TiO₂, SiO₂, and Al₂O₃. The mass flow rates were varied. An ANSYS models a simulation of the heat transfer phenomenon between the PV cell layer and the fluid. Only the heat transfer phenomenon generated from the natural convection of the PV cell layer is studied using steady-state thermal ANSYS with simulated controlled conditions. The radiation intensity of 1000 W/m² has the photovoltaic solar cells with the most negligible efficiency. The semicircular collector configuration with water at a mass flow rate of 0.5 kg/s demonstrated the highest electrical efficiency, achieving 11.98%.

Intensification of CO2 absorption and desorption by metal/non-metal oxide nanoparticles in bubble columns

In this study, four different metal/non-metal oxide nanoparticles including CuO, Fe₃O₄, ZnO, and SiO₂ were employed to improve CO₂ absorption and desorption in methyl diethanolamine (MDEA)-based nanofluid. CO₂ absorption experiment with various nanofluids was done in a bubble column reactor at ambient temperature. Also, CO₂ stripping experiments for all nanofluids were done at 60 and 70 °C. The influence of nanoparticles type, nanoparticle concentration, and the stability of nanoparticles were studied on both CO₂ absorption and stripping. The obtained results revealed that Fe₃O₄ nanoparticles at 0.01 wt.% concentration had the best influence on CO₂ absorption and it improved the CO₂ loading up to 36%. Also, CO₂ stripping experiments for all nanofluids were done at 60 and 70 °C. The desorption experiments illustrated that metal oxide nanoparticles can be more efficient in improving CO₂ desorption. In CO₂ desorption, the CuO nanoparticles at 0.05 wt.% had higher efficiency, and enhanced CO₂ concentration at outlet gas phase up to 44.2 vol.% at 70 °C. Finally, as an indication, the chemical stability of Fe₃O₄ NPs under optimum operational conditions was studied using XRD analysis and the result showed that the proposed operational condition did not have any negative effect on the chemical nature of Fe₃O₄ NPs.

Simultaneous effects of MWCNT and SiO2 on the rheological behavior of cooling oil and sensitivity analysis

Many scholars are attracted to nano-lubricants due to their unique properties. In the present study, the rheological behavior of a new generation of lubricants has been investigated. SiO₂ nanoparticles with an average diameter of 20-30 nm along with MWCNT with an internal diameter of 3-5 nm and the external diameter of 5-15 nm has been dispersed in 10W40 engine oil as base-lubricant and MWCNTs-SiO2 (20%-80%)/10W40 hybrid nano-lubricant has been produced. Nano-lubricant behavior agrees with the Herschel-Bulkley model and is of Bingham pseudo-plastic type below 55 ° C . Also, in the temperature of 55 ° C , nano-lubricant behavior has changed to Bingham dilatant. The viscosity is increased by 32% in the proposed nano-lubricant compared to base lubricant (Dynamics Viscosity Enhancement). Finally, a new correlation with a precision index of R-squared >0.9800, Adj. R-squared >0.9800, and the maximum margin of deviation of 2.72% has been presented, increasing the applicability of this nano-lubricant. Eventually, the sensitivity analysis of nano-lubricant has been conducted, studying the comparative effect of volume fraction and temperature on viscosity.

Double-diffusive stagnation point flow over a vertical surface with thermal radiation: Assisting and opposing flows

In numerous industrial procedures, the main concern of design engineers is ensuring adequate heat and mass transfer, such as in the heating and cooling practices of solar water heaters, geothermal systems, extrusion of metal, insulation of buildings, electronics, turbines, aerodynamics, electronics, paper manufacturing, and glass fiber production. The unsteady double-diffusive mixed convection flow of boundary layer nanofluids above a vertical region near stagnation point flow is developed and examined here. The Brownian motion and thermophoresis effects are incorporated by using Buongiorno's model. In the thermal energy equations, diffusion of regular and cross types is also used. By the use of the local similarity method along with suitable similarity transformations, nonlinear unsteady partial differential equations are converted to nonlinear ordinary differential equations and are numerically solved by the Keller-Box method. The investigation expresses that these profiles of solute concentration and nanoparticle concentration, temperature, and velocity in their boundary layers, respectively, depending on several parameters. A graphic analysis of all these parameters' possessions on nature's boundary layers is depicted. The highest rate of heat transfer is obtained with negligible thermophoresis effect. Furthermore, it is perceived that an increase in Nc and Nt results in a reduction in the reduced Sherwood number of nanoparticles, whereas addition results in an increase in the Nb number. There is a reverse effect on the temperature field and layer thickness for heat generation. In the wake of the above-mentioned potential applications, the current study of fluid flow has been found to be very interesting and innovative in the analysis of the influence of Brownian motion and thermophoresis effects near stagnation point flow, which will further make revolutions in industrial fields. Moreover, Buongiorno's model predicts the characteristics of double-diffusive fluids in enhancing heat transfers. This investigation has been established as a result of the numerous industrial applications mentioned above.

A novel design for solar collector used for water heating application having nanofluid as working medium: CFD modeling and simulation

A solar collector is a simple and cheap device that converts solar radiation into valuable heat energy. The thermal performance of the solar collectors can be enhanced significantly with the suspension of nanoparticles in the base fluid. A novel design for a solar-assisted water heater (SWH) is proposed in the current study, and the effect of nanofluid has been investigated on the thermal efficiency of the SWH. The use of nanofluid is one of the prominent methods in comparison to other techniques for improving the performance of solar collectors. Therefore, the base working fluid, i.e., water is mixed with the alumina nanoparticles of average particle size of 30 nm, and they are assumed to be spherical. The flow and thermal characteristics of nanofluid through the solar water heater are simulated numerically with the help of the Eulerian-Eulerian two-phase model using the finite volume method (FVM). The commercial package ANSYS Fluent, is used for modeling the problem under transient conditions with a pressure-based solver. In comparison to a conventional flat plate collector, the proposed solar water heater consists of a corrugated absorber-plate and the effect of the radius of curvature has been investigated on the heat transfer and collector efficiency. With the proposed design, the heat transfer area available with the riser tubes increases remarkably and it leads to a 43% and 14% increase in heat transfer augmentation and collector efficiency, in comparison to the conventional solar water heater.

Data on the cooling rate using nano carbon-fluid quenching medium and its effect on the hardness of S45C steel

This dataset provides the effect of cooling rate using nano-fluid quenchant. The nanofluid consists of 0.1, 0.3, and 0.5 gram of nano-sized carbon particles in 100 ml of distilled water. Pure distilled water was also used as a comparison control. The particle was produced by using planetary ball-mill at 500 rpm for 15 hours. Field-Emission Scanning Microscope (FE-SEM) and Energy Dispersive X-Ray (EDX) were also used to confirm the size, shape, and purity of the nanoparticles. These nanofluids were then applied to quench annealed S45C carbon steel samples. The samples were connected to a thermocouple with a temperature data logger to observe the cooling rate of the nano-fluid quenchant. The quenched samples were tested to get the information on the hardness of S45C carbon steel.

Entropy generation and characteristics of mixed convection in lid-driven trapezoidal tilted enclosure filled with nanofluid

The investigation of steady, incompressible, laminar mixed convective fluid flow within two different types of tilted lid-driven trapezoidal enclosures filled with nanofluid composed of water and Al₂O₃ nanoparticles has been carried out in this paper. The upper wall of the enclosure is an isothermal cold surface that travels at a constant speed, while the bottom surface of the cavity maintains a constant high temperature. Non-dimensional governing equations along with the appropriate boundary conditions are solved using Galerkin finite element technique. Parametric simulation has been conducted by varying tilt angle of the base wall from 0° to 45°, Reynolds number from 0.1 to 10³, Grashof number from 10^-2 to 10⁶, and Richardson number between 0.1 and 10 for three different cases. The streamlines and the isotherms are used to describe the fluid flow and heat transfer characteristics within the enclosure. Besides, the quantitative evaluations of thermal enhancement in terms of the average Nusselt number, average fluid temperature, and Bejan number of the enclosure are presented. Effects of base wall tilt angle and the presence of nanofluid on convection heat transmission characteristics as well as Bejan number are also explored.

Study of the performance of thermoelectric generator for waste heat recovery from chimney: impact of nanofluid-microchannel cooling system

A huge number of chimneys all over the world utilized in many industrial applications and applications like restaurants, homes, etc. contribute badly on the global warming and climate change due to their waste heat. So, in this paper, the performance of thermoelectric generator (TEG) cooled by microchannel heat spreader having nanofluid and used for waste heat recovery from vertical chimney is investigated. Using heat spreader with microchannel cooling system increases the output TEG power compared to natural convection cooling system. In this paper, the impact of microchannel sizes, using nanofluid and heat spreader with different sizes on the TEG performance and cooling, is considered. Three-dimensional mathematical models including TEG, microchannel, nanofluid, and heat spreader are presented and solved by Ansys Fluent software utilizing user-defined memory, user-defined function, and user-defined scalar. All TEG effects (Joule, Seebeck, and Thomson) are considered in TEG model. Results indicate that TEG power rises with increasing the heat spreader and microchannel sizes together. Increasing microchannel and heat spreader sizes four times of TEG size raises the TEG output power by 10%. This also achieves the maximum cooling system efficiency of 88.9% and the maximum net output power. Microchannel heat spreader cooling system raises the system (TEG power-pumping power) net power by 125.2% compared to the normal channel and decreases the required cooling fluid flow rate. Utilizing copper-water and Al₂O₃-water nanofluids rises maximally the TEG output power by 14% and 4%, respectively; however, it increases the pumping power. Moreover, using nanofluids increases the net output power at low Reynolds number and decreases it at higher Reynolds number.