Al2O3-water Nanofluid Research Articles

Investigation of heat transfer characteristics of Al2O3-water nanofluid in a coiled agitated vessel across varied operating conditions

Investigation of heat transfer characteristics of Al2O3-water nanofluid in a coiled agitated vessel across varied operating conditions

Free convection of Al2O3-water nanofluid inside a hexagonal-shaped enclosure with cold diamond-shaped obstacles and periodic magnetic field

The hydrothermal characteristics of fluid flow within a hexagonal enclosure hold immense significance due to their wide-ranging applications in various fields. Despite their potential importance, there is currently a limited understanding of free convection flow within these geometries. This study aims to tackle this aspect by considering the effect of cold diamond-shaped obstacles and periodic magnetic field. The cavity top inclined walls are uniformly heated while bottom inclined walls are considered as heaters. The straight top and bottom walls of the cavity are adiabatic. The numerical solution is obtained via finite element method. The results indicate a substantial augmentation of streamlines, x- and y-direction velocities, entropy and average Bejan number with increase in the Rayleigh number. Inducing stronger magnetic field force reduces x- and y-direction velocities, average Bejan number and entropy generation. The average Nusselt number improves by 76.16% for Rayleigh number ranging from 105 to 106 at several lengths of hot surface. Among the cases analyzed in this research, moving the diamonds from the middle (Case A) to top (Case B) and bottom (Case C) enhances and reduces the Nusselt number by 6.3% and 7.5%, respectively.

Second Law Analysis for Free Convection in an L-Shaped Cavity Filled with Nanofluid

The paper aims to analyze the effects of various Prandtl number and different nanoparticles for heat transfer and entropy generation of free convection laminar fluid flow in an L-shaped cavity filled by nanofluid. To investigate the second law characteristics of free convective flow and heat transfer from an L- shaped geometry filled by water and nanofluids (Cu-water, Ag-water, Al2O3-water), the effects of Prandtl number and various nanoparticles on the average Nusselt number, total entropy generation and Bejan number has been numerically analyzed. Isotherms, stream function and entropy generation caused by heat transfer are also presented for various Prandtl numbers and various nanoparticles. The governing equations are solved using penalty finite element method with Galerkins weighted residual technique. The results reveal that Ag-water nanofluid with highest Prandtl number gives the highest amount of irreversibility as well as rate of heat transfer. Cu-water and Ag-water nanofluid produces more irreversibilities than Al2O3-water nanofluid and base fluid. Also the results show that the Nusselt number and Bejan number increase with the increase of Prandtl number. Therefore, Prandtl number may be an important parameter for desired heat transfer increment with decreasing entropy generation in the given geometry.

Experimental analysis of thermal performance of direct absorption parabolic trough collector integrating water based nanofluids for sustainable environment applications

Integration of nanofluids with solar collectors to enhance collector's thermal performance stands out as one of the most effective techniques owning to nanofluids favorable thermo-physical properties. By improving the thermo-physical properties of heat transfer fluids, nanofluids enhance the efficiency of thermal systems by improving the thermal energy storage capacity. This experimental study serves as a novel comparison between water-based Al2O3 (Alumina) and Multi-walled Carbon Nanotubes (MWCNTs) nanofluids in such mass concentrations (0.1%, 0.2%, and 0.3%) at fixed mass flow rates of 0.012 kg/s and 0.024 kg/s to investigate the impact on the performance of Direct Absorption Parabolic Trough Collectors (DAPTC) under the arid climatic conditions of Pakistan. The peak thermal efficiencies were found to be 40%, 56% and 58% for distilled water (DW), Al2O3-water and CNTs-water nanofluids, respectively. Thermal efficiency of DAPTC was improved by 18% in comparison with the basefluid alone on account of increased surface area, thermal conductivity and overall heat transfer capabilities. The CNTs-water nanofluids were observed to be more thermal efficient Heat Transfer Fluids (HTFs) owing to the black color and comparatively lower specific heat capacity. These thermal efficient fluids are of great use in the thermal energy storage systems. In addition, the use of nanofluids for heating and cooling purposes in industries is preferable as operational and manufacturing costs can also be lowered by reducing the systems size.

Electro-enhanced natural convection analysis for an Al2O3-water-filled enclosure by considering the effect of thermal radiation

One of the most crucial topics in the thermal sciences is the analysis of how an external electric field affects the natural convection flow. In this study, the heat transfer of electro-hydrodynamic natural convection in an enclosure with a wavy hot wall is numerically studied. Al2O3-water nanofluid is considered as the working fluid, and furthermore, the effect of thermal radiation on the characteristics of fluid flow is simulated. Non-dimensional forms of governing equations are numerically solved using control volume finite element method. The effects of operational parameters such as Rayleigh number, nanoparticles volume-fraction, Lorentz force number, Eckert number, charge diffusivity number, and electric field number on the maximum absolute value of stream function and the average Nusselt number are investigated. Two new parameters are defined to evaluate the contribution of the electrical field and radiation effects on the fluid flow. The results show that ascends 7.95% when increases from 0 to 0.05 at Also, the values of and increase 27.6% and 37.2%, respectively, when goes up from 0 to 0.5 at The values of and decrease 48.7% and 27.1%, respectively, with decreasing the amplitude parameter from 0.1 to 0.3 at

Swirling jet impingements for thermal management of high concentrator solar cells using nanofluids

Large intensity of irradiance in high concentrator solar cells leads to extremely high temperatures causing an adverse effect on the performance of solar cells. Efficient cooling systems are crucial for the optimal performance of high concentrator cells, which are typically required to operate within a prescribed temperature range (⁓ 110 °C). The implementation of effective cooling strategies poses a significant challenge for High Concentrator Photovoltaic Thermal (HCPV/T) hybrid systems to ensure sustained performance and longevity of the modules. This study proposes a novel method for the thermal management of High Concentrator Solar Cells (HCSC) using swirling nanofluid jets impinging on a heat sink. The study applies RANS (Reynolds-Averaged Navier-Stokes) method with the SST k-ω turbulence model and energy equation to resolve a conjugate heat transfer analysis for three different flow ratios: Qr = 0, Qr = 0.5 and Qr = 1 and two water-based nanofluids: Al2O3-Water and CuO-Water. The numerical results demonstrate a significant decrease in cell temperatures, reaching as low as 71 °C. At a mass flow rate of 50 g/min, the use of Al2O3-Water nanofluid increases the overall electrical efficiency by a maximum of 39.43%. In contrast, a minimum electrical efficiency of 39% for CuO-Water nanofluid is obtained for a lower mass flow rate (25 g/min). Al2O3-Water nanofluid yielded a maximum PEC (Performance Evaluation Criteria) of 116%, while CuO-Water nanofluid yielded about 113%. In addition, an increase of the mass flow rate results in an improvement of temperature uniformity, as demonstrated by a reduction of temperature variation from 6.8 to 5.2. These results suggest that the use of nanofluids is promising. The proposed swirling jet impinging on a heat sink in combination with nanofluid provides an effective cooling technique for HCSC, thereby potentially contributing to the improvement of the cell's performance and longevity.

Natural Convection Cooling of a Heat Source Placed at the Bottom of a Square Cavity Filled with Water-Based Nanofluid

The present work deals with the cooling process of a heat source, placed in the center of the bottom wall of a square cavity. A numerical resolution using finite volume method was carried out. The cavity is filled with a water-based Nanofluid, where four different types have been assumed. The vertical and top walls are under low temperature TC. Two thermal conditions were assumed at the source (q-imposed or T-imposed), while the remaining parts of the same wall are isolated. The effects of Rayleigh number (Ranf), source length (SL), volume concentration of nanoparticles (Φ) and their types were analyzed. The case of pure water (Φ = 0%), studied first, served as a reference case. The results obtained for this case, showed the increase of disturbances in the dynamic and thermal fields, in addition to the average rate of heat transfer (Nu) when Ra increases and SL decreases. SL = 1.0 case showed exception. These effects are more important for the T-imposed case than the other. Subsequently, the Al2O3-Water Nanofluid is considered with 0 <Φ≤ 10%. An increase in circulation intensity with improvement of local (Nu) and average (Nu) heat exchange rates have been recorded when Φ increases, although mentioning that its effect is significantly stronger for the q-imposed case. In the last part of the work, three other types of Nanofluids were assumed, where the obtained results showed the main improving effect of higher thermal conductivity on the heat transfer intensity. An important result which can be summed up in the great rapprochement of the heat exchange intensities for strong Ranf and Φ for SL close to 1.0, for the two heating types. In other words, the condition on the source loses its importance for such considerations.

AI predicts MHD double-diffusive mixed convection and entropy generation in hybrid-nanofluids for different magnetic field inclination angles by ANN

The goal of the current numerical study is to determine how different magnetic field inclination angles along with Reynolds numbers affect mixed convective heat and mass transfer as well as entropy generation in a lid-driven trapezoidal enclosure with two rotating cylinders inside. As governing fluids, several water-based nanofluids and hybrid nanofluids with fixed solid volume fractions (5%) are employed. The impacts of three different types of SWCNT-Cu-Al2O3-water hybrid nanofluids, each made up of different ratios of SWCNT, Cu, and Al2O3 nanoparticles in water, are seen in this work, along with the effects of SWCNT-water, Cu-water, and Al2O3-water nanofluids separately. To obtain the results in the form of average Nusselt number, average Sherwood number, average temperature, and Bejan number as output parameters inside the enclosure for different magnetic field inclination angles (0° ≤ λ ≤ 90°) and other governing parameter values, the governing Navier-Stokes, thermal energy, and mass conservation equations are solved using the Galerkin weighted residual finite element method through numerical simulation. Then the simulation data is used to develop a novel artificial neural network model for efficient prediction. To achieve the best outcomes for the output parameters, the optimal values of each of these input parameters are determined by both FEM and ANN and a comparative study between these two is conducted. Cu-Al2O3-water hybrid nanofluid is used to test the performance of the developed ANN model for new cases. For each type of fluid in the present framework, maximum heat and mass transfer often take place when the magnetic field is applied at an inclined angle with respect to the horizontal axis. A satisfactory accuracy is obtained for the developed novel ANN model while predicting respective results. For training and validation data, it predicts convective heat and mass transfer with 96.81% accuracy and average dimensionless temperature and Bejan number with 98.74% accuracy. For test data, it predicts convective heat and mass transfer with 97.03% accuracy and average dimensionless temperature and Bejan number with 99.17% accuracy.

Variations of MHD double-diffusive mixed convection and entropy generation in various nanofluids and hybrid nanofluids due to the deviation of the spinning of double rotating cylinders

The current numerical study aims to investigate the effects of various rotating speeds of rotating cylinders on mixed convection and entropy generation in a lid-driven trapezoidal enclosure for fixed magnetic field inclination angle. Several water-based hybrid nanofluids are used as governing fluids. In this work, the impacts of SWCNT-water, Cu-water, and Al2O3-water nanofluids individually, as well as the effects of three different types of SWCNT-Cu-Al2O3-water hybrid nanofluids are examined. The average Nusselt number, average Sherwood number, average temperature, and average entropy generation because of heat transfer, diffusion, fluid friction, and the applied magnetic field as well as total entropy generation and Bejan number are evaluated as output parameters for different values of governing parameters. The Galerkin weighted residual finite element method is used to numerically solve the governing Navier-Stokes, thermal energy, and mass conservation equations. The optimal values of each governing parameter are established in order to produce the best results for the output parameters. To inspect the thermal and flow field within the trapezoidal enclosure as well as the variations in mass concentrations, isotherm contours, streamlines and isoconcentration contours are studied. Better performance is found for higher rotating speed regardless of other parameters.

Free convection of hybrid water/aluminum oxide-copper nanofluid in cubic cavity

Convective heat transfer is a physical phenomenon that continues to attract the interest of researchers in many fields of science and engineering. This work aims at numerically investigating the enhancement of heat transfer in a differentially heated three-dimensional cavity using a hybrid Al2O3-Cu-water nanofluid and Al2O3-water nanofluid. The partial differential equations are discretized in 3D by adopting the finite volume method and using the SIMPLEC algorithm for pressure correction. Heat transfer and fluid flow results are presented in the form of isotherms, velocity fields and mean Nusselt number. The results show that the effect of nanofluid and hybrid nanofluid on natural convection is more significant when the Rayleigh number is high. The use of hybrid nanofluid improves the heat transfer compared to nanofluid.

Performance improvement of a double tube heat exchanger using novel electromagnetic vibration (EMV) method in the presence of Al2O3-water and CuO-water nanofluid; An experimental study

In this research, the novel approach of the electromagnetic vibration (EMV) method was utilized for the first time to increase heat transfer in a double-tube heat exchanger (DTHEX). In this method, a magnetic turbulator (comprising a magnet and an oscillator) was installed inside a central tube that vibrated using an AC magnetic field. The influences of various parameters such as the geometry of the oscillator, magnet position, employing nanofluids, and fluid flow were assessed on the thermal-frictional behavior. The thermal enhancement factor (TEF) was assessed to select the optimal option. The studied options were economically evaluated based on energy efficiency. According to the results, the maximum heat transfer rate could be achieved when the magnet is positioned at 0.374. L from the tube inlet. The highest value observed for overall heat transfer was related to CuO-water 1% nanofluid, which was 277.5% more than simple heat exchanger. Also, the findings showed that heat transfer can be increased up to 13.3 times the energy used and reached to TEF = 3.92, which is a very significant number. Regarding the high potential of the EMV in reaching high thermal performance, it can be utilized as a game changer to save materials, energy, and compaction of the heat exchangers and solar systems.

Stability and thermophysical properties enhancement of Al2O3-water nanofluid using cationic CTAB surfactant

Excellent thermal characteristics of homogeneous dispersion of nano-sized particles in a carrier fluid (nanofluid) make it appealing for use in a variety of thermal applications. The study aims to prepare stable aqua-Al2O3 nanofluid utilizing a two-step method. To increase nanofluid stability, a cationic surfactant called cetyltrimethylammonium bromide (CTAB) is used. The carrier fluid is heated while magnetic stirring is used to increase nanoparticle distribution. Bath sonication with concurrent heating and probe sonication is used to improve long-term stability. The chemical composition of γ-Al2O3 was confirmed by X-ray diffraction (XRD) results, and Scanning Electron Microscopy (SEM) images revealed the shape and mean size of the particles. The stability of the synthesized sample is evaluated utilizing a variety of stability evaluation techniques, including visual examination, UV-vis spectrometry, and Dynamic Light Scattering (DLS), at various time intervals, including 1, 8, 15, and 30 days. After 15 days of manufacture, the stability of the nanofluid without surfactant was low. Due to improved particle suspension, nanofluid with surfactant has demonstrated greater UV-vis light absorption. After a month of synthesis, it was discovered that the mean particle sizes of suspended nanoparticles in carrier fluid were 80 nm and 536 nm for nanofluid with and without surfactant respectively. KD2Pro thermal analyzer and viscometer were used to measure the thermal conductivity and viscosity of nanofluid. As per the experimental results, a nanofluid's thermophysical characteristics were found to be improved with volume concentration of nanofluid. Maximum augmentation in thermal conductivity and dynamic viscosity is 8.5% and 76.2% respectively at 1% nanofluid volume concentration.

Heat and Mass Transfer Gravity Driven Fluid Flow over a Symmetrically-Vertical Plane through Neural Networks

This paper explores the numerical optimization of heat and mass transfer in the buoyancy-driven Al2O3-water nanofluid flow containing electrified Al2O3-nanoparticles adjacent to a symmetrically-vertical plane wall. The proposed model becomes a set of nonlinear problems through similarity transformations. The nonlinear problem is solved using the bvp4c method. The results of the proposed model concerning heat and mass transfer with nanoparticle electrification and buoyancy parameters are depicted in the Figures and Tables. It was revealed that the electrification of nanoparticles enhances the heat and mass transfer capabilities of the Al2O3 water nanoliquid. As a result, the electrification of nanoparticles could be an important mechanism to improve the transmission of heat and mass in the flow of Al2O3-water nanofluids. Furthermore, the numerical solutions of the nanofluid model of heat/mass transfer using the deep neural network (DNN) along with the procedure of Bayesian regularization scheme (BRS), DNN-BRS, was carried out. The DNN process is provided by taking eight and ten neurons in the first and second hidden layers along with the log-sigmoid function.

Application of Artificial Intelligence on Predicting the Effects of Buoyancy Ratio on Magnetohydrodynamics Double-Diffusive Mixed Convection and Entropy Generation in Different Nanofluids and Hybrid Nanofluids

Abstract The present computational investigation aims to investigate the effect of varied buoyancy ratios on mixed convection and entropy formation in a lid-driven trapezoidal enclosure under magnetic field with two rotating cylinders. The effects of SWCNT–water, Cu–water, and Al2O3–water nanofluids individually, as well as effects of three different types of SWCNT–Cu–Al2O3–water hybrid nanofluids are examined. The governing Navier–Stokes, thermal energy, and mass conservation equations are solved using the Galerkin weighted residual finite element method to obtain results as average Nusselt number, Sherwood number, temperature, and Bejan number as output parameters inside the enclosure for different parameter values. Then, an innovative artificial neural network model for effective prediction is created using the simulation data. The optimum values of each of these input parameters are obtained by finite element method (FEM) and artificial neural network (ANN), and a comparative study between FEM and ANN is done to get best results for the output parameters. The performance of the created ANN model for novel scenarios is evaluated using Cu–Al2O3–water hybrid nanofluid. The proposed innovative ANN model predicts the findings with less time and sufficient accuracy for each type of studied governing fluids. The model’s accuracy for predicting convective heat and mass transfer, along with average dimensionless temperature and Bejan number, was 96.81% and 98.74%, respectively, when tested on training and validation data. On test data, the accuracy was 97.03% for convective heat and mass transfer and 99.17% for average dimensionless temperature and Bejan number.

Thermo-Hydraulic Phenomena of Water-Al2O3 Nanofluid Flow Over a Rectangular Channel with Trapezoidal Obstacles

Numerical simulations of water-Al2O3 nanofluid flow in a rectangular channel with two trapezoidal obstacles have been studied, which has rmarkable effect in various engineering applications. The governing equations have been solved using SIMPLEC algorithm and FLUENT software has been used to visualize the simulation results. Motivation of this work is to examine the dynamic behavior of laminar water-Al2O3 nanofluid flow for volume fraction, ψ = 0%, 2%, and 4%. The present study analyzes different hydrothermal flow phenomena with the variation in obstacle height and ψ. Moreover, the simulation results, such as the profiles of velocity, normalized temperature (θ), poiseuille number (CfRe), local Nusselt number (Nu), average Nusselt number (Nuavg) and friction factor (f) have been portrayed with the variations in ψ and Reynolds number (Re). It has been observed that the obstacles increase the convective heat transfer (HT) significantly. At Re = 100, for all the configurations it has been found that the velocity profile become more pronounced for ψ = 4% as compared to ψ = 0%. A linear relationship has been found between the values of f and ψ. It is also found that an increase in Re increases vortex length. It is also shown that variation of volume fraction (ψ) and obstacle height resulted in an indicative change in the normalized temperature and velocity along the center line. In type-1 obstacle configuration, it has been found that Nuavg increases by 6.6% at ψ = 2%, and the same increases by 10.73% at ψ = 4% as compared to that at ψ = 0%. Moreover, it has been found that in type-2 obstacle configuration, value of f increases by approximately 7.9% at ψ = 2% and 13.84% at ψ = 4% as compared to that at ψ = 0%.

Application of novel double-layer micro-jet heat sinks for energy-efficient thermal management of motor inverters in electric vehicles

The relentless advancement in electronics miniaturization and performance has birthed a tremendous amount of heat flux, demanding effective dissipation techniques. Thermal effects pose a significant hurdle in the thermal management of electric vehicles (EVs) and having advanced cooling techniques in place is vital. To tackle this, the present study numerically evaluates the cooling attributes of two novel double-layer micro-jet heat sinks (DLMJHSs) to address the thermal management of insulated-gate bipolar transistors (IGBTs) in the motor inverters of EVs. The numerical analyses are carried out for Reynolds numbers ranging from 5000 to 25,000, IGBT heat fluxes of 100, 200, and 300 W/cm2, and different configurations of DLMJHSs. The potential of using nanofluids is assessed by employing Al2O3–water nanofluid with different volume fractions of 0.8% and 1.7%. The finite volume technique is implemented to solve the equations and the turbulence closure is modeled using the k-ԑ model. Results show that HS #2 provides a 10.2% higher convective heat transfer coefficient leading to a 7.44 ℃ lower baseplate temperature than HS #1. Besides, HS #2 prevents the occurrence of high-temperature spots owing to a more uniform temperature distribution in comparison with HS #1. HS #2 demonstrates the most uniform temperature distribution, with a Coefficient of Variation of only 0.00993 and a maximum heat transfer coefficient of 80.5 kW/m2 ℃. The heat sink’s baseplate temperature drops by increasing either the Reynolds number or the volume fraction. The baseplate temperature declines by up to 6.94 ℃ using a nanofluid volume fraction of 1.7% compared with only the base fluid. A minimum Reynolds number of 15,700 is required to prevent overheating at the peak heat flux. The performance evaluation criterion (PEC) is higher than 1 for Re ≤ 15,000.

MHD Mixed Convection of Non-Newtonian Bingham Nanofluid in a Wavy Enclosure with Temperature-Dependent Thermophysical Properties: A Sensitivity Analysis by Response Surface Methodology

The numerical investigation of magneto-hydrodynamic (MHD) mixed convection flow and entropy formation of non-Newtonian Bingham fluid in a lid-driven wavy square cavity filled with nanofluid was investigated by the finite volume method (FVM). The numerical data-based temperature and nanoparticle size-dependent correlations for the Al2O3-water nanofluids are used here. The physical model is a two-dimensional wavy square cavity with thermally adiabatic horizontal boundaries, while the right and left vertical walls maintain a temperature of TC and TH, respectively. The top wall has a steady speed of u=u0. Pertinent non-dimensional parameters such as Reynolds number (Re=10,100,200,400), Hartmann number (Ha=0,10,20), Bingham number (Bn=0,2,5,10,50,100,200), nanoparticle volume fraction (ϕ=0,0.02,0.04), and Prandtl number (Pr=6.2) have been simulated numerically. The Richardson number Ri is calculated by combining the values of Re with a fixed value of Gr, which is the governing factor for the mixed convective flow. Using the Response Surface Methodology (RSM) method, the correlation equations are obtained using the input parameters for the average Nusselt number (Nu¯), total entropy generation (Es)t, and Bejan number (Beavg). The interactive effects of the pertinent parameters on the heat transfer rate are presented by plotting the response surfaces and the contours obtained from the RSM. The sensitivity of the output response to the input parameters is also tested. According to the findings, the mean Nusselt numbers (Nu¯) drop when Ha and Bn are increased and grow when Re and ϕ are augmented. It is found that (Es)t is reduced by raising Ha, but (Es)t rises with the augmentation of ϕ and Re. It is also found that the ϕ and Re numbers have a positive sensitivity to the Nu¯, while the sensitivity of the Ha and Bn numbers is negative.

Heat Transfer Enhancement in Laminar Pipe Flow Using Al2O3–Water Nanofluid and Twisted Tape Inserts

Abstract In this study, an attempt has been made to carry out a numerical investigation using water-based Al2O3 nanofluid, flowing through a circular tube under constant inlet temperature and constant heat flux conditions in the laminar flow regime. The water-based Al2O3 nanofluid is used in a circular plain tube first, and then, this process is repeated for the same tube fitted with twisted tape inserts of twist ratio 1.85 at Reynolds numbers ranging from 680 to 2030. For the numerical analysis, ANSYS FLUENT is used to solve three-dimensional conservation equations of mass, momentum, and energy. The simulated results indicate that when twisted tape is used, heat transfer rates increase significantly with the use of nanofluid. In the case of nanofluid with the plain tube, only 10–24% enhancement in heat transfer rate is noted. On the other hand, almost 27–45% increase in heat transfer is observed compared to that with only water when twisted tape is inserted into it. Also, the friction factor increases as the nanoparticle volume fraction increases. However, the effect on the heat transfer rate is more significant than that on the friction factor. The best thermohydraulic performance factor achieved is 2.1 using nanofluids with a 5% volume fraction of the nanoparticles at a high Reynolds number when twisted tape is also inserted.

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

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

A review of nucleate pool-boiling heat transfer in different liquids and nanofluids

The goal of this review is to examine the current state of the art in nucleate pool boiling heat transfer in a variety of different fluids. The review is divided into many sections that discuss heat transfer in pool boiling, such as pool boiling of nanofluids, boiling behavior of water–glycerin combinations, and operational parameters. With the appropriate mixes of hydrocarbons and other commercial liquids, higher heat transfer coefficients may be produced. Coatings of nanoparticles with varying layer thicknesses applied to the heater surface may be optimized to improve heat transfer from the pool to the surrounding water. The heat transfer hypothesis elucidates the peculiarities of each pool’s boiling regime. It is also possible to expand it to flow boiling by combining pool boiling liquid motion with external mechanical force. Other phase transitions, such as condensation, solidification, and melting, can also be described using boiling heat flow processes. Pool boiling performance can be improved by making a variety of adjustments to the heating surfaces as well as by using pure liquids in the water. Improvements can be made to boiling parameters such as the heat flux, the critical heat flux, the heat transfer coefficient, bubble development and departure, and so forth. A nanoparticle addition to a pure liquid or a surface coating on a heating surface can improve heat transfer and boiling properties by increasing the surface area of the liquid. Pool boiling critical heat flux was enhanced with Al2O3-water nano fluid. Authors used three different powder sizes of Al2O3 which were 0.05, 0.3 and 1.0 μm. Addition of alumina particle in water increases the boiling heat flux. Critical heat flux (CHF) was significantly enhanced using Titania and Alumina nano particles in water as compared to pure water. Average size of nano particle used was 85 nm measured by scattering electron microscope. Enhancement in Critical heat flux is due to nano particle coating on heating surface. Characteristics of nucleate boiling are greatly affected by the operating pressure. Miniature flat heat pipe (MFHP) with evaporator having micro grooved heat transfer surface gives 50% increment in critical heat flux at atmosphere pressure whereas this value increases up to 150% at 7.4 kPa pressure. The addition of CNT (carbon nanotube) to the base liquid increases the critical heat flux. Transmission electron microscopy confirms the average size of a nanoparticle as 15 nm. Authors found that by decreasing pressure from atmosphere condition critical heat flux increases to 200% with CNT/water nano fluid as compared to deionized water. SiC-water nanofluids of 100 nm size were experimented with at volume concentrations of 0.001%, 0.001%, and 0.01%. The size of the nanoparticle was confirmed by a scattering electron microscope. Authors concluded that at 0.01% of nano particle enhances critical heat flux to 105%.