Nanoparticle Volume Concentration Research Articles

Machine learning specific heat capacities of nanofluids containing CuO and Al2O3

AbstractEmpirical work and modeling approaches have shown that fundamental thermophysical parameters of constituents, nanoparticles, and base liquids have complex but synergistic effects on the specific heat capacity of nanofluids. In this work, we develop the Gaussian process regression model to investigate the statistical relationship among temperature, specific heat capacities of nanoparticles and base liquids, nanoparticle volume concentrations, and specific heat capacities of nanofluids. The model is developed with a dataset containing nanofluids with CuO and Al2O3 nanoparticles, and water and ethylene glycol (EG) as base liquids. The model also applies well to nanofluids containing mixtures of water and EG, and Al2O3 nanoparticles with different particle size distributions. The model is highly accurate and stable that contributes to fast and low‐cost estimations of specific heat capacities of nanofluids over a wide range of compositions and temperature.

Conjugate heat transfer performance of stepped lid-driven cavity with Al2O3/water nanofluid under forced and mixed convection

Two-dimensional conjugate heat transfer performance of stepped lid-driven cavity was numerically investigated in the present study under forced and mixed convection in laminar regime. Pure water and Aluminium oxide (Al2O3)/water nanofluid with three different nanoparticle volume concentrations were considered. All the numerical simulations were performed in ANSYS FLUENT using homogeneous heat transfer model for Reynolds number, Re = 100 to 500 and Grashof number, Gr = 5000, 13,000 and 20,000. Effective thermal conductivity of the Al2O3/water nanofluid was evaluated by considering the Brownian motion of nanoparticles which results in 20.56% higher value for 3 vol.% Al2O3/water nanofluid in comparison with the lowest thermal conductivity value obtained in the present study. A solid region made up of silicon is present underneath the fluid region of the cavity in three geometrical configurations (forward step, backward step and no step) which results in conjugate heat transfer. For higher Re values (Re = 500), no much difference in the average Nusselt number (Nuavg) is observed between forced and mixed convection. Whereas, for Re = 100 and Gr = 20,000, Nuavg value of mixed convection is 24% higher than that of forced convection. Out of all the three configurations, at Re = 100, forward step with mixed convection results in higher heat transfer performance as the obtained interface temperature is lower than all other cases. Moreover, at Re = 500, 3 vol.% Al2O3/water nanofluid enhances the heat transfer performance by 23.63% in comparison with pure water for mixed convection with Gr = 20,000 in forward step.

Influence of rotating twisted tape turbulator and nanofluids on heat transfer characteristics in a tube

ABSTRACT In this study, the heat transfer characteristics of water and three different water based nano fluids comprising of copper oxide (CuO), zinc oxide (ZnO) and titanium dioxide (TiO2) with constant 0.2% volume concentration (φ) of respective nanoparticles in a bare tube and bare tube fitted with “rotating twisted tape turbulator (RTTT)” of twist ratio (y = 2.88) inside, was examined. The flow rate of the working fluids (1–6 LPM) and the rotational speed of the twisted tape turbulator (TTT) (0-300 RPM) were considered as variable constraints and their influence on heat transfer characteristics were evaluated. It was detected that for all the working fluids, the convective heat transfer coefficient intensifies with upsurge in the flow rate and rotational speed of the TTT. A constant wall heat flux condition was used in the contemporary investigation. The literature review reveals that most of the research work focuses on the study of heat transfer characteristics in a bare tube with TTT. Minimal research work has been carried out on the usage of ‘rotating twisted tape turbulators’ using nano fluids as working fluid to augment the heat transfer characteristics. Further, the results indicate that the heat transfer characteristics may be enhanced by rotating the twisted tape turbulator at 300 RPM in a plain tube and by maintaining the flow rate of the working fluids at 6 LPM.

Developing Convective Mass Transfer of Nanofluids in Fully Developed Flow Regimes in a Circular Tube: Modeling using Fuzzy Inference System and ANFIS

In this study, actual nanofluids Sherwood numbers were compared by the Look-up Table-based Fuzzy Inference System (LUT-based FIS) and the Fuzzy C-means Adaptive Nero Fuzzy Inference System (FCM-ANFIS) predicted data in a circular tube under both laminar and turbulent flow regimes. Three influential parameters including material types, Reynolds numbers, and nanoparticles volume concentrations were used as the input attributes. Intelligent models had also one output presented by Sherwood numbers. The results revealed that nanoparticles size and type could play an important role in determining the mass transfer in nanofluids and the optimum nanoparticle concentration. The maximum increase in mass transfer for all nanofluids occurred in laminar flow, 36% in a 0.03% TiO2, 21% in a 0.0057% SiO2, and 16.8% in 0.01% Al2O3 nanofluids. Comparison of the experimental data with the predicted ones by FIS and ANFIS models showed that these models could predict convective mass transfer in nanofluids, while ANFIS models with only 5 rules and the shorter running time (19 s) had a simpler structure and precisely imitated the mass transfer. The best RMSE and R2 for the test data under laminar and turbulent flow were 0.044, 0.98, and 0.022, 0.99, respectively.

Numerical Study on Thermal and Fluid Dynamic Behavior of Confined Impinging Slot Jets with Nanofluids in Partially Filled Configuration of Metal Foam

In this work a numerical analysis on confined slot impinging jets constituted by a partially filled configuration of metal foam in mixed convection is illustrated. The employed working fluids are pure water or Al2O3/water based nanofluids A two-dimensional model is constructed and several Peclet numbers (equal to 100, 200, 350, 750, 1500) are assumed. Rayleigh numbers is fixed equal to 30000. The nanoparticle volume concentrations are in a range from 0% to 4% and the nanoparticle diameter is considered equal to 30nm. The target surface is characterized by a constant temperature, evaluated according to the value of Rayleigh number. The distance of the target surface is five times greater than the slot jet width. Three different values of ratio between the total system and the metal foam length have been assumed. The thermal and fluid-dynamic properties of nanofluids are estimated by a single-phase model approach. The model of local thermal non equilibrium (LTNE) is assumed in order to replicate the behavior of the metal foam characterized by a number of pores per inch (PPI) equal to 20 and a porosity of 0.9005. Results show increasing values of the convective heat transfer coefficients for increasing values of Peclet number and nanoparticle concentration. This behaviour is more evident at low Peclet number values. In conclusion, the ratio between the thermal and pumping power is calculated in order to find a trade-off between the increase of heat transfer and pressure drop.

Performance analysis of solar parabolic collector using Al2O3 nanofluids

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

An Analytical Study to Compare the Heat Transfer Performances of Water-Based TiO2, SiO2, TiC and SiC Nanofluids

The thermophysical properties as well as the thermal performance of a nanofluid can be altered upon varying the nanoparticle type and/or nanoparticle volume concentration. Herein, the effects of variable nanoparticle concentration on water-based TiO2, SiO2, TiC, and SiC nanofluids have been studied analytically. The dispersion effects of 1-4% nanoparticle on the single-phase forced convection heat transfer performance of the nanofluids have been investigated. The effective thermophysical properties of the nanofluids are determined adopting the general correlations. The flow velocities of the nanofluids relative to their base fluids are assumed to be constant. Mouromtseff number has been employed as a convenient figure of merit to compare the nanofluids under fully developed internal laminar and turbulent flow conditions. The results indicate an increase in effective density, thermal conductivity, and dynamic viscosity of the nanofluids. Nanofluids containing carbide suspensions exhibit superior heat transfer properties compared to those having oxide suspensions.

Numerical simulation of three-dimensional thermo-solutal convection of micropolar multi-walled carbon nanotubes water nanofluid stabilized by lignin and sodium polycarboxylate

A computational analysis has been performed in this study to solve three-dimensional thermo-solutal natural convection in a differentially heated cubical enclosure filled with micropolar CNT/water nanofluid stabilized by two types of surfactants lignin and sodium polycarboxylate. The work is carried out for different pertinent parameters as Rayleigh number (104 \(\le\) Ra \(\le\) 106), micropolar parameter (0 \(\le\) K \(\le\) 10), buoyancy ratio (−1 \(\le\) N \(\le\) 0) and nanoparticles’s volume fraction (0.0055% \(\le \varphi \le\) 0.557%). It is observed that the heat and mass transfer rates are lower for a micropolar nanofluid model when compared to the pure nanofluid model. In fact, the enhancement of micropolar parameter results a decrease in average Nusselt and Sherwood numbers. The use of lignin as a surfactant ameliorates heat and mass transfer rate and nanofluid flow better than the use of sodium polycarboxylate as a surfactant. The nanoparticles volume fraction can be used as a control element for heat rate and fluid flow. Thus, for a nanoparticles volume concentration less than the critical value, the flow intensity is ameliorated and is deteriorated when it exceeds this value.

Numerical and artificial neural network modeling study on the first-law and second-law performance of a novel helical heat sink filled with water–silver nanofluid

This paper is devoted to studying the first-law and second-law performances of a novel helical heat sink (HS). The biologically synthesized water–Ag nanofluid is considered as the coolant. The impacts of volume concentration of nanoparticles ( $$\varphi$$ ), Reynolds number ( $$\mathrm{Re}$$ ) and geometrical parameters of HS on the hydrothermal aspects and irreversibility behavior of HS are evaluated, and their optimal values are found. It was noted that the intensification of both the $$\varphi$$ and $$\mathrm{Re}$$ causes an augmentation in the convection coefficient, average CPU temperature and maximum CPU temperature, while the thermal resistance diminishes by rising $$\varphi$$ and $$\mathrm{Re}$$ . In addition, the fluid friction and heat transfer irreversibilities growth by intensifying the $$\mathrm{Re}$$ diminished with the increment of $$\varphi$$ . Furthermore, the outcomes showed that the best first-law performance of the HS occurs at $$\varphi =1\%$$ and $$\mathrm{Re}=1500$$ , while the lowest irreversibility occurs at $$\varphi =1\%$$ and $$\mathrm{Re}=500$$ . Finally, the obtained numerical data were utilized to develop a predictive model for convective heat transfer coefficient, thermal entropy generation rate and frictional entropy generation rate. The accuracy of the models was evaluated based on three statistical indices including mean relative error percentage (MRE), root mean square error (RMSE) and coefficient of determination (R2). It was found that the $${R}^{2}$$ value for all the developed models is higher than 0.99.

Performance of compact heat exchanger in the presence of novel hybrid graphene nanofluids

Metals and metallic oxide nanoparticles have been studied extensively for heat transfer applications as compared to functionalized graphene and hybrid nanoparticles. Volume concentrations of nanoparticles studied have been greater than 0.01%. In the present work, an attempt is made to study the effect by adding carboxyl graphene (CG), graphene oxide (GO) and novel hybrid nanoparticles to a conventional hot fluid - 50:50 ethylene-glycol and water - at ultra-low volume concentrations, on the performance of compact heat exchanger (liquid-air, automotive radiator). Effect of Reynolds number of hot fluid, Reynolds number of air, the volume concentration of nanoparticles on the performance parameters such as Nusselt number, effectiveness, pressure drop and friction factor are studied in detail. A maximum of 3.59 and 4.92 times increase in Nusselt number is observed at 0.02 vol% of CG and 0.04 vol% of GO respectively. The same is found to be 11 times at 0.005 vol % of GO and 0.0075 vol % of CG hybrid nanofluid. The results indicate a significant increase in the performance of the compact heat exchanger, both in terms of effectiveness and pressure drop. Study indicates a maximum of 232% improvement in effectiveness with a 66% reduction in pressure drop at a volume concentration of 0.005 vol % of GO and 0.005 vol % of CG. Functionalized graphene and hybrid nanoparticles offer great scope for enhancing compact-heat-exchanger-performance and/or reduction in the size.

Modeling and assessment of the thermo-electrical performance of a photovoltaic-thermal (PVT) system using different nanofluids

The proposed study aims to test the thermo-electrical, and exergy efficiency of a hybrid PVT collector cooled by pure water, copper (Cu)/water, and aluminum-oxide (Al2O3)/water nanofluids, respectively. A model is mathematically constructed using the energy-balance equation across all the layers of the hybrid PVT collector. For the validation of the proposed mathematical model, the outcomes of the proposed numerical model are compared with the experimental data of the literature. The impact of volume fraction (vol%) and mass flow rate (m) of the nanofluids on the PVT outcomes has been analyzed and demonstrated. The study displays a better PVT performance with Cu/water nanofluid compared to Al2O3/water nanofluid and pure water. Merely a 2% volume concentration of Cu nanoparticles results in a 4.98% and 5.23% improvement in the average electrical and thermal efficiencies, respectively. At a mass flow rate of 0.03 kg/s, the thermo-electrical efficiency of the PVT with Cu/water nanofluid improve by 4.45% and 2.9%, respectively, concerning the pure water. Further, the impact of several tubes and their diameter is also investigated on the thermo-electrical efficiencies of the hybrid PVT collector. The tube diameter has not any substantial effect on the performance, whereas the thermo-electrical performance significantly enhanced with the rise in the number of tubes.

Enhanced magnetohydrodynamic thermal convection in a partially driven cavity packed with a nanofluid‐saturated porous medium

Convective heat transfer characteristics in the purview of fundamentals of flow physics in a two‐sided partially driven cavity (PDC) are addressed in this work. The effect of partial translational motion on the sidewalls of PDC can significantly alter the convective heat transfer characteristics. To explore this novel idea, a square enclosure packed with Cu–water nanofluid‐saturated porous media under the influence of the external magnetic field, heated around a protruded heater mounted at the bottom wall. The cavity is cooled at the upper half of the two sidewalls—partially translating upward or downward direction. Fundamentals of the evolved flow physics and mixed convection heat transfer characteristics are analyzed numerically using extensively validated FORTRAN code based on the finite volume approach. The impacts of the relevant parameters on fluid flow and heat transfer are investigated systematically. The governing parameters are wall speed (Reynolds number) and its direction, convection regime (Richardson number), permeability (Darcy number and porosity), magnetic field strength (Hartmann number), and nanoparticles volume concentration. The results show that the thermal performance of PDC is greatly influenced by all of the above parameters. Heat transfer is enhanced significantly at higher Reynolds number, Richardson number, Darcy number, and porosity and increases in the nanoparticles volume fraction for the opposing flow case.

Experimental study on heat transfer of an engine radiator with TiO2/EG-water nano-coolant

Nanofluid as a transport medium displays a great potential in engineering applications involving heat transfer. In this paper, the execution of water and ethylene glycol-based TiO2 nanofluid as a radiator coolant is resolved experimentally. The convective heat transfer coefficient of TiO2/EG-Water nanocoolant has been estimated and contrasted with the information acquired experimentally. Nanocoolant were set up by taking 25% ethylene glycol and 75% water with low volume concentration of TiO2 nanoparticles. All the experiments were led for the distinctive volume flow rates in the range going from 30 to 180 L/h (LPH). The nanocoolant made to flow through curved radiator tubes in every experiment, so that it can exchange heat effectively. Result shows that increasing the volume flow rate of nanocoolant flowing in the radiator tubes, increases the heat transfer as well as the convective heat transfer coefficient of nanocooant. Maximum heat transfer enhancement of 29.5% was recorded for nanocoolant with 0.03% nanoparticle concentration as compared to water at 150 LPH. Apart from this nanoparticle concentration into the base fluid, no further enhancement in heat transfer has been observed at any volume flow rate.

Latent Heat Phase Change Heat Transfer of a Nanoliquid with Nano–Encapsulated Phase Change Materials in a Wavy-Wall Enclosure with an Active Rotating Cylinder

A Nano-Encapsulated Phase-Change Material (NEPCM) suspension is made of nanoparticles containing a Phase Change Material in their core and dispersed in a fluid. These particles can contribute to thermal energy storage and heat transfer by their latent heat of phase change as moving with the host fluid. Thus, such novel nanoliquids are promising for applications in waste heat recovery and thermal energy storage systems. In the present research, the mixed convection of NEPCM suspensions was addressed in a wavy wall cavity containing a rotating solid cylinder. As the nanoparticles move with the liquid, they undergo a phase change and transfer the latent heat. The phase change of nanoparticles was considered as temperature-dependent heat capacity. The governing equations of mass, momentum, and energy conservation were presented as partial differential equations. Then, the governing equations were converted to a non-dimensional form to generalize the solution, and solved by the finite element method. The influence of control parameters such as volume concentration of nanoparticles, fusion temperature of nanoparticles, Stefan number, wall undulations number, and as well as the cylinder size, angular rotation, and thermal conductivities was addressed on the heat transfer in the enclosure. The wall undulation number induces a remarkable change in the Nusselt number. There are optimum fusion temperatures for nanoparticles, which could maximize the heat transfer rate. The increase of the latent heat of nanoparticles (a decline of Stefan number) boosts the heat transfer advantage of employing the phase change particles.

Natural Convective Effects on MHD Boundary Layer Nanofluid Flow over an Exponentially Accelerating Vertical Plate

The problem of unsteady natural convective nanofluid flow along with an exponentially accelerating vertical plate under the influence of transverse magnetic field is discussed in two important cases when the magnetic lines of force are fixed relative to the fluid or the moving plate. The governing equations are transformed into dimensionless form and tackled with the usual time-frequency Laplace transform technique. The impacts of various parameters on the heat transfer characteristics and nanofluid flow transport with thermal radiation, heat generation/absorption, and nanoparticle volume concentration have been studied through graphs.

Effect of Heat Transfer on the Growing Bubble with the Nanoparticles/Water Nanofluids in Turbulent Flow

This paper is devoted to study the effect of heat transfer on the temperature distribution in a superheated liquid during the growth of vapour bubbles immersed in different types of nanoparticles/water nanofluids between two-phase turbulent flow. The mathematical model is formulated and solved analytically depending on Scriven's theory and using the modification of the method of the similarity parameters between two finite boundaries. The characteristics of vapour bubble growth and temperature distribution are obtained by using the thermo-physical properties of nanoparticles nanofluids. The results indicate that the nanoparticle volume concentration reduces the bubble growth process under the effect of heat transfer. The better agreements are achieved, for bubble dynamics in turbulent nanofluid using the appropriate numerical and theoretical data for the values of concentration rate of nanoparticles χ=0,0.2,0.4. The temperature distribution surrounding the regime of bubble growth in pure water is more intensive than in other cases of Al2O3/H2O, Fe3O4/H2O and CuO/H2O nanofluids in turbulent flow. A Comparison of the current solution with previous works is carried out and discussed.

Single-Phase Natural Circulation Loop Using Oils and Ternary Hybrid Nanofluids: Steady-State and Transient Thermo-Hydraulics

Abstract Steady-state and transient behaviors of single-phase natural circulation loop (SPNCL) are investigated using four thermal oils (Therminol VP1, Paratherm CR, Dowtherm A, and Dowtherm Q) and water-based ternary hybrid (various combinations of different nature and shaped nanoparticles: Al2O3, Cu, carbon nanotube (CNT) and graphene) nanofluids as loop fluid. The influences of nanoparticle volume concentration and loop height-to-width ratio on the mass flow rate and total entropy generation rate of SPNCL are investigated. Results disclose that ternary hybrid nanofluids enhance flow initiation, reduce fluctuation and are expected to attain a steady-state faster than water. Steady-state mass flow rate increases/decreases for ternary hybrid nanofluid depending on the shape of the nanoparticle, and the total entropy generation rate decreases as compared to water. Thermal oil shows a higher mass flow rate and total entropy generation rate as compared to water. Al2O3–Cu–CNT–water and Paratherm CR show the best result among all ternary hybrid nanofluids and thermal oils, respectively. The nanoparticle shape decides the optimum nanoparticle volume fraction. Increasing the height-to-width ratio decreases the total entropy generation and upsurges the mass flow rate at specified input power. The optimum height-to-width ratio depends on the loop fluid.

Experimental evaluation of the lubrication performance of MoS2/TiO2 nanoparticles for diamond wheel bond in silicon carbide ceramic grinding

In this study, a new type of self-lubricating nanoparticle diamond grinding wheel with MoS2 and TiO2 nanoparticles as filling materials was proposed. According to the macro parameters (grinding force) and micro parameters (surface roughness, surface morphology, grinding wheel wear), the lubricated characteristic on tool and workpiece surface with various concentrations of nanoparticles was studied. The research indicated that the composite nanoparticles can effectively improve the lubricated characteristic of the tool. The nanoparticles released from the grinding wheel can participate in lubrication and decrease the adhesion of abrasive grains to the workpiece surface, so as to enhance the surface quality of the workpiece. Moreover, there is a suitable addition range of composite nanoparticles in the grinding wheel. Adding too little or exceeding this range will weaken the friction reduction performance of the nanoparticles. It had the best lubrication performance and surface quality of the workpiece at a nanoparticle volume concentration of 8%.

A systematic review on graphene-based nanofluids application in renewable energy systems: Preparation, characterization, and thermophysical properties

Graphene has attracted much attention from various researchers because of its enhanced mechanical, thermal, and physio-chemical properties. Graphene exhibits high thermal conductivity and stability, less erosion and corrosion than other available nanoparticles. Various existing literature signifies a large portion of the research focuses on stability, heat transfer characteristics and thermal conductivity of Graphene nanofluids. This review article represents a detailed analysis of the preparation techniques, characterization methods stability evaluation, and thermal properties enhancements of Graphene nanofluids. Comparative analysis of the effects of nanoparticle size, volume concentration and temperature on thermal conductivity and viscosity of Graphene nanofluids are reviewed based on heat transfer application. Graphene nanoparticles significantly enhances the thermal conductivity, viscosity, and heat transfer capacity of base fluid. It is noticed that the thermal conductivity of Graphene nanofluids increases with an increase in temperature and volume concentration. Applications of Graphene based nano coolant in automotive radiator, electronic cooling, solar cells and fuel cells are presented. This article can be the rapid reference model with investigational and theoretical analysis for highly critical considerations that impact the thermal performance of graphene based nanofluids in different heat transfer trends. This review also outlined the imminent challenges and future scope of research in Graphene.

Thermal-hydraulic performance of TiO2-water nanofluids in an offset strip fin heat exchanger

The flow and heat transfer characteristics of the TiO2-water nanofluid assuming as a single-phase in the rectangular offset strip fin structure for different Reynolds number (500-1000) and TiO2 nanoparticle volume concentration values (0-4%) were investigated numerically under 3-D, steady-state, and laminar flow conditions. Simulations were also performed for 1% and 4% nanoparticle volume concentrations of Al2O3-water nanofluid, and the results were compared with those of TiO2-water nanofluid. Results show that when the TiO2-water nanofluid is used, the heat transfer rate, heat transfer coefficient, and Nusselt number increase with increasing both Reynolds number and nanoparticle volume concentration, and parallel to these, both pressure loss, and pumping power increase. Considering the values of the performance evaluation criteria number, it is clear that the use of TiO2-water nanofluid in offset strip fin structure at all Reynolds numbers examined between 1-4% volume concentration values is quite advantageous. It is observed that TiO2-water nanofluid is much superior to Al2O3-water considering the performance evaluation criteria number. When the Reynolds number is 1000 and the volume concentration value of the TiO2 nanoparticle is 4%, the performance evaluation criteria number value is found to be 1.19, that is, there is a 19% increase compared to water. It is considered that the results of this study can be used as important data on the design of automobile radiators, air-conditioning, and defense.