Volume Concentration Of Nanofluid Research Articles

CHF enhancement partitioning based on surface wettability and porosity on CeO2 nanoparticle coated surface

The experimental boiling critical heat flux (CHF) behavior of CeO2 nanoparticles coated surface under various deposition condition was experimentally measured. The CHF behavior of CeO2 nanoparticles coated surface was analyzed based on coupled analysis of surface wettability and capillarity. The surface conditions were modulated by changing the volume concentration and deposition time during the nanoparticles coating process. The convex shaped CHF behavior was observed along with the volume concentration of nanofluid. The analysis based on a single parameter such as surface wettability and capillarity couldn’t explain the complex CHF behavior. The novel way to explain the complex CHF behaviors of CeO2 nanoparticles coated surface is proposed. The model in this study considered the coupling behavior of surface rewetting and liquid transport by capillary wicking motion through the CHF enhancement partitioning. This efforts for the coupling of different physical phenomena on the boiling crisis condition will be beneficial to precise prediction of boiling CHF values on the engineered heater surface.

Two Phase Flow Through Micro Channel Using Nanofluids

Micro/mini channel based circuits with cooling media is one of the most efficient solution for the thermal management of electronic components due to its higher heat transfer coefficient and higher heat transfer surface area per unit volume. Fluid flow and heat transfer characteristics of flow through microchannel under single phase and two phase flow conditions using Aluminium oxide nanofluid is experimentally investigated. An experimental set up with microchannel heat sink has been fabricated and the analysis has been performed for different volume percentage of nanoparticles like 0.001%, 0.01% and 0.1%.The single phase and two phase heat transfer coefficients were found to be high for flow with nanofluid compared to base fluid but with a pressure drop penalty. The single phase heat transfer coefficient increases with increasing concentration of nanofluid. But the two phase heat transfer coefficient increases up to certain value of the volume concentration of nanofluid and then decreases. The critical heat flux also found to be high for the flow with nanofluid than water and is found to be increasing with increasing concentration of nanofluid. The single phase flow results using water as the working fluid are compared with the standard correlations available in the literature and are found to be matching well.

Experimental study on Al2O3 /H2O nanofluid with conical sectional insert in concentric tube heat exchanger

ABSTRACT A parallel flow heat exchanger containing conical sectional inserts with three different pitch ratio (i.e., 1, 2, and 3) in a different orientation to the flow direction of the working fluid had been fabricated. Al2O3 with different volume concentration, i.e., 0%, 2%, and 4% nanoparticles (90 nm size) were added to De-ionized water as the working fluid. The combined effect of the Nanofluid and the inserts in different orientations was studied. It was concluded that the insert, flow direction, and Nanofluid volume concentration provided most augmented heat transfer and enhanced the thermal properties.

Experimental Testing of Thermo Physical Properties of Novel Water and Glycerol Mixture-Based Silica Nano Fluids

The main objectives of the present work embrace the preparation of cobalt nanofluids, amalgamation of silica nanofluid with optimum glycerol-water (G-W) mixture ratio and estimation of its thermal properties like thermal conductivity and viscosity experimentally. Optimum ratio of base liquid (G-W mixture) was selected for the preparation of nanofluids. Subsequently, thermophysical properties of the hybrid nano mixture have been determined experimentally using KD2Pro thermal properties analyzer and Brookfield viscometer at different volume concentrations of silica nanofluids. Attained results reveal that, the dynamic viscosity and thermal conductivity are found to be growing remarkably with the increase in nanoparticle weight concentration in base liquid mixture. The results are found to be in good agreement with the available data from the literature.

Effects of Fe3O4/Water Nanofluid on the Efficiency of a Curved Pipe

Different-radius of curvature pipes are experimentally investigated using distilled water and Fe3O4–water nanofluid with two different values of the nanoparticle volume fraction as the working fluids. The mass flow rate is approximately varied from 0.2 to 0.7 kg/min (in the range of laminar flow); the wall heat flux is nearly kept constant. The experimental results reveal that utilizing the nanofluid increases the convection heat transfer coefficient and Nusselt number in comparison to water; these outcomes are also observed when the radius of curvature is decreased and/or the mass flow rate is increased (equivalently, a rise in Dean number). The resultant pressure gradient is, however, intensified by an increase in the volume concentration of nanoparticles and/or by a rise in Dean number. For any particular working fluid, there is an optimum mass flow rate, which maximizes the system efficiency. The overall efficiency can be introduced to include hydrodynamic as well as thermal characteristics of nanofluids in various geometrical conditions. For each radius of curvature, the same overall efficiency may be achieved for two magnitudes of nanofluid volume concentration.

Experimental study of heat transfer performance of compact wavy channel with nanofluids as the coolant medium: Real time non-intrusive measurements

Heat transfer performance of nanofluids in the context of corrugated compact channels has been experimentally investigated through real-time, non-intrusive diagnostic technique. The corrugated channel (dimensions: 50 mm (length) × 10 mm (width) × 4 mm (depth); hydraulic diameter of 5.7 mm) comprises of two horizontal wavy plates aligned in an in-phase configuration. Amplitude and period of the wavy plates have been kept constant. Experiments have been performed with varying concentrations of Al2O3/water-based nanofluids for Re = 350–1000. For reference, experiments have also been conducted using water as the base fluid and a plane channel with the same hydraulic diameter as that of the corrugated channel. Convective field has been mapped using a Mach-Zehnder interferometer. Results have been qualitatively as well as quantitatively interpreted to characterize the heat transfer performance of nanofluids as the coolant medium. Interferograms recorded under infinite fringe setting mode captured the phenomena of flow detachment and re-attachment at the wavy sections of the corrugated channel and their dependence on nanofluids concentration. Thermal boundary layer profiles at such sections are seen to be locally perturbed due to flow detachment and its subsequent attachment to the principal wall of the channel. Quantitative data retrieved through the wedge fringe setting interferograms revealed a clear enhancement in heat transfer coefficient for the combination of nanofluids and corrugated channel in comparison with that achieved through water in the plane and/or corrugated channel. For any given Re and channel configuration, the heat transfer coefficient is seen to increase with increasing concentration of dilute nanofluids. For the wavy channel, an enhancement of ≈37% in heat transfer rates with 0.02% volume concentration of nanofluids is achieved at Re = 350 in comparison to the plane channel at the similar levels of nanoparticles volume concentration.

CFD analysis on heat and flow characteristics of double helically coiled tube heat exchanger handling MWCNT/water nanofluids

Double helically coiled tube heat exchangers are used in different heat transfer utilization due to higher heat transfer capabilities and with their compactness. The double helically coiled tube heat exchanger increases the turbulence and enhances the maximum heat transfer rate than the straight tubes. In this investigation, the heat transfer and pressure drop of the double helically coiled heat exchanger handling MWCNT/water nanofluids have been analyzed by the computational software ANSYS 14.5 version. The computational analysis was carried out under the laminar flow condition in the Dean number range of 1300–2200. The design of new shell and double helically coiled tube heat exchanger was done by using standard designing procedure and 3D modeling was done in Cre-O 2.0 parametric. The Finite Element Analysis software ANSYS Workbench 14.5 was used to perform CFD analysis under the standard working condition. The MWCNT/water nanofluids at 0.2%, 0.4%, and 0.6% volume concentrations have been taken for this investigation. The major factors like volume concentrations of nanofluids and Dean Number are considered for predicting the heat transfer rate and pressure drop. The simulation data was compared with the experimental data. It is studied that the heat transfer rate and pressure drop increase with increasing volume concentrations of MWCNT/water nanofluids. It is found that the Nusselt number of 0.6% MWCNT/water nanofluids is 30% higher than water at the Dean number value of 1400 and Pressure drop is 11% higher than water at the Dean number value of 2200. It is found that the simulation data hold good agreement with the experimental data. The common deviation between the Nusselt number and pressure dropof CFD data and the Nusselt number and pressure drop of experimental data are found to be 7.2% and 8.5% respectively.

Optimization of Performance of Heat Exchanger through Nano Fluid Particles

This paper study about the use nanofluid as base fluid, stability control, thermo- physical properties, pressure drop and CFD Analysis. Our project is based on CFD Analysis “Performance Analysis of Heat Exchanger” using Fluent. This paper presents the effect of using Al2O3 nanofluid in shell and tube type heat exchanger, addition surfactant on nanofluid for long term stability, and also shows the changes in heat transfer coefficient and pressure drop. Upon geometrical optimization, the first phase of this work aims at studying the influence of Al2O3 nanofluid at 0.2% concentrations size of 20nm by admitting water along the shell side and Al2O3 nanofluid along the tube side and also water as base fluid having water in both shell and tube side of heat exchanger. The shell and tube heat exchanger of various geometrical configurations is modelled using ANSYS 2019 R3. The heat transfer and fluid flow characteristics through the heat exchanger are obtained by using ANSYS Fluent CFD. Temperature, pressure contours and velocity streamlines of the shell and tube heat exchanger are obtained for various geometrical configurations and for 0.2% volume concentration of nanofluid. The use of nanofluid resulted in increase of both the pressure drop and heat transfer coefficient. The heat transfer coefficient is increased by 7.6% than water by using 0.2% volume fraction Al2O3 nanofluid and pressure drop is increased upto 11%.

Performance analysis for hybrid PV/T system using low concentration MWCNT (water-based) nanofluid

This paper presents experimental work on utilising Nanofluid as a working agent for Photovoltaic Thermal Systems (PV/T). PV/T systems are one kind of hybrid systems in energy utilisation. They convert the incident solar radiation into two energy types; electricity and heat. In this research, experimental outdoor tests were directed to assess the execution of PV/T system that utilises water-based Multi Walls Carbon Nano Tubes “MWCNT” as a heat storage/heat absorption agent. The effect of varying Nanofluid volume concentration ratio was studied within the range (0%:0.3%) while fixing the circulation rate at 1.2 l/min. By analysing the experimental results, it can be noted that adding Nano Particles to the base fluid caused the thermal properties to have a significant increment leading the PV/T system to have a better thermal and electrical efficiency. The best system efficiencies were obtained at 0.075% V of MWCNTs – water based Nanofluid. At this concentration, a temperature reduction of 12 °C for the PV panel was attained at maximum incident radiation leading to an overall system efficiency of 83.26%. Also, an average temperature reduction of 10.3 °C was achieved over the daytime leading to an overall efficiency of 61.23%.

Energetic and Exergetic Performances of Plate Heat Exchanger Using Brine-Based Hybrid Nanofluid for Milk Chilling Application

Theoretical study on the energetic and exergetic performances of a counter-flow corrugated plate heat exchanger using hybrid nanofluids for the milk chilling application has been done in the present investigation. Magnesia-silver and Alumina-silver nanoparticles have been dispersed in the ethylene glycol–water mixture and propylene glycol–water mixture (20:80 brine solutions) with different particle volume concentration separately. Effect of particle volume concentration and flow rate of the hybrid nanofluid on the heat transfer rate, convective, and overall heat transfer coefficients, mass flow rate of milk, pressure drop, pumping power, entropy generation rate, second law efficiency, irreversibility, irreversibility distribution ratio, non-dimensional exergy (NDE) destruction, and performance index have been studied. It has been observed that heat transfer rate, convective and overall heat transfer coefficients, pressure drop, pumping power, irreversibility, entropy generation rate, second law efficiency, and milk flow rate increase; while NDE destruction, performance index, and irreversibility distribution ratio decrease with the hybrid nanofluid flow rate and the volume concentration of the nanofluid. Within studied ranges, the hybrid nanofluid yields the maximum improvement of heat transfer rate and convective heat transfer coefficient of about 1.6% and 9.4%, respectively, compared to base fluid. It has also been found that silver + alumina shows slightly better performance improvement and hence hybrid nanofluid is recommended as a suitable alternative for the milk chilling units.

Heat transfer and effectiveness experimentally-based analysis of wire coil with core-rod inserted in Fe3O4/water nanofluid flow in a double pipe U-bend heat exchanger

Heat transfer, friction factor, and effectiveness-number of transfer units were estimated experimentally for different volume concentrations of Fe3O4 nanofluid flow in an inner tube of a double pipe U-bend heat exchanger with different pitch ratios (p/d) of wire coil with core-rod (WCCR) inserts. The experiments were conducted at different particle volume concentrations (0.005%, 0.01%, 0.03% and 0.06%), different Reynolds numbers (16000–29000) and different pitch ratios of WCCR inserts p/d=1,1.34and1.79. The Nusselt number, for a 0.06% volume concentration of nanofluid, is enhanced up to 9.76% and 14.76% at Reynolds number of 16545 and 28954, respectively when compared to water data with a pumping penalty of 10%. Similarly, the Nusselt number is further enhanced to 25.39% and 37.90% for 0.06% nanofluid with wire coil with core-rod insert of p/d=1 at Reynolds number of 16545 and 28954, respectively compared to water. Nusselt number and friction factor correlations were proposed based on the experimental data. The effectiveness-number of transfer units (NTU) were calculated for water/nanofluids flow in a tube with WCCR inserts.

Convective heat transfer studies on helically corrugated tubes with spiraled rod inserts using TiO2/DI water nanofluids

Convective heat transfer and friction factor studies are experimentally carried out in a smooth and five helically corrugated tubes of different heights and pitches of corrugation with spiraled rod inserts. The experiment is conducted under turbulent flow (Re = 4800–8900) and constant wall heat flux conditions. Deionized (DI) water and titanium dioxide (TiO2)/DI water nanofluids are used as working fluids. The average size of TiO2 nanoparticles is 32 nm. Two volume concentrations of nanofluids (0.25 and 0.5%) are used in this study. The combined effects of nanofluids, inserts and corrugation in tubes on Nusselt number and friction factor are investigated. The results indicate that (i) the addition of TiO2 nanoparticles in DI water upsurges the heat transfer rate, which increases with nanofluids volume concentrations; (ii) use of inserts and corrugation in tubes enhances the heat transfer rate further; (iii) among the corrugated tubes, the tube having highest corrugation height (hc = 1 mm) and lowest pitch (pc = 8 mm) with spiraled rod insert of smaller pitch (pi = 30 mm) shows the maximum thermal performance factor of 1.56 for 0.5% volume concentration of nanofluids.

Investigation On Heat Transfer Properties Of Water Based TiO2-ZnO Nanofluids

Nanofluids in heat transfer applications exhibit effective performance over conventional heat transfer fluids. High thermal loads due to miniaturization in a wide variety of applications offers technological challenges in designing efficient thermal management systems. Traditional heat transfer fluids such as air, water, engine oil, and ethylene glycol (EG) have very low thermal conductivities of 0.03, 0.613, 0.145 and 0.253 W/mK respectively. The poor thermal conductivity of these fluids is an obstacle in improving heat transfer and compactness of the heat exchangers. Determination of properties of nanofluids and its performance in water based base fluids has been studied by many researchers. However the heat transfer performance of mixed nanofluids ie., hybrid nanofluids is yet to be explored. TiO2 and ZnO nanofluids were prepared at 0.5%, 1.5% and 2.0% volume concentration. Thermal conductivity estimated for temperature range of 30-70°C. Significant enhancement of both heat transfer rate and effectiveness of heat exchanger was noticed with TiO2 nanofluids at 2.0% volume concentration and with 1.5% volume concentration of TiO2-ZnO hybrid nanofluids.

Heat Transfer and Fluid Flow Optimization of Titanium Dioxide–Water Nanofluids in a Turbulent Flow Regime

In this study, the convection heat transfer and pressure drop of titanium dioxide–water nanofluids were modeled by applying the fuzzy C-means adaptive neuro-fuzzy inference system approach for a completely developed turbulent flow based on experimentally obtained training and test datasets. Two models were proposed based on the effective parameters; one model was developed for the Nusselt number considering the effects of the Reynolds number, Prandtl number, nanofluid volume concentration and average nanoparticle diameter. Another model was suggested for the pressure drop of the nanofluid as a function of the Reynolds number, nanofluid volume concentration, and average nanoparticle diameter. The results of these two proposed models were compared with experimental data as well as the existing correlations in the literature. The validity of the proposed models was benchmarked by statistical criteria. Moreover, a modified non-dominated sorting genetic algorithm multiobjective optimization technique was applied to obtain the optimum design points, and the final result was shown in a Pareto front.

Comparative study of heat transfer and friction characteristics of water-based Alumina–copper and Alumina–CNT hybrid nanofluids in laminar flow through pipes

In this experimental work, a comparative study of convective heat transfer and drop in pressure characteristics of Alumina–Cu/water and Alumina–CNT/water hybrid nanofluids in fully developed laminar flow in a uniformly heated tube with circular cross section is presented. For this, Alumina–Cu hybrid nanoparticles (90:10 proportion was taken. Below this proportion for, e.g., 80:20, the nanofluid was not stable. Coagulation was happening) were prepared by using a hydrogen reduction technique. Characterization was done for the prepared powder through XRD and scanning electron microscope (SEM) to validate the chemical constitution, to establish the size of the particle and to investigate the morphology of surface. The synthesized Alumina–Cu hybrid nanopowder is dispersed in deionized water in an ultrasonic bath to form a well-dispersed 0.1% volume concentration of hybrid nanofluid. Carbon nanotube (CNT) functionalization was done by acid treatment method to convert the CNT surface from hydrophobic to hydrophilic. Scanning electron microscope was used for characterization of the aluminum oxide particles and functionalized multi-walled carbon nanotubes. To prepare 0.1% volume fraction of Alumina–CNT/water nanofluid, required quantities of Alumina powder and functionalized CNT were dispersed in deionized water in 90:10 proportion. Experiments were conducted in the laminar flow range with water, Alumina/water and hybrid nanofluids, and the results obtained have been compared. The convective heat transfer experimental results showed greater enhancement with Alumina–CNT/water hybrid fluid compared to Alumina–Cu/water hybrid fluid. The maximum enhancements of 30.65% and 20.48% in Nusselt number have been obtained for 0.3% volume fraction of Alumina–CNT/water hybrid nanofluid and Alumina–Cu/water hybrid nanofluid, respectively, at Reynolds number of 1350 as compared to the Nusselt number of water.

Experimental determination of thermal conductivity and viscosity of different nanofluids and its effect on a hybrid solar collector

In this research, three different volume concentrations (ϕ = 0.05, 0.1 and 0.2%) of Al2O3/water, CuO/water and Al2O3–CuO/water (50:50) nanofluids are prepared by adopting a two-step nanofluid preparation method. Al2O3 and CuO nanoparticles with the average diameter of 50 nm and 27 nm were dispersed in distilled water. The thermal conductivity and viscosity of prepared nanofluids are measured for different temperatures by using KD2 Pro thermal property analyzed and Brookfield viscometer, respectively. The effects of nanofluids on the thermal, electrical and overall efficiency of photovoltaic thermal (PVT) solar collector are also studied. The experimental results revealed that the thermal conductivity and viscosity increase with the increase in percentage volume concentration and viscosity decreases with the increase in temperature. Furthermore, the obtained maximum thermal and electrical efficiencies of a PVT solar collector for 0.2% volume concentration of hybrid nanofluids are 82% and 15%, respectively, at peak solar radiation. The highest overall efficiency of a PVT collector with .2% volume concentration of hybrid nanofluid was 97% at peak solar radiation. Results recommend that nanofluids can be used as a heat transfer in PVT solar collector.

Experimental Study on Heat Treatment of SS 420 and EN 24 Using Nanoparticulate Quenching Process

Heat transfer through nanotechnology is a current trend which occupies most research areas with improved results. Taking this concept, the present work has been focused on the analysis of quenching effect on steel such as EN 24 and SS 420 with nanoparticles dispersed in quenching medium. Quenching is the process of removing heat from the heat-treated elements which also take part in determining the hardness values depending on the heat transfer rate and quenching time. To ensure the outcome properties, different volume concentrations of nanofluids have been prepared by adding TiO2 nanoparticles with the average diameter of less than 20[Formula: see text]nm in synthetic oil. Here, it is planned to have four volume concentrations (0.25[Formula: see text]g/lit, 0.375[Formula: see text]g/lit, 0.5[Formula: see text]g/lit, 0.625[Formula: see text]g/lit) of nanofluids to be used in the experiment. The materials after facing heat treatment up to 850∘C (EN 24) and 980∘C (SS 420), are subjected to quenching by using nanofluid. The work has been carried out by altering the tempering temperature and volume of nanoparticles in the quenching medium. The outcome quality of the product desirably supports our expectations, such as improved hardness and reduced time consumption for quenching. Additionally, the comparative analysis shows an improvement in heat transfer characteristics as well as properties in quenched specimen with nanofluids.

Thermal performance prediction of wickless heat pipe with Al2O3/water nanofluid using artificial neural network

A wickless heat pipe (WHP) comprises of an evacuated-close tube filled with an appropriate amount of working fluid. In this study, the effect of Al2O3/water nanofluid as the working media on thermal performance of WHP investigated and compared with pure water by designing an optimized Artificial Neural Network (ANN). ANN trained with the collected test data obtained from experimental setup and validated. Multilayer Perceptron configuration (MLP) adopted for the ANN. The MLP architecture consists of four input nodes representing the parameters; input power, volume concentration of nanofluid, filling ratio and mass rate in condenser section, and a single output node representing the thermal efficiency of WHP. According to sensitivity analysis results, volume concentration is the most significant parameter which affects the WHP performance. Also, since the ANN test output data are sufficiently close to experimental one, it can be inferred that the ANN model can be applied to accurately model WHP thermal performance.

Effectiveness analysis of solar flat plate collector with Al2O3 water nanofluids and with longitudinal strip inserts

The solar flat plate collector effectiveness enhancement was studied experimentally using Al2O3/water nanofluids and with longitudinal strip inserts. The experiments were conducted in the Reynolds number range from 5000 to 13,500, longitudinal strip inserts of aspect ratios (AR) equal to 1, 1.5 and 3, volume concentrations of 0.1% and 0.3%. From the results, it is noticed that the Nusselt number enhancement for 0.3% volume concentration of nanofluid is 8.53% and 20.9% at Reynolds number of 5000 and 13,500, respectively compared with water data. The Nusselt number is further enhanced to 29.46% and 57.83%, as compared to water data, for 0.3% volume concentration of nanofluid with a longitudinal strip insert of aspect ratio (AR) equal to 1 at Reynolds number of 5000 and 13,500, respectively. The thermal effectiveness of plain collector is enhanced to 58% for 0.3% volume concentration of nanofluid at a Reynolds number of 13,500 and it is further enhanced to 84% for 0.3% volume concentration of nanofluid with longitudinal strip inserts of aspect ratio equal to 1 at a Reynolds number of 13,500.

Development of multilayer perceptron artificial neural network (MLP-ANN) and least square support vector machine (LSSVM) models to predict Nusselt number and pressure drop of TiO2/water nanofluid flows through non-straight pathways

In this study, Multilayer Perceptron Artificial Neural Network (MLP-ANN) model and Least Square Support Vector Machine (LSSVM), were developed to predict the thermal performance and pressure loss of nanofluid flow through coils as non-straight pathways. There different coils with various curvature ratios and coil pitches were constructed and used. Stable TiO2 (50 nm)/water nanofluid in different concentrations from 0.0 to 2.0% were prepared using appropriate method. As it is expected, considerable enhancement of heat transfer was achieved by application of nanofluids instead of water in system. Volume concentration of nanofluid, Prandtl number (ranging from 4.82 to 9.11) and Helical number (106.80 to 1282.87) were introduced to the developed models to obtain Nusselt number (9.89 to 53.30) and pressure drop (291.35 to 18784 kPa) as the output data of the models. According to the output results of developed models, MLP-ANN model was able to predict both Nusselt number and pressure drop of nanofluid flow more precisely in comparison to LSSVM model. The developed MLP model of this study exceeded LSSVM model to high correlation coefficient value of 0.97.