Nanofluid Samples Research Articles

How the dispersion of magnesium oxide nanoparticles effects on the viscosity of water-ethylene glycol mixture: Experimental evaluation and correlation development

In this paper, the effect of dispersion of magnesium oxide nanoparticles on viscosity of a mixture of water and ethylene glycol (50–50% vol.) was examined experimentally. Experiments were performed for various nanofluid samples at different temperatures and shear rates. Measurements revealed that the nanofluid samples with volume fractions of less than 1.5% had Newtonian behavior, while the sample with volume fraction of 3% showed non-Newtonian behavior. Results showed that the viscosity of nanofluids enhanced with increasing nanoparticles volume fraction and decreasing temperature. Results of sensitivity analysis revealed that the viscosity sensitivity of nanofluid samples to temperature at higher volume fractions is more than that of at lower volume fractions. Finally, because of the inability of the existing model to predict the viscosity of MgO/EG-water nanofluid, an experimental correlation has been proposed for predicting the viscosity of the nanofluid.

Experimental study of nanoparticles distribution in natural convection of Al2O3-water nanofluid in a square cavity

The objective of the present study is to investigate experimentally the non-homogenous distribution of nanoparticles in the nanofluid by natural convection heat transfer inside a square enclosure. There are some phenomenon such as fluid motion, Brownian effect, thermophoresis effect and gravity which cause nanoparticles movements throughout the nanofluid. An experimental set-up was built to carefully take micro-litter samples of nanofluid from a 8 × 8 × 18 (cm3) square cavity. The nanofluid was prepared using 20 nm-gamma type Al2O3 nanoparticles dispersed in deionized distilled water. The experiments were done for three Rayleigh numbers 0.992 × 107, 0.51 × 108 and 1.53 × 108 and the particle loading of 1% was constant during the experiments. The contours of nanoparticle fraction shows that the assumption of non-homogeneity is correct and the regions of high and low nanoparticle volume concentration are distinguishable. The fluid motion is the most important factor that may come in to play especially at higher Rayleigh number and causes the maximum differences between measured nanoparticle concentration. The result showed that the differences between maximum and minimum volume fraction in the whole cavity increases from 18% at Ra = 0.992 × 107 to 28.74% at Ra = 1.51 × 108. It was observed that the average nanoparticle volume fraction along cold wall is 3.10% greater than that along hot wall for minimum Ra number however at higher Ra numbers this difference would weaken. To check precision of replicates and ensure accuracy, the data were analyzed using analysis of variance method (ANOVA method).The present work reveals that there are still some issues for flow and thermal mechanisms in nanofluids, particularly regarding the nanoparticles distribution for future works.

Examination of effects of multi-walled carbon nanotubes on rheological behavior of engine oil (10W40)

In this study, effects of multi walled carbon nanotubes and temperature on rheological behavior of engine oil (10W40) have been examined. For this purpose, the experiments were carried out in the temperature range of 5-55°C for several suspensions with solid volume fractions of 0.025%, 0.05%, 0.1%, 0.25%, 0.5% and 0.75%. The viscosity of all samples was measured in the shear rate range of 666s-1 to 13333 s-1 at all temperatures considered. The viscosity measurements at different shear rates revealed that all nanofluid samples showed non-Newtonian behavior. The results also revealed that for an increase in the solid volume fraction from 0 to 0.75%, the viscosity increases to 2.5 times. The consistency and the power law index were attained by curve-fitting method for all samples and temperatures. Furthermore, the curve-fitting results revealed that the consistency index and apparent viscosity of nanofluid increases with augmenting the solid volume fraction and diminishes with growing temperature.

Studies on effect of various surfactants on stable dispersion of graphene nano particles in simarouba biodiesel

Discovery of graphene has inspired researchers a range of potential applications. Conventional fluids with nanoparticle of size 1-100nm dispersed in them are called Nanofluids. Nanofluids are found to possess increased physical and thermal properties like thermal diffusivity, viscosity, thermal conductivity and convective heat transfer coefficient. These properties can be explored in the field of IC engines as additives in improving the engine performance and reducing the harmful emissions like NOx, CO, UBHC etc. In this work, a comparative study of two anionic dispersants Sodium Dodecyl Sulfate (SDS) and Sodium Dodecyl Benzene Sulfonate (SDBS) as dispersants for stable dispersion of graphene in Simarouba biodiesel with 20%blend in diesel (SME20) was made. Nanofluids samples of graphene at 20ppm and different mass fraction of SDBS & SDS were prepared. Dispersion of graphene was achieved by ultrasonication and magnetic stirring. Dispersion was characterized with Ultra Violet Visible (UV-Vis) spectroscopy. The UV-Vis absorption spectra revealed the presence of Graphene with characteristic λmax at around 250 nm. Experimental result showed that with increase in concentration of dispersant, the value of absorbance also increased. There is a linear relation between stability of dispersion and UV absorbency. An optimum graphene- to-surfactant ratio was determined. Surfactant concentration above or below this ratio was shown to decreases the stability of dispersion. For a mass fraction of 1:4, Graphene to SBDS ratio, the absolute value of UV absorbency was highest. Dispersion stability of SDBS was better than SDS at all concentration levels.

Infrared thermography based magnetic hyperthermia study in Fe3O4 based magnetic fluids

Owing to the immense clinical benefits, magnetic hyperthermia is likely to emerge as an alternate cancer therapeutic procedure in the near future. Presently, radio frequency immune fiber optic based sensors are being used to monitor temperature changes during magnetic hyperthermia measurements, which have inherent limitations due to the requirement of physical contact of the sensor with the sample, contamination and temperature monitoring at a single point. Here, we investigate the field induced heating of oil based oleic acid coated Fe3O4 nanofluid, synthesized using co-precipitation method, using infrared thermal imaging (IRT) camera and compare the results with those of fiber optic temperature sensor. Experiments were performed on nanofluid samples of four different concentrations and under five different external field amplitudes. The specific absorption rate (SAR) of the samples were determined from the initial rate of temperature rise measured using both the techniques. The SAR values determined from both the techniques were in very good agreement with each other, with in an accuracy of 5%, after incorporating convection loss correction on the infrared thermal imaging data. The consecutive thermal cycling on the samples showed good thermal stability and thermal recovery. The maximum SAR obtained was 95.9W/gFe for a sample concentration and field amplitude of 23wt.% and 57.3kAm−1, respectively. This study showed the efficacy and accuracy of temperature measurement using IRT during field induced heating of magnetic nanofluid and its advantages over conventional point measurements techniques for real-time, non-contact and wide area temperature mapping without sample contamination.

An experimental study on rheological behavior of hybrid nanofluids made of iron and copper oxide in a binary mixture of water and ethylene glycol: Non-Newtonian behavior

This paper includes an experimental study on rheological behavior of hybrid nanofluids made of iron (Fe) and copper oxide (CuO) in a binary mixture of water and ethylene glycol. Nanofluid samples, with solid volume fractions of 0.05, 0.1, 0.25, 0.5, 1 and 1.5%, were prepared by dispersing an equal volumes of Fe and CuO nanoparticles in a binary mixture of water and ethylene glycol with the proportion of 20–80vol.%. Viscosity measurements were performed at temperatures ranging from 25°C to 50°C and the shear rate range of 3.669–122.3s−1 for all samples. Experimental findings revealed that the low concentration samples showed Newtonian behavior, while the high concentration samples had non-Newtonian behavior and followed the power law model. Moreover, the power law index and consistency index were obtained using curve-fitting on experimental shear stress-shear rate dependency. The curve-fitting results revealed that the power law index reduced to 0.36, indicating that the high concentration samples possessed shear-thinning behavior at all temperature considered.

The effects of temperature and volume fraction on the thermal conductivity of functionalized DWCNTs/ethylene glycol nanofluid

An experimental study on the effects of temperature and volume fraction of double-walled carbon nanotubes (DWCNTs) on the thermal conductivity of ethylene glycol (EG) was performed. In this way, the thermal conductivity of samples of nanofluid was examined at temperature ranging from 27 to 52 °C and concentrations range of 0.02, 0.05, 0.075, 0.1, 0.25, and 0.6 %. The results showed that the thermal conductivity of nanofluids enhances strangely with increase in volume fraction and temperature. Moreover, attempts were made to provide a new correlation for predicting the thermal conductivity of functionalized DWCNTs/EG nanofluid at different temperatures and concentrations. Finally, a deviation of margin analysis of the correlation revealed that there is a good agreement between experimental data and correlation outputs.

An experimental study on viscosity of alumina-engine oil: Effects of temperature and nanoparticles concentration

In the present study, the dynamic viscosity of alumina-engine oil nanofluid in different solid volume fractions and temperatures was experimentally investigated. The nanofluid samples were prepared in the solid volume fractions of 0.25%, 0.5%, 0.75%, 1%, 1.5% and 2% under the temperature range of 5 to 65°C. The measurements were carried out by CAP 2000+ Viscometer, supplied by Brookfield of the USA. Using the experimental data, new correlations for predicting the dynamic viscosity of alumina-engine oil at different temperatures were proposed. The experiment results at different shear rates showed that all nanofluid samples exhibit the Newtonian behavior. The results also revealed that the viscosity of the nanofluid increases with the solid volume fraction. Moreover, it has been found that with increasing temperature, the viscosity of nanofluids decreases, and it was more tangible at the lower temperatures. The comparison between experimental findings and theoretical models showed that these models failed to predict the correct values of the viscosity of the nanofluids at all solid volume fractions. The experimental data also indicated that the maximum viscosity enhancement of nanofluid was 132% compared with that of base fluid.

Experimental study on critical heat flux of highly efficient soft hydrophilic CuO–chitosan nanofluid templates

Nanofluids (NFs) are highly promising liquids for critical heat flux (CHF) enhancement in pool boiling, due to their environmental friendliness, easy chemical modification, tunability, low cost, and high thermal conductivity (TC). NFs based on CuO nanoparticles (NPs) are moderately good for CHF applications, but have low TC compared with other metal-oxide NFs. The development of ecofriendly NFs with enhanced thermal transfer properties is essential. In this study, we engineered a highly efficient, soft, hydrophilic CuO–chitosan (CS) NF template, the first of its kind. CS is a low-cost, naturally abundant, raw material, with hydroxyl, amine, and amide functional groups. When combined with CuO NPs, the CS functional groups create strong CuO–CS nanocomposites (CuO–CS NCs). In this research, 0.003, 0.006, 0.03 and 0.06-wt% CuO–CS NFs were produced by dissolving various concentrations of the CuO–CS NC in deionized water. A nichrome wire was coated with the NF samples during pool boiling experiments. The 0.06-wt% CuO–CS NF showed the highest CHF value, approaching 79%, which is much higher than that of pristine CuO NPs (28%). The chemical structure and crystallinity of the CuO–CS NCs were investigated using Fourier-transform infrared and X-ray photoelectron spectroscopy and X-ray diffraction; zeta potential and zeta size analyses were used to determine their charge, shape, and size. Atomic force microscopy, field-emission scanning electron microscopy, and transmission electron microscopy of the CuO–CS NC-coated nichrome wire after pool boiling experiments revealed a rough surface with high wettability and a low contact angle (42° for the 0.06-wt% CuO–CS NF sample), due to the formation of a nanoporous, soft template on the wire surface. We also demonstrated a method for in situ production of a naturally available, sustainably green, biodegradable raw material. The robust CuO–CS NF introduced here is expected to enhance pool boiling CHF, even at the lowest concentrations (0.003wt%) required for practical applications.

Experimental study on thermal conductivity of water-based Fe3O4 nanofluid: Development of a new correlation and modeled by artificial neural network

In this paper, the thermal conductivity of Fe3O4 magnetic nanofluids has been investigated experimentally. The nanofluid samples were prepared using a two-step method by dispersing Fe3O4 nanoparticles into the water with the solid volume fractions of 0.1%, 0.2%, 0.4%, 1%, 2% and 3%. Thermal conductivity measurements were performed by employing a KD2 Pro thermal properties analyser under temperatures ranging from 20°C to 55°C. Then, using experimental data, a new correlation was proposed to predict the thermal conductivity ratio of the magnetic nanofluid. Finally, an optimal artificial neural network was designed to predict the thermal conductivity ratio of the magnetic nanofluid. The experimental results indicated that the maximum enhancement of thermal conductivity of nanofluid was about 90%, which occurred at solid volume fraction of 3.0% and temperature of 55°C. The comparative results showed that there are deviations of 5% and 1.5%, respectively, for correlation and ANN from the experimental data. It was found from comparisons that the optimal artificial neural network model is more accurate compared to empirical correlation.

Effects of temperature and nanoparticles concentration on rheological behavior of Fe3O4–Ag/EG hybrid nanofluid: An experimental study

In this paper, the effects of temperature and nanoparticles concentration on the rheological behavior of Fe3O4–Ag/EG hybrid nanofluid have been experimentally investigated. Stable and homogeneous suspensions were prepared in solid volume fractions of 0.0375%, 0.075%, 0.15%, 0.3%, 0.6% and 1.2%. Viscosity measurements were performed at different shear rates (12.23–122.3s−1) under temperatures ranging from 25°C to 50°C. Results revealed that the nanofluid samples with solid volume fractions of less than 0.3% had Newtonian behavior, while those with higher solid volume fractions (0.6% and 1.2%) had non-Newtonian behavior, and followed the power-law model. Finally, the consistency index and power-law index were obtained from curve-fitting on shear stress–shear rate dependency. Curve-fitting results showed that all power-law indices were in the range of 0.5339–0.6706, indicating that the nanofluid samples possessed shear-thinning behavior at all temperatures considered.

Effects of particle shape and size on nanofluid properties for potential Enhanced Oil Recovery (EOR)

Application of Enhanced Oil Recovery (EOR) in oil and gas industry is very important to increase oil recovery and prolong the lifetime of a reservoir but it has been very costly and losing properties of EOR agent due to harsh condition. Nanoparticles have been used in EOR application since they are not degradable in reservoir condition and used in smaller amount compared to polymer usage. Commonly, EOR techniques are focusing on increasing the sweep efficiency by controlling the mobility ratio between reservoir fluid and injected fluid. Thus, this research aimed to analyze the nanofluid viscosity at different particle size and shape, volumetric concentration and types of dispersing fluid, as well as to determine the oil recovery performance at different nanofluid concentration. The nanofluid viscosity was investigated at nanoparticle sizes of 15nm and 60nm and shapes of 15nm spherical-solid and porous. Five nanofluid samples with concentration ranging from 0.1wt.% to 7wt.% were used to investigate the effect of volumetric concentration. Distilled water, ethanol, ethylene glycol (EG) and brine were used for the effect of dispersing fluids. Oil recovery was investigated at five different concentrations of nanofluid samples through flooding test. It was found that viscosity of nanofluid increased with decreasing particle size and increasing volumetric concentration. Solid shape particle and increasing dispersing fluid viscosity resulted in higher nanofluid viscosity. The higher the nanofluid concentration, the higher the oil recovery obtained. It can be concluded that nanofluid properties have been significantly affected by the environment and the particle used for potential EOR application.

Thermal conductivity, viscosity and stability of Al2O3-diathermic oil nanofluids for solar energy systems

Nanofluids have excellent potentiality in the field of heat transfer fluids and particularly for solar energy systems such as concentrated solar power plants. However they present many issues to be fixed in order to have a large diffusion. One of these is sedimentation. In this paper, stability, viscosity, FT-IR spectra, cluster size and thermal conductivity of Al2O3 – Therminol nanofluids have been investigated as heat transfer fluid in high temperature solar energy systems.Al2O3 – Therminol nanofluids have been prepared to investigate and to improve stability of the suspensions, varying temperature during mixing with magnetic stirrer, amount of surfactant and sonication time with ultrasonic vibrator. Stability of the nanofluid samples was investigated through backscattering technique and for cluster size analysis Dynamic Light Scattering (DLS) was used. Thermal conductivity of the sample was measured in order to evaluate not only the effect of both volume fraction and temperature, but also the influence of the surfactant (oleic acid).Stability of nanofluids depends on temperature during sample preparation and sedimentation phenomenon is inversely proportional to temperature during mixing with magnetic stirrer.Influence of concentration of surfactants was studied through preparation of samples having a solid phase particles concentration of 0.3%vol, 0.7%vol and 1.0%vol, respectively. The presence of surfactants creates some bonds with nanoparticles, which mainly helps nanofluids long-term stability. On the other hand, the presence of surfactants inside the nanofluids does not influence their thermal conductivity. From DLS measurements, a dependence of cluster size on volume fraction was observed for all nanofluid samples. Experimental data showviscosity increases by increasing volume concentration; nanofluids with and without surfactants show a non-Newtonian behavior and viscosity of nanofluids increases by increasing cluster size.

Experimental investigation on the correlation between nano-fluid characteristics and thermal properties of Al2O3 nano-particles dispersed in ethylene glycol–water mixture

This paper presents a multi-parameter investigation of Al2O3 nano-particles dispersed in distilled water, ethylene glycol and ethylene glycol–distilled water mixture (50/50vol.%). The nano-fluid samples were prepared with ultrasonic processing with particle concentration up to 9wt.%. Samples were characterized by transmission electron microscope imaging, particle surface charge (zeta potential), particle aggregate size, light absorbance and pH. The thermal conductivity and viscosity of the nano-fluid samples were measured. 10.9% enhancement in thermal conductivity was observed in ethylene glycol–distilled water mixture based nano-fluid with 5wt.% Al2O3 nano-particle loading. The results show multiple-perspective correlations between nano-fluid characteristics and thermal properties. The findings are summarized as follows. Combined effect of base fluid viscosity and particle surface charge determines the degree of nano-particle aggregation. Higher enhancement in thermal conductivity is observed with moderate particle aggregation, while either light or heavy aggregation lowers the enhancement. The ethylene glycol–water mixture based nano-fluids show overall higher thermal conductivity enhancement than the distilled water and ethylene glycol based nano-fluids. The degradation of nano-fluid thermal conductivity enhancement over time is found to be related to the gravity-driven particle sedimentation. Nano-fluids containing larger particle aggregates show higher viscosity augmentation. However, the extent of viscosity augmentation is not proportional to the extent of particle aggregation.

Influence of ultrasonication energy on the dispersion consistency of Al2O3–glycerol nanofluid based on viscosity data, and model development for the required ultrasonication energy density

ABSTRACTAchieving homogenised and stable suspensions has been one of the important research topics in nanofluid investigations. Preparing nanofluids, especially from the two-step method, is often accompanied with varying degrees of agglomerations depending on some parameters. These parameters include the physical structure of the nanoparticle, the prevalent particle charge, the strength of van der Waals forces of attraction and repulsiveness strength. Amongst the methods of deagglomeration, the use of ultrasonic vibration is most popular for achieving uniform dispersion. However, there are very few works related to its effect on the thermo-physical properties of nanofluids, and above all, standardising the minimum required ultrasonication time/energy for nanofluids synthesis. In this work, the optimum energy required for uniform and initially stable nanofluid has been investigated through experimental study on the combined influence of ultrasonication time/energy, nanoparticle size, volume fraction and temperature on the viscosity of alumina–glycerol nanofluids. Three different sizes of alumina nanoparticles were synthesised with glycerol using ultrasonication-assisted two-step approach. The viscosities of the nanofluid samples were measured between temperatures of 20–70 °C for volume fractions up to 5%. Based on the present experimental results, the viscosity characteristics of the nanofluid samples were dependent on particle size, volume fraction and working temperature. Using viscometry, the optimum energy density required for preparing homogenous nanofluid was obtained for all particle sizes and volume fractions. Finally, an energy density model was derived using dimensionless analysis based on the consideration of nanoparticle binding/interaction energy in base fluid, particle size, volume fraction, temperature and other base fluid properties. The model's empirical constants were obtained using nonlinear regression based on the present experimental data.

Effectiveness of vegetable oil based nanofluids as potential cutting fluids in turning AISI 1040 steel

The present work focuses on the performance of vegetable oil based nanofluids on machining performance during turning of AISI 1040 steel through minimum quantity lubrication (MQL). Different samples of nanofluids are formulated using dispersions of nanomolybdenum disulphide (nMoS2) in coconut (CC), sesame (SS) and canola (CAN) oils at varying nanoparticle inclusions (npi) and examined for basic properties. Machining parameters are measured during machining. It is observed that basic properties have increased with increase in npi, except absorbance. 0.5%CC+nMoS2is found to exhibit better machining performance compared to all the lubricant conditions. Cutting forces, temperatures, tool wear and surface roughness are approximately reduced by 37%, 21%, 44% and 39% respectively by using CC+nMoS2 at 0.5% npi compared to dry machining.

Dispersion behavior and breakdown strength of transformer oil filled with TiO<sub>2</sub> nanoparticles

Recently, the study of transformer oil-based nanofluids became of great interest, due to their prospective properties as a dielectric and cooling medium. However, agglomeration of nanoparticles limits the beneficial properties that can be obtained from nanofluids. So, the work presented in this paper aims to get enhanced dispersion behavior of nanoparticles within transformer oil-based nanofluids. Then, breakdown strength with the enhanced dispersion behavior is evaluated. In order to get enhanced dispersion behavior, nanofluids were prepared using nanoparticles with a surfactant. The surfactant plays a role in the stabilization of nanoparticles and maintaining suspension stability. The considered type of nanoparticles is TiO2 nanoparticles. Two series of nanofluid samples were prepared. Through the first series, the effect of surfactant concentration on dispersion behavior and agglomerate size was studied. The dispersion of nanoparticles was characterized using three different techniques. These techniques are optical microscope analysis, transmission electron microscope (TEM) analysis and zeta potential measurements. Based on these techniques, the suitable concentration of surfactant was identified. The second series of nanofluid samples was prepared with different weight percents of nanoparticles for assessing the breakdown strength. Weibull distribution was used to calculate the breakdown probability for the base oil as well as nanofluid samples. The results showed an enhancement in the breakdown strength by about 27% in comparison to the base oil. Based on the obtained results, mechanisms behind the dispersion behavior and breakdown strength were proposed and discussed.

Evaluation of acoustical parameters and thermal conductivity of TiO2-ethylene glycol nanofluid using ultrasonic velocity measurements

Abstract The nanosized titanium oxide (TiO2) nanoparticles (NPs) were synthesized via sol-gel method. The crystalline nature of the synthesized TiO2 nanoparticles was confirmed by X-ray powder diffractometry method. The surface morphology and particle size of the nanoparticles were analyzed by high-resolution scanning electron microscopic method. UV-visible spectroscopy was employed to determine its band gap energy value. The different concentrations of nanofluid samples of TiO2 NPs dispersed in ethylene glycol were prepared and mixed thoroughly by ultrasonication process. The value of ultrasonic velocity and density were measured for the different concentrations of TiO2 nanofluids. The acoustical parameters such as adiabatic compressibility, intermolecular free length, and acoustic impedance were calculated from the experimental data. It was observed that ultrasonic velocity showed linearity with particle concentration, and the results were discussed. In addition to the TiO2-ethylene glycol (particle-fluid) interaction studies, a new methodology was proposed to find the thermal conductivity of nanofluids using ultrasonic velocity.

An experimental study on thermal conductivity of MgO nanoparticles suspended in a binary mixture of water and ethylene glycol

In the present study, the effects of solid volume fraction and temperature on the thermal conductivity of MgO/water–EG (60:40) nanofluid are discussed. Samples of nanofluid are provided by two step method at different solid concentrations, including 0.1%, 0.2%, 0.5%, 0.75%, 1%, 1.5%, 2% and 3%. The experiments are performed for different temperatures ranging from 20 to 50°C, using KD2 pro thermal analyzer which employed transient hot wire to measure thermal conductivity. The finding shows that thermal conductivity of nanofluid increases with increasing solid volume fraction or temperature. Based on the experimental data, new correlation for modeling the thermal conductivity of MgO/water–EG (60:40) for different solid volume fractions and temperatures was proposed.

Ultrasonic technique for concentration characterization of copper nanofluids synthesized using μ-EDM: A novel experimental approach

Colloidal suspensions of copper nanoparticles were synthesized using a developed micro-electrical discharge machining (μ-EDM) method. Average size of the particles dispersed in de-ionized (DI) water is found to be in sub-micron size and that in DI water with stabilizers PolyVinyl Alcohol (PVA) and PolyEthylene Glycol (PEG) is less than 10nm. The present paper is focused on an exceptional technique using ultrasound which is used for concentration characterization of copper nanofluids in-line. The mass concentration of copper nanoparticles dispersed in suspension media is determined by Urick and Ament's relationship, and the results are found to be 7wt%, 7wt% and 6wt% in Cu-DI water, Cu-DI water+PVA and Cu-DI water+PEG nanofluids respectively. This study shows that the ultrasonic velocity in Cu-nanofluids increases as compared to the suspension media. However, it was observed that the nanoparticles in suspension media of determined concentrations alter the ultrasonic velocity by affecting the acoustic time of flight. The results demonstrate that due to strong particle–particle interaction conferred by the aggregation of particles, the ultrasonic velocity in the Cu-DI water nanofluid is found to be decreased as compared to the PVA and PEG nanofluid samples. Further, due to the reduction in size of the particles generated and less concentration in DI water+PEG mixture, the ultrasonic velocity in the Cu-DI water+PEG nanofluid is found to be decreased as compared to that in the PVA nanofluid sample.