Predicting thermal conductivity behaviour of ZnO, TiO2 and ball milled TiO2/ZnO based nanofluids with ethylene glycol as base fluid

Stability of nanofluids is one of the most important factors to ensure the most benefit of the properties of nanoparticles. Zinc oxide was used in the research with concentration between (0.2-1) wt. % with ethylene glycol base fluid. The stability of ZnO nanofluid was enhanced by adding two types of surfactants Tx-100 and Gum Arabic with concentration of (0.1-0.5) vol. % to stabilize the ZnO nanoparticles in the base fluid. The results showed that the Gum Arabic surfactant led to more stable fluid than that of Tx-100; this was shown from zeta potential and UV spectroscopy measurements. The thermal conductivity coefficient was also measured, and the results showed that the thermal conductivity increased with adding surfactant than without using a stabilizer.

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Analysis of nanofluids as a means of thermal conductivity enhancement in heavy machineries

Industrial Lubrication and Tribology ◽

10.1108/ilt-03-2012-0024 ◽

2014 ◽

Vol 66 (2) ◽

pp. 238-243 ◽

Cited By ~ 2

Author(s):

Ayush Jain ◽

Imbesat Hassan Rizvi ◽

Subrata Kumar Ghosh ◽

P.S. Mukherjee

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Ethylene Glycol ◽

Base Fluid ◽

High Concentration ◽

Content Type ◽

Conductivity Enhancement ◽

Heavy Machinery ◽

Heat Transfer Fluids ◽

Experimental Findings

Purpose – Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used in heavy machinery. For studying the heat transfer behaviour of the nanofluids, precise values of their thermal conductivity are required. For predicting the correct value of thermal conductivity of a nanofluid, mathematical models are necessary. In this paper, the effective thermal conductivity of various nanofluids has been reported by using both experimental and mathematical modelling. The paper aims to discuss these issues. Design/methodology/approach – Hamilton and Crosser equation was used for predicting the thermal conductivities of nanofluids, and the obtained values were compared with the experimental findings. Nanofluid studied in this paper are Al2O3 in base fluid water, Al2O3 in base fluid ethylene glycol, CuO in base fluid water, CuO in base fluid ethylene glycol, TiO2 in base fluid ethylene glycol. In addition, studies have been made on nanofluids with CuO and Al2O3 in base fluid SAE 30 particularly for heavy machinery applications. Findings – The study shows that increase in thermal conductivity of the nanofluid with particle concentration is in good agreement with that predicted by Hamilton and Crosser at typical lower concentrations. Research limitations/implications – It has been observed that deviation between experimental and theoretical results increases as the volume concentration of nanoparticles increases. Therefore, the mathematical model cannot be used for predicting thermal conductivity at high concentration values. Originality/value – Studies on nanoparticles with a standard mineral oil as base fluid have not been considered extensively as per the previous literatures available.

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Thermal conductivity enhancement in gold decorated graphene nanosheets in ethylene glycol based nanofluid

Scientific Reports ◽

10.1038/s41598-020-71740-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

M. C. Mbambo ◽

M. J. Madito ◽

T. Khamliche ◽

C. B. Mtshali ◽

Z. M. Khumalo ◽

...

Keyword(s):

Thermal Conductivity ◽

Ethylene Glycol ◽

Base Fluid ◽

Graphene Nanosheets ◽

Synthesis Method ◽

Particle Diameter ◽

Laser Wavelength ◽

Hybrid Nanofluid ◽

Average Particle ◽

Conductivity Enhancement

Abstract We report on the synthesis and thermal conductivity of gold nanoparticles (AuNPs) decorated graphene nanosheets (GNs) based nanofluids. The GNs-AuNPs nanocomposites were synthesised using a nanosecond pulsed Nd:YAG laser (wavelength = 1,064 nm) to ablate graphite target followed by Au in ethylene glycol (EG) base fluid to obtain GNs-AuNPs/EG hybrid nanofluid. The characterization of the as-synthesised GNs-AuNPs/EG hybrid nanofluid confirmed a sheet-like structure of GNs decorated with crystalline AuNPs with an average particle diameter of 6.3 nm. Moreover, the AuNPs appear smaller in the presence of GNs which shows the advantage of ablating AuNPs in GNs/EG. The thermal conductivity analysis in the temperature range 25–45 °C showed that GNs-AuNPs/EG hybrid nanofluid exhibits an enhanced thermal conductivity of 0.41 W/mK compared to GNs/EG (0.35 W/mK) and AuNPs/EG (0.39 W/mK) nanofluids, and EG base fluid (0.33 W/mK). GNs-AuNPs/EG hybrid nanofluid displays superior enhancement in thermal conductivity of up to 26% and this is due to the synergistic effect between AuNPs and graphene sheets which have inherent high thermal conductivities. GNs-AgNPs/EG hybrid nanofluid has the potential to impact on enhanced heat transfer technological applications. Also, this work presents a green synthesis method to produce graphene-metal nanocomposites for various applications.

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Ultrasonic and thermophysical studies of ethylene glycol nanofluids containing TiO2 nanoparticles and their heat transfer enhancements

Johnson Matthey Technology Review ◽

10.1595/205651320x15940360546454 ◽

2020 ◽

Author(s):

Mohit Gupta ◽

Devraj Singh ◽

Shakti Pratap Singh ◽

Ashish Mathur ◽

Shikha Wadhwa ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Ethylene Glycol ◽

Tio2 Nanoparticles ◽

Ultrasonic Velocity ◽

Base Fluid ◽

Sol Gel ◽

Interaction Force ◽

Thermal Conductivity Enhancement ◽

Conductivity Enhancement

In present investigation, TiO2 nanostructures were synthesized via simple sol-gel technique and characterized with XRD, SEM-EDX, HRTEM and UV-visible spectroscopy techniques. The temperature and concentration dependence of thermal conductivity enhancement and ultrasonic velocity have been explored in ethylene glycol (EG)-based TiO2 nanofluids. The obtained results showed 24% enhancement in thermal conductivity at higher temperature (80°C) of base fluid ethylene glycol by adding 1.0 wt.% of TiO2 nanoparticles. The behaviour of thermal conductivity enhancement and ultrasonic velocity with temperature in prepared nanofluids has been explained with help of existing phenomena. The increase the ultrasonic velocity in ethylene glycol with TiO2 nanoparticles shows that strong cohesive interaction force rises among the nanoparticles and base fluid. These results divulge that TiO2 nanoparticles can be considered for the applications of next-generation competent heat transfer in nanofluids.

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Studies on thermo physical property variations of graphene nanoparticle suspended ethylene glycol/water

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq200504036p ◽

2020 ◽

pp. 36-36

Author(s):

Manikandan Periasamy ◽

Rajoo Baskar

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Ethylene Glycol ◽

Physical Properties ◽

Specific Heat ◽

Specific Heat Capacity ◽

Base Fluid ◽

Physical Property ◽

Inlet Temperature ◽

Thermo Physical Properties

The objective of the study is to determine the thermo physical property variations (such as viscosity, density, specific heat capacity and thermal conductivity) of graphene suspended base fluid (Ethylene Glycol (EG) /Water (W)), with respect to graphene nanoparticle concentration and hot fluid inlet temperature. Graphene nanoparticle concentrations (0.2, 0.4, 0.6, 0.8 and 1 volume %) and the base fluid of 30:70 volume % of EG: Water is prepared initially. The impact of graphene nano particle addition on base fluids based on experimentation in the commercial plate heat exchanger was studied. In this experiment, the hot fluid inlet temperature was varied at 55? C, 65? C and 75? C. The experimental results of thermo physical properties were compared with the selected models proposed in the literature. Einstein (1956); Kitano (1981); and Bachelor models (1977) have been used to consider the effect of viscosity. The measured density and Specific heat capacity was validated with Pak and Cho and Xuan model respectively. To consider the effect of thermal conductivity, three different models (Maxwell, 1954; Vajjah, 2010; and Sahoo, 2012) have been used. Study revealed that the thermo physical properties of base fluid significantly affects with the graphene nanoparticle suspension.

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A Comparison of Empirical Correlations of Viscosity and Thermal Conductivity of Water-Ethylene Glycol-Al2O3 Nanofluids

Nanomaterials ◽

10.3390/nano10081487 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1487

Author(s):

Dorota Sawicka ◽

Janusz T. Cieśliński ◽

Slawomir Smolen

Keyword(s):

Thermal Conductivity ◽

Ethylene Glycol ◽

Dynamic Viscosity ◽

Base Fluid ◽

Pure Water ◽

Volume Ratio ◽

Al2o3 Nanoparticles ◽

Conductivity Enhancement ◽

Viscosity Increase ◽

New Generation

Because of their superb thermal conductivity, nanofluids are seen as new generation of cooling mediums in many engineering applications. It is well established that even a small amount of nanoparticles mixed with a base fluid may result in distinct thermal conductivity enhancement. On the other hand, addition of nanoparticles to the base fluid results in its substantial viscosity increase. Therefore, it is very difficult to evaluate the relative importance of viscosity and thermal conductivity of the nanofluid on convective heat transfer performance. In order to estimate such resultant impact properly, it is necessary to develop reliable correlation equations for predictions of these two thermophysical properties of nanofluids. In this paper, the thermal conductivity and dynamic viscosity of five fluids, i.e., pure water, ethylene glycol (EG) and three mixtures of water and EG with volume ratio of 40:60, 50:50 and 60:40 have been experimentally determined. The aforementioned fluids served as base fluids in nanofluids with Al2O3 nanoparticles at the concentration of 0.01%, 0.1% and 1% by weight. A set of 20 correlations for prediction of thermal conductivity and dynamic viscosity of base fluids and corresponding nanofluids has been developed. Moreover, present results have been confronted with literature data and predictions made by use of carefully selected recognized literature correlations.

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An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.3.2020.16.0620 ◽

2020 ◽

Vol 17 (3) ◽

Author(s):

A.M. Zetty Akhtar ◽

M.M. Rahman ◽

K. Kadirgama ◽

M.A. Maleque

Keyword(s):

Thermal Conductivity ◽

Zeta Potential ◽

Base Fluid ◽

Minimum Quantity Lubrication ◽

Cutting Fluid ◽

Cutting Zone ◽

Observation Method ◽

The Stability ◽

The Relationship ◽

Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

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A model for thermal conductivity of carbon nanotubes with ethylene glycol/water based nanofluids

Vietnam Journal of Science Technology and Engineering ◽

10.31276/vjste.59(2).10 ◽

2017 ◽

Vol 59 (02) ◽

pp. 10-13

Author(s):

Trong Tam Nguyen ◽

◽

Hung Thang Bui ◽

Ngoc Minh Phan ◽

◽

...

Keyword(s):

Thermal Conductivity ◽

Carbon Nanotubes ◽

Ethylene Glycol ◽

Water Based

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Effects of Plasma Treated Alumina Nanoparticles on Breakdown Strength, Partial Discharge Resistance, and Thermophysical Properties of Mineral Oil-Based Nanofluids

Materials ◽

10.3390/ma14133610 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3610

Author(s):

Norhafezaidi Mat Saman ◽

Izzah Hazirah Zakaria ◽

Mohd Hafizi Ahmad ◽

Zulkurnain Abdul-Malek

Keyword(s):

Thermal Conductivity ◽

Plasma Treatment ◽

Base Fluid ◽

Breakdown Strength ◽

Partial Discharge ◽

Mineral Oil ◽

Transformer Oil ◽

Alumina Nanoparticles ◽

Discharge Characteristics ◽

Nano Alumina

Mineral oil has been chosen as an insulating liquid in power transformers due to its superior characteristics, such as being an effective insulation medium and a great cooling agent. Meanwhile, the performance of mineral oil as an insulation liquid can be further enhanced by dispersing nanoparticles into the mineral oil, and this composition is called nanofluids. However, the incorporation of nanoparticles into the mineral oil conventionally causes the nanoparticles to agglomerate and settle as sediment in the base fluid, thereby limiting the improvement of the insulation properties. In addition, limited studies have been reported for the transformer oil as a base fluid using Aluminum Oxide (Al2O3) as nanoparticles. Hence, this paper reported an experimental study to investigate the significant role of cold plasma treatment in modifying and treating the surface of nano-alumina to obtain a better interaction between the nano-alumina and the base fluid, consequently improving the insulation characteristics such as breakdown voltage, partial discharge characteristics, thermal conductivity, and viscosity of the nanofluids. The plasma treatment process was conducted on the surface of nano-alumina under atmospheric pressure plasma by using the dielectric barrier discharge concept. The breakdown strength and partial discharge characteristics of the nanofluids were measured according to IEC 60156 and IEC 60270 standards, respectively. In contrast, the viscosity and thermal conductivity of the nanofluids were determined using Brookfield DV-II + Pro Automated viscometer and Decagon KD2-Pro conductivity meter, respectively. The results indicate that the 0.1 wt% of plasma-treated alumina nanofluids has shown the most comprehensive improvements in electrical properties, dispersion stability, and thermal properties. Therefore, the plasma treatment has improved the nanoparticles dispersion and stability in nanofluids by providing stronger interactions between the mineral oil and the nanoparticles.

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Special Issue on Nanofluids and Their Applications

Applied Sciences ◽

10.3390/app9071476 ◽

2019 ◽

Vol 9 (7) ◽

pp. 1476

Author(s):

Guan Yeoh ◽

Sherman Cheung

Keyword(s):

Ethylene Glycol ◽

Base Fluid ◽

Colloidal Suspensions ◽

Special Issue

Nanofluids can be considered as engineered colloidal suspensions of nanometer-sized particles in a base fluid of water, ethylene glycol, or oil [...]

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