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1

Influence of Al2O3 nanoparticle mass concentration and aerosol formation parameters on tool vibration during turning of Ti6Al4V titanium alloy

Dylewicz Weronika, Szczotkarz Natalia, Maruda Radosław, Gupta M. K.

International Journal of Applied Mechanics and Engineering

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2024

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Vol. 29, no. 2

52--66

EN

Machining difficult-to-cut materials involves challenging machining conditions, including higher temperatures in the cutting zone, cutting forces and friction. Another important phenomenon is vibration, which is undesirable when manufacturing high quality workpieces. One way to reduce vibration in the cutting zone is to use cooling methods. Due to its environmentally friendly nature, the minimum quantity lubrication (MQL) method has already been widely used in metalworking. However, when combined with nanofluids, it improves the ability of the aerosol to dissipate more heat and increase lubrication in the cutting zone. This paper presents the effect of a polyol ester-based Al2O3 nanofluid due to the varying mass concentration of nanoparticles on the vibration during turning of Ti6Al4V alloy and compares the results with dry cutting and the MQL method without nanoparticles. Four concentrations (0.25−1 wt%), variable nanofluid flow rate E = 0.388−1.182 g/min and air flow rate P = 10−40 l/min were considered. According to the statistical analysis, the most important factor influencing tool vibration was the mass concentration of nanoparticles in the cutting fluid. By combining the MQL method with 0.5 wt% Al2O3, the vibration acceleration RMS values were found to be the lowest. When compared to the MQL method without nanoparticles, the RMS values for dry cutting ranged from 17.8% to 24.9%, and for wet cutting they were reduced by about 10.9-18.5%.

2

Key factors enhancing the electrical properties of nanofluids. A mini-review of the applications in the energy-related sectors

Boiko Oleksandr, Stryczewska Henryka Danuta, Komarzyniec Grzegorz Karol, Ebihara Kenji, Aoqui Shin-Ichi, Yamazato Masaaki, Zagirnyak Mykhaylo

Archives of Electrical Engineering

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2024

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Vol. 73, nr 4

1137--1160

EN

The article presents a mini-review of key factors significantly affecting the electrical properties of nanofluids. One-step and two-step approaches, together with examples of vacuum sputtering-based techniques, chemical reduction, and mechanical mixing techniques, were explained. The crucial factors enhancing the electric and dielectric responses, such as nanofiller concentration, its type, geometry, uniformity of distribution in the base liquid as well as the base liquid’s type, temperature, chemical stability, etc., were analyzed. Special attention was paid to the impact of the parameters on electrical conductivity, permittivity, and dielectric losses. The selected models for nanofluid’s conductivity prediction have been presented. The potential and implemented applications of nanofluids in the energy-related industry branches with reference to their electrical properties have been reviewed. Examples of applications in power transformers, solar cell production processes, nanoelectrofuel flow batteries, and other electrotechnologies have been analyzed.

3

Influence of Aluminium Oxide Nanoparticles Mass Concentrations on the Tool Wear Values During Turning of Titanium Alloy Under Minimum Quantity Lubrication Conditions

Szczotkarz Natalia, Adamczuk Krzysztof, Dębowski Daniel, Gupta Munish Kumar

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no. 1

76--88

EN

Recently, environmental consciousness has led to the quest for ways to minimise negative elements in machining operations that threaten operator health and the environment. Titanium alloys are hard to cut, thus cooling the cutting zone is essential to reduce tool wear. Variations in Al2O3 nanoparticle concentrations supplied to the MQL cutting fluid affect cutting wedge wear during Ti6Al4V alloy turning. A diameter of 15 nm nanoparticles were utilised at 0.25, 0.5, 0.75, and 1 wt% mass concentrations. In the experiments, the flank face wear band width VBB and crater width KB were measured. Comparisons were also made using dry-cutting tools and the MQL approach without nanoparticles. X-ray microanalysis was used to quantify and qualitatively assess the chemical composition of chosen rake surface micro-areas. Studies showed that Al2O3 nanoparticle mass concentration affects tool wear when turning a hard-to-cut alloy. 0.5 and 0.75 wt% mass concentrations had the lowest flank and rake wear of the four mass concentrations. The SEM examination showed that 0.5 wt% mass concentration decreased adhesive wear the most.

4

Predictive analysis on the influence of AL2o3 and CuO nanoparticles on the thermal conductivity of R1234yf-based refrigerants

Bibin Baiju S., Bhramara Panitapu, Mystkowski Arkadiusz, Gundabattini Edison

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 3

474--482

EN

Nano-enhanced refrigerants are substances in which the nanoparticles are suspended in the refrigerantatthe desired concentration. They have the potential to improve the performance of refrigeration and air-conditioning systems that use vapour compression. This study focuses on the thermal conductivity of alumina (Al2O3) and cupric oxide (CuO) nanoparticles immersed in 2,3,3,3-tetrafluoropropene (R1234yf). The thermal conductivity of nano-refrigerants was investigated using appropriate models from earlier studies where the volume concentration of particles and temperatures were varied from 1% to 5% and from 273 K to 323K, respectively. The acquired results are supported by prior experimental investigations on R134a-based nano-refrigerants undertaken by the researchers. The main investigation results indicate that the thermal conductivity of Al2O3/R1234yf and CuO/R1234yf is enhanced with the particle concentrations, interfacial layer thickness, and temperature. Also, the thermal conductivity of Al2O3/R1234yf and CuO/R1234yf decreases with particle size. The thermal conductivity of Al2O3/R1234yf and CuO/R1234yf nano-refrigerants become enhanced with a volume concentration of nano-sized particles by 41.2% and 148.1% respectively at 5% volume concentration and 323K temperature. The thermal conductivity of Al2O3/R1234yf reduces with temperature, by upto 3% of nanoparticle addition and after that, it enhances. Meanwhile, it declines with temperature, by upto 1% of CuO nanoparticle inclusion for CuO/R1234yf. CuO/R1234yf has a thermal conductivity of 16.69% greater than Al2O3/R1234yf at a 5% volume concentration. This paper also concludes that, among the models for thermal conductivity study, Stiprasert’s model is the most accurate and advanced.

5

Entropy production due to conjugate natural convection in a nanofluid-filled enclosure with a stepped wall

Bouchoucha Abd el, Oztop Hakan F., Bessaih Rachid, Abu-Hamdeh Nidal

Engineering Transactions

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2023

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Vol. 71, iss. 2

161-183

EN

The main aim of this paper is to improve the heat transfer in a square cavity with a body at the left wall filled with a Al2O3/water nanofluid for different geometries. Numerous simulation experiments are conducted. A relative temperature is maintained at the vertical and top horizontal walls while the bottom wall is warm. The finite volume approach is considered to resolve the equations governing the thermal transfer flow in the physical domain based on the SIMPLER algorithm. In this study, different values of the following parameters are considered: Rayleigh number (104 ≤ Ra ≤ 105) and solid volume fraction (0 ≤ φ ≤ 0.1) of nanoparticles (NPs). Parameters, such as the Rayleigh (Ra) and Bejan (Be) numbers, thermal conductivity, body’s dimensions, and NPs volume fraction, which directly affect the entropy generation and heat transfer rate, are studied in a particular way. The obtained results show that entropy generation goes ahead with the Ra increase and inverse to the solid volume fraction increase. One can notice that the heat transfer has a proportional relation with φ and Ra.

6

Experimental Investigation on Free Convective Heat Transfer Performance of Oxide Nanofluids Along a Vertical Cylinder

Ravi Babu S., Pradeep Kumar P., Basha S. A., Maruthi Rao M.

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 5

185--194

EN

The multi criterion decision making (MCDM) method and experimental investigation on free convective heat transfer performance of oxide-based water nanofluids along a vertical cylinder are the two methods used to compare the performance in this paper. Al2O3, CuO, TiO2, SiO2, Fe3O4, and ZnO were the metal oxide nanoparticles used in the study to make water-based metal oxide nanofluids with volume fractions ranging from 0% to 1%. Two step method was used to create nanofluids. Thermo-physical properties like density, specific heat, viscosity, and thermal conductivity were measured after the various nanofluids were synthesized. Then, the performance of each nanofluid was evaluated based on various attributes using the weighted sum model (WSM) method, and the ranking of nanofluids was given. To begin, water served as the medium for free convection heat transfer experiments to validate the experimental setup. Free convection heat transfer experiments were carried out using metal oxide-based water nanofluids as mediums at volume fractions ranging from 0% to 1% for various heat inputs in the range of 30 W and 50 W. The heat transfer coefficient augments with percentage volume concentration up to 0.1 % for all types of nanofluids and then decreases until it reaches 0.6% volume fraction. Al2O3-water nanofluid performs better than other metal oxide nanofluids in both WSM and experimental methods.

7

Wear performance of Ti-6Al-4 V titanium alloy through nano-doped lubricants

Etri Hamza E. L., Singla Anil Kumar, Özdemir Mehmet Tayyip, Korkmaz Mehmet Erdi, Demirsöz Recep, Gupta Munish Kumar, Krolczyk J. B., Ross Nimel Sworna

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e147, 2023

EN

Titanium and its alloys are widely utilized in the biomedical sector, they still exhibit poor tribological properties and low wear resistance when employed against even weaker substances. The poor hardness, instability, high coefficient of friction, low load-carrying capacity, and insufficient resistance to not only abrasive but also adhesive wear are further disadvantages of titanium alloys. The focus of this investigation is on the tribological performance of Ti-6Al-4 V alloy in contact with WC carbide abrasive balls when subjected to nanodoped cooling and lubrication conditions. Tribological experiments were executed on Ti-6Al-4 V flat samples using a ball-on-flat tribometer in dry hybrid graphene/boron nitride combination nanoparticles (MQL, nano-3), nanographene with MQL (nano-1), and boron nitride with MQL (nano-2) conditions. After that, the most significant tribological characteristics were investigated, including volume loss, friction coefficient, wear rate, and micrographic structures. The outcomes also demonstrated that the hybrid nanoparticle situation experienced the least amount of volume loss.

8

Analysis of Power Grid Parameters Depending on the Variable Concentration and Size of Copper Nanoparticles and Aerosol Formation Parameters in the Minimum Quantity Lubrication Method During Turning of Ti6Al4V Titanium Alloy

Szczotkarz Natalia, Maruda Radosław, Leksycki Kamil, Feldshtein Eugene, Wojciechowski Szymon, Jurczak Paweł, Waligóra Michał

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 6

315--324

EN

Titanium alloys belong to the group of difficult-to-cut materials, machining of which leads to a number of challenges including large thermal loads on the cutting inserts and difficulties in obtaining a high quality machined surface. Great cutting forces, in turn, result in increased energy consumption. Therefore, it becomes important to attempt to reduce the amount of power consumed during machining, which can be achieved, among other things, by reducing the value of the coefficient of friction in the cutting zone. This paper presents a study on the influence of the size as well as the Cu nanoparticle concentration added to cutting fluid in MQL method on the power grid parameters while turning of Ti6Al4V titanium alloy. In this research, nanoparticles of 22 nm and 65 nm at concentrations of 0.5 wt% and 0.75 wt% were used. Turning process was carried out with constant cutting parameters and variable aerosol formation parameters, i.e. mass flow rate of nanofluid and volumetric flow rate of air. Based on the study, the use of 22 nm nanoparticles at 0.5 wt% concentration is recommended to achieve the smallest monitored values of the power grid parameters. The statistical analysis revealed that, out of the aerosol formation parameters considered, both the air flow rate and nanofluid flow rate do not significantly affect the values of the analysed power network parameters. However, the most significant factor is the variable nanoparticle size.

9

A review of enhancement of thermal performance of flat plate solar collectors through nanofluid implementation

Ali Zahra a H. Mohammed, Hussein Adnan M.

Advances in Mechanical and Materials Engineering

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2023

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Vol. 40, nr 1

139--148

EN

Nanofluids have found widespread practical applications in heat transfer, including cooling oils for diverse uses like automobile radiators, solar and nuclear power systems, biomedical devices, ventilation, heating, air conditioning, refrigeration, engine cooling, and transformers. Extensive scientific studies have investigated the impact of exotic fluids when combined with traditional heat transfer fluids, revealing that this combination enhances heat transfer performance beyond that of conventional working fluids. Collectively, these studies demonstrate the impressive heat transfer abilities of nanofluids. To optimize the efficiency of flat plate solar collectors, a comprehensive approach integrating theory and experimentation is essential. The results of such research highlight that increasing both the mass flow rate and concentration of nanofluids can lead to significant efficiency improvements, with potential enhancements ranging from 20% to 85%.

PL

Nanociecze znalazły szerokie praktyczne zastosowanie w wymianie ciepła. Oleje chłodzące w tym oleje stosowane są w różnych zastosowaniach, takich jak chłodnice samochodowe, systemy energii słonecznej i jądrowej, urządzenia biomedyczne, wentylacja, ogrzewanie, klimatyzacja, chłodnictwo, chłodzenie silników i transformatorów. Celem szeroko zakrojonych badań naukowych było zbadanie wpływu egzotycznych cieczy w połączeniu z tradycyjnymi cieczami przenoszącymi ciepło, ujawniając, że ta kombinacja poprawia wydajność wymiany ciepła w porównaniu z konwencjonalnymi cieczami roboczymi. Badania wykazały imponujące zdolności przenoszenia ciepła przez nanociecze. Optymalizacja wydajności płaskich kolektorów słonecznych polega na kompleksowym podejściu łączącym metody teoretyczne oraz badania eksperymentalne. Wyniki takich badań podkreślają, że zwiększenie zarówno masowego natężenia przepływu, jak i stężenia nanocieczy może prowadzić do potencjalnej poprawy wydajności w zakresie od 20% do 85%. Celem tego artykułu jest zaprezentowanie osiągnięć naukowych w zakresie implementacji nanocieczy do zwiększenia efektywności cieplnej płaskich kolektorów słonecznych.

10

Radiation and magnetohydrodynamic effects on convective nanofluid past an inclined plate in the presence of a chemical reaction

Palani G., Arutchelvi A.

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 3

115--126

EN

This computational work explores the heat and mass transfer of copper water nanofluid flowing along an inclined plate with varying surface temperature and concentration in the presence of a magnetic field and radiation through a permeable medium. The dimensionless governing equations are solved numerically using an efficient finite-difference technique, which is fast convergent and unconditionally stable. The findings are reviewed and illustrated through graphs for pertinent parameters.

11

Heat transfer study from square cylinder immersed in water-based nanofluid: Effect of orientation

Kaur Jaspinder, Ratar Jatinder Kumar, Tiwari Anurag Kumar

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

243-–250

EN

Heat transfer study from the heated square cylinder at a different orientation angle to the stream of nanofluids has been investigated numerically. CuO-based nanofluids were used to elucidate the significant effect of parameters: Reynolds number (1–40), nanoparticle volume fraction (0.00–0.05), the diameter of the NPs (30–100 mn) and the orientation of square cylinder (0–90). The numerical results were expressed in terms of isotherm contours and average Nusselt number to explain the effect of relevant parameters. Over the range of conditions, the separation of the boundary layers of nanofluids increased with the size of the NPs as compared to pure water. NPs volume fraction and its size had a significant effect on heat transfer rate. The square cylinder of orientation angle (45) gained a more efficient heat transfer cylinder than other orientation angles. Finally, the correlations were developed for the average Nusselt number in terms of the relevant parameters for 45 orientation of the cylinder for new applications.

12

An overview of heat transfer enhancement based upon nanoparticles influenced by induced magnetic field with slip condition via finite element strategy

Hafeez Muhammad B., Krawczuk Marek, Shahzad Hasan

Acta Mechanica et Automatica

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2022

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Vol. 16, no. 3

200--206

EN

The mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively to explore the phenomenon of thermal performance of the combination fluid. A remarkable enhancement in thermal performance is noticed when solid structures are dispersed in the working fluid. The Biot number determines the convective nature of the boundary. When the Biot number is increased, the fluid temperature decreases significantly. Among copper oxide, aluminium oxide, and titanium oxide nanoparticles, copper oxide nanoparticles are found to be the most effective thermal enhancers.

13

Hybrydowe procesy skrawania wspomagane nanocieczami. Część 2: Przykłady wpływu nanocieczy na proces skrawania

Grzesik Wit

Mechanik

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2021

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R. 94, nr 3

7--11

EN

The comprehensive knowledge of the applications of nano-fluids for hybrid machining processes assisted by liquid media, which, in general, are applied in MQL systems is presented. In the first part of the article properties of nano-additives, which are added to base cutting fluids (such as vegetable and mineral oils and emulsion), and their influence on the performance of machining processes were outlined. The tribological mechanisms including rolling and plowing of the nano-particles in the contact zones, as well as resulting thermal influences were characterized. In the second part of the article, some practical examples of the possible influences of different nano-fluids on the cutting temperature, tool wear and tool life, surface roughness and surface quality are provided and discussed. It was concluded that nano-fluids with graphene and carbon nanotubes additives are very effective in improving process behaviour.

PL

Przedstawiono zwięzłe informacje na temat zastosowania nanocieczy do wspomagania hybrydowych procesów skrawania mediami ciekłymi, które zasadniczo znalazły zastosowanie w minimalnym smarowaniu/chłodzeniu MQL. W pierwszej części artykułu omówiono właściwości dodawanych do cieczy bazowych (olejów roślinnych i mineralnych oraz emulsji) nanocząstek i ich wpływ na przebieg procesu skrawania. Scharakteryzowano mechanizmy tribologiczne w strefie kontaktu i pochodne oddziaływania termiczne. W drugiej części artykułu zostaną opisane praktyczne przykłady wpływu nanocieczy na temperaturę skrawania, przebieg zużycia i trwałość ostrza oraz chropowatość i jakość powierzchni. Wykazano dużą efektywność zastosowania nanocieczy z dodatkami grafenu i nanorurek.

14

Hybrydowe procesy skrawania wspomagane nanocieczami. Część 1: Właściwości i mechanizmy oddziaływania nanocieczy

Grzesik Wit

Mechanik

|

2021

|

R. 94, nr 2

6--9

EN

The comprehensive knowledge of the applications of nanofluids for hybrid machining processes assisted by liquid media, which, in general, are applied in MQL systems is presented. In the first part of the article properties of nano-additives, which are added to base cutting fluids (such as vegetable and mineral oils and emulsion), and their influence on the performance of machining processes are outlined. The tribological mechanisms including rolling and plowing of the nano-particles in the contact zones, as well as resulting thermal influences are characterized. In the second part of the article, some practical examples of the possible influences of different nano-fluids on the cutting temperature, tool wear and tool life, surface roughness and surface quality will be provided and discussed. It was concluded that nano-fluids with graphene and carbon nanotubes additives are very effective in improving process behaviour.

PL

Przedstawiono zwięzłe informacje na temat zastosowania nanocieczy do wspomagania hybrydowych procesów skrawania mediami ciekłymi, które zasadniczo znalazły zastosowanie w minimalnym smarowaniu/chłodzeniu MQL. W pierwszej części artykułu omówiono właściwości dodawanych do cieczy bazowych (olejów roślinnych i mineralnych oraz emulsji) nanocząstek i ich wpływ na przebieg procesu skrawania. Scharakteryzowano mechanizmy tribologiczne w strefie kontaktu i pochodne oddziaływania termiczne. W drugiej części artykułu zostaną opisane praktyczne przykłady wpływu nanocieczy na temperaturę skrawania, przebieg zużycia i trwałość ostrza oraz chropowatość i jakość powierzchni. Wykazano dużą efektywność zastosowania nanocieczy z dodatkami grafenu i nanorurek.

15

Navier slip condition on time-dependent radiating Nanofluid with the soret effect

Suneetha Sangapatnam, Subbarayudu Ketineni, Wahidunnisa Lalahamed, Reddy Polu Bala Anki

Engineering Transactions

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2020

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Vol. 68, iss. 2

177--198

EN

This work concentrates on the study of the two-dimensional hydromagnetic flow of nanofluids over an suddenly started nonlinear stretching sheet in the presence of radiation and dissipation. The Soret effect and heat generation are also taken into consideration. The transformed ordinary differential equations (ODEs) are solved numerically via the MATLAB RK4S approach bvp4c solver with the assistance of similarity variables. The effects of various parameters are explored and shown in graphs and tables. It is noted that the concentration increases as the Soret number increases within the boundary layer. An increase in velocity slip decreases the velocity and a reverse effect is observed for temperature. This model has significance in different areas such as polymer chemical and metallurgical industries, and other fields that use the latest technology and thermo-processed materials such as metallic and glass sheets.

16

Experimental investigation and characteristics of multiwalled carbon nanotube aqua nanofluids from a flat plate heater surface in a pool

Vasudevan D., Senthil Kumar D., Murugesan A., Vijayakumar C.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

|

Vol. 68, nr 3

547--554

EN

In this experimental investigation, the critical heat flux (CHF) of aqua-based multiwalled carbon nanotube (MWCNT) nanofluids at three different volumetric concentrations 0.2%, 0.6%, and 0.8% were prepared, and the test results were compared with deionized water. Different characterization techniques, including X-ray diffraction, scanning electron microscopy and Fourier transform infrared, were used to estimate the size, surface morphology, agglomeration size and chemical nature of MWCNT. The thermal conductivity and viscosity of the MWCNT at three different volumetric concentrations was measured at a different temperature, and results were compared with deionized water. Although, MWCNT-deionized water nanofluid showed superior performance in heat transfer coefficient as compared to the base fluid. However, the results proved that the critical heat flux is increased with an increase in concentrations of nanofluids.

17

Nanofluid flow and heat transfer of carbon nanotube and graphene platelette nanofluids in entrance region of microchannels

Fuller N. E., Liu J. T. C.

Archives of Mechanics

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2020

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Vol. 72, nr 4

355--379

EN

Suspensions of nano-scale particles in liquids, dubbed nanofluids, are of great interest for heat transfer applications. Nanofluids potentially offer superior thermal conductivity to alternative, pure fluids and are of particular interest in applications where active cooling of power-dense systems is required. In this work, the thermophysical properties of carbon nanotube nanofluids (CNTNf) and those of graphene nanoplatelette nanofluids (GNPNf) as functions of particle volume fraction are deduced from published experiments. These properties are applied to a perturbative boundary layer model to examine how the velocity and temperature profiles (and correspondingly shear stress and surface heat transfer) vary with the nanoparticle concentration in the entrance region of microchannels. Findings of this modeling effort indicate that both shear stress and heat transfer in GNPNf increase with increasing particle concentration. The normalized increase in shear stress is approximately twice that for heat transfer as a function of the GNP particle concentration. Interestingly, CNTNf shows anti-enhancement heat transfer behaviour; an increasing concentration of CNT nanoparticles is associated with both an increase in shear stress and a decrease in the surface heat transfer rate.

18

Effect of chemical reaction on mixed convective nanofluid flow on a vertical plate with uniform heat and mass fluxes

Mondal H., Goqo S. P., Sibanda P., De P.

International Journal of Applied Mechanics and Engineering

|

2019

|

Vol. 24, no. 2

329--342

EN

The purpose of this paper is to consider a two dimensional free convective flow of a nanofluid due to the combined effects of thermal and mass diffusion in the presence of a chemical reaction of first order. The objective of the present investigation is to analyze the free convective flow in the presence of prescribed wall heat flux and mass flux condition. The governing equations of the linear momentum, energy equation and concentration are obtained in a dimensionless form by introducing a suitable group of similarity transformations. The transformed coupled non-linear ordinary differential equations are solved numerically by using appropriate boundary conditions for the various values of physical parameters. Computations are performed for a wide range of values of the various governing flow parameters of the velocity, temperature and species concentration profiles and results are presented graphically. Numerical results for the skin friction coefficient and local Nusselt number are also presented and analyzed in detail. The obtained results are compared with previously published work and are found to be in excellent agreement. The results are a very useful source of information for researchers on the subject of a free convective flow of a nanofluid. This paper illustrates chemical reaction effects on free convective flow of a nanofluid from a vertical plate with uniform heat and mass fluxes.

19

Thermal conductivity of CNT - wated nanofluids: a review

Akhilesh M., Santarao K., Babu M. V. S.

Mechanics and Mechanical Engineering

|

2018

|

Vol. 22, nr 1

207--220

EN

In heat transportation applications, water is most commonly used fluid. The efficiency of equipment used in these applications depends on thermal characteristics of water used. The thermal characteristics of water could be upgraded by suspending high thermal conducting solid nanoparticles. In this paper an attempt has been made to know how the use of surfactants and functionalization of carbon nanotube walls can affect the thermal characteristics and stability of nanofluid. A thorough analysis of collected literature revealed that carbon nanotubes have much higher thermal conductivity than any other nanoparticles and hence improve the thermal properties of water when suspended in them. Further it is concluded that suspension of carbon nanotubes in water requires use of surfactant or functionalization of carbon nanotube walls with proper group. By setting optimum pH and better dispersion, better thermal conductivity is possible. Experimental studies in the literature survey reveal that chemical stabilization techniques and physical stabilization techniques together decide the stability of the nanofluid.

20

Physical properties improvement of the diesel engine lubricant oil reinforced nanomaterials

Hadi N. J., Al-Hussain R. K. A.

Journal of Mechanical and Energy Engineering

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2018

|

Vol. 2, No 3

233--244

EN

This research focuses on the effect of nanomaterials on the physical properties of a local Iraqi lubricant oil (20W-50), which is widely used in diesel engines. The concentrations of 0.001, 0.2 and 0.5 wt% of Al2O3 NPs and CNT are dispersed in the oil with the help of a suitable surfactant using a magnetic stirrer and a sonication process. The density, surface tension, dynamic viscosity, kinematic viscosity, flash point, fire point, pour point, thermal conductivity, thermal images, wear and the coefficient of friction of the oil with and without nanomaterials are tested. The results were shown that the higher concentrations of NPs, the better properties for the engine oil. The density for Al2O3 nanooil indicates a small change at 0.001 and 0.2 wt%, and a decrease at 0.5 wt% ratio. Also, the density of CNT oil shows a slight change at 0.001and then decreasing at 0.2 and 0.5 ratios. In addition, the surface tension of both nanooils are increased. The dynamic viscosity slightly change with an addition of the NPs especially at 20°C and 30°C. Also, there is a convergence in the viscosity values between base and nanooils at 40°C and 50°C. Also, the dynamic viscosity indicates shear thickening behavior at low shear rate, while in the high shear rate the viscosity attempts to be more stable. The kinematic viscosity increases with an increased concentration of the NPs at 40°C and 100°C for both nanooils. The flash and fire point are increasing for both nanooils and Al2O3 nanooil indicates a lower pour point than that of CNT oil. CNT oil indicates higher dissipating heat friction and thermal conductivity than that of Al2O3 nanooil. Thermal images are supported by thermal conductivity and flash point behavior, while the tribology tests are compatible with viscosity behavior. A significant reduction in the coefficient of friction and wear loss is produced for both nanooils.