Type Of Base Fluid Research Articles

Effect of Nanoparticles and Base Fluid Types on Natural Convection in a Three-Dimensional Cubic Enclosure

Convective heat transfer using nanofluids play an important role in thermal applications such as heat exchangers, automotive industries, and power generation. In this work, a numerical analysis is conducted to examine the heat transfer of nanofluid in three-dimensional differentially heated cavity. The finite volume method-based SIMPLEC algorithm is used to solve the system of the mass, momentum, and energy transfer governing equations. The left and the right vertical side walls of the cube are maintained at constant temperatures T C and T H , respectively. The remaining walls of the cube are insulated. Effective thermal conductivity and viscosity of the nanofluid are determined using Brinkman and Maxwell models, respectively. Studies are carried out for three types of nanoparticles and volume fractions of nanoparticles ( 0 – 5 % ). The effects of two binary liquid mixtures as a base fluid (propylene glycol-water and ethylene glycol-water) are also examined. Results show an enhancement of 13 % for Al2O3-EG in comparison to pure ethylene glycol in the case of Ra = 10 3 . In addition, heat transfer enhancement was increased with the rise of nanoparticle volume fractions.

Effects of different concentrations of Al2O3 nanoparticles and base fluid types on pool boiling heat transfer in copper foam with bottom condensed reflux

A closed-loop type experimental system of pool boiling heat transfer with condensed reflux in the bottom was developed to study the boiling heat transfer of copper foams in different working fluids, including deionized water, water-based Al2O3 nanofluids, ethylene glycol/deionized water mixed fluid and ethylene glycol/deionized water-based Al2O3 nanofluids. The pore densities of copper foams are 5, 30 and 60 pores per inch (PPI) and the foam thickness are 2, 4, 6 and 8 mm, while the porosity remains a fixed value of 0.9. Al2O3 nanoparticles with an average diameter of 50 nm are used in this study and their mass concentrations are 0.01%, 0.05% and 0.1%. The results show that the concentrations and types of nanofluids and the structural parameters of copper foams have significant effects on the boiling heat transfer performance. Introducing the condensed reflux back to the bottom of boiling chamber can enhance the boiling heat transfer performance compared with the conventional pool boiling experimental condition. Under the current experimental settings, the gravity-capillary driven condensed reflux can offer extra liquid replenishment to the copper foam surface, improving the rewetting ability and therefore enhancing the boiling heat transfer. In addition, the scouring effect of condensed reflux can promote the bubble departure and decrease the bubble release resistance, and inhibit the deposition of nanoparticles on the heating surface.

State of the Art in PEG-Based Heat Transfer Fluids and Their Suspensions with Nanoparticles.

Research on nanoparticle enhanced fluids has increased rapidly over the last decade. Regardless of several unreliable reports, these new fluids have established performance in heat transfer. Lately, polyethylene glycol with nanoparticles has been demarcated as an innovative class of phase change materials with conceivable uses in the area of convective heat transfer. The amplified thermal conductivity of these nanoparticle enhanced phase change materials (PCMs) over the basic fluids (e.g., polyethylene glycol—PEG) is considered one of the driving factors for their improved performance in heat transfer. Most of the research, however, is centered on the thermal conductivity discussion and less on viscosity variation, while specific heat capacity seems to be fully ignored. This short review abridges most of the recent investigations on new PEG-based fluids and is dedicated especially to thermophysical properties of the chemicals, while a number of PEG-based nanofluids are compared in terms of base fluid and/or nanoparticle type and concentration. This review outlines the possibility of developing promising new heat transfer fluids. To conclude, this research is in its pioneering phase, and a large amount of experimental and numerical work is required in the coming years.

A review of passive methods in microchannel heat sink application through advanced geometric structure and nanofluids: Current advancements and challenges

AbstractMicrochannel heat sink (MCHS) is an advanced cooling technique to fulfil the cooling demand for electronic devices installed with high-power integrated circuit packages (microchips). Various microchannel designs have been innovated to improve the heat transfer performance in an MCHS. Specifically, the utilisation of nanotechnology in the form of nanofluid in an MCHS attracted the attention of researchers because of considerable enhancement of thermal conductivity in nanofluid even at a low nanoparticle concentration. However, a high-pressure drop was the main limitation as it controls the MCHS performance resulted from heat transfer augmentation. Therefore, this study aimed to critically summarise the challenges and limitations of both single and hybrid passive methods of MCHS. Furthermore, the performance of nanofluid as a coolant in the MCHS as affected by the type and concentration of nanoparticle and the type of base fluid was reviewed systematically. The review indicated that the hybrid MCHS provides a better cooling performance than MCHS with the single passive method as the former results in a higher heat transfer rate with minimal pressure drop penalty. Besides that, further heat transfer performance can be enhanced by dispersing aluminium dioxide (Al2O3) nanoparticles with a concentration of less than 2.0% (v/v) in the water-based coolant.

Thermal conductivity, viscosity and heat transfer process in nanofluids: A critical review

Heat transfer efficiency has always been at the center of attractions for many researchers and industries and demand for higher efficiency methods and materials are increased in the last decades. One of the effective methods to enhance the thermal performance of instruments is using nanofluids as a solid-liquid suspension.  In the present paper, the thermal conductivity, viscosity, and heat transfer process of the nanofluids are discussed. The effect of volume fraction, temperature, particle size, shape, base fluid type, and other factors on thermal conductivity, viscosity, and convective heat transfer coefficient of nanofluids are presented. Also, the preparation methods of nanofluids are exhibited and the stability and the effective factors on the stability of nanofluids are brought in the manuscript. Besides, a summarized number of experimental and mathematical studies about the thermal conductivity, viscosity, and stability of nanofluids are listed, compared, and analyzed. The works about the Nusselt number in fluids and nanofluids are presented in detail to determine the future challenges of nanofluids.

A comparative study on best configuration for heat enhancement using nanofluid

Abstract Nanofluid is a class of fluid which enhances the heat extraction from a hot surface. The concentration of nanoparticles enhances the conductivity of the fluid; however, it may change the fluid from Newtonian to a non-Newtonian. In addition, the type of base fluid plays a significant role in heat extraction. In this present study, three different configurations (porous block, porous straight channel and porous wavy channels) setups were investigated numerically using four different types of nanofluids mainly, 0.5% vol Al2O3/Water, 0.5% vol TiO2/Water, 0.5% vol Al2O3/Ethylene Glycol and 0.5% vol TiO2/Ethylene Glycol. Different parameters were assessed such as the local Nusselt number, the friction coefficient, the pressure drop, the temperature uniformity and the efficiency index. It was found that each nanofluid have a different performance for different configuration. If one relies on the efficiency index which combine the Nusselt number and the pressure drop, the nanofluid of 0.5% vol Al2O3 in water base provided the highest efficiency index.

Analysis on Viscosity and Stability of Chinese Ink Nanofluids

Chinese ink nanofluids were prepared successfully by “two-step” method. The optical properties of Chinese ink nanofluids were investigated. And the effects of the base fluid types and ultrasonic time on their dispersion stability also were investigated. Results show that Chinese ink have high absorption characteristics and very low transmittance on light radiation in the wavelength range of 190-1100 nm; The dispersion stability of nanofluids increases first and then decreases with the increase of ultrasonic dispersion time. There is an optimal ultrasonic dispersion time of 90 min; the base fluid has a certain influence on the dispersion stability of Chinese ink nanofluid, among which DMF base solution has the best dispersion stability, followed by thermal conductive oil. Ethanol has no obvious improvement compared with water, both of which have lower dispersion stability than DMF and thermal conductive oil. This research provides a fundamental guidance for the preparation of Chinese ink nanofluids and their further application in Solar photo-thermal conversion.

Investigation of the effect of particle stability on the transport properties and thermal behavior of ethylene glycol-water/ binary nanofluids

Nanofluids (Nfs) are considered as an effective working media in different thermal processes. Over the years, much attention has been paid to the problem of nanoparticle stability in base fluids in an unconfined area of research, especially in the field of thermal applications. There is still concern about the stability of nanoparticles and their effects on the transport properties and thermal performance in thermal systems. In the present paper, the transport properties and thermal behavior of ethylene glycol-water/ binary Nfs are investigated in two sections, considering the effect of particle stability and size growth. The first section covering the experimental work, which includes the preparation and characterization of the Nfs where different percentages of base fluids at different pH values are used for this purpose. The characterization of the Nfs explains the effect of the zeta potential on the particle size distribution and the hydrodynamic diameter of suspended particles. The second section involves the theoretical study, where the transport properties and thermal behavior of the Nfs are estimated taking into consideration the effect of the particle stability and size growth. It is found that the binary Nfs that contain different types of base fluids show different stability behavior at different pH values at the same particle concentration. Ethylene glycol-water/ binary Nfs at pH = 9 contain a low hydrodynamic diameter of suspended particles, and Nfs have good stability behavior. On the other hand, the Nfs at pH = 2 contain the maximum size of the particle hydrodynamic diameter. The Nfs that include 25% water + 75% ethylene glycol show a better stability behavior in comparison with other types of Nfs that included 75% water + 25% ethylene glycol. Particle size growth shows a significant effect on the transport properties (thermal conductivity and viscosity) as well as the particle-fluid interaction Nusselt number, Biot number, and convection heat transfer coefficient.

Investigation of the effects of base fluid type of the nanofluid on heat pipe performance

Most recently, an ascending tendency in nanoparticles containing working fluid utilization has been observed in such thermal systems as double pipe heat exchangers and thermosiphons in so far as its advantages upon the performance of such systems. In order to investigate how the type of the base fluid affects the nanofluid’s properties used for thermal applications, an experimental test rig was setup and two different nanofluid each of which involves different base fluid, but same nanoparticles and surface active agent were tested. During the nanofluid preparation process, bauxite nanoparticles as nanoparticle material and sodium dodecyl benzene sulfonate as surface active agents were used in volume fractions of 2% and 0.5%, respectively. As the base fluid type, ethylene glycol and deionized water were utilized. The tests were conducted under diverse working conditions and vacuum pressure. Distribution of temperature ahead the heat pipe wall, efficiency and heat pipe’s thermal resistance was experimentally investigated. It was observed from the experiments that each nanofluid improved the heat pipe performance significantly; however, deionized water/bauxite nanofluid gave the best results in terms of heat pipe’s thermal performance. For each nanofluid, the maximum increment in efficiency was observed under 200 W heating power and 10 g/s cooling water mass flow rate conditions, and improvement rates were 29.5% and 13.3% for ethylene glycol-based and deionized water-based nanofluids, respectively. At least 20% of decline in thermal resistance of the heat pipe was also recorded, when nanofluid was employed as working fluid.

Investigation the effect of various factors in a convective heat transfer performance by ionic liquid, ethylene glycol, and water as the base fluids for Al2O3 nanofluid in a horizontal tube: A numerical study

Abstract The present research investigates the heat transfer enhancement by adding alumina nanoparticle to water, Ethylene glycol, and 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][EtSO4] ionic liquid (called ionic liquid-based nanofluid or INf in synonym) as a base fluid. A horizontal tube with constant heat flux was modeled in two-dimensional geometry with a diameter and length of 4.0 mm and 6.0 m, respectively. Al2O3 (20 nm in diameter) nanoparticles added to the base fluid in 0.5, 1.0 and 2.5 weight fraction percent. Various factors such as Reynolds number, nanofluids concentration, type of base fluid, and especially fluid inlet temperature studied in this research. Impressive results observed with variation in fluid temperature which for the temperature below room temperature (278.15 K) IL-based nanofluid shows greater heat transfer coefficient than water and Ethylene glycol-based nanofluids because of its higher thermal conductivity and viscosity at a lower temperature. And also, by adding nanoparticles to the base fluids and increasing the concentration of nanofluids, the heat transfer coefficient increased. Both the maximum heat transfer coefficient and heat transfer enhancement observed for IL-based nanofluid at 2.5 wt% concentration of nanoparticle. Finally, a correlation proposed for Nu number that satisfies for all studied nanofluids with R2 = 0.971 and AREP = 7.9%.

Study of the effects of particle shape and base fluid type on density of nanofluids using ternary mixture formula: A molecular dynamics simulation

Ternary mixture formula with consideration of the effect of nanolayer formation is capable of predicting nanofluid density more accurately compared with the traditional mixture rule. The aim of this investigation is to study the effect of particle shape and type of base fluid on density of nanofluid based on the ternary mixture formula using molecular dynamics simulations. In this regard, two types of base fluids, i.e. water and liquid argon, as well as four different particle shapes, i.e. spherical, planar, block and rod-shaped with different aspect ratios are examined. The results showed that different particle shapes show different behaviors in attracting base fluid molecules and forming nanolayer. The thickness of nanolayer is assumed from the surface of nanoparticle to the place that the density fluctuations stay within a tolerance of 2% of the base fluid density. Accordingly, the thicknesses of nanolayers are 0.9 nm and 1.3 nm for silver-water and silver-liquid argon nanofluids, respectively. Moreover, it was found that the density of nanofluids containing planar nanoparticles as well as spherical nanoparticles decreases with increasing nanoparticle diameter and planar nanoparticle has the highest density of nanolayer among planar, spherical and rod-shaped particles. The comparison between the densities of three nanofluids containing equal volume nanoparticles with different shapes reveals that the ternary mixture formula has significant advantages over the traditional binary mixture.

Entropy analysis for an MHD nanofluid with a microrotation boundary layer over a moving permeable plate

Entropy analysis of an electrically conducting boundary layer of a nanofluid with microrotation elements over a moving plate is presented in this article by applying the second law of thermodynamics. Two types of nanoparticles, copper oxide (CuO) and aluminum oxide (Al2 O3 ), are considered in addition to microstructure elements within a base fluid. The analysis is based on governing boundary layer equations associated with the linear and angular momentum as well as the energy transformed by introducing a suitable similarity transformation into a system of triple nonlinear differential equations that are solved analytically. On the physical side, this article examines the effect of the nanoparticle type and its concentration as well as the type of base fluid, whether Newtonian or non-Newtonian, on the rate of entropy generated and the rate of heat flux from the surface. This simulation involves the cooling stage of the metals during the heat treatment process, which controls the final mechanical properties of the plate, so controlling the entropy of the cooling system plays a great role on the results. The results obtained confirm that the entropy generation of the non-Newtonian fluids (fluids with microrotation elements) is higher than that of the Newtonian fluids and that the presence of nanoparticles in the cooling system increases the rate of entropy by 1–4% according to the type and concentration of the nanoparticles.

Entropy Generation and Heat Transfer in Drilling Nanoliquids with Clay Nanoparticles

Different types of nanomaterials are used these days. Among them, clay nanoparticles are the one of the most applicable and affordable options. Specifically, clay nanoparticles have numerous applications in the field of medical science for cleaning blood, water, etc. Based on this motivation, this article aimed to study entropy generation in different drilling nanoliquids with clay nanoparticles. Entropy generation and natural convection usually occur during the drilling process of oil and gas from rocks and land, wherein clay nanoparticles may be included in the drilling fluids. In this work, water, engine oil and kerosene oil were taken as base fluids. A comparative analysis was completed for these three types of base fluid, each containing clay nanoparticles. Numerical values of viscosity and effective thermal conductivity were computed for the nanofluids based on the Maxwell–Garnett (MG) and Brinkman models. The closed-form solution of the formulated problem (in terms of partial differential equations with defined initial and boundary conditions) was determined using the Laplace transform technique. Numerical facts for temperature and velocity fields were used to calculate the Bejan number and local entropy generation. These solutions are uncommon in the literature and therefore this work can assist in the exact solutions of a number of problems of technical relevance to this type. Herein, the effect of different parameters on entropy generation and Bejan number minimization and maximization are displayed through graphs.

The experimental investigation of the evaporation rate of nanofluids based on different fluids

The evaporation of the nanofluids based on Al2O3 nanoparticles and different fluids was experimentally investigated. The distilled water and isopropyl alcohol were used as base fluids. The average diameter of Al2O3 particles was 100 nm. The investigations of fluids evaporation rates were carried out using the Simultaneous Thermal Analyzer STA 449 C Jupiter (NETZSCH). The investigation of the evaporation rate dependence on the carrier media was carried out. It was found that the average relative evaporation rate of fluids increased, and the time of complete evaporation accordingly decreased with an increase in the volume concentration of nanoparticles. In addition, the absolute value of the evaporation rate was found to significantly depend on the type of base fluid. However, the relative value of the evaporation rate for different base fluids remains approximately the same.

A review of heat transfer application of carbon-based nanofluid in heat exchangers

Heat exchangers are very important equipment for cooling and heating processes in different industrial fields and applications. Nanofluids were employed to replace conventional working fluids of the same kind as water, ethyl-glycol and oil, with the aim to improve the heat transfer performance of heat exchange device. Nanofluids of different nanomaterials such as metal oxides, ceramic oxides and carbon nanomaterials have been widely used to enhance heat transfer. However, none improves the thermophysical properties as much as that of carbon nanomaterials such as Graphene and Carbon nanotubes. This study reviews and summarizes investigations on the application of carbon-based nanofluid in heat exchangers. It was observed that the thermal characteristics of the nanofluid depend on the type of base fluid, nanomaterial concentrations, temperature and surfactants used. The heat transfer characteristics and flow properties of the heat exchanger utilizing carbon-based nanofluids were also affected by nanomaterial concentration, Reynolds number, flow rates and inlet fluid temperature. It concluded by presenting challenges and scope for future studies.

Unsteady water functionalized oxide and non-oxide nanofluids flow over an infinite accelerated plate

The purpose of this communication is to examine the collective influence of heat and mass transfer on magnetohydrodyanmics (MHD) water functionalized oxide or non-oxide nanofluid flows through porous medium together with thermal radiation and chemical reaction effects. The Newtonian heating on the accelerated wall in the presence of different nanoparticles is considered first time and not explored in earlier investigations. To calculate the temperature and velocity fields, the Maxwell model for effective thermal conductivity with relatively large particles is used. Three types of base fluids namely water, kerosene and engine oil containing different types of oxide and non-oxide nanoparticles are taken for this study. Analytic solutions of the governing equations are obtained with the help of Laplace transform method (LTM). Some important cases such as free convection and motion of plate with variably accelerated, constant accelerated, uniform velocity as well as in the absence of free convection are obtained. Graphs are plotted to analyse the characteristics of different involved parameters on velocity, temperature and concentration.

Influence of single and multiple coupling factors on the stability of paraffin-based nanofluids

Nanofluids have been introduced to improve the thermal properties of phase-change materials. However, stability problems caused by agglomeration and deposition have greatly restricted the use of nanofluids. In this work, paraffin-based nanofluids were prepared under the dual coordination of magnetic stirring and ultrasonic oscillation, the influence of ultrasonic power and time, base fluid volume, particle concentration and type on fluid stability was studied by single factor method, and the influence degree of the above four factors on fluid stability was studied by fractional factor design method. The following conclusions were drawn from the experiment: (1) With the increase of ultrasonic power, the relative absorbance increases within the allowable range of the experimental instrument, and the maximum improvement is 3.06%.(2) The optimal ultrasonic time for nanofluids preparation is 2 h. (3) The sample volume under the optimal state is 45 ml. (4) With the increase in concentration, the absorbance per concentration decreases, and the reduction range becomes slow. (5) The stability of the nanofluid is also related to the characteristics of the particle surface. (6) The coupling effect of ultrasonic power - concentration (PC) has the most significant effect on the overall absorbance change. This study provides a clear improvement direction and basis for the preparation of highly stable nanofluids.

Stability analysis for model-based study of nanofluid flow over an exponentially shrinking permeable sheet in presence of slip

This article aims to present the nanofluid flow over an exponentially porous shrinking sheet in the presence of velocity slip and thermal slip. Single-phase fluid model for nanofluid has been used. In this investigation, the effects of silver (Ag) nanoparticle in two different types of base fluids (water and kerosene oil) are investigated. Using similarity transformations, the governing boundary-layer equations and the boundary conditions are reduced to the system of coupled nonlinear ordinary differential equations and then solved numerically with the help of shooting method. Dual solutions exist for some particular range of values of the governing parameters. A stability analysis has been performed to find out the stable solution. A comparison is made between the boundary-layer flow of Ag–water and Ag–kerosene. Impacts of various parameters on velocity, temperature profiles, skin friction coefficient, and Nusselt number are computed and presented in graphs and tables. The fluid velocity and temperature both increase with the increasing nanoparticle volume fraction.

Experimental investigation toward obtaining nanoparticles' surficial interaction with basefluid components based on measuring thermal conductivity of nanofluids

In this study the effect of temperatures, the CuO and TiO2 nanoparticles' mass fraction, and basefluid types were studied on thermal conductivity of nanofluid. CuO and TiO2 nanoparticles were dispersed in ethanol and liquid paraffin model 107,160 separately by using ultrasonic waves. The stability of nanoparticles in basefluids was estimated by exploiting DLS and Zeta Potential analysis. The results showed that the thermal conductivity enhances with the increase in temperature; conversely, with the increase in temperature the thermal conductivity of the basefluid decreases. The results of this study showed that by increasing the mass fractions of metal oxides nanoparticles the thermal conductivity of nanofluid increases. Also, by increasing the concentration of oxides nanoparticles in liquid paraffin, the changes in the thermal conductivity of nanofluid at concentrations of <1% are insignificant, but by increasing the concentration of nanoparticles from 1% mass to 5%, the changes in the thermal conductivity of nanofluid are remarkable. The results of the calculation for the interaction parameter showed that in the low concentrations of metal oxides nanoparticles, the interaction effect between surfaces of metal oxide nanoparticles and ethanol molecules is greater than the liquid paraffin. The results also showed that the thermal conductivity of ethanol/CuO is greater than the other nanofluids (ethanol/TiO2, liquid paraffin/ TiO2, and liquid paraffin/CuO) at various temperatures and nanoparticles' mass fraction. Finally an empirical equation including temperature, nanoparticles mass fraction, and physical properties of nanoparticles and basefluids was predicted by using hybrid GMDH-type neural network to estimate the interaction parameter between nanoparticles surface and basefluids molecules.

Application of Nanofluids in Thermal Performance Enhancement of Parabolic Trough Solar Collector: State-of-the-Art

The present review paper aims to document the latest developments on the applications of nanofluids as working fluid in parabolic trough collectors (PTCs). The influence of many factors such as nanoparticles and base fluid type as well as volume fraction and size of nanoparticles on the performance of PTCs has been investigated. The reviewed studies were mainly categorized into three different types of experimental, modeling (semi-analytical), and computational fluid dynamics (CFD). The main focus was to evaluate the effect of nanofluids on thermal efficiency, entropy generation, heat transfer coefficient enhancement, as well as pressure drop in PTCs. It was revealed that nanofluids not only enhance (in most of the cases) the thermal efficiency, convection heat transfer coefficient, and exergy efficiency of the system but also can decrease the entropy generation of the system. The only drawback in application of nanofluids in PTCs was found to be pressure drop increase that can be controlled by optimization in nanoparticles volume fraction and mass flow rate.