scholarly journals A REVIEW ON NANOFLUIDS: PREPARATION METHODS AND APPLICATIONS

2019 ◽  
Vol 16 (31) ◽  
pp. 365-380
Author(s):  
P. A. C. ROCHA ◽  
R. F. de M. SANTOS ◽  
R. J. P. LIMA ◽  
M. E. V. da SILVA
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermophysical Properties ◽  
Base Fluid ◽  
Solid Particles ◽  
Heat Transfer Characteristics ◽  
Preparation Methods ◽  
Automotive Electronic ◽  
New Generation ◽  
Suspended Nanoparticles

Research in heat transfer using suspensions of nanometer-sized solid particles in liquids as the base fluids have started in the last two decades. The nanofluid is a colloidal mixture composed of a base fluid and nanoparticles. The nanoparticles may be metallic, nonmetallic, ceramic, oxide and of several other categories, being the nanocomposites one of the areas of greater growth in the engineering of materials. Nanofluids are part of a new generation of high potential fluids in heat transfer applications due to their higher thermal conductivity. Most recent studies on nanofluids indicate that suspended nanoparticles markedly alter the properties and heat transfer characteristics of the suspension. This article summarizes some of the recent advances in the study of nanofluids and nanoparticles, such as their preparation methods, their thermophysical properties and finally presents various fields of applications such as solar thermal, mechanical, automotive, electronic, medical, biomedical etc.

Thermophysical Properties for ZnO-Water Nanofluid: Experimental Study

2021 ◽  
Vol 1025 ◽  
pp. 9-14
Author(s):  
Adnan H. Rasheed ◽  
Hajar Alias ◽  
Sami D. Salman
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Study ◽  
Zinc Oxide ◽  
Thermophysical Properties ◽  
Base Fluid ◽  
Volume Fraction ◽  
Nanoparticle Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Rotational Viscometer

This paper presents the thermophysical properties of zinc oxide nanofluid that have been measured for experimental investigation. The main contribution of this study is to define the heat transfer characteristics of nanofluids. The measuring of these properties was carried out within a range of temperatures from 25 °C to 45 °C, volume fraction from 1 to 2 %, and the average nanoparticle diameter size is 25 nm, and the base fluid is water. The thermophysical properties, including viscosity and thermal conductivity, were measured by using Brookfield rotational Viscometer and Thermal Properties Analyzer, respectively. The result indicates that the thermophysical properties of zinc oxide nanofluid increasing with nanoparticle volume fraction increasing, as well as the thermophysical properties of zinc oxide nanofluid affected by the change in temperature.

Pool Boiling Characteristics of Metallic Nanofluids

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
K. Hari Krishna ◽  
Harish Ganapathy ◽  
G. Sateesh ◽  
Sarit K. Das
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boiling Heat Transfer ◽  
Volume Fraction ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Solid Particles ◽  
Heater Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Nanofluids, solid-liquid suspensions with solid particles of size of the order of few nanometers, have created interest in many researchers because of their enhancement in thermal conductivity and convective heat transfer characteristics. Many studies have been done on the pool boiling characteristics of nanofluids, most of which have been with nanofluids containing oxide nanoparticles owing to the ease in their preparation. Deterioration in boiling heat transfer was observed in some studies. Metallic nanofluids having metal nanoparticles, which are known for their good heat transfer characteristics in bulk regime, reported drastic enhancement in thermal conductivity. The present paper investigates into the pool boiling characteristics of metallic nanofluids, in particular of Cu-H2O nanofluids, on flat copper heater surface. The results indicate that at comparatively low heat fluxes, there is deterioration in boiling heat transfer with very low particle volume fraction of 0.01%, and it increases with volume fraction and shows enhancement with 0.1%. However, the behavior is the other way around at high heat fluxes. The enhancement at low heat fluxes is due to the fact that the effect of formation of thin sorption layer of nanoparticles on heater surface, which causes deterioration by trapping the nucleation sites, is overshadowed by the increase in microlayer evaporation, which is due to enhancement in thermal conductivity. Same trend has been observed with variation in the surface roughness of the heater as well.

Enhancement of Heat Transfer Characteristics in an Absorber Tube of a Solar-Based Energy System Using Nanofluids

2015 ◽  
Author(s):  
Adnan Alashkar ◽  
Mohamed Gadalla
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermophysical Properties ◽  
Volume Fraction ◽  
Effective Density ◽  
Heat Transfer Characteristics ◽  
Overall Heat Transfer Coefficient ◽  
Transfer Characteristics

In this present paper, nanoparticles are dispersed into a base fluid, their effect on the thermophysical properties and overall heat transfer coefficient of the fluid inside a circular tube representing an absorber tube of a Parabolic Trough Solar Collector (PTSC) is studied. Different models are used to predict the effective density, specific heat capacity, viscosity and thermal conductivity of the nanofluids. For the analytical analysis, Alumina (Al2O3), Copper (Cu) and Single Wall Carbon Nanotubes (SWCNT) nanoparticles are dispersed into Therminol VP-1 oil. The resulting nanofluids are compared in terms of their thermophysical properties, their convective heat transfer characteristics and their overall heat transfer coefficient. Moreover, the effect on increasing the volume fraction on the properties and the heat transfer coefficient is studied. The computational analysis results show that the thermal conductivity increases with the increase of the volume fraction. In addition Therminol/SWCNT showed the highest thermal conductivity enhancement of 98% for a volume fraction of 3%. Further, the overall heat transfer coefficient increases with the increase of volume fraction, and Therminol/SWCNT showed the highest enhancement with 72% compared to Al2O3/Therminol and Cu/Therminol that showed an enhancement of 29% and 43% respectively.

scholarly journals Enhancement of heat transfer coefficient multi-metallic nanofluid with ANFIS modeling for thermophysical properties

2015 ◽  
Vol 19 (5) ◽  
pp. 1613-1620 ◽  
Author(s):  
Hyder Balla ◽  
Shahrir Abdullah ◽  
Wan Faizal ◽  
Rozli Zulkifli ◽  
Kamaruzaman Sopian
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermophysical Properties ◽  
Dynamic Viscosity ◽  
Base Fluid ◽  
Volume Fractions ◽  
The Heat Transfer Coefficient ◽  
Cu And Zn

Cu and Zn-water nanofluid is a suspension of the Cu and Zn nanoparticles with the size 50 nm in the water base fluid for different volume fractions to enhance its Thermophysical properties. The determination and measuring the enhancement of Thermophysical properties depends on many limitations. Nanoparticles were suspended in a base fluid to prepare a nanofluid. A coated transient hot wire apparatus was calibrated after the building of the all systems. The vibro-viscometer was used to measure the dynamic viscosity. The measured dynamic viscosity and thermal conductivity with all parameters affected on the measurements such as base fluids thermal conductivity, volume factions, and the temperatures of the base fluid were used as input to the Artificial Neural Fuzzy inference system to modeling both dynamic viscosity and thermal conductivity of the nanofluids. Then, the ANFIS modeling equations were used to calculate the enhancement in heat transfer coefficient using CFD software. The heat transfer coefficient was determined for flowing flow in a circular pipe at constant heat flux. It was found that the thermal conductivity of the nanofluid was highly affected by the volume fraction of nanoparticles. A comparison of the thermal conductivity ratio for different volume fractions was undertaken. The heat transfer coefficient of nanofluid was found to be higher than its base fluid. Comparisons of convective heat transfer coefficients for Cu and Zn nanofluids with the other correlation for the nanofluids heat transfer enhancement are presented. Moreover, the flow demonstrates anomalous enhancement in heat transfer nanofluids.

Thermophysical Properties of Two-Phase Refrigerant Based Nanofluids in a Refrigeration Cycle

2016 ◽  
Author(s):  
Bilgehan Tekin ◽  
Almila G. Yazicioglu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermophysical Properties ◽  
Base Fluid ◽  
Two Phase Flow ◽  
Cooling System ◽  
Heat Transfer Analysis ◽  
Refrigeration Cycle ◽  
Phase Flow ◽  
Two Phase

Nanofluids are a class of fluids with nanoparticles suspended in a base fluid. The aim for using nanofluids is often to improve the thermophysical properties of the base fluid so as to enhance the energy transfer efficiency. As the technology develops; the size of devices and systems needs to get smaller to fulfill the engineering requirements and/or to be leading among competitors. The use of nanofluids in heat transfer applications seems to be a viable solution to current heat transfer problems, albeit with certain limitations. As an enhancing factor for the thermal conductivity of the base fluid, nanofluids are considered to be use in cooling system applications. For these applications, the base fluid, the refrigerant, exists as a two-phase liquid-vapor mixture in parts of the refrigeration cycle. To analyze, design and optimize the cycle in such applications, the thermophysical properties of the refrigerant based nanofluids for two-phase flow of refrigerant are needed. There are different models present in the literature derived for the thermophysical properties of nanofluids. However, a majority of the existing models for nanofluid thermophysical properties have been proposed for water- and other liquids-based nanofluids, through theoretical, numerical and experimental research. Therefore, the existing models for determination of the nanofluid thermophysical properties are not applicable for refrigerant based nanofluid applications when the results are compared. Thus, in this work, a new model is derived for the thermal conductivity and viscosity of refrigerant based nanofluids, using existing data from both heat transfer and thermophysical property measurement experiments. The effect of the nanoparticles on heat transfer in two phase flow of the refrigerant is considered by applying the two phase heat transfer correlations in the literature to experimental data. As a result, the thermophysical properties of the known states are determined through known heat transfer performance. Even though the model is developed from the analysis of flow in an evaporator and flow in a single tube with evaporating refrigerant, it is aimed to cover the flows in both evaporator and condenser sections in a vapor compression refrigeration cycle to provide the necessary models for thermophysical properties in heat transfer devices which will allow the design of both cycle and evaporator or condenser in terms of sizing and rating problems by performing heat transfer analysis and/or optimization. The model can also be improved by considering the effects of slip mechanisms that lead to slip velocity between the nanoparticle and base fluid.

Thermophysical Properties of Nanofluids

2020 ◽  
Vol 16 ◽  
Author(s):  
Reyhan Arslan ◽  
Veysel Ahmet Özdemir ◽  
Emel Akyol ◽  
Ahmet Selim Dalkilic ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Surface Area ◽  
Thermophysical Properties ◽  
Heat Transfer Area ◽  
New Generation ◽  
Conductive Particles ◽  
Base Liquid

: Nanofluids, consist of base liquid and nano-sized conductive particles, are widely acclaimed as a new generation liquid for heat transfer applications. Since it possesses a variety of conductive particles, it can be efficiently utilized in the heat exchanger. These nano-sized conductive particles can increase the surface area, thus the heat transfer area, and change the thermophysical features of nanofluids. Density, thermal conductivity, viscosity, and heat capacity are crucial parameters and cannot be underestimated in heat transfer. These properties can be manipulated by the particle and base-liquid, and significantly influence the performance of nanofluids. For the last decade, several models, equations, and investigations were performed to examine the parameters that promote the properties. The review is necessary for terms of classifying the studies both compatible, and contradictory on the effects of density, thermal conductivity, viscosity, and heat capacity on the performance of nanofluids.

Thermal Conductivity Enhancement by Adding Nanoparticles to Ionic Liquids

2017 ◽  
Vol 261 ◽  
pp. 121-126 ◽  
Author(s):  
Alina Adriana Minea ◽  
Madalina Georgiana Moldoveanu ◽  
Oana Dodun
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Thermophysical Properties ◽  
Base Fluid ◽  
Thermal Conductivity Enhancement ◽  
Conductivity Enhancement ◽  
New Class ◽  
Enhanced Thermal Conductivity

Ionanofluids are a very new class of nanofluids having ionic liquids as the base fluid. Thermophysical properties of base ionic liquids (ILs) and nanoparticle enhanced ionic liquids (NEILs) are part of studying a new class of fluids for heat transfer. NEILs are formed by dispersing different volume fractions of nanoparticles in a base ionic liquid. In this article, only the thermal conductivity enhancement was considered for comparison of the different ionanofluids. NEILs show enhanced thermal conductivity compared to the base ILs. Maximum thermal conductivity enhancement was observed by adding 1 % MWCNT to [C4mim][(CF3SO2)2N] ionic liquid. However, if 0.05% MWCNT are added to [(C6)3PC14)][NTf2] no enhancement in thermal conductivity was noticed.

scholarly journals Thermophysical properties of nanofluids MWCNT (multi-walled carbon nanotubes) in water for emergency coolant from nuclear reactors

2021 ◽  
Vol 8 (3A) ◽  
Author(s):  
Alexandre Melo Oliveira ◽  
Amir Zacarias Mesquita ◽  
Enio Pedone Bandarra ◽  
Daniel Flórez Morales
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermophysical Properties ◽  
Nuclear Reactors ◽  
Energy Systems ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

To evaluate the synthesis and characterization of MWCNT (Multi-walled Carbon Nanotubes) with different degrees of functionalization in distilled water. The thermophysical properties (thermal conductivity and viscosity) of these nanofluids were measured at a temperature range (20-60°C) and concentrations (0.005-0.05%) by volume. Increases in thermal conductivity and viscosity were found 9.3% and 4.7%, respectively, at a volumetric concentration of 0.01% at a temperature of 30°C. The study of new fluids that improve the rate of removal of heat is fundamental to obtain greater efficiency of energy systems. Among the several factors that compromise the efficiency of the energy systems, we can highlight the thermophysical limitations of the conventional fluids, inhibiting in a very significant way some industrial applications. In this work we intend to improve the heat transfer characteristics of fluids commonly used by the addition of nanoparticles, made up of carbon nanotubes, in water which is the most used fluid for the cooling of nuclear reactors in operation today. It is intended to improve the heat transfer characteristics of fluids commonly used by the addition of nanoparticles, made of carbon nanotubes, through the addition of nanoparticles, made up of carbon nanotubes, in water which is the most used fluid for refrigeration of nuclear reactors currently in operation. In order to assess its benefits for the applicability and nuclear systems, ie primary coolant, safety systems, major accident mitigation strategies.

Prediction of effective thermal conductivity of nanofluids by modifying renovated Maxwell model

2016 ◽  
Vol 30 (3) ◽  
pp. 289-301 ◽  
Author(s):  
Deepti Chauhan ◽  
Nilima Singhvi
Keyword(s):  
Neural Network ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Base Fluid ◽  
Volume Fraction ◽  
Maxwell Model ◽  
Theoretical Models ◽  
Solid Particles ◽  
Nanoparticle Volume Fraction ◽  
Suspended Nanoparticles

Nanofluids, which are formed by suspending nanoparticles into conventional fluids, exhibit anomalously high thermal conductivity. Renovated Maxwell model was developed by Choi in which the presence of very thin nanolayer surrounding the solid particles was considered, which can measurably increase the effective thermal conductivity of nanofluids. A new model is proposed by introducing a fitting parameter χ in the renovated Maxwell model, which accounts for nanolayer, nonuniform sizes of filler nanoparticles together with aggregation. The model shows that the effective thermal conductivity of nanofluids is a function of the thickness of the nanolayer, the nanoparticle size, the nanoparticle volume fraction and the thermal conductivities of suspended nanoparticles, nanolayer and base fluid. The validation of the model is done by applying the results obtained by the experiments on nanofluids, other theoretical models, and artificial neural network technique. The uncertainty of the present measurements is estimated to be within 5% for the effective thermal conductivity.

Maximizing Heat Transfer Through Joint Fin Systems

2005 ◽  
Vol 128 (2) ◽  
pp. 203-206 ◽  
Author(s):  
A.-R. A. Khaled
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Performance ◽  
Critical Length ◽  
The Other ◽  
Rigid Fixation ◽  
Convection Coefficient ◽  
Heat Transfer Characteristics ◽  
Cold Side ◽  
Transfer Characteristics

Heat transfer through joint fins is modeled and analyzed analytically in this work. The terminology “joint fin systems” is used to refer to extending surfaces that are exposed to two different convective media from its both ends. It is found that heat transfer through joint fins is maximized at certain critical lengths of each portion (the receiver fin portion which faces the hot side and the sender fin portion that faces the cold side of the convective media). The critical length of each portion of joint fins is increased as the convection coefficient of the other fin portion increases. At a certain value of the thermal conductivity of the sender fin portion, the critical length for the receiver fin portion may be reduced while heat transfer is maximized. This value depends on the convection coefficient for both fin portions. Thermal performance of joint fins is increased as both thermal conductivity of the sender fin portion or its convection coefficient increases. This work shows that the design of machine components such as bolts, screws, and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties.

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