Class Of Heat Transfer Fluids Research Articles

Flow Characteristics of Heat and Mass for Nanofluid under Different Operating Temperatures over Wedge and Plate.

Nanofluids are a new class of heat transfer fluids that are used for different heat transfer applications. The transport characteristics of these fluids not only depend upon flow conditions but also strongly depend on operating temperature. In respect of these facts, the properties of these fluids are modified to measure the temperature effects and used in the governing equations to see the heat and mass flow behavior. Design of Model: Consider the nanofluids which are synthesized by dispersing metallic oxides (SiO2, Al2O3), carbon nanostructures (PEG-TGr, PEG-GnP), and nanoparticles in deionized water (DIW), with (0.025-0.1%) particle concentration over (30-50 °C) temperature range. The thermophysical properties of these fluids are modeled theoretically with the help of experimental data as a function of a temperature and volume fraction. These models are further used in transport equations for fluid flow over both wedge and plate. To get the solution, the equations are simplified in the shape of ordinary differential equations by applying the boundary layer and similarity transformations and then solved by the RK method. The solution of the governing equation is found in the form of velocity and temperature expressions for both geometries and displayed graphically for discussion. Moreover, momentum and thermal boundary layer thicknesses, displacement, momentum thicknesses, the coefficient of skin friction, and Nusselt number are calculated numerically in tabular form. The maximum reduction and enhancement in velocity and temperature profile is found in the case of flow over the plate as compared to the wedge. The boundary layer parameters are increased in the case of flow over the plate than the wedge.

A comprehensive review of recent progress of nanofluid in engineering application: Microchannel heat sink (MCHS)

Nanofluid is a new class of heat transfer fluid that is introduced to enhance the heat transfer performance in various heat exchanging systems. Prior to invention of nanofluid, water is the most common fluid used to extract heat generated from the systems. The application of water has reached thermal bottleneck since it can only enhance the heat transfer performance up to a certain extent. The suspension of nanoparticles with enhanced thermal conductivity provides augmentation in heat transfer performance. Since then, nanofluids have received great interest from scientists and researchers due to significant higher thermal conductivity. Due to enhanced thermophysical properties, nanofluids can be incorporated into high heat transfer device such as solar thermal conversion system, heat exchanger, and electronic equipment. Understanding the factors that influence the heat transfer performance is extremely important for appropriate selection and implementation of nanofluids. The influence of nanoparticles material, nanoparticles size, nanoparticles concentration, nanoparticles shape and surfactant are reviewed systematically to provide a comprehensive understanding of nanofluids. The review aims to extensively discuss the application of nanofluids in engineering application such as microchannel heat sink (MCHS). Finally, the review aims to update the readers about the current progress of nanofluids along with challenges of nanofluids in engineering field.

Silver-Water Nanofluid for Heat Transfer Applications

Introduction: Nanoscale materials have attracted a great deal of attention of many researchers and academician in mechanical engineering because of their size and shape dependent thermal properties. The attractiveness of its superior thermal properties compared to its base materials is the main reason for the effective utilization of nanomaterials for the energy systems. The rapid development and researches in nanotechnology led to the development of new class of heat transfer fluid called nanofluid for heat transfer enhancement. The nanoparticles dispersed in the fluid increase the surface area, heat capacity and thermal conductivity of the fluid making it very suitable for heat transfer enhancement (1). Methods: Silver being a safe material with higher thermal conductivity of 429 W/mK can be extensively used for the heat transfer applications. Silver-water nanofluid was prepared by dispersing silver nanoparticles of sizes 20, 30-50 and 50-80 nm in the volume concentrations of 0.01, 0.05 and 0.1%. Polyvinyl pyrrolidone (PVP) has been used as surfactant to stabilize the nanofluid. Thermal conductivity of nanofluid was measured by kD2 Pro thermal analyzer. The stability of nanofluid was analyzed by sedimentation technique, pH measurement, zeta potential and particle size distribution. The effect of surfactant on the thermal conductivity enhancement and stability of nanofluid was studied (1,2). Then the investigations on the heat transfer and pressure drop of silver-water nanofluid in a circular tube under constant wall heat flux condition were carried out in laminar and turbulent flow regimes. Results & Discussions: Among the three sizes of silver nanoparticles used in the investigation, nanofluid with 20 nm exhibited better thermal conductivity enhancement and stability due to lower size. The addition of surfactant improved the stability of nanofluid but caused reduction in thermal conductivity enhancement slightly. Increase of concentration of nanoparticles from 0.01 to 0.1% improved the thermal conductivity of nanofluid up to 50% (1). Experimental study on use of silver-water nanofluid for heat transfer applications showed enhancement in heat transfer coefficient of nanofluid up to 36% and 74% respectively for laminar and turbulent flow conditions. However, the addition of nanoparticles increases the pressure drop slightly. But the higher enhancement of heat transfer overcomes the increase of pressure drop of nanofluid. The proposed correlations for the prediction of Nusselt number and friction factor showed good agreement with the experimental results (3.4). Conclusions: Lower size and lower concentrations of silver water showed better hydrothermal performance of heat transfer systems. The effect of pressure drop and erosion problem due to the addition of nanoparticles will be minimized with low concentrations and lower size of silver nanoparticles. It can be a suitable nanofluid for the thermal energy systems requiring improvement in their performance. Keywords: Silver Nanoparticles, Nanofluid, Thermal conductivity, Heat transfer

Ionanofluids natural convection heat transfer and entropy generation in a rectangular cavity: Viscosity influence

Ionic liquids suspensions with nanoparticles are a new class of heat transfer fluids and this study aim is to outline and discuss the behavior of a new ionanofluid in a real life configuration. If it shortly describes the considered ionic liquid, its main drawback is the high viscosity, thus limiting its applicability in natural convection and turbulent flow applications. In this regard, this research is focused on the study of several suspensions based on a mixture between water and [C2mim][CH3SO3] and alumina nanoparticles behavior in natural convection. The study is considering different high aspect ratio cavities up to 4 and the Rayleigh number varies from 103 to 105. Nusselt number and Bejan number for heat transfer and entropy generation are evaluated. As a main conclusion, it may affirm that heat transfer decreases while the entropy generation increases with the addition of nanoparticles. Finally, even more studies are mandatory, it is recommended to use these new fluids in forced convection instead of natural convection.

HVDC Converter Cooling System with a Phase Change Dispersion

High voltage direct current converters require efficient cooling of thyristors via heat sinks. Currently, infrastructures use deionised water as a means of cooling the high voltage direct current converters; however, recent research has shown that other fluids have potential to offer more efficient cooling. Phase change dispersions are a new class of heat transfer fluids that employ the latent heat of phase change, thus offering isothermal cooling during melting. For cooling applications, the temperature increase during operation is thus lowered when using phase change dispersions (compared to water) and consequently, the heat sink and thyristors surface temperatures are reduced. In this investigation, a phase change dispersion with non-conductive components, high stability, high capacity and low viscosity has been developed and tested. An experimental setup of a real size heat sink has been installed and the heat transfer behaviour of both the formulated phase change dispersion and water have been investigated and a comparison has been presented. Using water as the heat transfer fluid, the temperature increase from inlet to outlet of the heat sink was 4 K and with the formulated phase change dispersion (at the same mass flow rate and heat input) the temperature increase was 2 K. The phase change dispersion caused a 50% reduction in the heat sink surface temperature. Furthermore, the global heat transfer coefficients obtained for the phase change dispersion were found to be independent of the heating input applied, unlike the trend found for water, additionally, the global heat transfer coefficients were found to be similar to those obtained for water at the same mass flow rates and reached a maximum value of 6100 W m2 K−1. Despite this, the pressure drops and viscosities obtained for the phase change dispersion were higher than for water. Overall, the current investigation demonstrates the ability of using a phase change dispersion as a cooling fluid for the cooling of electronic components, which thus far is limited to using air and water cooling and cannot reach the cooling capacity achieved by phase change dispersions.

Thermal and energy performance improvement of hybrid PV/T system by using olein palm oil with MXene as a new class of heat transfer fluid

In this research work, MXene with a chemical formula of Ti3C2 is synthesized using wet chemistry method and suspended in pure olein palm oil (OPO) to formulate a new class of heat transfer fluid to investigate its thermal and energy performance in a hybrid PV/T solar thermal system numerically using COMSOL Multiphysics. In addition to this research work, Al2O3-water based nanofluid is compared with MXene-OPO nanofluid in the hybrid PV/T solar thermal system. The MXene-OPO nanofluid is prepared with a loading concentration of 0.01, 0.03, 0.05, 0.08, 0.1, and 0.2 wt %. MXene-OPO nanofluid with 0.2 wt % loading concentration exhibit 68.5% higher thermal conductivity than the pure OPO at 25 °C. The highest viscosity reduction is found by 61% when the temperature is raised from 25 °C to 50 °C for nanofluid with 0.2 wt % of MXene. Compared to PVT with Al2O3-water based nanofluid, MXene based nanofluid display about 16% higher thermal efficiency improvement at 0.07 kg/s flow rate. About 9% heat transfer coefficient improvement is found for the PVT with MXene nanofluids compared to PVT with Al2O3-water heat transfer fluid. MXene nanofluid may reduce PV temperature by 40% compared to stand alone PV module.

Performance optimization of a hybrid PV/T solar system using Soybean oil/MXene nanofluids as A new class of heat transfer fluids

In this research, a new class of nanofluid is successfully formulated from Soybean oil and MXene (Ti3C2) particles to implement as working fluid on a hybrid photovoltaic-thermal (PV/T) solar collector for performance optimization. This study emphasizes on the preparation of the Soybean oil/MXene (SO/Ti3C2) nanofluid, optical and thermal characterization of the nanofluid including suspension stability. The SO/Ti3C2 nanofluid samples are formulated suspending two-dimensional (2D) MXene particles at 0.025–0.125 wt% concentrations into pure Soybean oil. SEM, UV–vis, FTIR and TGA analysis are performed for morphology, optical and thermal stability characterization respectively. Achieved thermal conductivity results of SO/Ti3C2 nanofluid for 0.125 wt% of Ti3C2 exhibited 60.82% enhancement at 55 °C compared to pure Soybean oil. The specific heat capacity (cp) of formulated nanofluids is measured employing a differential scanning calorimeter (DSC). Maximum cp augmentation is found to be 24.49% at 0.125 wt% loading of Ti3C2 in the base oil. Numerical implementation of the prepared SO/Ti3C2 nanofluids on PV/T is performed using COMSOL Multiphysics software resulted noteworthy improvement compared to conventional water, Alumina/water and MXene/palm oil nanofluids as working fluid. Overall thermal effectiveness of the PV/T system is achieved 84.25% using SO/Ti3C2 nanofluids at 0.07 kg/s mass flow rate. Furthermore, employing the nanofluids electrical output of the PV/T is improved by 15.44% in comparison with water/alumina nanofluids at an irradiance of 1000 W/m2 and mass flow rate of 0.07 kg/s. The stated findings indicate overall effectiveness of the Soybean oil based MXene nanofluids over conventional fluids used for cooling purpose in the PV/T collector.

Application of Fractional Derivative Without Singular and Local Kernel to Enhanced Heat Transfer in CNTs Nanofluid Over an Inclined Plate

Nanofluids are a novel class of heat transfer fluid that plays a vital role in industries. In mathematical investigations, these fluids are modeled in terms of traditional integer-order partial differential equations (PDEs). It is recognized that traditional PDEs cannot decode the complex behavior of physical flow parameters and memory effects. Therefore, this article intends to study the mixed convection heat transfer in nanofluid over an inclined vertical plate via fractional derivatives approach. The problem in hand is modeled in connection with Atangana–Baleanu fractional derivatives without singular and local kernel with a strong memory. Human blood is considered as base fluid and carbon nanotube (CNTs) (single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs)) are dispersed into it to form blood-CNTs nanofluid. The nanofluid is considered to flow in a saturated porous medium under the influence of an applied magnetic field. The exact analytical expressions for velocity and temperature profiles are acquired using the Laplace transform technique and plotted in various graphs. The empirical results indicate that the memory effect decreases with increasing fractional parameters in the case of both temperature and velocity profiles. Moreover, the temperature profile is higher for blood SWCNTs because of higher thermal conductivity whereas this trend is found opposite in the case of velocity profile due to densities difference.

Modified model for the effective thermal conductivity of metal oxide nanofluids

Nanofluids, a new class of heat transfer fluids, exhibit anomalously high thermal conductivity compared to the traditional heat transfer fluids. Though many models have been proposed to provide an explanation to the underlying phenomena but there are still some issues which need to be addressed in order to gain consistency with the available experimental data. This work accounts for the factors such as interfacial nanolayer, volume fraction, temperature, static and dynamic properties of nanoparticles in formulating a modified effective thermal conductivity model. The present model shows a better agreement with the experimental data in comparison to other models for metal oxide nanofluids.

Analysis of heat transfer characteristics of nanofluid synthesized using green method

The use of additives in the base fluid is one of the techniques to strengthen the heat transfer with the amelioration in the field of nanotechnology. A new class of heat transfer fluids has been engineered, a base fluid (host) in which nano particles (guests) are dispersed and suspended stably. Researches have showed that these fluids exhibit higher thermal conductivity than the base fluid. As a result, the study of nanofluids has materialized as a new field of scientific interest and innovative application. The present work mainly focus es on the study of heat transfer characteristics and to analyze the thermal stability & other properties of nanofluid prepared by dispersing nanoparticles that are synthesized using green method. This work not only focuses on the heat transfer enhancement but also on the phenomena that are possible for this enhancement.

Novel empirical correlation for ionanofluid PEC inside tube subjected to heat flux with application to solar energy

Ionic liquid-based nanofluids are a very novel group of fluids used for enhancing heat transfer in different applications, especially in solar energy ones where the parabolic trough pipe receiver is subjected to heat flux due to the sun beam radiation. In regard to this new class of fluids, no empirical correlations are available for their heat transfer capabilities inside tubes even if some research on local Nusselt number of regular flow is present in the current literature. This paper introduces new correlation for heat transfer and friction factor in pipes subjected to constant heat flux considering [C4mim] [NTf2] ionic liquid-based nanofluids flow. In addition, the performance evaluation criteria as an optimization parameter between heat transfer enhancement and pressure drop penalty have been evaluated. In this particular application, the flow is laminar, as recommended in low heat flux applications (solar beam radiation), with Reynolds number in the range of 100–2000 and nanoparticles volume concentration varying from 0 to 2.5%. In addition, according to the change in the [C4mim] [NTf2] ionic liquid thermophysical properties with temperature, the Prandtl number consequently has been changed. As an overall conclusion, the proposed correlations can be seen as favorable for the heat transfer enhancement estimation of the parabolic trough for the solar energy applications. Finally, this pioneering class of heat transfer fluids (ionic liquid-based nanofluids) reveals a great potential in advanced heat transfer applications; therefore, the new correlations aim to collaborate to this progress.

Nanofluids: A Review on Current Scenario and Future prospective

The use of additives in the base fluid is one of the techniques to strengthen the heat transfer With the amelioration in the field of nanotechnology, a new class of heat transfer fluids has been engineered, a base fluid (host) in which nano particles (guests) are dispersed and suspended stably. Researches have showed that these fluids exhibit higher thermal conductivity than the base fluid. As a result, the study of nanofluids has materialized as a new field of scientific interest and innovative application. This paper focuses on the recent advancements in the study of nanofluids such as preparation methods, stability of nanofluids and presents the extensive area of applications.

A numerical approach in describing ionanofluids behavior in laminar and turbulent flow

Ionic liquids are a new class of fluids to be considered for heat transfer due to their remarkable thermophysical properties. Experimental researches on ionic liquids have increased over the last few years and, as an extension, a new class of heat transfer fluids, the ionanofluids were considered in some recent experimental studies. Ionanofluids consists in suspending little amounts of high conductive nanoparticles in ionic liquids. In spite of a lot of inconsistent reports—mainly due to the deficient understanding of the involved mechanisms—ionanofluids have been demonstrated as a new favorable heat transfer fluid. The enhanced thermal conductivity of ionanofluids over the basic ionic liquids is considered one of the driving factors for enhancing convection. Nonetheless, the thermal conductivity is the most studied parameter in spite of the important influence of viscosity variation on the convective flow. This numerical study employed Ansys Fluent commercial code and showed that a correct description of thermophysical properties may make ionanofluids a very promising new heat transfer fluid since the preliminary results are encouraging.

Natural convection heat transfer utilizing ionic nanofluids with temperature-dependent thermophysical properties

Ionic liquid based nanofluids are a very new and novel class of fluids used for heat transfer. The thermophysical properties of these new fluids are extremely encouraging in comparison to base ionic liquids and recommend these new fluids for solar applications. This paper deals with a numerical implementation of an ionic liquid nanofluid in a square enclosure considering two heating situations; bottom heating and lateral heating of the enclosure. Comparison with a regular alumina nanofluid in terms of Nusselt number is inserted. Thermophysical properties of these Ionic liquid based nanofluids were considered variable with temperature and the numerical results are correlated asa function of Ra and volume concentration (ϕ) for the two studied cases in the range of 104≤Ra≤106 and 0%≤ϕ≤2.5%. As an overall conclusion, this innovative class of heat transfer fluids reveals great potential in advanced heat transfer applications.

Prediction of Thermal Conductivity and Viscosity of Ionic Liquid-Based Nanofluids Using Adaptive Neuro Fuzzy Inference System

ABSTRACTNowadays, ionic liquid-based nanofluids are introduced as a new class of heat transfer fluids, which exhibit superior thermal properties compared to their base ionic liquids. Potential applications of these nanofluids make it necessary to know their thermophysical properties such as thermal conductivity and viscosity. Therefore, adaptive neuro fuzzy inference system (ANFIS) has been successfully developed to predict thermal conductivity and viscosity of ionic liquid-based nanofluids. The developed models have investigated the influence of temperature, nanoparticle concentration, and ionic liquid molecular weight on the thermophysical properties of nanofluids. After developing ANFIS structure, the capability and accuracy of the developed neuro fuzzy models have been evaluated by comparison of model predictions with experimental data extracted from the literature and calculation of statistical parameters such as coefficient of determination (R2) and average relative deviation (ARD). The ARD of ANFIS model in prediction of thermal conductivity of nanofluids is 0.72%, with a high R2 of 0.9959. The values of ARD and R2 for estimation of nanofluids viscosity are 5.1% and 0.9934, respectively, which indicates a satisfactory degree of accuracy for the proposed models.

Phase change dispersion, potentially a new class of heat transfer fluids

The authors present values and an application of a phase change dispersion, where the dispersed phase change material within water changes from solid to liquid while absorbing heat and changes from liquid to solid while releasing heat at constant temperature. The phase change enthalpy increases the “apparent specific heat capacity” significantly in comparison to water. As the heat transfer takes place at constant temperature, the heat transfer fluid itself remains at constant temperature while absorbing heat. Isothermal heating and cooling of devices with a liquid is feasible.

Experimental investigation on thermophysical properties of solar glycol dispersed with multi-walled carbon nanotubes

ABSTRACTThis article deals with well-dispersed solar glycol-based nanofluids containing multi-walled carbon nanotube (MWCNT) nanoparticles with different particle volume concentrations of 0.1%, 0.2%, 0.3%, and 0.4% prepared by typical two-step method. Thermal conductivity, viscosity and specific heat capacity of solar glycol (SG)-based MWCNT nanofluids, in the temperature range of 30°C–70°C were measured. The values of density showed a noticeable deviation from the predictions of Pak and Cho correlation. Hence, correlations are developed for thermal conductivity and viscosity from the experimental results obtained from the various range parameters of interest. The presence of MWCNT enhanced the thermal conductivity of the nanofluids by 17.26% at 0.4 vol.% particle concentration at 70°C. The relative viscosity of MWCNT nanofluids depends on the nanoparticles percentage concentration and decreases significantly with increase in temperature for higher concentrations. The presence of MWCNT enhances the specific heat of the nanofluids significantly, and this enrichment decreases with the increase of the MWCNT concentration. MWCNT/SG represents a new and innovative class of heat-transfer fluid, which possesses excellent thermophysical properties. The MWCNT/SG-based nanofluids could be suitable working fluids for solar thermal and automobile applications.

Synthesis and thermo-physical properties of deep eutectic solvent-based graphene nanofluids

This study introduces a new class of heat transfer fluids by dispersing functionalised graphene oxide nanoparticles (GNPs) in ammonium and phosphonium-based deep eutectic solvents (DESs) without the aid of a surfactant. Different molar ratios of salts and hydrogen bond donors (HBD) were used to synthesise DESs for the preparation of different concentrations of graphene nanofluids (GNFs). The concentrations of GNPs were 0.01 wt%, 0.02 wt% and 0.05 wt %. Homogeneous and stable suspensions of nanofluids were obtained by high speed homogenisation and an ultrasonication process. The stability of the GNFs was determined through visual observation for 4 weeks followed by a centrifugal process (5000–20 000 rpm) for 30 min in addition to zeta potential studies. Dispersion of the GNPs in DES was observed using an optical microscope. The synthesised DES-based GNFs showed no particle agglomeration and formation of sediments in the nanofluids. Thermo-physical properties such as thermal conductivity and specific heat of the nanofluids were also investigated in this research. The highest thermal conductivity enhancement of 177% was observed. The findings of this research provide a new class of engineered fluid for heat transfer applications as a function of temperature, type and composition DESs as well as the GNPs concentration.

Convective heat transfer performance of aggregate-laden nanofluids

With the recent progress in nanotechnology, nanofluids are emerging as a new class of heat transfer fluids formed by adding nanometer-sized structures (e.g., particles, fibers, tubes) in conventional base fluids (e.g., water, ethylene glycol, engine oil). Due to attractive van der Waals forces, nanoparticles tend to agglomerate to form aggregates in nanofluids to form the so-called aggregate-laden nanofluids. Aggregation affects the nanofluid properties such as thermal conductivity and viscosity and further affects the heat transfer performance. The discrepancies regarding the influence of nanoparticles on thermophysical properties and heat transfer characteristics in the literature might arise due to nanoparticle aggregation. Firstly, three performance comparison criteria for nanofluids were proposed for thermally developing laminar flow, fully developed laminar flow and fully developed turbulent flow to evaluate the nanofluid efficiency as coolants. Secondly, parametric effects of aggregates on nanofluid viscosity and thermal conductivity were investigated. The cooling efficiency of the aggregate-laden nanofluids depends on aggregate parameters such as aggregate ratios, interfacial thermal resistance, volume fraction of aggregates in nanofluids and volume fraction of nanoparticles in the aggregates. One method to tailor the aggregate morphology is presented by dispersing nanoparticles of different size into a base fluid. By this method, the volume fraction of nanoparticles in the aggregates might increase, which thus enhances the nanofluid effectiveness due to reduction of viscosity.

Effect of surface tension on SiO2 -methanol nanofluids

Surface tension, the cohesive energy of an interface dominated the transportation behaviour of the liquids play an important role in the heat transfer performance. A new class of heat transfer fluid denoting “Nanofluids” with impressive thermo-physical properties, proved its promising potentiality in the heat transfer performance. However, very few numbers of studies observed for the effect of nanoparticles on the surface tension of liquids, also noted controversial results. In the present study, SiO2 nanoparticles dispersed in methanol solution to investigate the effect of surface tension with the change of concentration and their sizes. The most common Du-Nouy ring method was used to measure the surface tension of methanol based nanofluids by an automatic surface tensiometer.The results denote that the surface tension of the nanofluids increases with increase in concentration. On the other hand, the results indicate that the surface tension decreases with the increase in temperatures. Besides, the surface tension of SiO2-methanol nanofluids enhances compared to pure methanol. All in all, the enhancement observed 1.7% to 8.9% of the variation of volume fractions (0.05 Vol % to 0.25 Vol %) and the temperature change of 25 °C to 50 °C.