Traditional Heat Transfer Fluids Research Articles

Heat Transfer Application of Nanofluids and Testing of Thermal Conductivity

In response to the growing demand for more efficient heat transfer technologies in various industrial processes, the development of nanofluids has emerged as a promising solution. Traditional heat transfer fluids like mineral oil, ethylene glycol, and water have relatively low thermal conductivities compared to solids, limiting the compactness and efficiency of heat exchangers. Nanofluids, which are created by suspending ultrafine metallic or nonmetallic solid powders in base fluids, exhibit enhanced thermal properties due to the superior thermal conductivities of solid materials. This paper reviews the preparation, thermal conductivity measurement, and influencing factors of nanofluids, with a focus on thermal conductivity as the primary driver for improved heat transfer. The preparation of nanofluids involves either a one-step or two-step method, with the two-step method being more commonly used for oxide nanoparticles (NPs) such as Al2O3, ZnO, MgO, TiO2, and SiO2. The study discusses stabilization techniques like ultrasonication and magnetic force agitation to ensure homogeneous suspension and long-term stability of the nanofluids. The thermal conductivity measurements are conducted using short hot wire (SHW) and transient hot wire (THW) techniques, with considerations of the nonsteady-state nature and potential error sources. The research underscores the importance of rigorous experimental design and accurate data analysis to address the complexities and variability in thermal conductivity measurements, ultimately contributing to the advancement of nanofluid technologies for efficient heat transfer solutions.

Statistical analysis of radiative solar trough collectors for MHD Jeffrey hybrid nanofluid flow with gyrotactic microorganism: entropy generation optimization

PurposeA parabolic trough solar collector is an advanced concentrated solar power technology that significantly captures radiant energy. Solar power will help different sectors reach their energy needs in areas where traditional fuels are in use. This study aims to examine the sensitivity analysis for optimizing the heat transfer and entropy generation in the Jeffrey magnetohydrodynamic hybrid nanofluid flow under the influence of motile gyrotactic microorganisms with solar radiation in the parabolic trough solar collectors. The influences of viscous dissipation and Ohmic heating are also considered in this investigation.Design/methodology/approachGoverning partial differential equations are derived via boundary layer assumptions and nondimensionalized with the help of suitable similarity transformations. The resulting higher-order coupled ordinary differential equations are numerically investigated using the Runga-Kutta fourth-order numerical approach with the shooting technique in the computational MATLAB tool.FindingsThe numerical outcomes of influential parameters are presented graphically for velocity, temperature, entropy generation, Bejan number, drag coefficient and Nusselt number. It is observed that escalating the values of melting heat parameter and the Prandl number enhances the Nusselt number, while reverse effect is observed with an enhancement in the magnetic field parameter and bioconvection Lewis number. Increasing the magnetic field and bioconvection diffusion parameter improves the entropy and Bejan number.Originality/valueNanotechnology has captured the interest of researchers due to its engrossing performance and wide range of applications in heat transfer and solar energy storage. There are numerous advantages of hybrid nanofluids over traditional heat transfer fluids. In addition, the upswing suspension of the motile gyrotactic microorganisms improves the hybrid nanofluid stability, enhancing the performance of the solar collector. The use of solar energy reduces the industry’s dependency on fossil fuels.

Experimental study on the influence of volume concentration on natural convection heat transfer with Al2O3-MWCNT/water hybrid nanofluids

Recent research has focused on combining multiple types of nanoparticles with a base fluid, a process known as the hybridisation of nanofluids. Studies showed that hybrid nanofluids demonstrated improved rheological and thermal properties compared to mono nanoparticle nanofluids. In this study, alumina–multiwalled carbon nanotube/water hybrid nanofluid was prepared using a two-step procedure at a percentage weight ratio of 10:90 Al2O3: MWNCT at various volume concentrations of 0.00, 0.05, 0.10, 0.15, and 0.20 vol%. The natural convection of the formulated hybrid nanofluid was experimentally studied inside a square cavity with an aspect ratio of 1. An exhaustive investigation on the influence of volume concentration of hybrid nanofluid on natural convection heat transfer was performed. Results showed that an increase in volume concentration improved the heat transfer to an optimum value of 49.27% enhancement, at 0.10% volume concentration in comparison to the base fluid. However, a further increment of volume concentration led to a deterioration of natural convection heat transfer. There is evidence from this study that hybrid nanofluids offer an edge over traditional heat transfer fluids. It is concluded that the application of Al2O3-MWCNT/water hybrid nanofluid in a square cavity demonstrated enhanced natural convection heat transfer.

EXPERIMENTAL ANALYSIS ON ENHANCEMENT OF HEAT TRANSFER IN COMPACT HEAT EXCHANGER USING NANO PARTICLES

This study aims to experimentally investigate the enhancement of heat transfer in a compact heat exchanger (CHE) using nano particles, without considering the Reynolds number effect. In recent years, nanofluids have attracted attention as a promising alternative to traditional heat transfer fluids due to their improved thermal conductivity. The experimental setup consisted of a counter-flow CHE with a nanofluid circulating through the tubes. The nanofluid was prepared by dispersing Aluminium Oxide (Al2O3) and Copper (II) oxide (CuO) nanoparticles into distilled water. The effects of various parameters such as nanoparticle concentration and heat flux on heat transfer enhancement were investigated. Results showed that the addition of nanoparticles significantly increased the heat transfer rate compared to the base fluid. Moreover, the enhancement was found to be more significant at higher concentrations of nanoparticles and heat fluxes. The results also showed that the increase in heat transfer was due to the improved thermal conductivity of the nanofluid. Overall, the study demonstrated that the use of nanofluids in CHEs can significantly improve their performance, making them more efficient and compact for a wide range of industrial applications, even without considering the Reynolds number effect

A Review of Enhancement of Thermal Performance of Flat Plate Solar Collectors through Nanofluid Implementation

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%.

Preparation, Characterization, Stability and Thermophysical Properties of Bio, Non-Bio (Metallic and Non-Metallic) and Hybrids Nanofluids: A Review

Traditional heat transfer base fluids, such as ethylene glycol, ethanol, kerosene, oil, methanol, water etc. are normally used to enhance the heat transfer performance in many industrial applications. These traditional heat transfer fluids have many limitations. One of the limitations is the poor thermophysical properties of each of the base fluids and this results in a lower heat transfer rate in Thermal Engineering systems. Nanofluids are considered a new generation heat transfer fluid with higher thermal conductivity. Nanofluids have enhanced thermophysical properties compared to single-phase traditional heat transfer fluids. This paper highlights detailed reviews of the various methods of preparation, characterization, stability and thermophysical properties of bio, non-bio and hybrids nanofluids. Thermophysical properties such as density, viscosity, thermal conductivity and specific heat capacity from different works of literature were summarized, discussed and presented. There are many different parameters to be considered while investigating the thermophysical properties of nanofluids. Density and specific heat capacity are strongly dependent on the material type while the viscosity and thermal conductivity are highly affected by temperature and concentration. The most influential parameters on thermophysical properties of nanofluids are material type and temperature. The majority of the literature revealed that bio nanofluids have low viscosity values and hybrids have high thermal conductivity values. The novelty of this review paper is the presentation of the various methods of synthesizing, characterization, stability and factors affecting the thermophysical properties of metallic, non-metallic and hybrid nanofluids.

Highly accurate wavelet-homotopy solutions for mixed convection hybrid nanofluid flow in an inclined square lid-driven cavity

The classic problem of mixed convection flow within an inclined square lid-driven cavity is extended to hybrid nanofluid case. The governed partial differential equations with non-homogeneous boundary conditions are studied by means of our proposed Coiflet wavelet-homotopy method. Highly accurate solutions with very clear vortex structures are obtained. The effectiveness and efficiency of these solutions are strictly checked through a series of comparisons with published ones in literature. Results show that our proposed approach holds both strong nonlinear processing capability and excellent local display characteristics so that it can be used to attack complicated nonlinear problems more efficiently and accurately than the traditional homotopy analysis method and the Coiflet wavelet analysis approach. Besides, physical properties of hybrid nanofluid behaviors are examined, it is noticed that, similar to nanofluids, the hybrid nanofluid is superior to traditional heat transfer fluids for heat transfer enhancement but it could be easier and cheaper.

Review: Observation on CFD Analysis of ZnO and TiO2 Nanofluid with Oil and Ethylene Glycol in Square and Helical Coil Heat Exchanger

Abstract: Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide the excellent thermal performance in helical coil heat exchangers. Research studies on heat transfer enhancement have gained serious momentum during recent years and have been proposed many techniques by different research groups [1]. A fluid with higher thermal conductivity has been developed to increase the efficiency of heat exchangers. The dispersion of 1-100nm sized solid nanoparticles in the traditional heat transfer fluids, termed as nanofluids, exhibit substantial higher convective heat transfer than that of traditional heat transfer fluids. Nanofluid is a heat transfer fluid which is the combination of nanoparticles and base fluid that can improve the performance of heat exchanger systems. In this present paper the efforts are made to understand that how to compare the heat transfer rate in Copper helically coiled tube and squared coiled tube heat exchanger using Zinc Oxide and Titanium Dioxide Nano fluid by studying research papers of various authors. Keywords: Helical Coil, Nano-fluid, Heat Exchanger, CFD, Pressure Drop, Temperature Distribution.

Combined Convective Transport of Brinkman-viscoelastic Fluid Across Horizontal Circular Cylinder with Convective Boundary Condition

Traditional heat transfer fluids frequently encounter several limitations in the heat transfer process, due to the lower thermal conductivity in heat transfer process industries, and also has an impact on the performance of heat transfer in industrial sectors. In order to overcome the problem, researchers have currently considered an alternative development of heat transfer of fluids. Hence, this study will concentrate on the problem of steady combined convective transport. In particular, the flow of Brinkman-viscoelastic fluid over a horizontal circular cylinder with the influence of convective boundary condition (CBC) was investigated. Using the necessary similarity transformation, the governing equations were converted into a less complicated form and numerically solved by using Runge-Kutta-Fehlberg-method, which was programmed in Maple software. The influence of Biot number, combined convection, Brinkman and viscoelastic parameters are analyzed and demonstrated in graphs and tables. Numerical result showed that the fluid velocity increased with improving conjugate and combined convection parameter, but decreased with increasing Brinkman and viscoelastic parameter. It is also discovered the reverse trend on temperature profiles.

Experimental study on properties of hybrid stable & surfactant-free nanofluids GNPs/CNCs (Graphene nanoplatelets/cellulose nanocrystal) in water/ethylene glycol mixture for heat transfer application

The heat transfer capacity of any thermal cooling system depends on two factors, i.e., the selection of the coolant and the geometrical pattern of the approach. This article summarizes nanofluids' preparation ranging from 0.01 % to 0.2 % using Graphene nanoplatelets & CNC dispersed in a base fluid. The combination of water with ethylene glycol (EG) is a form of customary heat transmit liquids regularly utilized in numerous energy practices to maintain the water's decent cooling (or heating) capability; thus, 60:40 ratio of EG: W mixture used as the base fluid for thermo-physical properties enhancements. These nanofluids prepared are not used with surfactants as it results in generating bubbles and contaminating the heat transfer channels, influencing the overall performance. XRD &FESEMtechniques were used to analyze the surface. The investigated nanofluids remained stable, with no substantial sedimentation for 30 days. The results of GNPs/CNC nanofluids at 0.1% volume concentration has proper stability showing excellent colloidal stability in the base fluid of EG: W at a ratio of 60:40. The present hybrid nanofluid has the ability to switch the traditional heat transfer fluids leading to efficient & compact thermal structures.

A Critical Review of Experimental Investigations about Convective Heat Transfer Characteristics of Nanofluids under Turbulent and Laminar Regimes with a Focus on the Experimental Setup

In this study, several experimental investigations on the effects of nanofluids on the convective heat transfer coefficient in laminar and turbulent conditions were analyzed. The aim of this work is to provide an overview of the thermal performance achieved with the use of nanofluids in various experimental systems. This review covers both forced and natural convection phenomena, with a focus on the different experimental setups used to carry out the experimental campaigns. When possible, a comparison was performed between different experimental campaigns to provide an analysis of the possible common points and differences. A significant increase in the convective heat transfer coefficient was found by using nanofluids instead of traditional heat transfer fluids, in general, even with big data dispersion from one case to another that depended on boundary conditions and the particular experimental setup. In particular, a general trend shows that once a critic value of the Reynolds number or nanoparticle concentrations is reached, the heat transfer performance of the nanofluid decreases or has no appreciable improvement. As a research field still under development, nanofluids are expected to achieve even higher performance and their use will be crucial in many industrial and civil sectors to increase energy efficiency and, thus, mitigate the environmental impact.

Thermal Conductivity of Nanofluids: A Review on Prediction Models, Controversies and Challenges

In recent years, the nanofluids (NFs) have become the main candidates for improving or even replacing traditional heat transfer fluids. The possibility of NFs to be used in various technological applications, from renewable energies to nanomedicine, has made NFs and their thermal conductivity one of the most studied topics nowadays. Hence, this review presents an overview of the most important advances and controversial results related to the NFs thermal conductivity. The different techniques used to measure the thermal conductivity of NFs are discussed. Moreover, the fundamental parameters that affect the NFs thermal conductivity are analyzed, and possible improvements are addressed, such as the increase of long-term stability of the nanoparticles (NPs).The most representative prediction classical models based on fluid mechanics, thermodynamics, and experimental fittings are presented. Also, the recent statistical machine learning-based prediction models are comprehensively addressed, and the comparison with the classical empirical ones is made, whenever possible.

Hybridized nanofluid with stagnation point past a rotating disk

Hybrid nanofluid is a mixture of two different nanoparticles that offer better heat transfer performance and thermophysical properties than traditional heat transfer fluids (water, oil, and refrigerant-134A) and nanofluid with single nanoparticles. Here, a type of hybrid nanofluid containing single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs) nano-sized particles with water and refrigerant-134A as base fluid is analytically modeled to establish the problem of the steady laminar MHD stagnation-point flow of a SWCNT–MWCNT/water-refrigerant-134A hybrid nanofluid through a rotating disk. Further, the influence of partial slip, viscous dissipation, and thermal slip are examined. Variables of von Karman are being used to transform partial differential equations in ordinary differential equations, which are solved numerically applying boundary value problem solver (bvp4c) in the MATLAB software. A comparison table for specific cases is provided to see the accuracy of our numerical results with recent data. The velocity and temperature behavior are plotted for various parameters. It is perceived that the fluid temperature is higher for hybrid nanofluid as compared to simple nanofluid and reverse behavior is observed for radial velocity. Further, the azimuthal velocity diminishes with the increasing value of magnetic and velocity slip parameters.

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.

Experimental Testing of Hydrophobic Microchannels, with and without Nanofluids, for Solar PV/T Collectors

Solar energy can be converted into useful energy via photovoltaic cells or with a photothermal absorber. While these technologies are well-developed and commercially viable, significant benefits can be realised by pulling these two technologies together in photovoltaic/thermal (PV/T) systems which can provide both heat and electricity from a single collector. Emerging configurations in the PV/T field aim to incorporate micro and/or nanotechnology to boost total solar utilisation even further. One example of this is the nanofluid-based PV/T collector. This type of solar collector utilises nanofluids—suspensions of nanoparticles in traditional heat transfer fluids—as both an optical filter and as a thermal absorber. This concept seeks to harvest the whole solar spectrum at its highest thermodynamic potential through specially engineered nanofluids which transmit the portion of solar spectrum corresponding to the PV response curve while absorbing the rest as heat. Depending on the nanoparticle concentration, employing nanofluids in a flowing system may come with a price—an efficiency penalty in the form of increased pumping power (due to increased viscosity). Similarly, microchannel-based heat exchangers have been shown to increase heat transfer, but they may also pay the price of high pumping power due to additional wall-shear-related pressure drop (i.e., more no-slip boundary area). To develop a novel PV/T configuration which pulls together the advantages of these micro and nanotechnologies with minimal pumping power requirements, the present study experimentally investigated the use of nanofluids in patterned hydrophobic microchannels. It was found that slip with the walls reduced the impact of the increased viscosity of nanofluids by reducing the pressure drop on average 17% relative to a smooth channel. In addition, flowing a selective Ag/SiO2 core–shell nanofluid over a silicon surface (simulating a PV cell underneath the fluid) provided a 20% increase in solar thermal conversion efficiency and ~3% higher stagnation temperature than using pure water. This demonstrates the potential of this proposed system for extracting more useful energy from the same incident flux. Although no electrical energy was extracted from the underlying patterned silicon, this study highlights potential a new development path for micro and nanotechnology to be integrated into next-generation PV/T solar collectors.

Preparation and property studies of SiO2/H2O nanofluid

Abstract Recently nanofluids are gaining attention in the heat transfer domain due to some of their unique properties. Nanofluids are found to have improved heat transfer ability when compared to traditional heat transfer fluids. In the present study we have examined the thermophysical properties of SiO2/water based nanofluids such as particle size, viscosity and heat transfer behaviours. The study was carried out using instruments like Brookfield viscometer and KD2Pro Thermal Analyzer

Visualisation of subcooled pool boiling in nanofluids

High-performance cooling is of vital importance for the cutting-edge technology of today, from micro-electronic devices to nuclear reactors. Boiling heat transfer is expected to play a critical role for the safe and efficient operation of components exposed to high heat flux in future nuclear fusion reactors. Recent advances in nanotechnology have allowed the development of a new category of coolants, termed nanofluids, which exhibit superior thermophysical characteristics over traditional heat transfer fluids. Qualitative experimental results of Al2O3-H2O nanofluids under subcooled pool boiling conditions are reported and compared to deionised water that served as a benchmark in the current work. A visual evaluation of the impact of nanoparticles on bubble dynamics and nucleation site activity at the heated surface of a bare NiCr wire is performed with the use of a Guppy F-080 FireWire camera. It was observed that the presence of nanoparticles significantly modifies the nucleation site density, bubble size at departure and frequency of bubble generation from the surface of the heating wire. Intense nanoparticle deposition on the heating wire surface was identified as a key mechanism for the observed differences via scanning electron microscopy. The deposited nanolayer reported to alter the surface texture of the wire. The outcome of this work is a step forward towards the evaluation of the applicability of nanofluids in cooling applications via boiling heat transfer.

Investigation On Heat Transfer Properties Of Water Based TiO2-ZnO Nanofluids

Nanofluids in heat transfer applications exhibit effective performance over conventional heat transfer fluids. High thermal loads due to miniaturization in a wide variety of applications offers technological challenges in designing efficient thermal management systems. Traditional heat transfer fluids such as air, water, engine oil, and ethylene glycol (EG) have very low thermal conductivities of 0.03, 0.613, 0.145 and 0.253 W/mK respectively. The poor thermal conductivity of these fluids is an obstacle in improving heat transfer and compactness of the heat exchangers. Determination of properties of nanofluids and its performance in water based base fluids has been studied by many researchers. However the heat transfer performance of mixed nanofluids ie., hybrid nanofluids is yet to be explored. TiO2 and ZnO nanofluids were prepared at 0.5%, 1.5% and 2.0% volume concentration. Thermal conductivity estimated for temperature range of 30-70°C. Significant enhancement of both heat transfer rate and effectiveness of heat exchanger was noticed with TiO2 nanofluids at 2.0% volume concentration and with 1.5% volume concentration of TiO2-ZnO hybrid nanofluids.

Influence of surfactant and volume fraction on the dispersion stability of TiO2/deionized water based nanofluids for heat transfer applications

Nanofluids are the implausible outcome of nanotechnology which fascinates many researchers by owing incredible thermal transport properties in different domains, including heating-cooling of systems, power generation, nuclear and space technology. Due to the higher surface area of nanomaterials, their suspension in traditional heat transfer fluids extensively enriches the heat transfer characteristics. In this research work, commercially available bulk Titania (TiO2) powder is used for the synthesis of TiO2 nanoparticles (NPs). Scanning electron microscopy confirmed the spherical shape of NPs with an average diameter of 18.88 nm. X-ray Diffraction (XRD) and Thermal Gravimetric analysis (TGA) is performed for material characterization. Dispersion stability of TiO2/Deionized water nanofluids for 0.05 vol% and 0.5 vol% concentration of NPs has been studied, using UV–vis Spectrometry. Sodium dodecyl sulfate (SDS) is used as a surfactant and its effect on the stability of nanofluids is analyzed. Experimental results revealed that the addition of surfactant to the nanofluids at a given volume concentration increase the dispersion stability.

Heat Enhancement Of Heat Exchanger Using Aluminium Oxide(Al2o3), Copper Oxide(Cuo)Nano Fluids With Different Concentrations

Active and passive heat transfer techniques are commonly employed for heat transfer augmentation in fluids. Conventional heat transfer fluids like water, oil, and glycols have poor heat transport capabilities and they hardly meet the present day requirements of high heat dissipation rates in compact heat exchangers. Design of Compact heat exchanger and miniaturizing of high energy devices are possible only with the fluids having better heat transfer performance.The nano fluids are considered to be new generation fluids characterized by better heat transfer capabilities over traditional heat transfer fluids. The nanofluid is an emerging area of research and has lot of potential in heat transfer applications. Particles of size less than 100nm exhibit properties different from those of conventional solids. Nano materials have unique mechanical, electrical, optical, magnetic and thermal properties.Thermo physical properties of Al2O3 and CuO with water as base fluid have been experimentally determined at different volume concentrations. Present study is aimed at estimating the heat transfer enhancement for different Reynolds number in turbulent range at volume concentration of 0.1%, 0.25% and 0.4%.