Glycol Water Nanofluid Research Articles

Heat transfer performance study of Cu-ethanol/ethylene glycol/propylene glycol-water nanofluids in a wavy-walled tube heat exchanger

With the rapid consumption of nonrenewable energy sources, improving the heat transfer efficiency of conventional fixed tube plate heat exchangers, optimizing their structure, and finding more efficient coolants have become popular topics. In this paper, the cooling effect of ethanol/ethylene glycol/propylene glycol-water solution with a mass fraction of 50 % in a wavy-walled tube heat exchanger was investigated, while Cu nanoparticles with volume fractions of 1.5 % and 3.0 % were added to the cold working mass to form three different nanofluids. The effects of the three nanofluids at different volume fractions on the heat transfer performance of the wavy-walled tube heat exchanger were analyzed with numerical simulations, while the microscopic mechanism of the enhanced thermal conductivity of the nanofluids was investigated using molecular dynamics simulations. The results showed that the thermal conductivity of the nanofluids was greatly enhanced due to the formation of adsorption layers with different properties on the nanoparticle surfaces, and the Cu–ethylene glycol-water nanofluid showed the largest increase in thermal conductivity among the three nanofluids. It was also found that the shell-side pressure drop, convective heat transfer coefficient, and heat exchange quantity of the nanofluid in the wavy-walled tube heat exchanger significantly increased with an increase of volume fraction. The comprehensive heat transfer performance of the three nanofluids was found to be better compared to the base fluid. Cu-ethanol/EG/PG-water nanofluid with a volume fraction of 3.0 % increased the PEC of the heat exchanger by 10.4 %, 19.8 % and 27.6 %, respectively, at a volume flow rate of 1.53 m3/h. Therefore, the Cu-propylene glycol-water nanofluid had the best comprehensive heat transfer performance. Cu-ethanol-water nanofluid volume fraction of 3.0 % reaches a maximum PEC value of about 3.12 at Qv near about 2.0 m3/h, and Cu-EG-water nanofluid volume fraction of 3.0 % has a peak PEC value of about 4.07 at Qv of near about 2.0 m3/h. Therefore, the Cu-ethanol-water and Cu-ethylene glycol-water nanofluids are the optimal solutions for the combined heat transfer performance within the study.

Evaluation of electrical properties of graphene nanopowder-dispersed propylene glycol-water solutions

Nanofluids, which are suspensions of nanoparticles in base fluids, have gained significant attention in recent years due to their enhanced thermal and electrical properties. In particular, propylene glycol-water nanofluids have been extensively investigated for their electrical properties. The primary goal of this study is to evaluate the electrical characteristics of nanofluids containing graphene powder distributed in propylene glycol-water. Compositions containing 100:0, 75:25, as well as 50:50 of Propylene Glycol as well as Water were created, along with other nano fluids. Both types of base fluids were infused with graphene at quantities of 0.25 as well as 0.5 percent, respectively. The assessment of electrical characteristics in nanofluids includes the analysis of parameters like breakdown voltage, permittivity, resistivity, and electrical conductivity. With the increase in the diameter there is an increase in the value of resistivity with the dispersion of graphene nano powder whereas breakdown voltage, permittivity and electrical conductivity have been decreased with the increase in the diameter. Overall with the dispersion of graphene in nano powder the electrical properties have been enhanced. Furthermore, it discusses the underlying mechanisms and provides insights into potential applications of propylene glycol-water nanofluids in electrical and electronic systems.

Heat Transfer and Transport Aspects of a ZnO/Ethylene Glycol-Water Nanofluid Through a Nonlinearly Stretching Sheet

This section proposes investigating the heat transfer and transport phenomena of nanofluid passing through a non-linear stretching sheet. The 50%:50% water-ethylene glycol mixture is accepted as a base fluid to prepare a nanofluid. The influences of viscous dissipation, Joule heating, and thermal radiation in modelling are further exerted into attention. For converting partial differential systems to ordinary systems, a transformation technique is adopted. For the validation part, the numerical solution is computed by embracing a fourth-order exactness program (Bvp4c) and compared to the previously published literature. When modest quantities of zinc oxide nanoparticles are introduced to a mixture of water and ethylene glycol (EG), the effect on heat transfer relative to the base fluid is also noticeable. Furthermore, the influence of flow rate change in nanoparticle concentration on heat transfer performance is investigated. Graphical decisions reveal the values of miscellaneous-arising parameters on the velocity, temperature profile. The heat transfer rate is higher for the non-linear stretching surface than the flat surface. In comparison to nanofluid, a mixture of ethylene glycol-water with ZnO nanoparticles has superior cooling capability than the ZnO/water nanofluid.

Experimental investigation of thermal efficiency and thermal performance improvement of compound parabolic collector utilizing SiO2/Ethylene glycol-water nanofluid.

A compound parabolic collector has been used in the present study to lower operating costs per unit of heat increase compared to other tracker concentrators. This type of collector has been given more attention in industrial and domestic applications in the temperature range of 60 to 300°C. Also, to increase the thermal efficiency, nanofluid containing SiO2 nanoparticles in ethylene glycol-water hybrid base fluid (10-90 vol.%) have been used in three different volumetric fractions. The innovation of this present study includes the utilization of mentioned nanofluids for the first time in this collector, which has good stability and is cost-effective compared to other nanoparticles. In addition, the experimental measurement of thermal and hydraulic properties of nanofluids represents new aspects of the present study. The experiments used three volumetric fractions of 0.5%, 1%, and 1.5% under extensive solar radiation. Thermal performance of the collector at four volumetric flow rates of 1, 1.5, 2, and 2.5 Lit/min have been investigated according to ASHRAE standard 93-2010 (RA2014). According to the experimental data, the thermal efficiency of the collector improved by 5% to 11.6% when the nanofluid was applied. The maximum enhancement of the average Nusselt number of the nanofluid versus the base fluid at the volumetric flow rate of 1 Lit/min and the volumetric fraction of 1.5% was equal to 7.3%. Besides, nanofluid increased the pressure drop, and consequently, the pumping power slightly. Finally, considering both the impacts of heat transfer and pressure drop, performance evaluation criteria and overall efficiency for nanofluid have been analyzed. The results represented that in all volumetric fractions, the values of performance evaluation criteria and overall efficiency enhanced compared to the base fluid. This research provides researchers and engineers with important information to better understand the thermal and hydraulic parameters of the parabolic compound concentrator in the presence of nanofluid to improve its thermal performance. The results also highlight the potential of using SiO2 nanoparticles to improve the thermal efficiency of solar collectors despite their low thermal conductivity compared to other conventional nanoparticles.

Experimental analysis of heat pipe based evacuated tube solar collector using graphene/ ethylene glycol-water nanofluids.

ABSTRACT The efficiency of a heat pipe-based evacuated tube solar collector (HPBETSC) with graphene nanoparticle/ethylene glycol-water as a working fluid has been experimentally investigated in the present study. In this research work, the base fluid was prepared with a 60:40 ratio of ethylene glycol and water (EG-W). Graphene nanoparticles have been added to the base fluid with three different volume concentrations (0.025, 0.075, and 0.1 vol. %). The results showed that for three different graphene nanofluids (GNFs) concentrations of 0.025, 0.075, and 0.1 vol. %, the enhancement in their thermal conductivities observed was 21.9%, 25.8%, and 28.7%, respectively. The HPBETSC achieved its highest efficiency when the temperature of the inlet fluid equals the ambient temperature with 0.1 vol. % concentration of GNFs at 0.41 kg/sec mass flow rate. The efficiency is 36.3% higher when EG-W individually was used as a heat transfer fluid. Also, the achieved efficiency with 0.1 vol. % GNFs was 4.31% higher than 0.075 vol. % and 6.66% higher than 0.025 vol. % of GNFs concentrations at the same mass flow rate. Besides, this experimental study confirmed that nanofluids are highly favorable to replace the traditional fluids used in solar collectors.

A highly stable hydroxylated graphene/ethylene glycol-water nanofluid with excellent extinction property at a low loading for direct absorption solar collectors

In order to explore a graphene-containing nanofluid with good dispersion stability as the working fluid for a low-temperature direct absorption solar collector (DASC), firstly, two kinds of functionalized graphene, hydroxylated graphene (GOH) and carboxylated graphene (GCOOH), were dispersed into a mixture of ethylene glycol (EG) and water (1:1 mass ratio), at the same loadings. It is found that, although the obtained GOH nanofluid exhibits a slight lower zeta potential than the GCOOH one, its optical absorption property is obviously higher. Consequently, GOH was employed to prepare the EG-water based nanofluids at different loadings, followed by the investigations on their optical absorption and thermophysical properties, photo-thermal conversion performance, and dispersion stability. It is shown that, at a loading as low as 0.007 wt%, the transmittance of the corresponding GOH/water-EG nanofluid is reduced to zero, and its extinction coefficient is 100 times higher than that of the base fluid. Under the illumination of 1000 W/m2, the 0.007 wt% GOH/EG-water nanofluid can reach a high final temperature of 55 °C. More significantly, the zeta potential of the 0.007 wt% GOH/EG-water nanofluid increases with temperature and reaches 47.63 mV at 60 ℃, suggesting its good dispersion stability at the elevated temperatures. These good characteristics of the GOH/EG-water nanofluid make it a very promising working fluid for a low temperature DASC.

Experimental investigation on using Al2O3/ethylene glycol-water nano-fluid in different types of horizontal ground heat exchangers

This study presents the experimental results for the first time use of Al2O3/ethylene glycol-water (EG-water) nano-fluid (NF) in ground heat exchangers (GHE) within the ground source heat pump (GSHP) system which is prepared with 8 nm γ-Al2O3 nanoparticles. A test room with an area of 21 m2 was prepared in the cold climate region (39°42′24.8″ N, 37°02′01.5″E) of Turkey, and GSHP system was installed into the room. Horizontal GHE designs are preferred as GHE design in order to maintain cost and efficiency balance. Although numerical studies on the use of NF-assisted fluids in GSHP systems are guiding in the literature, these studies have not been supported experimentally. In this study to see performance of NFs in real environment conditions Al2O3 nanoparticles were examined experimentally in horizontal U-type GHE and spiral GHE by adding different volume concentrations (0.1%, 0.2%) to EG-water (25–75%) base fluid. Our results showed that, with a volume concentration of 0.1%, NF provided a 19% and 22% increase compared to EG-water in U-type GHE and spiral GHE, respectively, concerning GHE output temperatures. In addition, the coefficient of performance (COP) of the system using NF with a volume concentration of 0.1% showed a higher performance of 2.5% in U-type GHE and 3% in spiral GHE compared to EG-water base fluid. On the other hand, in both GHE designs, the NF with a volume concentration of 0.2% did not achieve any performance increase. The NF with a volume concentration of 0.1%, which is the most successful variation of the U-type GHE and spiral GHE systems, showed a 2.7% higher COP value than the spiral GHE in U-type GHE. As a result, it has been determined that the use of low concentration of NF in GHEs for the GSHP system provides performance improvements independent of the GHE design.

Terrific effect of H2 on 3D free convection MHD flow of C2H6O2[sbnd]H2O hybrid base fluid to dissolve Cu nanoparticles in a porous space considering the thermal radiation and nanoparticle shapes effects

In this article, the physical aspects of natural convection magnetohydrodynamic flow of Cu/Ethylene glycol-water nanofluid past a porosity vertical stretching sheet under impact of thermal radiation, shape and slip factor and suction/injection process has been analyzed using Runge- Kutta Fehlberg fifth order (RKF 5) numerical method. The influence of variable, different parameters such as nanoparticles shape factor, named hexahedron and Lamina on temperature and velocity profiles are exemplified quantitatively through graphs. Outputs demonstrate thermal radiation impact causes to produce heat and increase the temperature profile by increasing nanofluid molecules energy. Lamina shape nanoparticle has a greater effect on increasing Nusselt number (Nu) compared to hexahedron.

Precise smart model for estimating dynamic viscosity of SiO2/ethylene glycol–water nanofluid

ABSTRACTArtificial neural network (ANN) is widely being used in engineering applications in order to provide predicting models to estimate the performance of the studied system under specific working conditions. One of the significant characteristics that are highly practical in fluid mechanics and heat transfer systems is the dynamic viscosity which highly affects pressure drop and also has an influence on the heat transfer performance. Due to the lack of a precise model to predict the dynamic viscosity, in this research, experimentally measured dynamic viscosity of SiO2/ethylene glycol–water nanofluid data is collected from the literature and used to present a smart model based on the ANN technique. In order to provide a precise smart model, Multilayer Perceptron (MLP) and Radial Basis Function (RBF) algorithms are applied in the neural network. The accuracy of the proposed model is validated through performing error analysis. It is monitored that the employed approach is highly potent in estimating high accuracy responses since the results of mean square and correlation coefficient analyses are 5.5 and 0.998 Pa s.

Experimental Investigation of the Influence of Particle Disaggregation on Shear Thinning of Fe3O4 Ethylene Glycol-Water Nanofluid

Experimental Investigation of the Influence of Particle Disaggregation on Shear Thinning of Fe₃O₄ Ethylene Glycol-Water Nanofluid

Numerical investigation of laminar convective heat transfer of graphene oxide/ethylene glycol-water nanofluids in a horizontal tube

The study provides a numerical analysis of laminar forced convective heat transfer of graphene oxide nanosheets suspended in the mixture of water and ethylene glycol in laminar flow regime using single phase approach in a circular horizontal tube under constant heat flux conditions. The length and diameter of the simulation domain for numerical investigation are 2 m and 4.5 mm respectively. The effect of various flow conditions and weight concentrations have been investigated on local heat transfer coefficient, average heat transfer coefficient, friction factor, pressure drop and thermal performance factor of the nanofluids. The range of weight concentration and Reynolds number used in this study are 0.01–0.1 wt.% and 400–2000 respectively. The maximum percentage enhancement in average heat transfer coefficient was 13.04% for weight concentration and Reynolds number of 0.1 wt.% and 2000 respectively. The maximum pressure drop enhancement ratio was 2.12 at Reynolds number and weight concentration of 400 and 0.10 wt.%. The enhancement in heat transfer coefficient was found lower as compared to corresponding enhanced pressure drop for all weight concentrations. The thermal performance factor of nanofluids is less than one for all weight concentrations and nanofluids showed no advantage over base fluid as heat transfer fluid in laminar flow regime.

The Effect of Particle Disaggregation on Viscosity of Fe3O4 Ethylene Glycol–Water Nanofluid

The Effect of Particle Disaggregation on Viscosity of Fe₃O₄ Ethylene Glycol–Water Nanofluid

Experimental and Numerical investigation of Heat transfer enhancement using Al2O3-Ethylene Glycol/Water nanofluids in straight channel

A study of computational fluid dynamics has been conducted to study the characteristics of the heat transfer and friction factor of Al2O3/Ethylene glycol-water nanofluid flowing in straight channel. The three dimensional realizable k-e turbulent model with enhanced wall treatment was utilized. As well as were used Temperature dependent thermophysical properties of nanofluid and water. The evaluation of the overall performance of the tested channel was predicated on the thermohydrodynamic performance index. The obtained results showed that the difference in behaviour depending on the parameter that has been selected to compare the nanofluid with the base fluid. In addition, the friction factor and the heat transfer coefficient increases with an increase of the nanoparticles volume concentration at the same Reynolds number. The penalty of pressure drop is negligible with an increase of the volume concentration of nanoparticles. Conventional correlations that have been used in turbulent flow regime to predict average heat transfer and friction factor are Dittus-Boelter and Blasius correlations, for channel are also valid for the tested nanofluids which consider that the nanofluids have a homogeneous fluid behave.

Experimental Investigation of Laminar Convection Heat Transfer of Al2O3-Ethylene Glycol-Water Nanofluid as a Coolant in a Car Radiator

In this experimental study, heat transfer of a coolant nanofluid, obtained by adding alumina nanoparticles to Ethylene Glycol-water (60:40 by mass), in a car radiator has been investigated. For this purpose, an experimental setup has been designed and constructed. Firstly, to investigate the accuracy of the results, the experiments have been done for the base fluid. Then the experiments have been performed for the nanofluid with different nanoparticles volume fractions of 0.003, 0.006, 0.009 and 0.012. To ensure laminar flow regime three coolant flow rates of 9, 11 and 13 lit/min have been tested. The thermophysical properties have been calculated using the recently presented temperature dependent models in the literature. According to the results, both the convective heat transfer coefficient and Nusselt number increase (about 9%) with increasing the coolant flow rate. Also, convective heat transfer coefficient increases with increasing the nanoparticles volume fraction. Although Nusselt number decreases when nanofluid is utilized, it enhances as the nanoparticles volume fraction increases. Based on the experimental results obtained, A new empirical correlation has been developed for average Nusselt number of Al2O3-EG-water nanofluid in developing region of flat tubes of car radiator for laminar flow and its maximum error is 3%.

An experimental correlation approach for predicting thermal conductivity of water-EG based nanofluids of zinc oxide

In this study, the effects of temperature (20°C<T<50°C) and volume fracti°n (0<φ<4%) on the thermal conductivity of zinc oxide/ethylene glycol-water nanofluid have been presented. Nanofluid samples were prepared by a two-step method and thermal conductivity measurements were performed by a KD2 pro instrument. Results showed that the thermal conductivity increases uniformly with increasing solid volume fraction and temperature. The results also revealed that the thermal conductivity of nanofluids significantly increases with increasing solid volume fraction at higher temperatures. Moreover, it can be seen that for more concentrated samples, the effect of temperature was more tangible. Experimental thermal conductivity enhancement of the nanofluid in comparison with the Maxwell model indicated that Maxwell model was unable to predict the thermal conductivity of the present nanofluid. Therefore, a new correlation was presented for predicting the thermal conductivity of ZnO/EG-water nanofluid.

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF HEAT TRANSFER AUGMENTATION USING AL&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-ETHYLENE GLYCOL NANOFLUIDS UNDER TURBULENT FLOWS IN A FLAT TUBE

A study of computational fluid dynamics has been conducted to study the characteristics of the heat transfer and friction factor of Al2O3/Ethylene glycol-water nanofluid flowing inside flat tube. The three dimensional realizable k–e turbulent model with an enhanced wall treatment was utilized. The evaluation of the overall performance of the tested tube was predicated on the thermo-hydrodynamic performance index. The obtained results showed that the difference in behaviour depending on the parameter that has been selected to compare the nanofluid with the base fluid. In addition, the friction factor and the heat transfer coefficient increases with an increase of the nanoparticles volume concentration at the same Reynolds number. The penalty of pressure drop is negligible with an increase of the volume concentration of nanoparticles. Conventional correlations that have been used in turbulent flow regime to predict average heat transfer and friction factor are Dittus-Boelter and Blasius correlations, for tubes are also valid for the tested nanofluids which consider that the nanofluids have a homogeneous fluid behaviour.

Sand-propylene glycol-water nanofluids for improved solar energy collection

Experiments were carried out on the preparation, thermophysical properties' measurement and application of surfactant-free, sand-propylene glycol-water nanofluids for solar energy collection. Thermal conductivity enhancement of 16.3% and viscosity reduction of 47% were observed for 2 vol % sand-PG-water nanofluid at 28 °C. Microconvection caused by Brownian motion was identified as one of the mechanisms of thermal conductivity enhancement. The relative viscosity of sand-propylene glycol-water nanofluid was less than 1 over a temperature range of 10–60 °C and sand nanoparticle concentration range of 0.5–2 vol %. The lower viscosity of sand-PG-water nanofluids in comparison to that of propylene glycol-water mixture is attributed to non-covalent interactions between sand nanoparticles and propylene glycol, leading to perturbation of hydrogen bonding network. The use of 2 vol % sand-PG-water nanofluid resulted in enhancement of heat transfer and solar energy collection by 16.5%. Our results demonstrate that sand-PG-water nanofluids are suitable for use as heat transfer fluid in solar collectors.

ZnO⿿propylene glycol⿿water nanofluids with improved properties for potential applications in renewable energy and thermal management

ZnO⿿propylene glycol⿿water (ZnO⿿PG⿿water) nanofluids of higher thermal conductivity and lower viscosity than PG⿿water mixture were prepared by the sequential method. The unsteady state heat transfer performance of ZnO⿿PG⿿water nanofluids revealed 16.5% increase in heat transfer rate for 2vol% nanofluids under constant heat flux conditions. The coolant side heat transfer coefficient increased by 29% on use of 2vol% ZnO⿿PG⿿water nanofluid for heat removal from constant temperature source (simulated thermal energy storage). The collection efficiency of solar collectors employing ZnO⿿PG⿿water nanofluid was found to increase linearly with nanoparticle concentration with about 9% increase in collection efficiency for 2vol% nanofluid. These results summarily indicate that ZnO⿿PG⿿water nanofluids perform better than PG⿿water mixture for solar energy collection and discharging of solar thermal energy storage.

Second law analysis of a nanofluid-based solar collector using experimental data

The present study deals with the entropy generation analysis of a flat-plate solar collector using SiO2/ethylene glycol–water nanofluids. For this purpose, available experimental data on the performance of a flat-plate solar collector are exploited for estimating the entropy generation in the system. Ethylene glycol–water (EG–water) and EG–water-based nanofluids having three different nanoparticle volume fractions including 0.5, 0.75, and 1 % are considered as the working fluids. The results are presented in terms of exergy efficiency, entropy generation parameter, and Bejan number for three different mass flow rates and various solar radiation intensities. It is found that when nanofluid concentration increases from 0 to 1 %, exergy efficiency enhances up to 62.7 % for a mass flow rate of 1 L min−1, whereas the corresponding increases in mass flow rates of 1.75 and 2.5 L min−1 are 45.2 and 39.7 %, respectively. The results also elucidate that entropy generation parameter, which is a function of entropy generation, ambient temperature, and solar radiation, reduces with increasing the nanofluid concentration.

Thermal conductivity enhancement of COOH-functionalized MWCNTs/ethylene glycol–water nanofluid for application in heating and cooling systems

In this paper, an experimental investigation on the effects of temperature and nanotubes concentration on the thermal conductivity of MWCNTs/EG–water (40:60vol.%) nanofluids is presented. The experiments were performed at temperatures ranging from 25°C to 50°C and solid volume fraction range of 0–1.0%. They showed that the thermal conductivity ratio enhances with increasing the solid volume fraction and temperature. Moreover, at higher concentration of MWCNTs, the effect of temperature on the thermal conductivity ratio was more tangible. The thermal conductivity measurements also indicated that the maximum enhancement of thermal conductivity of nanofluid was 34.7%, which occurred at solid volume fraction of 1.0% and temperature of 50°C. The experimental results were compared with data obtained from Maxwell model. Since, this model failed to predict the thermal conductivity of the nanofluid, for engineering applications, using experimental findings, an accurate correlation was presented to predict the thermal conductivity of MWCNTs/EG–water (40:60vol.%) nanofluids. The maximum value of the deviation was obtained ±1.8% for the proposed correlation.