Mass Fraction Of Nanoparticles Research Articles

Investigation of factors influencing the performance of nanofluid-based direct absorption solar collector using Taguchi method

The performance of nanofluid-based solar collector depends on different factors like nanoparticle material, base fluid, mass fraction of nanoparticles, height of the collector, length of the collector, incident solar flux, mass flow rate of the nanofluid in the collector. In order to quantify the effect of nanoparticle material, optical properties of different nanofluids (different nanoparticles dispersed in DI water) were measured using spectrophotometer. After studying the optical signatures of the nanofluids, solar-weighted absorptivity of the nanofluids was calculated to evaluate the efficient nanoparticle material for harnessing solar irradiation. It has been found that amorphous carbon nanoparticles-based fluid has highest absorptivity at low mass fractions and is suitable for harnessing solar energy. Further, the performance of nanofluid-based solar collector has been investigated numerically using amorphous carbon nanoparticles. For the purposes of this analysis, a two-dimensional steady-state heat transfer model has been developed for a collector in which the nanofluid flows horizontally and is heated with normally incident solar irradiation. During the analysis carried out in this study, five factors were chosen (height of the collector, nanofluid mass flow rate, solar irradiation incident flux, nanoparticle mass fraction, and length of the collector). The influence of variation in these five factors on the overall performance of the solar collector (i.e., outlet temperature) was analyzed using the Taguchi method. In order to carry to this analysis, the values of these five factors were varied at three levels. Based on these variations, the L18 standard orthogonal array was prepared, and the matrix containing the 18 sets of combinations was organized. The results showed that two factors (length of the collector, and the incident solar flux) exhibited a strong increasing trend, while one factor (nanoparticle mass fraction) exhibited an optimizing trend on the output (outlet collector temperature). Further, from the calculations it has been observed that 60 mg L−1 is an optimum mass fraction at which maximum collector efficiency can be achieved for the length of the collector (= 1 m), height of the collector (= 10 mm), incident flux (= 1000 W m−2), mass flow rate (= 0.010 kg s−1).

Evaporation characteristics of fuel sessile droplets with nanoparticles

ABSTRACTThe nano-fuel are prepared by dispersing CNT, CeO2, and Co3O4 nanoparticles in n-tetradecane (C14). This experimental study investigates the effect of nanoparticles mass fraction as well as the variation of nanoparticles sizes on the viscosity and evaporation characteristics. It is revealed that the viscosity increases with the increase in mass fraction and the decrease in particle size. In addition, the presence of nanoparticles leads to a reduction of the evaporation rate during constant contact line phase. However, the droplet evaporation rate is augmented remarkably in constant contact angle and hybrid phase. As a result, the whole evaporation time of nano-fuel droplets is shorter than base fuel.

Solar-driven phase change microencapsulation with efficient Ti4O7 nanoconverter for latent heat storage

A sort of novel microencapsulated phase change materials (PCMs) has attracted much attention for energy storage. However, the solar energy utilization efficiency of traditional microcapsulated PCMs is still not very high up to date. In this work, new core@shell structured paraffin@SiO2/Ti4O7 composite microcapsules were developed to harvest environmental full-spectrum sunlight by smart and rational design using a sol-gel method. The SiO2 shell not only prevented the leakage of paraffine, but also improves its thermal conductivity. The black 300 nm Ti4O7 particles, which were successfully embedded into the SiO2 shell, can achieve the efficient absorption of sunlight and simultaneously high conversion from light to thermal. The resultant paraffin@SiO2/Ti4O7 microcapsules retained most enthalpy of paraffin, increased its stability, and exhibited an excellent thermal energy storage performance. The thermal conductivity of paraffin@SiO2/Ti4O7 microcapsules was significantly enhanced by 334.87% (1.322 W m−1 K−1) compared with 0.304 W m−1 K−1 of one for paraffin. When the mass fraction of Ti4O7 nanoparticles is 3 wt% of paraffin, these paraffin@SiO2/Ti4O7 microcapsules exhibited remarkable 85.36% of photo-thermal storage efficiency compared with 24.14% of one for paraffin. Due to their huge superiority of high efficient use of abundant solar energy in natural resources, these new photo-driven PCMs are very promising materials for solar-to-thermal conversion and energy storage.

Cooling performance of Al2O3-water nanofluid flow in a minichannel with thermal buoyancy and wall conduction effects

The effect of highly conductive thick walls on the mini channel heat transfer performance is systematically addressed while two constant heat flux sources are considered at the bottom of the channel. The influence of using different mass fractions of Al2O3 nanoparticles dispersed in water as working fluid are studied. The buoyancy effects on the thermal performance and pressure drop of the mini channel are also investigated. The finite volume method is employed to simulate the flow and heat transfer of nanofluid in the channel. The results show that the axial heat transfer is an important effect in mini channels with thermal conductive walls and should be taken into account. It is found that the presence of nanoparticles with the mass fraction of 5% and 10% drops the maximum temperature (and increases the pressure drop) by 1.28% (17.0%) and 1.48% (41.0%), respectively when Reynolds number is 500 and neglecting buoyancy effects. The presence of buoyancy effects reduces the pressure drop by 21.08% in a case with Reynolds number 500 and the nanoparticles mass fraction 5%. This is while the presence of buoyancy effects would decrease the maximum temperature by 1 °C.

Effects of magnetic field on thermo-hydraulic performance of Fe3O4-water nanofluids in a corrugated tube

An experimental system is established to investigate the thermo-hydraulic performance of Fe3O4-water nanofluids in a corrugated tube under various magnetic fields. The influences of magnetic induction intensities (B = 0 G, 100 G, 200 G, 300 G), nanoparticle mass fractions (ω = 0.0%, 0.1%, 0.3%, 0.5%), electromagnet arrangement modes (one-side electromagnet and two-side staggered electromagnet), kinds of tubes (smooth tube and corrugated tube), Reynolds numbers (Re = 800–12,000) on flow and heat transfer characteristics are discussed. It is obtained that the augmentation of heat transfer is more sensitive to high nanoparticle mass fraction, high magnetic induction intensity, two-side staggered electromagnet and corrugated tube. A Comprehensive evaluation index is applied to estimate the thermo-hydraulic performance. It can be discovered that the comprehensive evaluation index increases with the increasing Reynolds number at first and then decreases, and the rough surface of corrugated tube delays the appearance of critical Reynolds number.

Effects of twisted tape structures on thermo-hydraulic performances of nanofluids in a triangular tube

An experiment set for flow and heat transfer characteristics of nanofluids is established and the reliability of this experiment set is verified. Thermo-hydraulic performances of nanofluids flowing through a triangular tube with different structure twisted tapes are experimentally studied. The effects of nanoparticle mass fractions (ω = 0.1 wt%, 0.3 wt% and 0.5 wt%), Reynolds numbers (Re = 400–9000), different structure twisted tapes (P = 25 mm, 40 mm, 55 mm, 65 mm, 75 mm) on the Nusselt number and resistance coefficient enhancement ratios are experimentally investigated. It is found that the triangular tube with twisted tape can improve the Nusselt number by 52.5% and 34.7% at best in laminar and turbulent flow respectively compared with the corresponding smooth tube with the same fluid. The comprehensive performances of nanofluids in the triangular tube with twisted tape are also analyzed based on a comprehensive evaluation index. It is found that large nanoparticle mass fraction and small length of each twisted tape unit are more sensitive to the high comprehensive performance index. In addition, comprehensive performances between the triangular tube with twisted tape and the corrugated tube are compared. It is found that the triangular tube with twisted tape has an advantage over the corrugated tube in laminar flow.

Experimental investigation toward obtaining the effect of interfacial solid-liquid interaction and basefluid type on the thermal conductivity of CuO-loaded nanofluids

In this study the effect of temperatures, the CuO nanoparticles mass fraction, and basefluid of deionized water, ethanol and ethylene glycol were studied on thermal conductivity of nanofluid. CuO nanoparticles were dispersed in deionized water, ethanol and ethylene glycol separately by using ultrasonic waves. The stability of nanoparticles in basefluids was estimated by using DLS and Zeta Potential analysis. The results showed that with increase in the temperature and mass fraction of nanoparticles the relative thermal conductivity of nanofluid increases and for CuO/ethanol nanofluid the value of thermal conductivity is much higher than other nanofluids at higher temperatures and CuO nanoparticles mass fractions. In addition, the results showed that the interfacial interaction between basefluid molecules and nanoparticles' surface has major effect on nanofluid thermal conductivity; consequently, CuO/water nanofluid has higher interfacial interaction at various temperatures and nanoparticles mass fractions. Furthermore, the results showed that with the increase of nanofluid mass fraction up to 0.5 wt% insignificant change in relative thermal conductivity is resulted while for the values above 0.5 wt% the relative thermal conductivity of nanofluids enhance tangibly. Finally an empirical equation including temperature, nanoparticles mass fraction, and physical properties of nanoparticles and basefluid was obtained by using hybrid GMDH-type neural network to estimate relative thermal conductivity of nanofluid. The comparison between results of experimentation and proposed correlation showed that the deviation of calculated thermal conductivity from experimental values is majorly less than 10%.

Forced convective heat transfer of solar salt-based Al2O3 nanofluids using lattice Boltzmann method

Though solar salt has been used in concentrated solar plants, the small specific heat capacity and low thermal conductivity still set a limitation on further application. A combination with nanoparticles shows potential to overcome these disadvantages. In present work, a freeze-drying method was employed to formulate solar salt-based Al2O3 nanofluids to modify the effective thermal properties. The investigation of forced convective heat transfer was taken by a modified lattice Boltzmann method. The effect of Al2O3 nanoparticle mass fractions on both effective cp and heat transfer performance was analyzed. Results indicate that within the nanoparticle mass fraction range (0–2.0%), cp and heat transfer coefficient increase with the increase of nanoparticle mass fractions. With 2.0 wt% Al2O3, the enhancement on effective cp, heat transfer coefficient and Nusselt are 12.33%, 7.26% and 3.52%, respectively. In the meantime, a comparison between simulation results and Shah-London correlation prediction was carried out and good agreement was obtained.

GMDH modeling and experimental investigation of thermal performance enhancement of hemispherical cavity receiver using MWCNT/oil nanofluid

Nowadays, nanofluids are introduced as an effective technique for enhancing the thermal efficiency in solar collectors. In this work, the MWCNT/oil nanofluid with 0.8% nanoparticle mass fraction is investigated experimentally in a solar dish concentrator coupled to a hemispherical cavity receiver. The main objective of this research is to examine the effect of the nanofluid application for improving the solar thermal performance of the hemispherical cavity receiver. The results revealed that thermal efficiency of the hemispherical cavity receiver has averagely increased equal to 12.93%, using application of the MWCNT/oil nanofluid compared to the application of the basefluid. In the steady state periods, the average thermal efficiency of 76.23% and 67.50% were calculated for the hemispherical cavity receiver using the MWCNT/oil nanofluid and pure oil, respectively. It was conducted that the receiver heats gain and the thermal efficiency of the cavity receiver has a similar trend with the working fluid difference temperature. Two experimental models were suggested based on the overall performance versus Tin-TambIbeam for the MWCNT/oil nanofluid and the pure oil. Finally, it is found that the use of the examined nanofluid is able to enhance the thermal performance of the examined collector about 13%. Also, in this study, group method of data handling (GMDH) artificial neural networks is applied in order to model the dependency of thermal efficiency and the cavity heat gain of the Hemispherical Cavity Receiver on the mentioned factors.

Nanofluid based grid connected PV/T systems in Malaysia: A techno-economical assessment

In this study, the techno-economic assessment of a Grid-Connected Photovoltaic Thermal (GCPVT) system with nanofluid as base fluid is carried out. The investigation blinds both theoretical and experimental work. The reason why a grid-connected PV is considered is due to grid-connected PV configurations constituting about 86% of the PV tsystem, with 54% of them being centralised while 32% are being distributed, which shows the importance of such systems and the potential they can achieve with PV/T collectors. The study focuses on the electrical and thermal performance of PV/T. The yield and capacity factors are used to investigate the productivity and utilisation of the PV panel, respectively. In addition, the assessment of the cost analysis and economic aspect was conducted through Cost of Energy (CoE) and Payback Period (PBP) calculations. This system was installed, tested, and data has been collected in the green innovation and technology park in UKM, Bangi. Furthermore, an evaluation of the panel production in terms of current, voltage, power and efficiency is presented. The average daily ambient temperature and total global solar energy in Bangi are 38.89 °C and 4062 Wh/m2, respectively. A MATLAB software code is developed and used for the data analysis. The results of the assessment show that the GCPVT system has an annual yield factor and capacity factor of (128.34–183.75) kWh/kWp and (17.82–25.52)%, respectively. While the cost of energy, payback period, and efficiency are 0.196 USD/kWh, 7–8 years and 14.25%, respectively. Moreover, different nanoparticle mass fractions in the nanofluid were considered and the optimum fraction was found to be 3%. Additionally, different comparisons of this system with other systems and countries are presented to show its improvement and cost-effectiveness. This study indicates how the GCPVT system with nanofluid improved the PV technical and economic performance.

Characteristic oscillation phenomenon after head-on collision of two nanofluid droplets

One falling liquid droplet impacting a sessile droplet and then undergoing oscillation is a common phenomenon in both nature and industry. However, to the best of our knowledge, the head-on collision of two nanofluid drops has not been studied when both the nanoparticle and surfactant exist in the drop. In this work, the characteristics of oscillation after head-on collision of two TiO2-water nanofluid drops were investigated experimentally. The effects of impact velocity, drop size, and nanoparticle concentration have been considered to understand how they influence the drop spreading, recoiling, and rebounding. For the influence of the drop size, it shows that in 0% and 0.001% of nanoparticle concentrations, the relative spreading radius of small drop size is higher than that with large size, while it is reversed in 0.01% and 0.1% of nanoparticle mass fractions. Interestingly, it was found that there is an optimal nanoparticle mass fraction of 0.1% for nanofluid droplets where the oscillation of head-on collision can be damped much more rapidly than that for nanoparticle-free droplets. A hypothesis considering the comprehensive interaction of surfactant redistribution, surfactant gradient, and particle initial effect was proposed to explain the observed phenomenon. This work will be of significant reference to various practical applications especially when the drop collision oscillation characteristics are supposed to be under control.

Specific heat of aluminum-oxide nanolubricants

This paper presents specific heat measurements for a synthetic polyolester (POE) based aluminum oxide (Al2O3) nanolubricant with a polymeric surfactant over a temperature range from approximately 4 °C to 45 °C. Al2O3 nanolubricants with two nominal surface-area-based diameter nanoparticles were investigated: 20 nm and 40 nm. The number-based diameter of the nanoparticles, as determined by dynamic light scattering (DLS), were 112 nm and 148 nm, respectively. The nanoparticle mass fractions were varied from 0.076 to 0.249 for the 112-nm diameter nanolubricant, and from 0.059 to 0.394 for the 148-nm diameter nanolubricant. The measurements showed that the specific heat of the nanolubricant linearly increased with increasing temperature, and linearly decreased with respect to increasing nanoparticle mass fraction. The size of the nanoparticle was shown to have no effect on the magnitude of the specific heat of the nanolubricant. The measurements were compared with two existing models. The mass fraction weighted model exhibited excellent agreement with the measurements (within ±1.01%). In contrast, the volume mass fraction model failed to predict the measurements for most conditions to within ±5%.

Thermal-hydraulic noise analysis of a VVER-1000 reactor with nanofluid as coolant

The noise issue, especially in industrial scale systems including nuclear power plants, there has been always an interesting subject in system stability analysis. In this paper the effects of fluctuations in coolant temperature and velocity at the inlet of a fuel assembly of a VVER-1000 reactor with Al2O3 nanofluid coolant water were investigated. This analysis is performed by using a Fourier transformed conservation equation (mass, momentum and energy) in frequency space. The transformed equations were discretized with finite volume method and numerically solved. Thermodynamic properties of nanofluid were evaluated by adding new subroutines to IPAWS IF97 steam table libraries. The comparison between the achieved results of the applied model and previous studies performed with porous media approach and COBRA-EN code, showed a good agreement. Thermal-hydraulic effects of nanofluid on noise fluctuations were calculated based on different concentrations of Al2O3 nanoparticle and noise frequencies. Calculations showed that any increment in nanoparticles mass fraction will result in reduction of fluctuations in coolant temperature and velocity.

Thermal-hydraulic analysis of a novel design super critical water reactor with Al2O3 nanofluid as a coolant

In this study the thermal-hydraulic analysis of the SCWR reactor with a new geometric design is discussed. In the new design, coolant and moderator circuits are separated and nanofluid has been used as coolant of the reactor core. In the performed sub-channel analysis, the conservation equations of mass, momentum and energy are solved numerically. Since in the new geometry the coolant and moderator circuits are separated, compared to previous plans, using the nanofluids with higher mass fraction of nanoparticles is applicable. In this article, the thermal-hydraulic analysis is performed for various mass fractions of Al2O3 nanoparticle and moderator velocities. Calculations show that the core outlet temperature grows up with increasing nanoparticle mass fraction. As it was expected, by increasing the nanoparticle mass fraction the core pressure drop will be raised, but in the proposed design this pressure drop is much lower.

Experimental investigation toward obtaining a new correlation for viscosity of WO3 and Al2O3 nanoparticles-loaded nanofluid within aqueous and non-aqueous basefluids

In this study, the effect of temperature and mass fraction of Al2O3 and WO3 nanoparticles dispersed in deionized water and liquid paraffin was investigated on dynamic viscosity of nanofluid. The results of the TEM tests showed that the size of Al2O3 and WO3 nanoparticles was ranged from 10 to 60 nm, and the results showed that nanoparticles were semi-spherical. Also the results of DLS and zeta potential tests, respectively, exhibited the uniform size and high stability of the nanoparticles in the basefluid environment. The findings showed that adding a certain amount of nanoparticles to water and liquid paraffin increases dynamic viscosity, and in the case of various shear rates, the viscosity is constant for the water-based nanofluids, which indicates the Newtonian behavior of the nanofluid. In addition, for those prepared by liquid paraffin as a basefluid, the viscosity does not remain constant at different shear rates and at low amount of shear rate the viscosity achieves higher value, indicating non-Newtonian behavior of liquid paraffin-based nanofluids. The results showed that by increasing the temperature in liquid paraffin-based nanofluid the uniformity and linearity of the viscosity curve at various shear rates could be observed, which represents an approach for Newtonian behavior of nanofluid at higher temperatures. These results also showed that with increasing the mass fraction of nanoparticles in water and liquid paraffin, the viscosity increases at different shear rates. Finally, the correlation presented in this study shows that for nanofluid viscosity as a function of nanoparticles load and temperature, the deviation of correlated data from experimental values is less than 10%.

Experimental studies on ferrofluid pool boiling in the presence of external magnetic force

The past decade has witnessed rapid advances in thermal-fluid applications involving nanoparticles due to existing heat transfer enhancements. The main challenges in working with nanoparticles are clustering, sedimentation and instability encountered in many studies. In this study, magnetically actuated Fe3O4 nanoparticles were coated with a fatty acid and dispersed inside a base fluid (water) in order to avoid clustering, sedimentation and instability as well as to improve the thermal performance. Boiling heat transfer characteristics of the ferrofluids were experimentally investigated with magnetic actuation and compared to the results without magnetic actuation. Nanoparticle mass fraction was the major parameter. Boiling heat transfer coefficient of the magnetically actuated system was found to be significantly higher compared to the case without magnetic actuation. The results showed that boiling heat transfer coefficient was not sensitive to the nanoparticle mass fraction.

Effect of rotating twisted tape on thermo-hydraulic performances of nanofluids in heat-exchanger systems

Stable TiO2-H2O nanofluids are prepared and their stabilities are studied. An experimental set for studying the heat transfer and flow characteristics of nanofluids is established. Heat transfer and flow characteristics of TiO2-H2O nanofluids in a circular tube with rotating and static built-in twisted tapes are experimentally investigated and compared. An innovative performance evaluation plot of exergy efficiency is developed and the exergy efficiency of tube with rotating and static built-in twisted tapes filled with nanofluids is analyzed in this paper. The results indicate that the combination of rotating built-in twisted tape and TiO2-H2O nanofluids shows an excellent enhancement in heat transfer, which can increase the heat transfer by 101.6% compared with that of in a circular tube. The effects of nanoparticle mass fractions (ω= 0.1%, 0.3% and 0.5%) and Reynolds numbers (Re = 600–7000) on the heat transfer and flow characteristics of TiO2-H2O nanofluids are discussed. It is found that there is a critical Reynolds number (Re = 4500) for the maximum value of relative heat transfer enhancement ratio. The comprehensive performance of the experimental system is analyzed. It can be found that the comprehensive performance index of the experimental system firstly increases and then reduces with Reynolds number, and it can reach 1.519 at best. However, for the performance evaluation of exergy efficiency, the coupling of rotating twisted tape and nanofluids deteriorates the exergy efficiency. Also, it can be found that the exergy efficiency of the circular tube with twisted tape is greater than that of circular tube under the same pumping power and pressure drop, but it shows deterioration under the same mass flow rate.

Electrochemical–Thermal Evaluation of an Integrated Thermal Management System for Lithium‐Ion Battery Modules

AbstractThermal management of lithium‐ion (Li‐ion) batteries using phase change materials (PCM) demonstrate advantages such as compactness and reduced weight compared to conventional active cooling systems. However, the heat accumulation in PCM due to ineffective cooling and added thermal inertia may lead to thermal management system failure. In this study, a hybrid active–passive thermal management system for a Li‐ion battery module is presented. Graphite nanopowder and highly oriented pyrolytic graphite sheets are employed to improve the low thermal conductivity of the PCM. The thermophysical properties of the nano‐enhanced PCM (NePCM) with various mass fractions are experimentally explored. A streamlined electrochemical–thermal coupled model for batteries is used to develop an air‐assisted hybrid thermal management system model. The effects of nanoparticles mass fraction, thickness of the PCM layer, and air inlet temperature on the module thermal behavior during a standard driving cycle are investigated. The hybrid system can maintain the module temperature within the safe limits and provide excellent temperature uniformity. The results reveal that an enhanced thermal conductivity is essential to recover the thermal energy storage capacity of PCM during the driving cycle. The proposed cooling approach presents a promising avenue for enhanced thermal management of Li‐ion battery modules.

Experimental research on stabilities, thermophysical properties and heat transfer enhancement of nanofluids in heat exchanger systems

Abstract Stable TiO2–water nanofluids are prepared by a two-step method, stabilities of nanofluids are investigated by precipitation method and transmittance method respectively, and thermal conductivities and viscosities are also measured. An experimental system for studying the heat transfer enhancement of nanofluids is established, and heat transfer and flow characteristics of TiO2–water nanofluids in heat exchanger systems with a triangular tube and circular tube are experimentally studied. The effects of nanoparticle mass fractions (ω = 0.1 wt%–0.5 wt%) and Reynolds numbers (Re = 800–10000) on the heat transfer and flow performances of nanofluids are analyzed. Fitting formulas for Nusselt number and resistance coefficient of nanofluids in a triangular tube are put forward based on the experimental data. The comprehensive performances of nanofluids in a triangular tube are investigated. It is found that nanofluids in a triangular tube can significantly improve the heat transfer performance at the cost of a small increase in resistance coefficient compared with that in a circular tube, especially the resistance coefficients are almost the same between different nanoparticle mass fractions at turbulent flow. It is also found that the comprehensive evaluation index η decreases with Reynolds number at laminar flow but a critical maximum value appears at turbulent flow.

Demonstration of plausible application of gallium nano-suspension in microchannel solar thermal receiver: Experimental assessment of thermo-hydraulic performance of microchannel

The present study experimentally investigates the potential application of a liquid metal enriched with aluminum oxide nanoparticles in a microchannel, which can have further applications in designing the next generation of solar thermal receivers equipped with microchannel fluid passages. The gallium nano-suspensions were prepared at mass fractions of 5%, 10% and 15% of aluminum oxide in gallium and were utilized in a copper-made rectangular microchannel liquid block at 200 °C. Effects of different operating parameters such as heater heat flux, mass fraction of nanoparticles and peristaltic flow rate on the overall heat transfer coefficient, value of the pressure drop and thermo-hydraulic performance index of the microchannel were experimentally investigated. Results showed that gallium nano-suspension offers a great potential for cooling the surface of the microchannel at high heat flux condition. The highest thermal performance index of 3.5 and 2.9 were achieved for the flow in laminar and turbulent regimes at mass fraction of 10%. Likewise, heat flux and peristaltic flow rate plausibly enhanced the heat transfer coefficient, however, for the mass concentration, the thermo-hydraulic performance was decreased at wt% = 15, due to the augmentation in the viscosity and agglomeration of aluminum oxide nanoparticles within the gallium, which was attributed to the increase in friction forces between layers of gallium.