CuO Al2O3 Research Articles

Thermal enhancement of PEM fuel cell cooling with novel configurations of Tesla valve and hybrid nanofluids: A numerical study

The operating temperature and thermal distribution play a significant role in the appropriate performance of the proton exchange membrane fuel cell (PEMFC). A suitable cell cooling method can guarantee uniform temperature distribution and preservation of membrane water content under harsh conditions in a PEMFC. The compact structure of PEM fuel cells and the size of the cooling system impose a great challenge to achieve a proper design of cooling plate. In this numerical study, four designs of the multi-stage Tesla valve with straight and reverse configuration are proposed to be employed as a cooling channel in which three different hybrid nanofluids such as TiO2–Cu, Al2O3–CuO, and Ag–MgO dispersed in water and Ethylene glycol flow inside the channels. A validated numerical model is developed using a commercial computational fluid dynamics (CFD) code to investigate the effect of inlet temperatures and mass flow rates of cooling fluid and volume fraction of nanoparticles on heat transfer coefficient, pressure drop, index of uniform temperature (IUT), and performance evaluation criteria (PEC). The results demonstrated that the reverse configuration of the Tesla valve (CASE E) experienced outstanding uniform thermal distribution while the heat transfer coefficient increased by 15% in this case compared to the straight-line cooling channel. The Ag–MgO hybrid nanoparticles showed better thermal performance than the two other nanoparticles with a 4% reduction in temperature difference in the cooling plate.

Investigating the effects of synthesis parameter on textural and catalytic properties of ZnO–CuO–Al2O3–Cr2O3 mixed oxide in water gas shift reaction

The present study has investigated the influence of preparing conditions, including aging temperature and time, pH, and Tcalcination, on the co-precipitated ZnO–CuO–Al2O3–Cr2O3 mixed oxide at a high-temperature water gas shift reaction. XRD, BET, FTIR, TG-DTA, SEM, TEM, and H2-TPR were used to characterize the relationships between the synthesis parameters and the physicochemical features. The investigation proved that the activity in aging 5 h could be related to higher pore volume and lower crystalline size of 0.24 cm3g-1 and 6.4 nm, respectively. Also found that increasing the aging temperature to 60 °C results in a rise in the surface area and particle size of less than 6 nm, enhancing the catalyst activity. The findings showed that raising the Tcalcination reduced the surface area from 132 to 65 m2 g−1. It has been concluded that the CO conversion of 70 % was obtained when aged at 60 °C and calcination temperature of 400 °C.

Effect of heating rate on crystallisation and properties of R2O–CaO–MgO–CuO–Al2O3–SiO2 glass-ceramics

R2O–CaO–MgO–CuO–Al2O3–SiO2 (RNa, K) glass-ceramics were fabricated using the melt-quenching method and the effect of heating rate on the microstructure and properties of the glass-ceramics was investigated. The results demonstrated that the main crystal phase of the samples was clinoenstatite, and the secondary crystal phases were forsterite and diopside. With an increase in heating rate, the diffraction peak intensity of clinoenstatite gradually increased, and the morphology of the particles changed from short columns to long needles. When the heating rate was 1 °C/min, the sample exhibited flexural strength and Vickers hardness of 7.38 GPa and 84.33 MPa, respectively. When the heating rate was 10 °C/min, the Cu+ content in the sample reached the maximum of 2.1 wt%, which is 1.4 times of Cu+ in the brown sample obtained by heat-treatment at 1 °C/min. The colour of the sample intensified as the heating rate was increased from 1 °C/min to 20 °C/min, and the sample heated at 10 °C/min was brownish-red. The heating rate has a significant effect on the colour of glass-ceramics with the same CuO content, providing a new approach for regulating the colour of glass-ceramics. Further, this study has significant prospects in enriching the colour of glass-ceramics for architectural decoration and reducing production costs.

Investigation of entropy generation and thermohydraulic characteristics of Al2O3–CuO hybrid nanofluid flow in a pipe at different inlet fluid temperatures

This work investigates the thermohydraulic behavior and the rate of thermodynamic irreversibility of water-based Al2O3 and Al2O3 + CuO hybrid nanofluid (HNF) in a circular copper tube subjected to a constant heat flux (CHF) of 8625 W/m2. The fluids under discussion flow in a tube at inlet fluid temperatures of 30, 45, and 60 °C. The thermophysical characteristics of the Al2O3 and HNF were studied at various temperatures and concentrations. The Nusselt number (Nu), entropy generation number (EGN), and friction factor were determined for the HNF (0–1 vol%) at different ranges of Reynolds numbers (Re) from 7000 to 44,662. The outcome of the HNF for 1 vol% is compared with that of Al2O3 nanofluid (NF). The findings show that the maximum amplification of Nu is 51, 59, and 79.7% observed for 1 vol% of HNF compared to water at 30, 45, and 60 °C. The pressure drop (Δp) and exergy efficiency (ηexe) of HNF increases with concentration and Re. The friction factor of HNF rises with concentration; however, it reduces at higher Re. Total entropy generation (TEG) of HNF reduces at higher Re and concentration. The thermal performance factor (TPF) of HNF is determined at various inlet fluid temperatures. The highest and lowest TPF of 1.7 and 1.02 were found for 1 and 0.1 vol% of HNF at 60 and 30 °C, respectively. The novel regression equations were developed to estimate the Nu, TEG and friction factor of HNF. Overall, Al2O3 + CuO HNFs can be employed as an alternative fluids thermal system cooling.

Unsteady hybrid nanofluid (Cu-UO2/blood) with chemical reaction and non-linear thermal radiation through convective boundaries: An application to bio-medicine

This study is focused on modeling and simulations of hybrid nanofluid flow. Uranium dioxide UO2 nanoparticles are hybrid with copper Cu, copper oxide CuO and aluminum oxide Al2O3 while considering blood as a base fluid. The blood flow is initially modeled considering magnetic effect, non-linear thermal radiation and chemical reactions along with convective boundaries. Then for finding solution of the obtained highly nonlinear coupled system we propose a methodology in which q-homotopy analysis method is hybrid with Galerkin and least square Optimizers. Residual errors are also computed in this study to confirm the validity of results. Analysis reveals that rate of heat transfer in arteries increases up to 13.52 Percent with an increase in volume fraction of Cu while keeping volume fraction of UO2 fixed to 1% in a base fluid (blood). This observation is in excellent agreement with experimental result. Furthermore, comparative graphical study of Cu,CuO and Al2O3 for increasing volume fraction is also performed keeping UO2 volume fraction fixed. Investigation indicates that Cu has the highest rate of heat transfer in blood when compared with CuO and Al2O3. It is also observed that thermal radiation increases the heat transfer rate in the current study. Furthermore, chemical reaction decreases rate of mass transfer in hybrid blood nanoflow. This study will help medical practitioners to minimize the adverse effects of UO2 by introducing hybrid nano particles in blood based fluids.

Methanol steam reforming over highly efficient CuO–Al2O3 nanocatalysts synthesized by the solid-state mechanochemical method

Methanol steam reforming over highly efficient CuO–Al2O3 nanocatalysts synthesized by the solid-state mechanochemical method

Numerical analysis of magneto-radiated annular fin natural-convective heat transfer performance using advanced ternary nanofluid considering shape factors with heating source

ApplicationsThe fins performance under natural convection is essential to make it more functional for large scale applications more specifically in thermal engineering. For this, it is important to introduce new techniques to enhance the fins performance instead of traditional way. Thus, this study introduces a new way to make the fin more efficient using ternary nanomaterial under nanoparticles shape factor. The annular fin significantly contributes in electronics to exhaust the hot air, injector pumps and applied thermal engineering. Purposeand Methodology: This work focuses on the fin energy model using shape factors. Therefore, the ternary nanofluid, natural convection, thermal radiation and magnetic field used to develop the model. Then, the RKF-45 implemented to investigate physical results. Core findingsKeen analysis of the physical results reveal that the coefficient of thermal conductivity ranging from 0.0% < α1 < 3.0% and natural convection have major role in the fins energy performance. Induction of magnetic field and thermal radiation Rd are reliable for the fin cooling and, heating source Q1 = 0.2,0.4,0.6,0.8 promote the fin energy capability in the existence of (Al2O3–CuO–Cu) ternary nanomaterial with concentration factor up to 2%. On the comparative basis, ternary nanomaterial makes the fin more efficient than hybrid nanomaterial.

Effect of PbO on the elastic and radiation shielding properties of B2O3–Bi2O3–Al2O3–CuO glasses

Investigations of quinary B2O3–Bi2O3–Al2O3–CuO–PbO glasses have been accomplished. The density and the ultrasonic velocities variations were exploited to establish the elastic parameters of the glasses. In addition, a correlation between the ultrasonic parameters and the structural modifications characterized by the FTIR spectra to clarify the function of PbO was achieved. The FTIR spectra suggest that PbO is possibly implanted into the aluminum-borobismuthate network forming [PbO6] units, while Bi2O3 and Al2O3 affect the network with [BiO6] and [AlO6] structural units. Furthermore, the changes of the structure and the elastic moduli were understood based on the vibrations of lead, aluminates, bismuthate, and borate structural units on one side and the substitution of high-bond strength B2O3 via low-bond strength PbO. The results of γ-ray attenuation-coefficients indicate that the values of the mass attenuation coefficient (μm), effective atomic number (Zeff), and electron density (Ne) of the prepared samples increase as a function of PbO content. Additionally, the half-value layer (HVL) and the mean free path (MFP) decrease with increasing PbO content. The glass sample 60.5B2O3–20Bi2O3–7Al2O3–0.5CuO–12PbO (mol%) exhibits the highest values of μm (0.15521 at 356 keV), Zeff (26.67 at 356 keV), and Nel (3.24 at 356 keV) and the lowest elastic moduli (Young’s modulus 80.7 GPa and bulk modulus 48.6 GPa).

Investigation of heated fins geometries on the heat transfer of a channel filled by hybrid nanofluids under the electric field

In this study, Galerkin Finite Element Method or GFEM is used for modeling the heat transfer in a channel filled by hybrid nanofluids under the electric field. Three voltages of 1, 3 and 5V are supplied to the inlet boundary condition and four types of hybrid nanofluid were used (TiO2–CuO, TiO2–Al2O3, Al2O3–CuO and Al2O3–Cu) to improve the average Nusselt number. 11 different cases also were proposed to examine the effect of fins geometries on the heat transfer by Central composite design (CCD). Number of fins (4–8), length of fins (10–20 cm) and thickness of fins (2–4 cm) are the considered variables and levels. Results indicated that TiO2–Al2O3 with ϕ=0.05 had the greatest Nusselt number among the other experienced cases. Also, increasing the nanoparticles concentrations by 0.01 could improve the Nusselt number up to 5.19%. Furthermore, Results showed that increasing the supplied voltage for electric field from 1V to 5V can improve the heat transfer process in the channel.

Thermal Properties of Glass and Melts of the CaO–B2O3–Al2O3–CuO System

Thermal Properties of Glass and Melts of the CaO–B2O3–Al2O3–CuO System

Impact of hybrid nanoparticles on transport mechanism in magnetohydrodynamic fluid flow exposed to induced magnetic field

The study of the laminar, boundary layer, MHD (CuO–Al2O3) hybrid nanofluid flow and heat transfer driven by mixed convection adjacent to a vertical porous plate in the existence of magnetic induction is accounted for. Nonlinear thermal radiations are modeled in order to examine their impacts on energy transport. The influences of conduction-radiation along with magnetic Prandtl number are examined. System of equations that governs the model is simplified using a boundary layer approach along with pertinent dimensionless variables which are further analyzed numerically through a very efficient finite element method. The suitable ambient position is determined through numerical experiments. The convergence is ensured and mesh free analysis is done. Numerical solutions are exposed graphically against assorted parameters for nanofluid as well as hybrid nanofluid and are compared to examine heat transfer characteristics. The induced magnetic field has shown a decreasing behavior when Hartmann and magnetic Reynolds numbers increased.

The Creation of Multicomponent Octahedral Crystals with Spinel Structure Using Solid-Phase Synthesis in the Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-BaO-CuO-Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-Mn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-NiO-SrO-TiO&lt;sub&gt;2&lt;/sub&gt;- ZnO and Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-BaO-CuO-Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-NiO-SrO-TiO&lt;sub&gt;2&lt;/sub&gt;-WO&lt;sub&gt;3&lt;/sub&gt;- ZnO Systems

This paper presents the results of an experimental study of the possibility of high-entropy oxide phases creation using the of solid-phase synthesis method in the Al2O3–BaO–CuO–Fe2O3–Mn2O3–NiO–SrO–TiO2–ZnO and Al2O3–BaO–CuO–Fe2O3–NiO–SrO–TiO2–WO3–ZnO systems. As a result of the study, a microcrystalline octahedral multicomponent phase was found in the crystallized sample. Judging by the composition, this phase has a spinel structure and is characterized (judging by the components concentrations and its ratio) by rather high values of the mixing configurational entropy. It is shown that barium, strontium and tungsten are not included in this phase in appreciable amounts. The obtained results indicate the possibility of synthesizing high-entropic spinels using these Al2O3–CuO–Fe2O3–Mn2O3–NiO–TiO2–ZnO systems.

Magnetic field effects on forced convection flow of a hybrid nanofluid in a cylinder filled with porous media: a numerical study

The magnetic field can serve as a proper controlling parameter for heat transfer and fluid flow; it can be also employed to maximize the thermodynamic efficiency in various fields. Nanofluids and porous inserts are among the conventional approaches of heat transfer enhancements. Porous media, in addition to improving the heat transfer, can enhance the pressure drop. This research presents a numerical investigation on the magnetohydrodynamics forced convection effects of Al2O3–CuO–water nanofluid inside a partitioned cylinder within a porous medium. The calculations were carried out for a broad range of governing parameters. The nanofluid flow is modeled as a two-phase flow using two-phase mixture model, and the Darcy–Brinkman–Forchheimer equation is employed to model fluid flow in porous media. Simulation was also conducted under the laminar flow regime by finite volume method. Furthermore, the thermal boundary condition of constant uniform heat flux was imposed on the cylinder walls. The average Nusselt number as well as the performance evaluation criteria (PEC) were examined for diverse Darcy numbers (0.0001 < Da < 0.1) and Hartmann numbers (0 < Ha < 40). The results indicate the significant impact of Hartmann and Darcy number enhancement on the elevation of heat transfer coefficient. Additionally, incorporation of nanoparticles to the base fluid increased the PEC in all cases. Moreover, the PEC reached to its maximum value in configurations involving permeable porous media (i.e., a medium with Da = 0.1 and Ha = 40).

Properties of -O-Cu-O- Bridged Copper Phosphate-Based Thermal Insulation Materials.

P–O–H polycondensation −O–Cu–O– ion-bonded bridges were formed in copper phosphate thermal insulation materials by mixing Al(OH)3 dissolved in H3PO4 with CuO filler and Al2O3, SiC, ZrC, and Cr2O3 as curing accelerators, alone or in combination. The effects of different additive combinations on the curing behavior and thermal stability of the copper phosphate thermal insulation material matrixes were compared using thermogravimetry/differential scanning calorimetry, X-ray diffractometry, and scanning electron microscopy. The copper phosphate materials exhibit good thermal stabilities and low thermal conductivities. The thermal weight losses before and after ceramic reinforcement were 4–19.8 and 3.8–9.4%, respectively, and the thermal conductivities of the P–O–H polycondensation −O–Cu–O– ion-bonded bridges formed in the copper phosphate thermal insulation materials were in the range of 0.656–1.824 W/(m·K).

Synthesis and characterization of Al2O3 and CuO nanoparticles into nanofluids for solar panel applications

Nanofluids are the new class of fluids with the suspension of nanomaterials which have the average particle size below 100 nm. The nanometer-sized materials are nanoparticles, nanofibers, nanotubes, nanowires, nanorods, nanosheet or droplets. In this research work, oxide ceramics of CuO and Al2O3 are synthesized successfully by two-step combustion route while using glycine as an organic fuel followed by heat treatment. The obtained nanoparticles are characterized by powder X-ray diffractometer. It confirms the formation of CuO and Al2O3 with the phase pure of monoclinic and rhombohedral respectively. Morphological studies carried out by Scanning electron microscopy which shows spherical shape nanoparticles of CuO and leaf-shaped Al2O3 in particles with submicron range. The importance in the choice of coolant materials with base fluids for solar panel applications is briefly discussed by plotting I-V and P-V spectrum. As a result, the cooling efficiency of both CuO and Al2O3 are found as 18.2%, which is higher than the conventional one. The obtained efficiency value has been also compared with the reported data. This shows that CuO and Al2O3 will be a promising candidate with a base fluid of water for solar panel applications.

Augmentation of ferromagnetism in CuO–Al2O3 nanocomposite synthesized via solution combustion method

The finite size effect of CuO nanoparticles and their effect on the magnetic behavior of a CuO–Al2O3 nanocomposite synthesized via a solution combustion method are discussed here. It is observed that the introduction of CuO nanoparticles of ∼20 nm in size on the surfaces of Al2O3 nanosheets strongly influences the magnetic moment of the nanocomposite. The X-ray diffraction pattern reveals the presence of a CuO phase in the CuO–Al2O3 nanocomposite. Electron microscopy imaging shows the presence of CuO nanoparticles distributed over the surfaces of Al2O3 nanosheets. Magnetic measurements performed at 5 and 300 K revealed a strong enhancement in the saturation magnetization of the CuO–Al2O3 nanocomposite at both temperatures. This increase is due to the formation of CuO nanoparticles on the surfaces of the Al2O3 nanosheets. These CuO nanoparticles show a ferromagnetic nature due to the uncompensated surface Cu2+ spins of the copper ions. The presence of the Cu2+ state in the CuO nanoparticles in the CuO–Al2O3 nanocomposite was confirmed by X-ray photoelectron spectroscopy (XPS) measurements.

Hydrothermal performance of different alumina hybrid nanofluid types in plate heat exchanger

To enhance the energetic and exergetic performances of the counter-flow plate heat exchanger with corrugations, several experiments were conducted using different Al2O3 hybrid nanofluids as a coolant. The combinations studied were Al2O3–SiC, Al2O3–AlN, Al2O3–MgO, Al2O3–CuO and Al2O3–MWCNT in 4:1 nanoparticle volume ratio and 100% Al2O3 with 0.1 vol% concentration suspended in DI water. Parameters which were varied are the coolant flow rate ranging from 2.0 to 4.0 lpm and coolant inlet temperature from 10 to 25 °C. Effect of coolant flow rates and inlet temperatures on different parameters like heat transfer coefficient ratio, heat transfer coefficient to pressure drop ratio, pump work, performance index and irreversibility has been investigated. A maximum enhancement of around 31.2% has been observed in the heat transfer coefficient for Al2O3–MWCNT (4:1) hybrid nanofluid with the negligible enhancement of 0.08% in the pump work and 12.46% enhancement in the performance index. The maximum enhancement in the irreversibility is around 1.6% for Al2O3–CuO (4:1) hybrid nanofluid. Among the studied nanoparticle combinations, Al2O3–MWCNT (4:1) gives better performance. This study suggests that Al2O3–MWCNT hybrid nanofluid can be a good alternative to enhance thermal performance.

Antagonistic Effects of Sublethal Concentrations of Certain Mixtures of Metal Oxide Nanoparticles and the Bulk (Al2O3, CuO, and SiO2) on Gill Histology inClarias gariepinus

Background. The effect of nanoparticles (NPs) on aquatic environments is poorly studied.Aim. This study evaluates the toxicity of joint effects of these different metal nanoparticles and their bulk in mixtures (Al2O3, CuO, and SiO2) on fish using histological biomarker.Materials and Methods. The bulk and nano sizes of three salts (Al2O3, CuO, and SiO2) were used. Nanosizes ranged from 25 nm to 100 nm. The juvenile fishes ofClarias gariepinus(mean Length: 12.3 ± 3.5 cm; mean weight: 18.52 ± 6.41 g) were used for the acute and chronic toxicity tests. They were exposed to 7 mg/L each of the bulk and nano sizes of the three metallic oxides either singly or in mixtures for 28 days. The basis for the sublethal concentration was that the 96 hr acute toxicity of the varied sizes of the three metallic oxides was nontoxic up to the concentrations of 100 mg/L with no significant mortality at the highest exposure concentrations. The gills were collected for histopathology.Results. Of the three metal oxide nanoparticles, SiO was the most toxic, with histopathological alteration index (HAI) of 20.0, followed by nano-CuO (HAI, 10.0) and nano-Al2O3(HAI, 2.0). In single exposure, the gill alterations include high frequencies of erosion of gill lamella (EGL), hypertrophy (HPT), oedema (OD), and necrosis (N). Less damage was observed at the combination of the metal oxide nanoparticles of SiO + Al2O3,SiO + CuO and SiO + Al2O3 + CuO in equal (1 : 1—HAI, 2 and 6; 1 : 1 : 1—HAI, 6) and unequal ratios (1 : 2—HAI, 16 and 6; 2 : 1—HAI, 8 and 6). Similarly, all bulk combinations were also antagonistic except for the equal ratio of bulk CuO (HAI, 20) and bulk Al2O3(HAI, 10) that gave additive effect with HAI of 32.Conclusion. The joint actions of nano Al2O3and CuO with SiO produced a low toxic effect, unlike the high toxicity of their single trials; this also indicates that nano Al2O3and CuO are antagonists. Similarly, among the bulk metal oxides (SiO, Al2O3, and CuO), CuO was the most toxic. Bulk SiO and Al2O3are antagonistic on the effects of CuO on the fish gill. There is need to properly document the ecological implications of nanoparticles in the aquatic environment.

Conventional fluid- and nanofluid-based photovoltaic thermal (PV/T) systems: a techno-economic and environmental analysis

ABSTRACTIn this study, the techno-economic impacts of nanofluids used as coolants to enhance the overall performance of a photovoltaic/thermal PV/T system, in comparison with conventional fluids, are discussed. A transient mathematical analysis was performed to evaluate the technical aspects and energy performance of the PV/T system. The proposed model is used to predict the annual thermal and electrical power outputs of a PV/T system based on CuO nanofluid, Al2O3 nanofluid, and conventional fluids. Economic and environmental analyses of the PV/T systems were performed by taking into account energy payback period, energy production factor, net CO2 mitigation, and net CO2 credit. Because of their greater energy unit area and levelized energy cost, nanofluid based PV/T systems have a lower payback period and better economic savings than those of conventional collectors. Using water, Al2O3 nanofluid, and CuO nanofluid, the net CO2 mitigation and net CO2 credit are 6.4 tons and 156.8 USD, 6.9 tons and 171.2 USD, and 7.4 tons and 181.6 USD, respectively, for 30 years life of the PV/T system. For typical industrial applications, PV/T systems with nanofluids should be considered as competitors to water-based PV/T collectors.

Effects of alkali promoters on the textural and catalytic properties of mesoporous Fe–Al–Cu catalysts for water gas shift reaction

ABSTRACTMesoporous Fe2O3–Al2O3–CuO catalysts promoted with alkali oxides were synthesized and used in water gas shift reaction (WGSR) at high temperatures for hydrogen purification. These chromium-free catalysts were characterized using nitrogen adsorption/desorption, hydrogen temperature programmed reduction, X-ray diffraction (XRD), and transmission electron microscopy techniques. The synthesized catalysts with narrow single-modal pore size distribution in mesopore region possessed high specific surface area. The catalytic results revealed that except Cs, the addition of other alkali promoters declined the catalytic activity. However, all catalysts showed higher catalytic performance than the conventional commercial catalyst. The results showed an optimum content of Cs promoter (3 wt.%) for the promoted Fe–Al–Cu catalyst (3 wt.% Cs-FAC), which exhibited the highest activity in WGSR at high temperature.