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Benchmark assessment of performance indices of a selection of hybrid nanofluids in a hybrid photovoltaic/thermal system

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Clean Energy 2022年第2期6卷 247-270页

作者： O.M.Amoo R.O.Fagbenle M.O.Oyewola Department of Mechanical Engineering University of IbadanIbadanOyo StateNigeria School of Mechanical Engineering Fiji National UniversityFiji

This research is a study assessing the performance of hybrid nanofluids in hybrid photovoltaic(PV)-thermal systems.This study addresses 10 hybrid nanofluids applied to hybrid PV-thermal systems.The transition to carbon-free energy can mitigate the worst effects of climate change,ensuring that global sustainability is addressed.Clean energy is now responsible for one-third of the global capacity,of which 20%is attributed to solar energy.Renewables continue to be economically viable,with declining costs driving growth.This study aims to compare the yearly performances of a model hybrid PV-thermal system using 10 different hybrid nanofluids.hybrid nanofluids constitute two or more dissimilar materials stably suspended in a base fluid(e.***.water).MATLAB and COMSOL Multiphysics®computational fluid dynamics software are employed together for the benchmarking assessment with good agreement observed.Various fluid inlet temperatures(Tin∈[300,360]K),nanofluid volume concentrations(φ∈[0,4]%)and storage-tank volumes(V∈[50,300]L)were simulated.The meteorological data applied were those for Lagos,Nigeria(6°27’55.5192”N,3°24’23.2128”E).The assessment based on analytical-numerical solutions reveals that the thermal enhancement by hybrid nanofluids ranges from 6.7%(graphene oxide[GO]-multiwalled carbon nanotube[MWCNT]/water)to 7%(ZnO-Mn-ZnFe2O4/water)forφ=2%and V=300 L.The yearly exergy efficiency ranges from 2.8%(ZnO-Mn-ZnFe2O4/water)to 2.9%(GO-MWCNT/water),also forφ=2%and V=300 L.These findings have implications for a vast range of industrial processes,expanding the knowledge that is critical to a sustainable future.

关键词： energy transformation hybrid photovoltaic-thermal(PV/T)system hybrid nanofluids COMSOL Multiphysics® MATLAB enhancements

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Efficiency enhancement of building multi-layer solar collector with SiO2–TiO2 hybrid nanofluids

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Building Simulation 2023年第10期16卷 1851-1862页

作者： N.N.M.Zawawi W.H.Azmi Z.A.A.Majid R.A.Rahim H.M.Ali Lebuhraya Tun Razak Centre for Research in Advanced Fluid and Processes26300GambangKuantanPahangMalaysia Faculty of Mechanical and Automotive Engineering Technology Universiti Malaysia PahangPekanPahang26600Malaysia Kulliyyah of Allied Health Sciences International Islamic University of MalaysiaBandar Indera Mahkota25200KuantanPahangMalaysia ECE Department Kulliyyah of EngineeringInternational Islamic University MalaysiaJalan GombakKuala LumpurMalaysia Mechanical Engineering Department King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia

Due to the depletion of conventional energy sources and its limitless resources,solar energy is currently being considered as a viable alternative,especially for water heating systems.The thermal performance of multilayer solar collectors for water heating systems can be improved further by introducing hybrid nanofluids as advanced fluids.This study demonstrates the utilisation of hybrid nanofluids in heating systems by employing a multilayer absorber solar collector.The SiO2–TiO2 hybrid nanofluids at volume concentrations up to 2.0%were tested at various flow rates(1.7 to 3.7 LPM)and solar radiation intensities(250 to 1000 W/m2).The thermal performance of the solar collector was assessed by measuring the temperature variation,heat loss,and overall efficiency of the collector.At the optimal volume concentration,the temperature difference for solar collectors employing SiO2–TiO2 hybrid nanofluids increased significantly.The optimal volume concentration of 1.5%yields a maximum temperature difference of 9.5°C.In addition,the efficiency and fluid temperature of the solar collector containing hybrid nanofluids have been enhanced by 22%and 37%,respectively.The SiO2–TiO2 hybrid nanofluids with the optimal volume concentration of 1.5%were therefore recommended for maximum efficiency in the solar collector.

关键词： solar collector hybrid nanofluids solar water heating system solar simulator thermal efficiency

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Experimental Performance Evaluation and Artificial-Neural-Network Modeling of ZnO-CuO/EG-W hybrid nanofluids

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Fluid Dynamics & Materials Processing 2022年第3期18卷 629-646页

作者： Yuling Zhai Long Li Zihao Xuan Mingyan Ma Hua Wang Engineering Research Center of Metallurgical Energy Conversion and Emission Reduction Ministry of EducationKunming University of Science and TechnologyYunnan650093China

The thermo-physical properties of nanofluids are highly dependent on the used base fluid.This study explores the influence of the mixing ratio on the thermal conductivity and viscosity of ZnO-CuO/EG(ethylene glycol)-W(water)hybrid nanofluids with mass concentration and temperatures in the ranges 1-5 wt.%and 25-60C,respectively.The characteristics and stability of these mixtures were estimated by TEM(transmission electron microscopy),visual observation,and absorbance tests.The results show that 120 min of sonication and the addition of PVP(polyvinyl pyrrolidone)surfactant can prevent sedimentation for a period reaching up to 20 days.The increase of EG(ethylene glycol)in the base fluid leads to low thermal conductivity and high viscosity.Thermal conductivity enhancement(TCE)decreases from 21.52%to 11.7%when EG:W is changed from 20:80 to 80:20 at 1 wt.%and 60C.A lower viscosity of the base fluid influences more significantly the TCE of the nanofluid.An Artificial Neural Network(ANN)has also been used to describe the effectiveness of these hybrid nanofluids as heat transfer fluids.The optimal number of layers and neurons in these models have been found to be 1 and 5 for viscosity,and 1 and 7 for thermal conductivity.The corresponding coefficient of determination(R^(2))was 0.9979 and 0.9989,respectively.

关键词： hybrid nanofluids base fluid ratio viscosity thermal conductivity ANN model

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Thermally stratified flow of hybrid nanofluids with radiative heat transport and slip mechanism: multiple solutions

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Communications in Theoretical Physics 2022年第1期74卷 142-151页

作者： Rai Sajjad Saif Hashim Maria Zaman Muhammad Ayaz Department of Humanities and Sciences School of Electrical Engineering and Computer Science(SEECS)National University of Sciences and Technology(NUST)IslamabadPakistan Department of Pure&Applied Mathematics University of Haripur22620HaripurPakistan Department of Mathematics&Statistics Riphah International University IslamabadPakistan Department of Mathematics Abdul Wali Khan UniversityMardan23200Pakistan

Research on flow and heat transfer of hybrid nanofluids has gained great significance due to their efficient heat transfer capabilities.In fact,hybrid nanofluids are a novel type of fluid designed to enhance heat transfer rate and have a wide range of engineering and industrial applications.Motivated by this evolution,a theoretical analysis is performed to explore the flow and heat transport characteristics of Cu/Al_(2)O_(3) hybrid nanofluids driven by a stretching/shrinking geometry.Further,this work focuses on the physical impacts of thermal stratification as well as thermal radiation during hybrid nanofluid flow in the presence of a velocity slip mechanism.The mathematical modelling incorporates the basic conservation laws and Boussinesq approximations.This formulation gives a system of governing partial differential equations which are later reduced into ordinary differential equations via dimensionless variables.An efficient numerical solver,known as bvp4c in MATLAB,is utilized to acquire multiple(upper and lower)numerical solutions in the case of shrinking flow.The computed results are presented in the form of flow and temperature fields.The most significant findings acquired from the current study suggest that multiple solutions exist only in the case of a shrinking surface until a critical/turning point.Moreover,solutions are unavailable beyond this turning point,indicating flow separation.It is found that the fluid temperature has been impressively enhanced by a higher nanoparticle volume fraction for both solutions.On the other hand,the outcomes disclose that the wall shear stress is reduced with higher magnetic field in the case of the second solution.The simulation outcomes are in excellent agreement with earlier research,with a relative error of less than 1%.

关键词： multiple numerical solutions hybrid nanofluids thermal radiation thermal stratification slip conditions heat transfer

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