Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely us...Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).展开更多
Electrical and electronic devices face significant challenges in heatmanagement due to their compact size and high heat flux,which negatively impact performance and reliability.Conventional coolingmethods,such as forc...Electrical and electronic devices face significant challenges in heatmanagement due to their compact size and high heat flux,which negatively impact performance and reliability.Conventional coolingmethods,such as forced air cooling,often struggle to transfer heat efficiently.In contrast,thermoelectric coolers(TECs)provide an innovative active cooling solution to meet growing thermal management demands.In this research,a refrigerant based on mono ethylene glycol and distilled water was used instead of using gases,in addition to using thermoelectric cooling units instead of using a compressor in traditional refrigeration systems.This study evaluates the performance of a Peltierbased thermalmanagement systemby analyzing the effects of using two,three,and four Peltiermodules on cooling rates,power consumption,temperature reduction,and system efficiency.Experimental results indicate that increasing the number of Peltier modules significantly enhances cooling performance.The four-module system achieved an optimal balance between cooling speed and energy efficiency,reducing the temperature of a liquidmixture(30% mono ethylene glycol+70% distilled water plus laser dyes)to 8℃ in just 17 min.It demonstrated a cooling rate of 0.794℃/min and a high coefficient of performance(COP)of 1.2 while consuming less energy than the two-and three-module systems.Furthermore,the study revealed that increasing the number of modules led to faster air cooling and improved temperature reduction.These findings highlight the importance of selecting the optimal number of Peltier modules to enhance efficiency and cooling speed whileminimizing energy consumption.This makes TEC technology a sustainable and effective solution for applications requiring rapid and reliable thermal management.展开更多
Oxygen evolution reaction(OER)is a critical process in electrocatalytic water splitting.However,the development of low-cost,highly efficient OER electrocatalysts by a simple method that can be used for industrial appl...Oxygen evolution reaction(OER)is a critical process in electrocatalytic water splitting.However,the development of low-cost,highly efficient OER electrocatalysts by a simple method that can be used for industrial application on a large scale is still a huge challenge.Recently,high entropy alloy(HEA)has acquired extensive attention,which may provide answers to the current dilemma.Here,we report bulk Fe_(50)Mn_(30)Co_(10)Cr_(10),which is prepared by 3D printing on a large scale,as electrocatalyst for OER with high catalytic performance.Especially,an easy approach,corrosion engineering,is adopted for the first time to build an active layer of honeycomb nanostructures on its surface,leading to ultrahigh OER performance with an overpotential of 247 mV to achieve a current density of 10 mA cm^(-2),a low Tafel slope of 63 mV dec^(-1),and excellent stability up to 60 h at 100 mA cm^(-2)in 1 M KOH.The excellent catalytic activity mainly originates from:(1)the binder-free self-supported honeycomb nanostructures and multi-component hydroxides,which improve intrinsic catalytic activity,provide rich active sites,and reduce interfacial resistance;and(2)the diverse valence states for multiple active sites to enhance the OER kinetics.Our findings show that corrosion engineering is a novel strategy to improve the bulk HEA catalytic performance.We expect that this work would open up a new avenue to fabricate large-scale HEA electrocatalysts by 3D printing and corrosion engineering for industrial applications.展开更多
The reliability of electromechanical product is usually determined by the fault number and working time traditionally. The shortcoming of this method is that the product must be in service. To design and enhance the r...The reliability of electromechanical product is usually determined by the fault number and working time traditionally. The shortcoming of this method is that the product must be in service. To design and enhance the reliability of the electromechanical product, the reliability evaluation method must be feasible and correct. Reliability evaluation method and algorithm were proposed. The reliability of product can be calculated by the reliability of subsystems which can be gained by experiment or historical data. The reliability of the machining center was evaluated by the method and algorithm as one example. The calculation result shows that the solution accuracy of mean time between failures is 97.4% calculated by the method proposed in this article compared by the traditional method. The method and algorithm can be used to evaluate the reliability of electromechanical product before it is in service.展开更多
Introducing vacancy defects and unique morphology is an effective strategy to improve the catalytic performance of transition metal compounds.However,precisely controlling the amount of vacancy defects remains challen...Introducing vacancy defects and unique morphology is an effective strategy to improve the catalytic performance of transition metal compounds.However,precisely controlling the amount of vacancy defects remains challenging.Here,we propose a facile and efficient hydrothermal accompanying an annealing method to synthesize a series of Mn-doped CoO nanomaterials with controllable oxygen vacancies and unique morphology.The oxygen vacancies amount can be precisely controlled by adjusting the Mndoping content and is positively correlated with catalytic performance.It was found that the oxygen vacancies amount can reach up to 38.2%over the Mn-doped CoO nanomaterials,resulting in ultra-high hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalytic activity(HER:25.6 and 37 m V at 10 m A cm^(-2);OER:301 and 322 m V at 50 m A cm^(-2))under both basic and acidic conditions,while reaching 10 m A cm^(-2) for an ultra-low cell voltage of only 1.52 V,which exceeds that of Pt/C/RuO_(2) and all reported non-noble metal oxide catalysts.The DFT calculations reveal oxygen vacancies can optimize H*and HOO*intermediates adsorption free energy,thus improving the HER and OER performance.Interestingly,the Mn-doped CoO with rich oxygen vacancies exhibits excellent antibacterial properties in vitro of biomedicine.This work provides new ideas and methods for the rational design and precise control of vacancy defects in transition metal compounds and explores their potential application value in electrochemical water splitting and biomedical fields.展开更多
Needles,as some of the most widely used medical devices,have been effectively applied in human disease prevention,diagnosis,treatment,and rehabilitation.Thin 1D needle can easily penetrate cells/organs by generating h...Needles,as some of the most widely used medical devices,have been effectively applied in human disease prevention,diagnosis,treatment,and rehabilitation.Thin 1D needle can easily penetrate cells/organs by generating highly localized stress with their sharp tips to achieve bioliquid sampling,biosensing,drug delivery,surgery,and other such applications.In this review,we provide an overview of multiscale needle fabrication techniques and their biomedical applications.Needles are classified as nanoneedles,microneedles and millineedles based on the needle diameter,and their fabrication techniques are highlighted.Nanoneedles bridge the inside and outside of cells,achieving intracellular electrical recording,biochemical sensing,and drug delivery.Microneedles penetrate the stratum corneum layer to detect biomarkers/bioelectricity in interstitial fluid and deliver drugs through the skin into the human circulatory system.Millineedles,including puncture,syringe,acupuncture and suture needles,are presented.Finally,conclusions and future perspectives for next-generation nano/micro/milli needles are discussed.展开更多
Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed,...Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed, developed and made applicable. This paper introduces a three dimensional opt ical measurement method based on digital fringe projection technique in RE to im prove the technique through its application. A practical example is presented an d the result demonstrates the applicability and feasibility of the measurement s ystem as well as the reliability and validity of relevant methods and algorithms .展开更多
Electronic engineering of gallium nitride(Ga N) is critical for enhancement of its electrode performance.In this work, copper(Cu) cation substituted Ga N(Cu-Ga N) nanowires were fabricated to understand the electronic...Electronic engineering of gallium nitride(Ga N) is critical for enhancement of its electrode performance.In this work, copper(Cu) cation substituted Ga N(Cu-Ga N) nanowires were fabricated to understand the electronically engineered electrochemical performance for Li ion storage. Cu cation substitution was revealed at atomic level by combination of X-ray photoelectron spectroscopy(XPS), X-ray absorption fine structure(XAFS), density functional theory(DFT) simulation, and so forth. The Cu-Ga N electrode delivered high capacity of 813.2 m A h g^(-1) at 0.1 A g^(-1) after 200 cycles, increased by 66% relative to the unsubstituted Ga N electrode. After 2000 cycles at 10 A g^(-1),the reversible capacity was still maintained at326.7 m A h g^(-1). The DFT calculations revealed that Cu substitution introduced the impurity electronic states and efficient interatomic electron migration, which can enhance the charge transfer efficiency and reduce the Li ion adsorption energy on the Cu-Ga N electrode. The ex-situ SEM, TEM, HRTEM, and SAED analyses demonstrated the reversible intercalation Li ion storage mechanism and good structural stability. The concept of atomic-arrangement-assisted electronic engineering strategy is anticipated to open up opportunities for advanced energy storage applications.展开更多
Based on the programming method, an electromechanical coupling adaptive statically indeterminate truss structure is controlled for increasing its load capacity. Several main parameters during the process of design of ...Based on the programming method, an electromechanical coupling adaptive statically indeterminate truss structure is controlled for increasing its load capacity. Several main parameters during the process of design of the adaptive structure are selected for a study of its characteristic during the control stage. The curves of each parameter for the effect of control results are plotted and corresponding conclusions are drawn. Thus, the theoretical basis is presented for optimal design, manufacture and control of the adaptive structure.展开更多
The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni...The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni_(3)Se_(2)lamellas by pre-lithiation technique,which can be acted as a novel class of battery-type cathode for hybrid supercapacitors.Appropriately modulating the contents of the preembedded lithium(Li) ions can induce a controllable vacancy content in the series of as-prepared products,effectively endowing a fast reaction kinetic and high activity for the cathode.Benefiting from the distinct design,the optimized cathode(Li2-Ni_(3)Se_(2)) presents a high specific capacity of 236 mA h g^(-1)at1 A g^(-1),importantly,it can still possess 117 mA h g^(-1)when the current density is increased up to 100A g^(-1),exhibiting relatively high rate capability.It is much superior to other battery-type TMC cathodes reported in previous studies.Moreover,the cathode also shows the excellent cycling stability with 92%capacity retention after 3,000 cycles.In addition,a hybrid supercapacitor(HSC) is assembled with the obtained Li2-Ni_(3)Se_(2)as the cathode and active carbon(AC) as the anode,which delivers a high energy density of 77 W h kg^(-1)at 4 kW kg^(-1)and long-term durability(90% capacitance retention after 10,000 cycles).Therefore,the strategy not only provides an effective way to realize the controllable vacancy content in TMCs for achieving high-perfo rmance cathodes for HSC,but also further promotes their large-scale applications in the energy storage fields.展开更多
The development of highly active,stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great challenge.Herein,S vacancies-rich Ni_(3)S_(2)@Cu_(2)S nan-otube he...The development of highly active,stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great challenge.Herein,S vacancies-rich Ni_(3)S_(2)@Cu_(2)S nan-otube heterojunction arrays were in-situ grown on copper foam(V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF)for efficient electrocatalytic overall water splitting.With the merits of nanotube arrays and efficient electronic mod-ulation drived by the OD vacancy defect and 2D heterojunction defect,the resultant V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF electrocatalyst exhibits excellent electrocatalytic activity with a low overpotential of 47 mV for the hydrogen evolution reaction(HER)at 10 mA cm^(-2) current density,and 263 mV for the oxygen evolution reaction(OER)at 50 mA cm^(-2) current density,as well as a cell voltage of 1.48 V at 10 mA cm^(-2).Moreover,the nanotube heterojunction arrays endows V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF with outstanding stability in long-term catalytic processes,as confirmed by the continuous chronopotentiom-etry tests at current densities of 10 mA cm^(-2) for 100 h.展开更多
The design and construction of an experimental solar hybrid vehicle based on the combination of photovoltaic solar energy as the main source of electricity and electric power supplied by a generator activated by the d...The design and construction of an experimental solar hybrid vehicle based on the combination of photovoltaic solar energy as the main source of electricity and electric power supplied by a generator activated by the driver＇s pedaling is introduced. The vehicle has a battery to store the energy provided by both systems. The development was motivated by a Latin American solar car race through the Atacama Desert in Chile and the initiative to promote the use of clean energy for transport. A general description of the vehicle, its energetic aspects and experimental results are presented.展开更多
In the process of mechanical and electrical equipment installation quality will directly affect the mechanical and electrical equipment operation quality and efficiency in the late, so the staff in the process of inst...In the process of mechanical and electrical equipment installation quality will directly affect the mechanical and electrical equipment operation quality and efficiency in the late, so the staff in the process of installation of electromechanical equipment need pay attention to some possible concerns, adopt scientific and effective way to as much as possible to reduce or avoid these hazards, so as to guarantee the quality in the process of mechanical and electrical equipment installation, which improves the efficiency and safety of mechanical and electrical equipment operation. Based on this, with the author's project, home air-conditioning, commercial air conditioning and core components as the research case, in the process of the project electrical and mechanical equipment installation exist some hidden dangers are analyzed and discussed, and puts forward some scientific and effective solution, in order to reduce the hidden dangers in the process of mechanical and electrical equipment installation, so as to improve installation quality and operation efficiency of equipment.展开更多
With the continuous development of wearable electronics,wireless sensor networks and other micro-electronic devices,there is an increasingly urgent need for miniature,flexible and efficient nanopower generation techno...With the continuous development of wearable electronics,wireless sensor networks and other micro-electronic devices,there is an increasingly urgent need for miniature,flexible and efficient nanopower generation technology.Triboelectric nanogenerator(TENG)technology can convert small mechanical energy into electricity,which is expected to address this problem.As the core component of TENG,the choice of electrode materials significantly affects its performance.Traditional metal electrode materials often suffer from problems such as durability,which limits the further application of TENG.Graphene,as a novel electrode material,shows excellent prospects for application in TENG owing to its unique structure and excellent electrical properties.This review systematically summarizes the recent research progress and application prospects of TENGs based on graphene electrodes.Various precision processing methods of graphene electrodes are introduced,and the applications of graphene electrode-based TENGs in various scenarios as well as the enhancement of graphene electrodes for TENG performance are discussed.In addition,the future development of graphene electrode-based TENGs is also prospectively discussed,aiming to promote the continuous advancement of graphene electrode-based TENGs.展开更多
Thermoelectric air conditioning systems based on the Peltier effect had two modes:heating and cooling.In this work,the proposed design provides continuous improvement in COP from the first minute of operation.In cooli...Thermoelectric air conditioning systems based on the Peltier effect had two modes:heating and cooling.In this work,the proposed design provides continuous improvement in COP from the first minute of operation.In cooling mode,the coefficient of performance(COP)was 1.176 due to the techniques used in this device,and it increased to 1.24 in the last minute of operation.Concerning the steady-state scenario,from the first minute,the Qc was larger than the W for the entire duration of the operation.The output temperature reaches 18.97℃ ,and the temperature on the cold side reaches 4.96℃ in the fifteen minutes of operation.The cooling mood was checked in Iraq/Baghdad in October with a temperature of 31℃ .Furthermore,the heating mode was checked in December with a temperature of 22℃ .Due to the size of the component on the cold side being small compared with the size of the component on the heat side,it reached a steady state in 13 min.This means the COP in heating mode reached 1.01 in 14 min.Furthermore,due to the presence of a thermal insulator made inside the device to separate the cold side and the hot side,the difference in temperature causes a noticeable little ascent.This is why the COP increased because it kept the degree differences low.Performance enhancements were achieved by optimizing the behavior of thermoelectric materials.The device contains 3 Peltier elements,a water-cooled system with one Peltier,a heat sink,and a fan.The design of the dehumidification system addresses the humidity issue commonly associated with thermoelectric air conditioners.In this context,the results indicate that the humidity rates had decreased and the cooling rate had increased with these innovative techniques,and thus,excellent performance can be achieved even if the Seebeck coefficient is not at its highest based on the condition of providing the Peltier elements’reliability and optimal thermal performance for various applications requiring both cooling and heating functions.The insulation plays a critical role in maintaining the efficiency of the system,reducing energy consumption,and ensuring long-term functionality.The proposed system is valuable for devices or environments that demand precise and dual thermal control with minimal energy wastage.展开更多
Aimed at the problem of the low computational efficiency of the existing urethral-valve reliability analysis,an efficient reliability analysis method of the wireless energy-transmitting urethral-valve(WETUV)was propos...Aimed at the problem of the low computational efficiency of the existing urethral-valve reliability analysis,an efficient reliability analysis method of the wireless energy-transmitting urethral-valve(WETUV)was proposed.The method is called FTA-AK-SS,based on the active learning Kriging(AK)model,subset simulation(SS)algorithm,and fault tree analysis(FTA).According to the principle of FTA,we established the fault tree model of the WETUV to determine its minimum cut set and bottom events.Then we defined the random variables affecting its reliability.The U learning function was used to selectively add the sample points of random variables to update the initial Kriging surrogate model.At the same time,combined with the SS algorithm,the reliability and sensitivity analyses of the WETUV were realized.The result shows that compared with the traditional Monte Carlo simulation and FTA-Kriging-SS methods,the proposed method significantly improves the calculation efficiency of the WETUV under the premise of ensuring calculation accuracy.The reliability of the WETUV is greatly affected by the rubber pad’s aging,the receiver coil’s corrosion,and the position deviation.This study can provide a new way to realize a high-efficiency reliability calculation and analysis for urethral valves.展开更多
To optimize the bit selection for large-diameter wellbore in the upper section of an ultra-deep well S-1,a full-well dynamic model integrating drill string vibration and bit rock-breaking was established and then veri...To optimize the bit selection for large-diameter wellbore in the upper section of an ultra-deep well S-1,a full-well dynamic model integrating drill string vibration and bit rock-breaking was established and then verified using measured vibration data of drilling tools and actual rate of penetration(ROP)from Well HT-1 in northern Sichuan Basin.This model was employed to calculate and analyze drill string dynamic characteristics during large-diameter wellbore drilling in the Jurassic Penglaizhen Formation of Well S-1,followed by bit optimization.Research results show that during the drilling in Penglaizhen Formation of Well S-1,considering both the ROP of six candidate bits and the lateral/axial/torsional vibration characteristics of downhole tools,the six-blade dual-row cutter bit with the fastest ROP(average 7.12 m/h)was optimally selected.When using this bit,the downhole tool vibration levels remained at medium-low values.Field data showed over 90%consistency between actual ROP data and dynamic model calculation results after bit placement,demonstrating that the model can be used for bit program screening.展开更多
The comparison of experimental performance was studied for soda cans:longitudinal,transverse,diagonal,and smooth cases to improve the heat transfer rate and thermal performance of the solar air heater,in this study us...The comparison of experimental performance was studied for soda cans:longitudinal,transverse,diagonal,and smooth cases to improve the heat transfer rate and thermal performance of the solar air heater,in this study using a frame which has 1.5 m×0.5 m×0.05 m dimensions,the arrangements were placed on the absorber plate inside the channel,raising the air’s exit temperature as it passed by.The work was carried out for 4 cases in January in Baghdad,Iraq,under specific conditions to compare them to reach the ideal case and the best performance evaluation.When the collector was tilted 350 to the horizontal facing south,The range of mass flow rate was from 0.012 to 0.049 kg/s,and the range of Re was from 2000 to 10,000.The results show that the best Nusselt number in the diagonal AL cans case was increased to 112 at Re=10,000.Then the thermal efficiency increased to 98% accompanied by a moderate decrease in the fraction factor to reach 0.435.Aluminum cans also provide good economic support for solar systems due to their low cost,in addition to their recycling and reducing pollution.展开更多
To improve the heat transfer rate and thermal performance of the solar air heater due to low efficiency,new techniques,such as artificial roughness,barriers,and obstacles,should be used to increase the heat exchange b...To improve the heat transfer rate and thermal performance of the solar air heater due to low efficiency,new techniques,such as artificial roughness,barriers,and obstacles,should be used to increase the heat exchange between the fluid and the absorber.In this research,perforated V-shaped blockages with new geometric shapes,which are circular,hexagonal,square,rectangular,and triangular,were used.They were fixed on the absorber plate inside the channel with dimensions of 1.5 m×0.5 m×0.05 m,which increased the exit temperature of the air passing through the channel.The experimental work consists of six cases that were carried out during November in Baghdad,Iraq,to obtain an optimal result.These cases included using barriers that have holes with different geometric shapes for the barriers inside the solar air heater in addition to the reference case without any barriers.A comparison ismade between the cases under the same conditions and limits to reach the optimal case.The range of mass flow rate was from 0.0098 to 0.049 kg/s,and the range of Re was from 2000 to 10,000.Another goal of the comparison was to maximize Nu and minimize the friction factor.TheNu value improved by 1.77 and the fraction factor by 1.75 for the hexagonal perforated,which had the best performance.As for the triangle perforated,Nu improved by 1.58 and the fraction factor by 3.84,which had the worst performance.The Nu value improved by 1.39,1.22,and 1.4,and the fraction factor improved by 1.967,1.28,and 2.33 for square,circular,and rectangular,respectively.The thermal efficiency is evaluated by analyzing the heat losses from convection with the surrounding air and long-wave radiation exchange with the atmosphere.The experimental results indicated that using barriers with hexagonal holes is the best performance.展开更多
Achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge since the absorption peaks of common metal particles are usually located in the visible part of the radiation spectrum.T...Achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge since the absorption peaks of common metal particles are usually located in the visible part of the radiation spectrum.This paper aims to present the results of experimental investigations on the thermal performance of heat pipe-type evacuated solar collectors.The experimented system consists of 15 tubes,providing the hot nanofluid to 100-L storage in a closed flow loop.The solar collector with a gross area of 2.1 m^(2)is part of the solar hot water test system located in Baghdad-Iraq.Al2O3 nanofluid at 0.5%volume concentration in water as working fluid was used in three flow rates of 3.3,6.6,and 10 L/min over two months,March and April.The experimental results indicated that maximum solar irradiation was 1070 and 1270 W/m^(2)in March and April,respectively.The maximum daily average of rate heat gain 11,270 and 12,040 W was recorded in March and April,respectively.In terms of the best operational flow rate,the system performs better at 3.3 L/min nanofluid flow rate.For the considered study period,the average monthly maximum energy efficiencies of the solar collector in March and April were 86%and 80%,respectively.展开更多
基金Key-Area Research and Development Program of Guangdong Province(2023B0909020004)Project of Innovation Research Team in Zhongshan(CXTD2023006)+1 种基金Natural Science Foundation of Guangdong Province(2023A1515011573)Zhongshan Social Welfare Science and Technology Research Project(2024B2022)。
文摘Laser powder bed fusion(LPBF)is highly suitable for forming 18Ni300 mold steel,thanks to its excellent capability in manufacturing complex shapes and outstanding capacity for regulating microstructures.It is widely used in fields such as injection molding,die casting,and stamping dies.Adding reinforcing particles into steel is an effective means to improve its performance.Nb/18Ni300 composites were fabricated by LPBF using two kinds of Nb powders with different particle sizes,and their microstructures and properties were studied.The results show that the unmelted Nb particles are uniformly distributed in the 18Ni300 matrix and the grains are refined,which is particularly pronounced with fine Nb particles.In addition,element diffusion occurs between the particles and the matrix.The main phases of the base alloy are α-Fe and a small amount of γ-Fe.With the addition of Nb,part of the α-Fe is transformed into γ-Fe,and unmelted Nb phases appear.The addition of Nb also enhances the hardness and wear resistance of the composites but slightly reduces their tensile properties.After aging treatment,the molten pools and grain boundaries become blurred,grains are further refined,and the interfaces around the particles are thinned.The aging treatment also promotes the formation of reverted austenite.The hardness,ultimate tensile strength,and volumetric wear rate of the base alloy reach 51.9 HRC,1704 MPa,and 17.8×10^(-6) mm^(3)/(N·m),respectively.In contrast,the sample added with fine Nb particles has the highest hardness(56.1 HRC),ultimate tensile strength(1892 MPa)and yield strength(1842 MPa),and the volume wear rate of the sample added with coarse Nb particles is reduced by 90%to 1.7×10^(-6) mm^(3)/(N·m).
文摘Electrical and electronic devices face significant challenges in heatmanagement due to their compact size and high heat flux,which negatively impact performance and reliability.Conventional coolingmethods,such as forced air cooling,often struggle to transfer heat efficiently.In contrast,thermoelectric coolers(TECs)provide an innovative active cooling solution to meet growing thermal management demands.In this research,a refrigerant based on mono ethylene glycol and distilled water was used instead of using gases,in addition to using thermoelectric cooling units instead of using a compressor in traditional refrigeration systems.This study evaluates the performance of a Peltierbased thermalmanagement systemby analyzing the effects of using two,three,and four Peltiermodules on cooling rates,power consumption,temperature reduction,and system efficiency.Experimental results indicate that increasing the number of Peltier modules significantly enhances cooling performance.The four-module system achieved an optimal balance between cooling speed and energy efficiency,reducing the temperature of a liquidmixture(30% mono ethylene glycol+70% distilled water plus laser dyes)to 8℃ in just 17 min.It demonstrated a cooling rate of 0.794℃/min and a high coefficient of performance(COP)of 1.2 while consuming less energy than the two-and three-module systems.Furthermore,the study revealed that increasing the number of modules led to faster air cooling and improved temperature reduction.These findings highlight the importance of selecting the optimal number of Peltier modules to enhance efficiency and cooling speed whileminimizing energy consumption.This makes TEC technology a sustainable and effective solution for applications requiring rapid and reliable thermal management.
基金supported by the Science and Technology Development Fund from Macao SAR(FDCT)(Nos.0102/2019/A2,0035/2019/AGJ,0154/2019/A3,0081/2019/AMJ,0033/2019/AMJ and 0125/2018/A3)Multi-Year Research Grants(MYRG2018-00003IAPME)from the University of Macao。
文摘Oxygen evolution reaction(OER)is a critical process in electrocatalytic water splitting.However,the development of low-cost,highly efficient OER electrocatalysts by a simple method that can be used for industrial application on a large scale is still a huge challenge.Recently,high entropy alloy(HEA)has acquired extensive attention,which may provide answers to the current dilemma.Here,we report bulk Fe_(50)Mn_(30)Co_(10)Cr_(10),which is prepared by 3D printing on a large scale,as electrocatalyst for OER with high catalytic performance.Especially,an easy approach,corrosion engineering,is adopted for the first time to build an active layer of honeycomb nanostructures on its surface,leading to ultrahigh OER performance with an overpotential of 247 mV to achieve a current density of 10 mA cm^(-2),a low Tafel slope of 63 mV dec^(-1),and excellent stability up to 60 h at 100 mA cm^(-2)in 1 M KOH.The excellent catalytic activity mainly originates from:(1)the binder-free self-supported honeycomb nanostructures and multi-component hydroxides,which improve intrinsic catalytic activity,provide rich active sites,and reduce interfacial resistance;and(2)the diverse valence states for multiple active sites to enhance the OER kinetics.Our findings show that corrosion engineering is a novel strategy to improve the bulk HEA catalytic performance.We expect that this work would open up a new avenue to fabricate large-scale HEA electrocatalysts by 3D printing and corrosion engineering for industrial applications.
基金Project(2013ZX04013047)supported by the Major Program of National Natural Science Foundation of ChinaProject(51275014)supported by the National Natural Science Foundation of China
文摘The reliability of electromechanical product is usually determined by the fault number and working time traditionally. The shortcoming of this method is that the product must be in service. To design and enhance the reliability of the electromechanical product, the reliability evaluation method must be feasible and correct. Reliability evaluation method and algorithm were proposed. The reliability of product can be calculated by the reliability of subsystems which can be gained by experiment or historical data. The reliability of the machining center was evaluated by the method and algorithm as one example. The calculation result shows that the solution accuracy of mean time between failures is 97.4% calculated by the method proposed in this article compared by the traditional method. The method and algorithm can be used to evaluate the reliability of electromechanical product before it is in service.
基金supported by the National Natural Science Foundation of China(52072196,52002199,52002200,52102106)the Major Basic Research Program of the Natural Science Foundation of Shandong Province(ZR2020ZD09)+1 种基金the Innovation and Technology Program of Shandong Province(2020KJA004)the Taishan Scholars Program of Shandong Province(ts201511034)。
文摘Introducing vacancy defects and unique morphology is an effective strategy to improve the catalytic performance of transition metal compounds.However,precisely controlling the amount of vacancy defects remains challenging.Here,we propose a facile and efficient hydrothermal accompanying an annealing method to synthesize a series of Mn-doped CoO nanomaterials with controllable oxygen vacancies and unique morphology.The oxygen vacancies amount can be precisely controlled by adjusting the Mndoping content and is positively correlated with catalytic performance.It was found that the oxygen vacancies amount can reach up to 38.2%over the Mn-doped CoO nanomaterials,resulting in ultra-high hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalytic activity(HER:25.6 and 37 m V at 10 m A cm^(-2);OER:301 and 322 m V at 50 m A cm^(-2))under both basic and acidic conditions,while reaching 10 m A cm^(-2) for an ultra-low cell voltage of only 1.52 V,which exceeds that of Pt/C/RuO_(2) and all reported non-noble metal oxide catalysts.The DFT calculations reveal oxygen vacancies can optimize H*and HOO*intermediates adsorption free energy,thus improving the HER and OER performance.Interestingly,the Mn-doped CoO with rich oxygen vacancies exhibits excellent antibacterial properties in vitro of biomedicine.This work provides new ideas and methods for the rational design and precise control of vacancy defects in transition metal compounds and explores their potential application value in electrochemical water splitting and biomedical fields.
基金National Natural Science Foundation of China(Grant Nos.52175446,51975133,51975597)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2021A1515011740,2019A1515011011)Shenzhen Fundamental Research Program(Grant No.JCYJ20170818163426597).
文摘Needles,as some of the most widely used medical devices,have been effectively applied in human disease prevention,diagnosis,treatment,and rehabilitation.Thin 1D needle can easily penetrate cells/organs by generating highly localized stress with their sharp tips to achieve bioliquid sampling,biosensing,drug delivery,surgery,and other such applications.In this review,we provide an overview of multiscale needle fabrication techniques and their biomedical applications.Needles are classified as nanoneedles,microneedles and millineedles based on the needle diameter,and their fabrication techniques are highlighted.Nanoneedles bridge the inside and outside of cells,achieving intracellular electrical recording,biochemical sensing,and drug delivery.Microneedles penetrate the stratum corneum layer to detect biomarkers/bioelectricity in interstitial fluid and deliver drugs through the skin into the human circulatory system.Millineedles,including puncture,syringe,acupuncture and suture needles,are presented.Finally,conclusions and future perspectives for next-generation nano/micro/milli needles are discussed.
基金Project supported by the Science Foundation of Shanghai Munici pal Commission of Science and Technology ( Grant No.011461059)
文摘Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed, developed and made applicable. This paper introduces a three dimensional opt ical measurement method based on digital fringe projection technique in RE to im prove the technique through its application. A practical example is presented an d the result demonstrates the applicability and feasibility of the measurement s ystem as well as the reliability and validity of relevant methods and algorithms .
基金supported by the National Natural Science Foundation of China(51672144,51572137,5170218121905152,52072196,52002199,52002200)the Major Basic Research Program of Natural Science Foundation of Shandong Province(ZR2020ZD09)+5 种基金the Shandong Provincial Key Research and Development Program(SPKR&DP)(2019GGX102055)the Natural Science Foundation of Shandong Province(ZR2019BEM042 ZR2020QE063,ZR2020MB045)the Innovation and Technology Program of Shandong Province(2020KJA004)the Innovation Pilot Project of Integration of Science,Education and Industry of Shandong Province(2020KJC-CG04)the Guangdong Basic and Applied Basic Research Foundation(019A15151109332020A1515111086,2020A1515110219)the Shandong Provincial Universities Young Innovative Talent Incubation ProgramInorganic Non-metallic Materials Research and Innovation Team,and Taishan Scholars Program of Shandong Province(ts201511034)。
文摘Electronic engineering of gallium nitride(Ga N) is critical for enhancement of its electrode performance.In this work, copper(Cu) cation substituted Ga N(Cu-Ga N) nanowires were fabricated to understand the electronically engineered electrochemical performance for Li ion storage. Cu cation substitution was revealed at atomic level by combination of X-ray photoelectron spectroscopy(XPS), X-ray absorption fine structure(XAFS), density functional theory(DFT) simulation, and so forth. The Cu-Ga N electrode delivered high capacity of 813.2 m A h g^(-1) at 0.1 A g^(-1) after 200 cycles, increased by 66% relative to the unsubstituted Ga N electrode. After 2000 cycles at 10 A g^(-1),the reversible capacity was still maintained at326.7 m A h g^(-1). The DFT calculations revealed that Cu substitution introduced the impurity electronic states and efficient interatomic electron migration, which can enhance the charge transfer efficiency and reduce the Li ion adsorption energy on the Cu-Ga N electrode. The ex-situ SEM, TEM, HRTEM, and SAED analyses demonstrated the reversible intercalation Li ion storage mechanism and good structural stability. The concept of atomic-arrangement-assisted electronic engineering strategy is anticipated to open up opportunities for advanced energy storage applications.
基金the National Natural Science Foundation of China(10072005)Beijing Educational Committee(99LG-11)Beijing Natural Science(3002002)Foundation
文摘Based on the programming method, an electromechanical coupling adaptive statically indeterminate truss structure is controlled for increasing its load capacity. Several main parameters during the process of design of the adaptive structure are selected for a study of its characteristic during the control stage. The curves of each parameter for the effect of control results are plotted and corresponding conclusions are drawn. Thus, the theoretical basis is presented for optimal design, manufacture and control of the adaptive structure.
基金supported by the National Natural Science Foundation of China(Grant No.51672144,51572137,51702181,52072196,52002199,52002200)the Major Basic Research Program of Natural Science Foundation of Shandong Province(Grant No.ZR2020ZD09)+6 种基金the Shandong Provincial Key Research and Development Program(SPKR&DP)(Grant No.2019GGX102055)the Natural Science Foundation of Shandong Province(Grant No.ZR2019BEM042,ZR2020QE063)the Innovation and Technology Program of Shandong Province(Grant No.2020KJA004)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2019A1515110933)the China Postdoctoral Science Foundation(Grant No.2020M683450)the Taishan Scholars Program of Shandong Province(No.ts201511034)the Postdoctoral Innovation Project of Shandong Province(Grant no.202101020)。
文摘The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni_(3)Se_(2)lamellas by pre-lithiation technique,which can be acted as a novel class of battery-type cathode for hybrid supercapacitors.Appropriately modulating the contents of the preembedded lithium(Li) ions can induce a controllable vacancy content in the series of as-prepared products,effectively endowing a fast reaction kinetic and high activity for the cathode.Benefiting from the distinct design,the optimized cathode(Li2-Ni_(3)Se_(2)) presents a high specific capacity of 236 mA h g^(-1)at1 A g^(-1),importantly,it can still possess 117 mA h g^(-1)when the current density is increased up to 100A g^(-1),exhibiting relatively high rate capability.It is much superior to other battery-type TMC cathodes reported in previous studies.Moreover,the cathode also shows the excellent cycling stability with 92%capacity retention after 3,000 cycles.In addition,a hybrid supercapacitor(HSC) is assembled with the obtained Li2-Ni_(3)Se_(2)as the cathode and active carbon(AC) as the anode,which delivers a high energy density of 77 W h kg^(-1)at 4 kW kg^(-1)and long-term durability(90% capacitance retention after 10,000 cycles).Therefore,the strategy not only provides an effective way to realize the controllable vacancy content in TMCs for achieving high-perfo rmance cathodes for HSC,but also further promotes their large-scale applications in the energy storage fields.
基金supported by the National Natural Science Foundation of China under Grant No.52072196,52002200,52102106,52202262,22379081,22379080Major Basic Research Program of Natural Science Foundation of Shandong Province under Grant No.ZR2020zD09the Natural Science Foundation of Shandong Province under Grant No.ZR2020QE063,ZR202108180009,ZR2023QE059.
文摘The development of highly active,stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great challenge.Herein,S vacancies-rich Ni_(3)S_(2)@Cu_(2)S nan-otube heterojunction arrays were in-situ grown on copper foam(V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF)for efficient electrocatalytic overall water splitting.With the merits of nanotube arrays and efficient electronic mod-ulation drived by the OD vacancy defect and 2D heterojunction defect,the resultant V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF electrocatalyst exhibits excellent electrocatalytic activity with a low overpotential of 47 mV for the hydrogen evolution reaction(HER)at 10 mA cm^(-2) current density,and 263 mV for the oxygen evolution reaction(OER)at 50 mA cm^(-2) current density,as well as a cell voltage of 1.48 V at 10 mA cm^(-2).Moreover,the nanotube heterojunction arrays endows V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF with outstanding stability in long-term catalytic processes,as confirmed by the continuous chronopotentiom-etry tests at current densities of 10 mA cm^(-2) for 100 h.
文摘The design and construction of an experimental solar hybrid vehicle based on the combination of photovoltaic solar energy as the main source of electricity and electric power supplied by a generator activated by the driver＇s pedaling is introduced. The vehicle has a battery to store the energy provided by both systems. The development was motivated by a Latin American solar car race through the Atacama Desert in Chile and the initiative to promote the use of clean energy for transport. A general description of the vehicle, its energetic aspects and experimental results are presented.
文摘In the process of mechanical and electrical equipment installation quality will directly affect the mechanical and electrical equipment operation quality and efficiency in the late, so the staff in the process of installation of electromechanical equipment need pay attention to some possible concerns, adopt scientific and effective way to as much as possible to reduce or avoid these hazards, so as to guarantee the quality in the process of mechanical and electrical equipment installation, which improves the efficiency and safety of mechanical and electrical equipment operation. Based on this, with the author's project, home air-conditioning, commercial air conditioning and core components as the research case, in the process of the project electrical and mechanical equipment installation exist some hidden dangers are analyzed and discussed, and puts forward some scientific and effective solution, in order to reduce the hidden dangers in the process of mechanical and electrical equipment installation, so as to improve installation quality and operation efficiency of equipment.
基金supported by the National Natural Science Foundation of China(grant No.52422511,U20A6004)the Guangdong Basic and Applied Basic Research Foundation(grant No.2022B1515120011)Guangzhou Basic and Applied Basic Research Foundation(grant No.2024A04J6362).
文摘With the continuous development of wearable electronics,wireless sensor networks and other micro-electronic devices,there is an increasingly urgent need for miniature,flexible and efficient nanopower generation technology.Triboelectric nanogenerator(TENG)technology can convert small mechanical energy into electricity,which is expected to address this problem.As the core component of TENG,the choice of electrode materials significantly affects its performance.Traditional metal electrode materials often suffer from problems such as durability,which limits the further application of TENG.Graphene,as a novel electrode material,shows excellent prospects for application in TENG owing to its unique structure and excellent electrical properties.This review systematically summarizes the recent research progress and application prospects of TENGs based on graphene electrodes.Various precision processing methods of graphene electrodes are introduced,and the applications of graphene electrode-based TENGs in various scenarios as well as the enhancement of graphene electrodes for TENG performance are discussed.In addition,the future development of graphene electrode-based TENGs is also prospectively discussed,aiming to promote the continuous advancement of graphene electrode-based TENGs.
文摘Thermoelectric air conditioning systems based on the Peltier effect had two modes:heating and cooling.In this work,the proposed design provides continuous improvement in COP from the first minute of operation.In cooling mode,the coefficient of performance(COP)was 1.176 due to the techniques used in this device,and it increased to 1.24 in the last minute of operation.Concerning the steady-state scenario,from the first minute,the Qc was larger than the W for the entire duration of the operation.The output temperature reaches 18.97℃ ,and the temperature on the cold side reaches 4.96℃ in the fifteen minutes of operation.The cooling mood was checked in Iraq/Baghdad in October with a temperature of 31℃ .Furthermore,the heating mode was checked in December with a temperature of 22℃ .Due to the size of the component on the cold side being small compared with the size of the component on the heat side,it reached a steady state in 13 min.This means the COP in heating mode reached 1.01 in 14 min.Furthermore,due to the presence of a thermal insulator made inside the device to separate the cold side and the hot side,the difference in temperature causes a noticeable little ascent.This is why the COP increased because it kept the degree differences low.Performance enhancements were achieved by optimizing the behavior of thermoelectric materials.The device contains 3 Peltier elements,a water-cooled system with one Peltier,a heat sink,and a fan.The design of the dehumidification system addresses the humidity issue commonly associated with thermoelectric air conditioners.In this context,the results indicate that the humidity rates had decreased and the cooling rate had increased with these innovative techniques,and thus,excellent performance can be achieved even if the Seebeck coefficient is not at its highest based on the condition of providing the Peltier elements’reliability and optimal thermal performance for various applications requiring both cooling and heating functions.The insulation plays a critical role in maintaining the efficiency of the system,reducing energy consumption,and ensuring long-term functionality.The proposed system is valuable for devices or environments that demand precise and dual thermal control with minimal energy wastage.
基金Foundation item:the National Natural Science Foundation of China(No.52075101)the Natural Science Foundation of Guangdong Province(No.2017A030313265)Guangzhou Scientific Research Plan(No.201904010184)。
文摘Aimed at the problem of the low computational efficiency of the existing urethral-valve reliability analysis,an efficient reliability analysis method of the wireless energy-transmitting urethral-valve(WETUV)was proposed.The method is called FTA-AK-SS,based on the active learning Kriging(AK)model,subset simulation(SS)algorithm,and fault tree analysis(FTA).According to the principle of FTA,we established the fault tree model of the WETUV to determine its minimum cut set and bottom events.Then we defined the random variables affecting its reliability.The U learning function was used to selectively add the sample points of random variables to update the initial Kriging surrogate model.At the same time,combined with the SS algorithm,the reliability and sensitivity analyses of the WETUV were realized.The result shows that compared with the traditional Monte Carlo simulation and FTA-Kriging-SS methods,the proposed method significantly improves the calculation efficiency of the WETUV under the premise of ensuring calculation accuracy.The reliability of the WETUV is greatly affected by the rubber pad’s aging,the receiver coil’s corrosion,and the position deviation.This study can provide a new way to realize a high-efficiency reliability calculation and analysis for urethral valves.
基金Supported by the National Natural Science Foundation of China(52225401)。
文摘To optimize the bit selection for large-diameter wellbore in the upper section of an ultra-deep well S-1,a full-well dynamic model integrating drill string vibration and bit rock-breaking was established and then verified using measured vibration data of drilling tools and actual rate of penetration(ROP)from Well HT-1 in northern Sichuan Basin.This model was employed to calculate and analyze drill string dynamic characteristics during large-diameter wellbore drilling in the Jurassic Penglaizhen Formation of Well S-1,followed by bit optimization.Research results show that during the drilling in Penglaizhen Formation of Well S-1,considering both the ROP of six candidate bits and the lateral/axial/torsional vibration characteristics of downhole tools,the six-blade dual-row cutter bit with the fastest ROP(average 7.12 m/h)was optimally selected.When using this bit,the downhole tool vibration levels remained at medium-low values.Field data showed over 90%consistency between actual ROP data and dynamic model calculation results after bit placement,demonstrating that the model can be used for bit program screening.
文摘The comparison of experimental performance was studied for soda cans:longitudinal,transverse,diagonal,and smooth cases to improve the heat transfer rate and thermal performance of the solar air heater,in this study using a frame which has 1.5 m×0.5 m×0.05 m dimensions,the arrangements were placed on the absorber plate inside the channel,raising the air’s exit temperature as it passed by.The work was carried out for 4 cases in January in Baghdad,Iraq,under specific conditions to compare them to reach the ideal case and the best performance evaluation.When the collector was tilted 350 to the horizontal facing south,The range of mass flow rate was from 0.012 to 0.049 kg/s,and the range of Re was from 2000 to 10,000.The results show that the best Nusselt number in the diagonal AL cans case was increased to 112 at Re=10,000.Then the thermal efficiency increased to 98% accompanied by a moderate decrease in the fraction factor to reach 0.435.Aluminum cans also provide good economic support for solar systems due to their low cost,in addition to their recycling and reducing pollution.
文摘To improve the heat transfer rate and thermal performance of the solar air heater due to low efficiency,new techniques,such as artificial roughness,barriers,and obstacles,should be used to increase the heat exchange between the fluid and the absorber.In this research,perforated V-shaped blockages with new geometric shapes,which are circular,hexagonal,square,rectangular,and triangular,were used.They were fixed on the absorber plate inside the channel with dimensions of 1.5 m×0.5 m×0.05 m,which increased the exit temperature of the air passing through the channel.The experimental work consists of six cases that were carried out during November in Baghdad,Iraq,to obtain an optimal result.These cases included using barriers that have holes with different geometric shapes for the barriers inside the solar air heater in addition to the reference case without any barriers.A comparison ismade between the cases under the same conditions and limits to reach the optimal case.The range of mass flow rate was from 0.0098 to 0.049 kg/s,and the range of Re was from 2000 to 10,000.Another goal of the comparison was to maximize Nu and minimize the friction factor.TheNu value improved by 1.77 and the fraction factor by 1.75 for the hexagonal perforated,which had the best performance.As for the triangle perforated,Nu improved by 1.58 and the fraction factor by 3.84,which had the worst performance.The Nu value improved by 1.39,1.22,and 1.4,and the fraction factor improved by 1.967,1.28,and 2.33 for square,circular,and rectangular,respectively.The thermal efficiency is evaluated by analyzing the heat losses from convection with the surrounding air and long-wave radiation exchange with the atmosphere.The experimental results indicated that using barriers with hexagonal holes is the best performance.
基金The University of Technology,specifically the Department of Electromechanical Engineering,provided invaluable assistance during the experimental work,for which the authors are quite grateful.
文摘Achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge since the absorption peaks of common metal particles are usually located in the visible part of the radiation spectrum.This paper aims to present the results of experimental investigations on the thermal performance of heat pipe-type evacuated solar collectors.The experimented system consists of 15 tubes,providing the hot nanofluid to 100-L storage in a closed flow loop.The solar collector with a gross area of 2.1 m^(2)is part of the solar hot water test system located in Baghdad-Iraq.Al2O3 nanofluid at 0.5%volume concentration in water as working fluid was used in three flow rates of 3.3,6.6,and 10 L/min over two months,March and April.The experimental results indicated that maximum solar irradiation was 1070 and 1270 W/m^(2)in March and April,respectively.The maximum daily average of rate heat gain 11,270 and 12,040 W was recorded in March and April,respectively.In terms of the best operational flow rate,the system performs better at 3.3 L/min nanofluid flow rate.For the considered study period,the average monthly maximum energy efficiencies of the solar collector in March and April were 86%and 80%,respectively.
