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Impact of Fin Arrangement on Heat Transfer and Melting Characteristics of Phase Change Material

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Journal of Thermal Science 2024年第2期33卷 435-456页

作者： Arun UNIYAL Yogesh K.PRAJAPATI department of mechanical engineering National Institute of Technology UttarakhandSrinagar(Garhwal)246174India department of mechanical engineering BIT SindriDhanbadJharkhand828123India

Present work investigates the heat transfer and melting behaviour of phase change material(PCM) in six enclosures(enclosure-1 to 6) filled with paraffin *** enclosures are equipped with distinct arrangements of the fins while keeping the fin's surface area equal in each *** analysis has been presented to recognize the suitable fin arrangements that facilitate improved heat transfer and melting rate of the *** wall of the enclosure is maintained isothermal for the temperature values 335 K,350 K and 365 *** length of the enclosure including fins is ranging between 0 and *** have been illustrated through the estimation of important performance parameters such as energy absorbing capacity,melting rate,enhancement ratio,and Nusselt *** has been found that melting time(to melt 100% of the PCM) is 60.5%less in enclosure-2(with two fins of equal length) as compared to the enclosure-1,having no *** the fin surface area equal,if the longer fin is placed below the shorter fin(enclosure-3),melting time is further decreased by 14.1% as compared to ***,among all the configurations,enclosure-6 with wire-mesh fin structure exhibits minimum melting time which is 68.4% less as compared to the *** on the findings,it may be concluded that fins are the main driving agent in the enclosure to transfer the heat from heated wall to the *** design and positioning of the fins improve the heat transfer rate followed by melting of the PCM in the entire area of the *** of the favourable vortices and natural convection current in the enclosure accelerate the melting phenomenon and help to reduce charging time.

关键词： phase change material enclosure fin melting fraction energy storage heat transfer

Synthesis and Thermal Characterization of Solar Salt-Based Phase Change Composites with Graphene Nanoplatelets

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Journal of Thermal Science 2024年第2期33卷 491-500页

作者： Pethurajan VIGNESHWARAN Saboor SHAIK Sivan SURESH Müslüm ARICI Asif AFZAL department of Thermal and Energy engineering School of Mechanical Engineering(SMEC)Vellore Institute of TechnologyVelloreTamil NaduIndia Nanotechnology Research Laboratory Department of Mechanical EngineeringNational Institute of TechnologyTiruchirappalliTamil NaduIndia mechanical engineering department Engineering FacultyKocaeli UniversityUmuttepe CampusKocaeli41001Turkey department of mechanical engineering P.A.College of Engineering(affiliated to Visvesvaraya Technological UniversityBelagavi)Mangaluru574153India

Thermal energy storage(TES) systems use solar energy despite its irregular availability and day-night temperature *** work reports the thermal characterizations of solar salt-based phase change composites in the presence of graphene nanoplatelets(GNP).Solar salt(60:40 of NaNO_(3):KNO_(3)) possessing phase transition temperature and melting enthalpy of 221.01℃ and 134.58 kJ/kg is proposed as a phase change material(PCM) for high-temperature solar-based energy storage *** conductivity must be improved to make them suitable for widespread applications and to close the gap between the system needs where they are *** is added at weight concentrations of 0.1%,0.3%,and 0.5% with solar salt using the ball milling method to boost its thermal *** studies indicated the formation of a uniform surface of GNP on solar *** spectrum peaks identified the physical interaction between salt and *** characterization of the composites,such as thermal conductivity,DSC and TGA was carried out for the samples earlier and later 300 thermal cycles.0.5% of GNP has improved the thermal conductivity of salt by 129.67% and after thermal cycling,the enhancement reduced to 125.21% indicating that thermal cycling has a minor impact on thermal *** change temperature decreased by around 2.32% in the presence of0.5% GNP and the latent heat reduced by 4.34% after thermal *** thermograms depicted the composites initiated the weight loss at around 550℃ after which it was *** thermal cycling,the weight loss initiated at ~40℃ lower compared to pure salt,which was found to be a minor *** characterization of solar salt and GNP-based solar salt composites revealed that the composites can be used for enhanced heat transfer in high-temperature solar-based heat transfer and energy storage applications.

关键词： thermal energy storage high temperature solar salt graphene nanoplatelets thermal characterization

Simulation and analysis of soil homogenization drills based on discrete element method and response surface methodology

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Particuology 2024年第5期88卷 128-148页

作者： Zhipeng Wang Tong Zhu Youzhao Wang Song Yang Feng Ma Xu Li Institute of process Equipment and Environmental engineering School of Mechanical Engineering and AutomationNortheastern UniversityShenyang110819China Liaoning Coning Testing Co. Ltd.Shenyang110170 China

Currently,rotary drilling is one of the main pieces of equipment used for in-situ remediation of contaminated ***,this equipment has problems such as uneven mixing and low utilization efficiency,which affect the efficiency of in-situ soil *** improve the efficiency of in-situ soil remediation,this paper takes contaminated black soil as the research object,and the structural design of the new three-stage soil remediation auger is carried out based on *** mixing process of soil and heavy metal passivator under different motion and structural parameters was investigated by the discrete element method(DEM)and response surface *** experimental design was based on rotational speed,homogenizing mixing time,crushing section pitch,and homogenizing section pitch as factors,and soil fragmentation ratio,the coefficient of dispersion,and torque as optimization *** kinematic and structural parameters of the three-stage auger drill bit were then optimized using the one-factor method,the orthogonal test,and the response surface methodology,*** test method uses a one-way test to determine the central level value of the orthogonal test and a comprehensive balance method to determine the best combination of parameters for the orthogonal test,which is then used as the central value of the response surface test for parameter *** optimal combinations of kinematic and structural parameters of the three-stage auger drill bit are determined and validated using response surface *** optimum combination of parameters was found to be a speed of 129 rpm,a homogenizing mixing time of 24 s,a pitch of 165 mm in the crushing section,and a pitch of 132 mm in the homogenizing *** error between the optimal value of the predicted model using the response surface method and the actual simulated value under the optimal parameters is 4.2%,4.9%,and 5.3%,*** optimized factor parameters provide a refe

关键词： Black soil Mixing homogeneity Orthogonal method Response surface methodology Discrete element method Soil remediation

A numerical investigation into the effect of altering compression ratio, injection timing, and injection duration on the performance of a diesel engine fuelled with diesel-biodiesel-butanol blend

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Clean Energy 2024年第5期8卷 73-96页

作者： Abdulkarim Youssef Amr Ibrahim mechanical engineering department Beirut Arab University115020 BeirutLebanon mechanical engineering department Alexandria UniversityAlex 21544Egypt

Using renewable fuels for diesel engines can reduce both air pollution and dependence on fossil fuels.A computer simulation was constructed to predict the performance,combustion characteristics,and NOx emissions of a diesel engine fuelled with diesel-biodiesel-butanol *** simulation was validated by comparing the modelling results against experimental data and a good agreement between the results was *** fuels used for the validation were diesel(B0),biodiesel(B100),diesel-biodiesel blend(B50),and two diesel-biodiesel-butanol blends with 45%diesel-45%biodiesel-10%butanol(Bu10)and 40%diesel-40%biodiesel-20%butanol(Bu20)by *** results showed that the addition of butanol reduced NOx emissions but deteriorated the engine *** aim of the current work was the numerical optimization of the different parameters to enhance the engine performance while using butanol to decrease NOx *** engine compression ratio(CR)varied from 14 to 24,in increments of *** injection timing(IT)was reduced from 30°before top dead centre(bTDC)to 5°bTDC in increments of 5°.Also,the fuel injection duration(IDur)was extended from 20°to 50°in increments of 10°.Results showed that the increase in the CR improved engine performance for the two investigated fuels,Bu10 and *** maximum engine brake power(BP),thermal efficiency(BTE),and minimum brake-specific fuel consumption(BSFC)of 1.46 kW,32.3%,and 0.273 kg/kWh respectively,were obtained when the Bu10 fuel was injected under the optimum conditions of 24 CR,15°bTDC IT,and 40°*** these optimum conditions,the BP,BTE,and BSFC improved by 3%-3.5%for Bu10 and Bu20 fuel blends compared with the base engine conditions of a CR of 22,30°IDur,and 10°bTDC *** heat release rate during the premixed phase increased when the IT was advanced,while the mixing-controlled combustion phase was enhanced when the IT was *** emissions increased with increasing CR,while both an increase in IDur at con

关键词： compression ratio injection timing injection duration butanol biodiesel diesel

A thermodynamic perspective on electrode poisoning in solid oxide fuel cells

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1449-1455页

作者： Kevin Huang department of mechanical engineering University of South CarolinaColumbiaUSA

A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell(SOFC)technology is the insuf-ficient stack lifespan caused by a variety of degradation mechanisms,which are associated with cell components and chemical *** components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions,whereas the latter regards impurities in feedstocks of oxidant(air)and reductant(fuel).This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in *** discussion focuses on using thermodynamic ana-lysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr,CO_(2),H_(2)O,and SO_(2) and in the anode by species such as S(or H_(2)S),SiO_(2),and P_(2)(or PH_(3)).The author hopes the presented fundamental insights can provide a theoretical foundation for search-ing for better technical solutions to address the critical degradation challenges.

关键词： impurities air fuel reaction activity

Kinematics ofmandibular advancement devices(MADs):Why do some MADs move the lower jaw backward duringmouth opening?

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Bio-Design and Manufacturing 2024年第5期7卷 637-650页

作者： Juan A.Cabrera Alex Bataller Sergio Postigo Marcos García mechanical engineering department University of Malaga29071 MalagaSpain

Mandibular advancement devices(MADs)are widely used treatments for obstructive sleep *** function by advancing the lower jaw to open the upper *** increase patient comfort,most patients allow the mouth to be ***,not all systems maintain the lower jaw in a forward position during mouth opening,which results in the production of a retrusion that favors the collapse of the upper ***,the kinematic behavior of the mechanism formed by the mandible-device assembly depends on jaw *** means that,during mouth opening,some devices cause lower jaw protrusion in some patients,but cause its retraction in *** this study,we report the behavior of well-known devices currently on *** do so,we developed a kinematic model of the lower jawdevice *** validated for all devices analyzed using a high-resolution camera *** results show that some of the devices analyzed here did not produce the correct behavior during patient mouth opening.

关键词： Mandibular advancement devices Lower jaw kinematics Sleep apnea

Effect of cooling media on bead geometry,microstructure,and mechanical properties of wire arc additive manufactured IN718 alloy

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Advances in Manufacturing 2024年第1期12卷 124-149页

作者： Parveen Kumar Satish Kumar Sharma Ratnesh Kumar Raj Singh department of mechanical engineering Thapar Institute of Engineering and TechnologyPatialaPunjab147004India

This work aims to present and explore thermal management techniques for the wire arc additive manufacturing(WAAM)of IN718 *** heat can be mitigated via air or water *** this study,the material was deposited under four different heat-input conditions with air or water *** air cooling,the layer is deposited in a normal atmospheric air environment,whereas with water cooling,the material is deposited inside a water tank by varying the water *** validate the air and water cooling thermal management techniques,IN718 single-pass and multilayer linear walls were deposited using the bidirectional gas metal arc welding based WAAM setup under four different heat input *** the deposition of single layers,the temperature profiles were recorded,and the geometric and microstructural features were *** multilayer wall structures,the mechanical properties(hardness,tensile strength,and elongation)were determined and assessed using the corresponding microstructural features explored through scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and electron backscatter diffraction(EBSD)*** microstructure observed through SEM analysis in the building direction was found to be nonhomogenous compared with that in the deposition ***,water cooling was found to govern bead characteristics,such as wall width and *** grain size and anisotropy of the mechanical properties also decreased in the water-cooled ***,water cooling is an economical and efficient method to mitigate excessive heat accumulation in WAAM-deposited IN718.

关键词： Air cooling Water cooling IN718 Bead characteristics Microstructure Electron backscatter diffraction(EBSD)

Nickel Sulfide Modified NiCu Nanoalloy with Excellent Oxygen Evolution Reaction Properties Prepared through Electrospinning and Heat Treatment

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 320-326页

作者：李涛凌帅 ZHONG Shujie LOU Qiongyue department of Materials engineering School of Mechanical EngineeringChengdu UniversityChengdu 610106China

Ni^(2+)/Cu^(2+)/SO_(4)^(2-)/polyvinyl alcohol precursor fibers with uniform diameters were prepared through ***-based composite nanoalloys containing Ni,Cu,and S were prepared through heat treatment in an Ar *** experimental results show that the main components of the prepared nanoalloys are NiCu,Ni_(3)S_(2),Ni,and *** nanoalloys exhibit fine grain sizes about 200-500 nm,which can increase with increasing heat treatment *** test results show that the nickel sulfidemodified NiCu nanoalloy composites exhibit excellent oxygen evolution reaction properties,and the oxygen evolution reaction properties gradually improve with the increasing heat treatment *** sample prepared at 1 000℃ for 40 min show a low overpotential of 423 mV and a small Tafel slope of 134 mV·dec^(-1) at a current density of 10 mA·cm^(-2).

关键词： NiCu nanoalloy Ni_(3)S_(2) structure transformation oxygen evolution reaction

Characterization and Analysis of Inconel 718 Alloy Ground at Different Speeds

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Chinese Journal of mechanical engineering 2024年第2期37卷 137-149页

作者： Hao Liu Huili Han Qinghong Jiang Minglin He Bi Zhang department of mechanical and Energy engineering Southern University of Science and TechnologyShenzhen 518055China department of mechanical engineering Hong Kong Polytechnic UniversityHong KongChina

Inconel 718(IN718)alloy is widely applied to fabricate high temperature resistant or corrosion resistant parts due to its excellent mechanical ***,the machining of IN718 alloy is difficult as it may cause serious tool wear and poor surface quality(SQ)of the *** this work,grinding experiments on IN718 alloy at different speeds were conducted by using a CBN grinding *** relationship between grinding speed,SQ and subsurface damage(SSD)was well *** increasing grinding speed,surface roughness decreased,and SQ was greatly ***,the microhardness of the grinding surface declined as the grinding speed *** SSD depth was almost unchanged when the grinding speed was lower than 15 m/s,then it decreased with higher grinding *** was attributed to the mechanical-thermal synergistic effect in the grinding *** results indicated that increasing grinding speed can effectively improve the SQ and reduce the SSD of IN718 *** conclusion in the work may also provide insight into processing other hard-to-machining materials.

关键词： Surface integrity Grinding speed IN718 alloy Precision machining CBN grinding wheel