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作者： Mitishita, Rodrigo S. Barreira, Eduardo M. Negrão, Cezar O.R. Hermes, Christian J.L. Thermal Science Laboratory Postgraduate Program of Mechanical and Materials Engineering Federal University of Technology - Paraná Av. Sete de Setembro 3165 80230901 Curitiba PR Brazil Center for Applied Thermodynamics Department of Mechanical Engineering Federal University of Paraná P.O. Box 19011 81531990 Curitiba PR Brazil

An optimization methodology aiming at energy and cost savings in frost-free refrigerators is advanced. A steady-state simulation model was devised and its predictions for energy consumption were compared with experimental data obtained elsewhere, with differences not exceeding a +/- 9% error band. The model was used to find out the evaporator air flow rate, the number of evaporator and condenser fins, the compressor size and efficiency, and the insulation thicknesses of both fresh- and frozen-food compartments which yield the minimum energy consumption when the total cost is constrained. The optimization led to a refrigeration system with energy consumption 18% lower than that observed for the baseline system without any cost penalty. The system performance for four different compressors, including a high efficiency, a large capacity and a variable-speed one, was also analyzed. For the refrigerator under analysis, it was found that, to ensure an economically feasible design, the variable-speed compressor should not cost 26% more than a single-speed one with the same piston displacement. © 2012 Elsevier Ltd. All rights reserved.

关键词： Compressors

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Thermoeconomic analysis and optimization of residential split-type air conditioners

Thermoeconomic analysis and optimization of residential spli...

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作者： Barreira, Eduardo M. Negrão, Cezar O.R. Hermes, Christian J.L. Thermal Science Laboratory Postgraduate Program of Mechanical and Materials Engineering Federal University of Technology - Paraná Av. Sete de Setembro 3165 80230-901 Curitiba PR Brazil Center for Applied Thermodynamics Department of Mechanical Engineering Federal University of Paraná P.O. Box 19011 81531-990 Curitiba PR Brazil

A simulation-based optimization methodology for designing unitary residential air conditioners with focus on both energy performance enhancement and cost savings is presented. A steady-state system simulation model was put forward for a 2.5-ton nominal cooling capacity split-type air conditioning unit operating with R-410A as the working fluid. The model predictions for cooling capacity, sensible heat ratio (SHR) and coefficient of performance (COP) were compared with experimental data, when it was found that the model is able to predict the experimental trends within a ±6% error band. The model was then used to find out the condenser and evaporator geometries (face area, heat transfer area) that enhance the system COP for a fixed cost. On one hand, it was observed that the COP can be increased by 7% if the cost is held fixed. On the other hand, cost savings of 33% were achieved when the system COP was held constant. © 2012 Elsevier Ltd. All rights reserved.

关键词： Air conditioning

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Lanthanum Manganite and Cobaltite-based Composite Cathodes for SOFCs

Lanthanum Manganite and Cobaltite-based Composite Cathodes f...

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2012 International Conference on Power and Energy Systems(ICPES 2012)

作者： Daniel A.Macedo Moisés R.Cesário Beatriz Cela Carlos A.Paskocimas Dulce M.A.Melo Rubens M.Nascimento Antonio.E.Martinelli Materials Science and Engineering Postgraduate Program UFRN 59072-97 Natal/RN Brazil Chemistry Postgraduate Program UFRN 59072-970 Natal/RN Brazil Forschungszentrum Jülich GmbH Central Department of Technology (ZAT) Jülich Germany

The development of novel high-performance cathodes is essential to reduce Solid Oxide Fuel Cell (SOFCs) operation to low and intermediate temperatures. To that end, the performance of CeO 2 -based composite cathodes is very attractive. In the present work, LSM (La0.8 Sr0.2 MnO3 ), LSCF (La0.5Sr0.5Co0.8Fe0.2O3 ) and SDC (Ce0.8Sm0.2O1.9 ) powders were synthesized by different synthesis methods and used to prepare SOFC composite film cathodes. LSM-SDC and LSCF-SDC composite powders were obtained by milling. Composite films were deposited onto yttria stabilized zirconia (YSZ) electrolytes and characterized by scanning electron microscopy. Preliminary performance tests were carried out using a single cell having a LSCF-SDC cathode. I-V curves indicated that the cell had qualitatively good performance with maximum power density of 19 mW/cm 2 at 800℃. The preparation of LSM and LSCF composites by mixing SDC, synthesized by the method proposed herein is an innovative alternative for the production of high performance ceramic materials for SOFC cathodes.

关键词： Modified Pechini Method, Microwave-assisted Combustion, Composite materials, SOFC cathodes.

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Alkali-Aggregate Reaction and its Mineral Reactive Phases Contribution to the Microstructural Consolidation of Portland Cement and Geopolymeric Mortars with Metakaolin-Based Precursors

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SSRN 2023年

作者： Valenga, Matheus Villian de Lima, Rubia Catarina Przybysz Pereira, Elias Pereira, Eduardo Farias, Marcelo Miranda Pianaro, Sidnei Antonio State University of Ponta Grossa Postgraduate Program in Engineering and Materials Science Carlos Cavalcanti Avenue 4748 Uvaranas Paraná Ponta GrossaCEP: 84030-900 Brazil

HIGHLIGHTS Metakaolin-based geopolymeric mortars are not negatively affected by *** aggregates contribute to geopolymer matrix consolidation and *** cement partial replacement by metakaolin reduces AAR effects in *** ... 详细信息

关键词： Mortar

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Patterning Colloidal Films via Evaporative Lithography

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Physical Review Letters 2007年第14期98卷 148301-148301页

作者： Daniel J. Harris Hua Hu Jacinta C. Conrad Jennifer A. Lewis Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Corporate Engineering Technical Lab The Procter and Gamble Company West Chester Ohio 45069 USA INEST Group Postgraduate Program Philip Morris USA Richmond Virginia 23234 USA

We investigate evaporative lithography as a route for patterning colloidal films. Films are dried beneath a mask that induces periodic variations between regions of free and hindered evaporation. Direct imaging reveals that particles segregate laterally within the film, as fluid and entrained particles migrate towards regions of higher evaporative flux. The films exhibit remarkable pattern formation that can be regulated by tuning the initial suspension composition, separation distance between the mask and underlying film, and mask geometry.

关键词： Liquid films

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Facile Synthesis, Structure and Battery-Type Behavior of Graphene Oxides

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SSRN 2023年

作者： Silva, Jullyani M.D. Fenandes, Filipe P.M. Silva, Mariana de O. Maraschin, Thuany G. Ferreira, Luciena S. Macedo, Daniel A. da Silva, Lucineide B. Fim, Fabiana de C. Materials Science and Engineering Postgraduate Program UFPB João Pessoa58051-900 Brazil Department of Materials Engineering UFPB Paraíba João Pessoa58051-900 Brazil RS Porto Alegre90619-900 Brazil

Graphene oxide (GO) is one of the main precursors for the production of graphene and other graphene-based materials. In this work, we report a simple, safe and fast synthesis method for obtaining graphene oxide as a functional material for battery-type electrodes. The method provides to obtain an aqueous solution of graphene oxide suitable for drying by freeze-drying (sample GO1). Washing and freeze-drying processes are performed to assess their effects on the exfoliation and removal of functional groups from the graphene sheets (sample GO2). GO1 sample consists of a stack of 10 oxidized graphene layers without any additional exfoliation process, while the GO2 sample has 8 stacked layers, after two washing and freeze-drying processes. FTIR results indicate that bulkier groups such as carboxylic acid are most likely to be found on the edges and surfaces of the graphene sheets of both samples. The presence of point defects such as vacancies was also observed in both samples, with the GO2 sample having a higher content of vacancies. The electrochemical performance of graphene oxide-based electrodes, classified as battery-type, indicate an improved specific capacity of 10.15 C g-1 for GO1 against 4.55 C g-1 for GO2 at a specific current of 0.5 A g-1. This superior battery-type behavior of the GO1 electrode, also confirmed by electrochemical impedance spectroscopy, is most likely due to a higher degree of oxygenated groups on its surface, as shown by EDS and FTIR studies. © 2023, The Authors. All rights reserved.

关键词： Washing

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Low-density steels scientific and technological macro-indicators

Low-density steels scientific and technological macro-indica...

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materials science and Technology 2018, MS and T 2018

作者： Andrade, Malena Aissa De Oliveira, Bráulio Salumão Milanez, Douglas Henrique Leiva, Daniel Rodrigo Zepon, Guilherme Materials Engineering Department Federal University of São Carlos Rodovia Washington Luis km 235 São Carlos. São Paulo State Brazil Center for Technological Information in Materials Federal University of São Carlos Rodovia Washington Luis km 235 São Carlos. São Paulo State Brazil Postgraduate Program in Materials Science and Engineering Federal University of São Carlos Rodovia Washington Luis km 235 São Carlos. São Paulo State Brazil

ISBN: (纸本)0873397681

Low-density steels are studied aiming to increase the specific strength and consequently decrease automobile weight. Scientific and technological indicators can be elaborated based on information contained in articles and patent documents and assists to detect trends in emerging topics. This study evaluated recent developments in low-density steel alloys through bibliometric techniques. The results show Japan, South Korea, China, Germany and USA as the main players. Ductility and corrosion resistance figures as important technological challenges apart from strengthening. Beyond aluminum, manganese and carbon - mainly used for density reduction - silicon and chromium stand out as the main alloying elements studied for stacking fault energy control. The indicators suggest that new technologies and its insights shall be expected and monitored in near future, mainly for supporting material selection and R&D decision makings. Copyright © 2018 MS&T18®

关键词： Corrosion resistance

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Incorporation of Oregano Essential Oil Microcapsules in Starch-Poly (Butylene Adipate Co-Terephthalate) (PBAT) Films

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Macromolecular Symposia 2019年第1期383卷

作者： de Medeiros, João Augusto Salviano Blick, Ana Paula Galindo, Marcella V. Alvim, Izabela D. Yamashita, Fabio Ueno, Cláudio Takeo Shirai, Marianne Ayumi Grosso, Carlos Raimundo Ferreira Corradini, Elisângela Sakanaka, Lyssa Setsuko Federal University of Technology of Paraná − Department of Materials Engineering LondrinaParana Brazil Londrina State University − Department of Food Science and Technology Londrina Parana Brazil Federal University of Technology of Paraná − Department of Food Technology LondrinaParana Brazil Institute of Food Technology − Bakery and Confectionary Technology Center LondrinaParana Brazil Federal University of Technology of Paraná − Postgraduate Program in Food Technology LondrinaParana Brazil Federal University of Technology of Paraná − Postgraduate Program in Materials Science and Engineering LondrinaParana Brazil

Summary Cassava starch and poly(butylene adipate-co-terephthalate) (PBAT) based films containing microencapsulated oregano essential oil (OEO) and free OEO are produced by blow extrusion. Microcapsules produced by ionic gelation were characterized with respect to average size, morphology, and encapsulation efficiency. The microcapsules were spherical and ranged in size from 20 to 1000 μm. Encapsulation efficiency (EE) is 83%. The films are analyzed in terms of their morphology, mechanical properties, water vapor permeability (WVP) and antibacterial properties. The films containing OEO microcapsules exhibited lower ultimate tensile strength, Young's modulus and elongation at break than the control films and the films containing free OEO. The WVP of films containing free OEO is slightly lower, while that of films containing microencapsulated OEO did not differ significantly from the control films. Scanning electron microscopy (SEM) images showed that the surface of films containing microencapsulated OEO are less homogeneous than those of the control and free OEO films. Films containing free or microencapsulated OEO presented inhibitory activity against Staphylococcus aureus, but not against Escherichia coli. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词： Elastic moduli

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Using sugar cane bagasse ash into clay products

Journal of Solid Waste Technology and Management

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Journal of Solid Waste Technology and Management 2012年第1期38卷 5-10页

作者： Acchar, Wilson Paranhos, Raimundo Jorge Santos Physics Department Federal University of Rio Grande Do Norte Natal-RN 59072-970 Brazil Postgraduate Program of Science and Materials Engineering University of Rio Grande Do Norte Natal-RN 59072-970 Brazil

The agro and industrial activities are currently responsible for the production of large amounts of solid wastes. The use of industrial wastes such as granite, marble, kaolin and pegmatite and agro-industrial rejects into clay products has been widely developed over the last few decades. Clay materials used in the ceramic industry exhibit a large diversification of compositions that al-low the addition of different types of waste materials to the clay mixture. Sugar cane bagasse ash (SCBA), a by-product of the sugar process, is exacerbating the environmental problem. Bra-zil produces an enormous amount of sugar and the lack of adequate landfill areas available for disposal of sugar cane bagasse ash rejects poses a critical problem for the agro-industry. This work describes, for the first time, research carried out on the manufacturing of ceramic tile mate-rials with sugar cane bagasse ash additions. SCBA, consisting basically of potassium oxide, was added to the clay formulations as an alternative to feldspar. Clay with different sugar cane ba-gasse ash content was mixed and sintered. Sintered specimens were characterized by X-ray dif-fraction, density, porosity, thermal analysis and strength measurements. The results obtained showed that the sugar cane ash residue can be added to clay materials as an alternative to feld-spar, without degrading their properties.

关键词： Sintering

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A flexible ultrasonic velocity profiler development environment

A flexible ultrasonic velocity profiler development environm...

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IEEE Instrumentation and Measurement Technology Conference

作者： César Yutaka Ofuchi Fabio Rizental Coutinho Raquel dos Santos Rasia Lucia Valeria Ramos de Arruda Flávio Neves Rigoberto Eleazar Melgarejo Morales Graduate School of Electrical Engineering and Computer Science (CPGEI) Federal University of Technology-Paraná (UTFPR) Curitiba Brazil Mechanical & Materials Engineering Postgraduate Program (PPGEM) Federal University of Technology-Paraná (UTFPR) Curitiba Brazil

ISBN: (纸本)9781467363846

Ultrasonic velocity profiler method is now an accepted tool in modern experimental fluid mechanics and fluid engineering. As a relative new technology, different applications and improvements of the technique are being researched over the last years. This paper presents an environment to develop new algorithms to improve the ultrasonic velocity estimation technique. The system uses the LabVIEW modular platform integrated with mathematical script language used in many signal-processing software. The phase-shift algorithm was implemented and tested using the proposed system. The results are validated with standard velocity measurements generated by a rotating cylinder.

关键词： Acoustics Velocity measurement Software Signal processing algorithms Ultrasonic variables measurement Fluids Doppler effect

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