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Mechanical stability of adhesives under water storage

MANSO, Adriana P.; BEDRAN-RUSSO, Ana K.; SUH, Byoung; PASHLEY, David H.; CARVALHO, Ricardo M.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.53%
Objectives. To evaluate the effects of storage condition (wet or dry) and storage time (24 h and 3 months) on the ultimate tensile strength (UTS) of Single Bond (SB), 3M-ESPE; Opti Bond Solo Plus (OB), Kerr; One Step (OS), Bisco, and Prime & Bond NT (PB), Dentsply adhesive resins. Methods. Hourglass-shaped specimens were obtained from a metallic matrix. Each adhesive was dispensed to fill the molds completely and left undisturbed in a dark chamber for 4 min at 37 degrees C for solvent evaporation. They were individually light-cured for 80 s at 500 mW/cm(2) and randomly divided into three groups: 24 h of water storage; 3 months of water storage; 3 months of dry storage. The specimens were tested in tension at 0.5 mm/min using the microtensile method and data were analyzed by two-way ANOVA and SNK tests for each material. Results. Water storage for 3 months did not cause significant changes in the UTS of any of the adhesives (p-value). Values for water storage ranged from 25.9 MPa for Single Bond at 24 h to 32.7 MPa for Prime & Bond NT after 3 months. Dry storage for 3 months yielded significantly higher UTS for most adhesives, which ranged from approximately 20% for Opti Bond to 160% higher values for Single Bond compared to their 3 months wet storage values. Conclusion. The effects of storage condition and time on the UTS of adhesives were material-dependent. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Avaliação das perdas qualitativas no armazenamento da soja; Qualitative losses evaluation on soybeans storage

Gilmar Valente Teixeira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/12/2001 PT
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À medida que a globalização é uma realidade mundial e aumenta a competitividade de abastecimento de alimentos, e sendo o Brasil um país tradicionalmente agrícola, torna-se uma prioridade produzir e armazenar cada vez melhor. Nestes processos a qualidade da matéria prima é fundamental pois os produtos alimentares apresentam sua qualidade condicionada à qualidade da matéria-prima que lhes deu origem. O armazenador de grãos deve ter como objetivo principal a preservação da qualidade dos produtos sob sua responsabilidade. Portanto, entender como as perdas ocorrem durante o armazenamento com e sem sistema de aeração, em diferentes níveis de umidade; verificar a variação do teor de óleo, proteína e acidez e obter modelos matemáticos para prever o comportamento da soja em função dos indicadores de qualidade foram os objetivos do trabalho. Armazenou-se soja durante 238 dias com três teores iniciais de umidade (12,70; 14,50 e 15,50% b.u.), em silos metálicos, sendo que 9 silos com sistema de aeração e 9 silos sem sistema de aeração. A temperatura foi registrada e amostras de grãos coletadas. Modelos de regressão foram ajustados em função do período de armazenamento e do teor de umidade inicial. A deterioração da soja ocorrida durante o experimento (aumento do percentual de grãos ardidos...

Avaliação da demanda, do consumo eletrico e do controle de temperatura para condicionamento de ambientes, usando sistemas de refrigeração com termoacumulação.; Evaluation of demand, electric consumption and control of temperature for environment conditioning, using refrigeration systems with thermal storage.

Klicia Araujo Sampaio
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/08/2006 PT
Relevância na Pesquisa
36.53%
Os prédios financeiros e os comerciais juntos representam uma grande parcela do consumo de energia elétrica no setor comercial, cerca de 24,6 % do total. Os sistemas de condicionamento de ambientes e refrigeração comercial neste tipos de prédios são responsáveis por um grande consumo de energia elétrica e de demanda, estando na faixa de 35 % a 40 % do consumo total. O deslocamento da demanda elétrica do horário de ponta para horários fora de ponta traz uma redução de custos para os consumidores, devido às tarifas diferenciadas nesses horários. Além disso, a concessionária que fornece a energia pode economizar no investimento da geração e distribuição, pela diminuição da demanda nos horários de ponta. Os sistemas de termoacumulação têm como principal objetivo à racionalização da demanda elétrica, devido à utilização da mesma em períodos de baixa demanda, além da redução do investimento inicial. A acumulação de energia a baixa temperatura pode ser feita através de bancos água gelada ou bancos de gelo, sendo que estes últimos têm elevada capacidade de armazenamento em menores volumes, devido à mudança de fase. Neste trabalho utilizou-se como sistema de termoacumulação, o banco de gelo, para o condicionamento térmico de cinco diferentes ambientes com duas estratégias de operação: termoacumulação com carga total e carga simultânea. Para o controle das temperaturas dos respectivos ambientes foram utilizadas as lógicas de controle convencionais ("On-off" e PID) nas vazões de água gelada em cada "fan-coil". Comparouse as diferenças dos tipos de controladores...

Efeito do tempo de armazenamento do leite cru e da temperatura de esticagem do leite pasteurizado sobre sua vida de prateleira.; Effects of raw milk storage time and pasteurized milk storage temperature on milk shelflife.

Gustavo Braga Sanvido
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/07/2007 PT
Relevância na Pesquisa
36.56%
O objetivo do trabalho foi avaliar o efeito do tempo de armazenamento do leite cru e da temperatura de estocagem do leite pasteurizado sobre sua qualidade físicoquímica, microbiológica e vida de prateleira. Para cada experimento utilizouse 150 litros de leite cru que foram divididos em 3 latões de 50 litros armazenados por 0, 4 ou 7 dias a 5 ± 1ºC antes da pasteurização. Durante o armazenamento refrigerado, amostras de leite cru foram avaliadas quando a presença de resíduos de antibióticos, contagem de células somáticas, pH, acidez, densidade, extrato seco total, gordura, nitrogênio total e solúvel em pH 4,6 e em TCA 24%, coliformes a 3035 ºC e a 45ºC e a contagem dos seguintes microorganismos: aeróbios mesófilos, psicrotróficos, Pseudomonas spp., termodúricos mesófilos e psicrotróficos, esporos mesófilos e psicrotróficos. Após o período de armazenamento refrigerado o leite foi pasteurizado (7275 ºC/1520 segundos), refrigerado (5±1ºC) e envasado em embalagens plásticas de polietileno, as quais foram divididas em dois lotes e estocadas a 5±1ºC ou a 10±1ºC. Durante o armazenamento refrigerado amostras dos leites pasteurizados foram avaliadas para as mesmas características, excetuandose contagem de células somáticas e a presença de resíduos de antibióticos e incluindose os testes de eficiência de pasteurização (peroxidase e fosfatase) e a pesquisa de Salmonela spp. O final da vida de prateleira do leite pasteurizado foi estabelecido como sendo o primeiro dia em que as amostras apresentassem contagem total de microorganismos mesófilos aeróbios superior a 8 x 10 4 UFC/mL. O experimento completo foi repetido três vezes e o delineamento experimental utilizado foi o Splitsplitplot com três fatores. Durante o armazenamento refrigerado do leite cru observouse o aumento significativo da proteólise...

Logistica de armazenamento de frutos e hortaliças em supermercado; Storage logistic of fruits and vegetables in suprmarket

Daniela de Freitas Borghi
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 10/10/2008 PT
Relevância na Pesquisa
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O principal objetivo deste estudo é minimizar as grandes perdas de frutos e hortaliças que ocorrem durante seu armazenamento em supermercados, usando um modelo matemático para otimizar a distribuição dos produtos em depósito e minimizar os custos referentes ao seu armazenamento. Para tanto, foram utilizados dados da literatura do tempo de vida dos produtos estudados (aipo, alface, alho-porro, ameixa, beterraba, cebola, cenoura, chicória, couve-flor, espinafre, mamão papaya, morango, nabo, pepino, pêssego, pimentão, rabanete, salsinha, tomate e uva). O modelo matemático desenvolvido usa uma formulação de programação mista inteira e linear (MILP). O modelo foi implementado no software GAMSe o solver utilizado foi o CPLEX. Foram realizadas otimizações considerando diversas temperaturas de armazenamento e preços de aquisição para os produtos, visando minimizar os custos referentes ao seu armazenamento. Foi possível realizar uma análise em relação ao tempo de vida de cada produto em função da temperatura. Os resultados mostraram que quanto mais distante a temperatura real de armazenamento de um produto estiver de sua temperatura ideal, maiores serão os custos com a perda de qualidade deste produto. Verificou-se que o custo referente à perda de qualidade dos produtos tem grande influência no custo total de armazenamento...

Conexão entre os processos de degradação das reservas de proteinas e carboidratos e o edfeito dos hormonios e açucares em sementes de Sesbania virgata (Cav.) Pers; Connection between storage proteins and carbohydrates degradation and the effects of hormones and sugars in seeds of Sesbania virgata (Cav.) Pers

Patricia Pinho Tonini
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/12/2008 PT
Relevância na Pesquisa
36.53%
Sementes de Sesbania virgata (Cav.) Pers. acumulam suas reservas de carbono no endosperma na forma de um polissacarídeo de parede celular, o galactomanano. A mobilização deste ocorre após a germinação e envolve três enzimas hidrolíticas, dentre elas a a-galactosidase. Além da reserva de carbono, há uma grande quantidade de corpos protéicos, no citoplasma das células endospérmicas, que constituem a principal reserva de nitrogênio nestas sementes. Para que ocorra a correta distribuição dos produtos de degradação das reservas deve haver sincronização entre os processos de degradação das reservas de carbono e nitrogênio, porém para compreender tais mecanismos, é necessário estudar aspectos do controle da produção e ação das enzimas responsáveis pela hidrólise das reservas. Buscando determinar em que ponto do metabolismo a semente de S. virgata se encontra em relação à produção destas enzimas hidrolíticas, durante e após a germinação, e supostamente os tecidos envolvidos nesta produção, sementes desta espécie foram embebidas em actinomicina-D (inibidor de transcrição) e cicloheximida (inibidor de tradução) e os efeitos destes inibidores verificados através da atividade e detecção da a-galactosidase no tegumento e endosperma destas sementes. Além disso...

Projeção e localização da infraestrutura de armazenamento das safras de grãos; Projection and localization of storage infrastructure for grain crops

Marina Falascina Machado
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/02/2013 PT
Relevância na Pesquisa
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A agricultura brasileira apresentou, nos últimos anos, altas taxas de crescimento, sobretudo no setor de grãos. Para o acondicionamento de toda a produção de forma adequada, as redes de armazenamento são indispensáveis, e os armazéns, por sua vez, devem estar localizados em áreas de maior concentração de produção de grãos evitando a perda desnecessária do produto e garantindo a sua qualidade. O presente trabalho buscou diagnosticar a capacidade de armazenamento existente e, comprovar, calculando a previsão futura da produção, da produtividade e da área a necessidade de infraestrutura de armazenamento de grãos, assim como simular o tamanho, o número, o custo e a localização de novas unidades de armazenamento nas principais microrregiões produtoras. O trabalho foi dividido em três etapas: a primeira consistiu no diagnóstico da quantidade existente de unidades estáticas de armazenamento de grãos no país e na previsão da produção da produtividade e área das culturas da soja, do milho e do arroz. Na segunda etapa foram identificadas as 100 principais microrregiões produtoras de grãos do Brasil, e a localização de novas unidades de armazenamento. A terceira etapa consistiu na definição do número e tamanho das unidades de armazenamento que devem ser instaladas para suprir a futura necessidade de armazenamento de grãos...

Análise computacional da cromatina de espermatozóides de galo (Gallus gallus) e determinação do período de armazenamento dos espermatozóides nas espermatecas de galinhas; Computacional analysis of the chromatin of fowl’s spermatozoa (Gallus gallus) and determination of the storage time of spermatozoa in the sperm storage tubules in fowl hens

Rodrigues, Ana Carolina Nunes
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
36.54%
Os objetivos desse trabalho foram testar novas variantes metodológicas utilizando coloração com azul de toluidina, até se estabelecer um protocolo confiável para a avaliação computacional da compactação da cromatina em espermatozóides de galo, buscar alterações na compactação da cromatina durante o armazenamento dos mesmos na espermateca de galinhas, observar a duração do período de armazenamento e estimar a variação na quantidade de espermatozóides armazenados nos segmentos cranial, médio e caudal da região da espermateca durante 23 dias. Para avaliação computacional da compactação da cromatina, foram utilizadas 20 amostras de sêmen de galo, sendo 10 amostras de galos com 35 semanas de idade (Galos Novos) e 10 amostras de galos com 60 semanas de idade (Galos Velhos). Para a análise dos espermatozóides durante o armazenamento nas espermatecas das galinhas, foram utilizadas 48 matrizes pesadas (44 fêmeas e 4 machos) da linhagem Cobb avian 48 com 36 semanas de idade. Foi coletado material da junção utero-vaginal das fêmeas por 23 dias após a cópula com os machos, sendo que a cada 4 dias, 6 fêmeas foram sacrificadas para confecção de lâminas histológicas da região da espermateca. Foram testados diferentes métodos de desnaturação e coloração com AT...

The integration of fluctuating renewable energy using energy storage

Connolly, David
Fonte: University of Limerick Publicador: University of Limerick
Tipo: Doctoral thesis; all_ul_research; ul_published_reviewed; ul_theses_dissertations; none
ENG
Relevância na Pesquisa
36.53%
peer-reviewed; Energy storage is often portrayed as an ideal solution for the integration of fluctuating renewable energy (RE) due to the flexibility it creates. However, there is uncertainty surrounding energy storage in terms of the technologies that currently exist, the additional RE it enables, and its role in modern electricity markets. These uncertainties have hampered the deployment of large‐scale energy storage and hence, this research examined these concerns. This research began by identifying the most feasible energy storage technology available for the integration of fluctuating RE, specifically for Ireland. Due to its technical maturity and large‐scale capacities, pumped hydroelectric energy storage (PHES) was deemed the most viable technology, but the literature outlined a lack of suitable sites for its construction. Therefore, a new software tool was developed in this study to search for suitable PHES sites, which was then applied to two counties in Ireland. The results indicate that these two counties alone have over 15 sites suitable for freshwater PHES, which in some cases could be twice as large as Ireland’s only existing PHES facility. Hence, the next stage of this research assessed the benefits of constructing large‐scale energy storage in Ireland. To do this...

Improving Storage with Stackable Extensions

Guerra, Jorge
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
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Storage is a central part of computing. Driven by exponentially increasing content generation rate and a widening performance gap between memory and secondary storage, researchers are in the perennial quest to push for further innovation. This has resulted in novel ways to “squeeze” more capacity and performance out of current and emerging storage technology. Adding intelligence and leveraging new types of storage devices has opened the door to a whole new class of optimizations to save cost, improve performance, and reduce energy consumption. In this dissertation, we first develop, analyze, and evaluate three storage exten- sions. Our first extension tracks application access patterns and writes data in the way individual applications most commonly access it to benefit from the sequential throughput of disks. Our second extension uses a lower power flash device as a cache to save energy and turn off the disk during idle periods. Our third extension is designed to leverage the characteristics of both disks and solid state devices by placing data in the most appropriate device to improve performance and save power. In developing these systems, we learned that extending the storage stack is a complex process. Implementing new ideas incurs a prolonged and cumbersome de- velopment process and requires developers to have advanced knowledge of the entire system to ensure that extensions accomplish their goal without compromising data recoverability. Futhermore...

Site characterisation for geological storage of carbon dioxide: examples of potential sites from the North West Shelf, Australia.

Gibson-Poole, Catherine Mary
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
36.54%
Release of anthropogenic greenhouse gas emissions to the atmosphere is a concern for global warming. Thus, practical and economic solutions are being sought to combat this problem. One possible methodology for reducing emissions is the geological storage of carbon dioxide (CO₂). The subsurface behaviour of CO₂is influenced by many variables; therefore, accurate appraisal of a potential CO₂storage site requires detailed site characterisation. In particular, potential sites need to be evaluated geologically in terms of their injectivity, containment and capacity. Detailed site characterisation was undertaken for two possible sites for geological storage of CO₂, located offshore northwest Australia in the Petrel and Barrow sub-basins. The injection targets in the Petrel Sub-basin are the Jurassic Plover and Elang formations, locally sealed by the Frigate Formation, and the overlying Cretaceous Sandpiper Sandstone, regionally sealed by the Bathurst Island Group. The Plover/Elang formations are laterally extensive, fluvio–deltaic sandstones of fair to good reservoir quality, with likely excellent lateral and vertical connectivity. The Frigate Formation may not be an effective seal up-dip, but the overlying secondary reservoir (Sandpiper Sandstone) and thick regional seal (Bathurst Island Group) will ensure continued CO₂containment. The Jurassic–Cretaceous post-rift sediments are structurally simple and dip gently up towards the basin margins with no defined structural closures. Therefore...

Some Policy and Research Questions Related to Energy Storage

SIOSHANSI, Ramteen
Fonte: Instituto Universitário Europeu Publicador: Instituto Universitário Europeu
Tipo: Trabalho em Andamento Formato: application/pdf; digital
EN
Relevância na Pesquisa
36.53%
This paper provides a survey of the history and future of storage development in the US and policy and analytical questions relating to storage. The paper discusses the history of storage development in the US, and some of the limitations in how storage investment was justified beginning in the 1970s, when much of the US’s current storage capacity was built. Then we discuss potential uses of storage beyond serving as an alternative to peaking capacity and uses of storage by entities other than a traditional vertically-integrated utility. After we lay out some policy and research questions related to energy storage and show how questions such as regulation, market products, and ownership can greatly affect the true value of storage and incentives for and efficiency of storage use and investment.; Loyola de Palacio Programme on Energy Policy

Heat transfer and thermal storage in fixed and fluidized beds of phase change materials

Izquierdo Barrientos, Maria Asunción
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
36.55%
Thermal energy storage is a key technology for energy conservation since many energy sources are intermittent in nature. Latent heat storage is considered one of the most efficient ways of storing thermal energy because, unlike sensible heat storage, it provides a high-energy storage density with a small temperature swing. There are available many storage techniques, including sensible and latent heat storage or a combination of both. Fixed and fluidized beds may be feasible technologies when the storing materials may be encapsulated in cans, spheres or microencapsulated in highly porous structures with protecting envelopes. This PhD thesis deals with thermal storage and heat transfer in fixed and fluidized beds with phase change materials (PCMs). The behavior of a bed with granular PCM as a thermal storage system is studied. Charging and discharging experiments are carried out and models for the transient response of the bed are developed for fixed and fluidized bed configurations. Moreover, a model for the heat transfer coefficient between the bed of PCM and an immersed surface is presented and validated with experimental measurements. The experimental studies are conducted in a cylindrical bed filled with granular PCM and with air as the working fluid. The bed has an internal diameter of 200 mm. The granular PCMs used consist of paraffin...

Autonomous storage management for low-end computing environments

Post, Ansley
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: 188 p.; application/pdf
ENG
Relevância na Pesquisa
36.57%
To make storage management transparent to users, enterprises rely on expensive storage infrastructure, such as high end storage appliances, tape robots, and offsite storage facilities, maintained by full-time professional system administrators. From the user's perspective access to data is seamless regardless of location, backup requires no periodic, manual action by the user, and help is available to recover from storage problems. The equipment and administrators protect users from the loss of data due to failures, such as device crashes, user errors, or virii, as well as being inconvenienced by the unavailability of critical files. Home users and small businesses must manage increasing amounts of important data distributed among an increasing number of storage devices. At the same time, expert system administration and specialized backup hardware are rarely available in these environments, due to their high cost. Users must make do with error-prone, manual, and time-consuming ad hoc solutions, such as periodically copying data to an external hard drive. Non-technical users are likely to make mistakes, which could result in the loss of a critical piece of data, such as a tax return, customer database, or an irreplaceable digital photograph. In this thesis...

A Novel Business Model for Aggregating the Values of Electricity Storage

HE, Xian; DELARUE, Erik; D'HAESELEER, William; GLACHANT, Jean-Michel
Fonte: Instituto Universitário Europeu Publicador: Instituto Universitário Europeu
Tipo: Trabalho em Andamento Formato: application/pdf
EN
Relevância na Pesquisa
36.54%
Electricity storage is considered a valuable source of flexibility whose applications cover the whole electricity value chain. However, most of the existing evaluation methods for electricity storage are conceived for only one specific use of the storage, which often leads to the conclusion that the investment on storage does not pay off. We think that the value of storage cannot be properly estimated without taking into account the possibility of aggregating the services that storage can offer to different actors. In this paper, we propose a new business model that allows aggregating multiple revenue streams of electricity storage in a systematic way. The main idea of the business model is to coordinate a series of auctions in which the right to utilize the storage unit is auctioned in different time horizons. The model consists of an optimization module and a coordination mechanism. The former simulates the optimal strategy of a certain actor using the available storage capacities in a certain auction, while the latter ensures non-conflicting uses of storage by actors in different auctions. The functioning of the model is demonstrated by a case study. The results show that a storage unit can achieve a higher return on investment in the manner proposed in the business model.

Storage Media For Avulsed Teeth: A Literature Review

Poi,Wilson Roberto; Sonoda,Celso Koogi; Martins,Christine Men; Melo,Moriel Evangelista; Pellizzer,Eduardo Pizza; Mendonca,Marcos Rogerio de; Panzarini,Sonia Regina
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2013 EN
Relevância na Pesquisa
36.54%
Dental avulsion is the most severe type of traumatic tooth injuries because it causes damage to several structures and results in the complete displacement of the tooth from its socket in the alveolar bone. The ideal situation is to replant an exarticulated tooth immediately after avulsion because the extraoral time is a determinant factor for treatment success and for a good prognosis. However, it is not always possible. The success of replantation depends on a number of factors that may contribute to accelerate or minimize the occurrence of root resorption or ankylosis, among which is the type and characteristics of the medium used for temporary storage during the time elapsed between avulsion and replantation. Maintaining the tooth in an adequate wet medium that can preserve, as longer as possible, the vitality of the periodontal ligament cells that remain on root surface is the key to success of replantation. Recent research has led to the development of storage media that produce conditions that closely resemble the original socket environment, with adequate osmolality (cell pressure), pH, nutritional metabolites and glucose, and thus create the best possible conditions for storage. Although these storage media can now be purchased in the form of retail products...

Parametric studies and optimisation of pumped thermal electricity storage

McTigue, Joshua; White, Alexander; Markides, Christos N.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; accepted version
EN
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This is the accepted manuscript of a paper published in Applied Energy Volume 137, 1 January 2015, Pages 800?811, DOI: 10.1016/j.apenergy.2014.08.039; Several of the emerging technologies for electricity storage are based on some form of thermal energy storage (TES). Examples include liquid air energy storage, pumped heat energy storage and, at least in part, advanced adiabatic compressed air energy storage. Compared to other large-scale storage methods, TES benefits from relatively high energy densities, which should translate into a low cost per MW h of storage capacity and a small installation footprint. TES is also free from the geographic constraints that apply to hydro storage schemes. TES concepts for electricity storage rely on either a heat pump or refrigeration cycle during the charging phase to create a hot or a cold storage space (the thermal stores), or in some cases both. During discharge, the thermal stores are depleted by reversing the cycle such that it acts as a heat engine. The present paper is concerned with a form of TES that has both hot and cold packedbed thermal stores, and for which the heat pump and heat engine are based on a reciprocating Joule cycle, with argon as the working fluid. A thermodynamic analysis is presented based on traditional cycle calculations coupled with a Schumann-style model of the packed beds. Particular attention is paid to the various loss-generating mechanisms and their effect on roundtrip efficiency and storage density. A parametric study is first presented that examines the sensitivity of results to assumed values of the various loss factors and demonstrates the rather complex influence of the numerous design variables. Results of an optimisation study are then given in the form of trade-off surfaces for roundtrip efficiency...

Impacts of Geological Variability on Carbon Storage Potential

Eccles, Jordan Kaelin
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2011
Relevância na Pesquisa
36.55%

The changes to the environment caused by anthropogenic climate change pose major challenges for energy production in the next century. Carbon Capture and Storage (CCS) is a group of technologies that would permit the continued use of carbon-intense fuels such as coal for energy production while avoiding further impact on the global climate system. The mechanism most often proposed for storage is injection of CO2 below the surface of the Earth in geological media, with the most promising option for CO2 reservoirs being deep saline aquifers (DSA's). Unlike oil and gas reservoirs, deep saline aquifers are poorly characterized and the variability in their properties is large enough to have a high impact on the overall physical and economic viability of CCS. Storage in saline aquifers is likely to be a very high-capacity resource, but its economic viability is almost unknown. We consider the impact of geological variability on the total viability of the CO2 storage system from several perspectives. First, we examine the theoretical range of costs of storage by coupling a physical and economic model of CO2 storage with a range of possible geological settings. With the relevant properties of rock extending over several orders of magnitude...

Large scale quantification of aquifer storage and volumes from the Peninsula and Skurweberg Formations in the southwestern Cape

Blake,Dylan; Mlisa,Andiswa; Hartnady,Chris
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
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The Western Cape Province of South Africa is a relatively water-scarce area as a result of the Mediterranean climate experienced. Due to the increased usage of groundwater, and the requirement to know how much water is available for use, it is imperative as a 1st step to establish an initial estimate of groundwater in storage. The storage capacity, namely, the total available storage of the different aquifers, and the storage yield of the fractured quartzitic Peninsula and Skurweberg Formation aquifers of the Table Mountain Group (TMG), are calculated with a spreadsheet and Geographic Information System (GIS) model. This model is based on the aquifer geometry and estimated values (based on measured data) for porosity and specific storage (calculated using the classic Jacob relation). The aquifer geometry is calculated from 1:50 000 and 1:250 000 geological contacts, faults and major fractures, with dips and aquifer formation thickness calculated through structural geology 1st principles using a Digital Elevation Model (DEM). Balanced geological cross-sections constructed through the model areas provide an important check for the aquifer top and bottom surface depth values produced by the GIS model. The storage modelling undertaken here forms part of the City of Cape Town TMG Aquifer Feasibility Study and Pilot Project...

Comparison of GRACE with in situ hydrological measurement data shows storage depletion in Hai River basin, Northern China

Moiwo,Juana Paul; Yang,Yonghui; Li,Huilong; Han,Shumin; Hu,Yukun
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2009 EN
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Water storage change has implications not only for the hydrological cycle, but also for sustainable water resource management in especially semi-arid river basins. Satellite/remote sensing techniques have gained increasing application in monitoring basin and regional hydrological processes in recent decades. In this study, the latest version of GRACE (Gravity Recovery and Climate Experiment) is used to estimate total water storage change in the Hai River basin (HRB) of Northern China for the period January 2003 to December 2006. Time-series comparisons show a good agreement between the estimated storage change from the GRACE satellite data and in situ hydrological measurement data at especially the seasonal cycle with R = 0.82 and RMSE = 17.25 mm. The good agreement suggests that GRACE detects storage change in the 318 866 km² HRB study area. It also implies that the in situ hydrological measurements of soil moisture and groundwater sufficiently characterise storage change in the semi-arid river basin. Change in soil moisture storage is less than that in saturated storage, suggesting that storage depletion in the basin is mainly in the saturated zone. Both the GRACE and hydrological measurement data indicate storage loss in the range of 12.72 to 23.76 mm/yr - a phenomenon that has been detected in previous studies in the basin. GRACE hydrology data could therefore be handy in monitoring storage dynamics and water availability in the study area. As GRACE data are available for virtually every region of the world...