Analysis of a molten carbonate fuel cell: cogeneration to produce electricity and cold water

The fuel cell is an emerging cogeneration technology that has been applied successfully in Japan, the USA and some countries in the European Union. This system performs direct conversion of the chemical energy of the oxidation of hydrogen from fuel with atmospheric oxygen into direct current electricity and waste heat via an electrochemical process relying on the use of different electrolytes (phosphoric acid, molten carbonate and solid oxide, depending on operating temperature). This technology permits the recovery of waste heat, available from 200 degreesC up to 1000 degreesC depending on the electrolyte technology, which can be used in the production of steam, hot or cold water, or hot or cold air, depending on the associated recuperation equipment. In this paper, an energy, exergy and economic analysis of a fuel cell cogeneration system (FCCS) is presented. The FCCS is applied in a segment of the tertiary sector to show that it is a feasible alternative for rational decentralized energy production under Brazilian conditions. The technoeconomic analysis shows a global efficiency or fuel utilization efficiency of 86%. Analysis shows that the exergy losses in the fuel cell unit and the absorption refrigeration system are significant. Furthermore, the payback period estimated is about 3 and 5 years for investments in fuel cells of 1000 and 1500 US$/kW, respectively. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Thermoeconomic analysis applied in cold water production system using biogas combustion

In this paper is proposed the use of biogas generated in the Wastewater Treatment Plant of a Dairy industry. The objective is to apply a thermoeconomic analysis to the supplementary cold water production of an absorption refrigeration system (NH3 + H2O) by the burning of such gas. The exergoeconomic analysis is carried out to allow a comparison between an absorption refrigeration system and of an equivalent compression refrigeration system that uses NH3 as work fluid. The proposed exergoeconomic model uses functional diagrams and allows one to obtain the exergetic incremental functions for each component individually and for the system as a whole. The model minimizes the exergetic manufacturing cost (EMC) which represents the cost of supplementary cold water production at 1degreesC (exergetic base) needed for this dairy's cold storage. As a conclusion, the absorption refrigeration system is better than compression refrigeration system, when the biogas cost is not considered. 2004 Elsevier Ltd. All rights reserved.

Electricity, hot water and cold water production from biomass. Energetic and economical analysis of the compact system of cogeneration run with woodgas from a small downdraft gasifier

Wood gasification technologies to convert the biomass into fuel gas stand out. on the other hand, producing electrical energy from stationary engine is widely spread, and its application in rural communities where the electrical network doesn't exist is very required. The recovery of exhaust gases (engine) is a possibility that makes the system attractive when compared with the same components used to obtain individual heat such as electric power. This paper presents an energetic alternative to adapt a fixed bed gasifier with a compact cogeneration system in order to cover electrical and thermal demands in a rural area and showing an energy solution for small social communities using renewable fuels. Therefore, an energetic and economical analysis from a cogeneration system producing electric energy, hot and cold water, using wooden gas as fuel from a small-sized gasifier was calculated. The energy balance that includes the energy efficiency (electric generation as well as hot and cold water system; performance coefficient and the heat exchanger, among other items), was calculated. Considering the annual interest rates and the amortization periods, the costs of production of electrical energy, hot and cold water were calculated, taking into account the investment, the operation and the maintenance cost of the equipments. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.

How do cold water biota arrive in a tropical bay near Rio de Janeiro, Brazil?

Previous ecological studies on foraminifera and ostracoda from the tropical Sepetiba Bay, located in the southern part of the State of Rio de Janeiro, Brazil, have noted the presence in this area of some cool water taxons typical of the Argentine continental platform. These studies have proposed that parcels of these temperate waters with their associated biological indicators are advected northward along the platform, penetrating into some tropical entrances of the southeast coast of Brazil. In the present study, ecological data (foraminifera, ostracoda and microbivalves), are used together with information obtained by satellite tracked drifting buoys and digital thermal imagery obtained from NOAA satellites to indicate the path taken by these high latitude species along the southern Brazilian coast to arrive in the Sepetiba Bay, near the city of Rio de Janeiro. Our general conclusion is that biotic elements native to the colder, less saline marine waters seen to the south of Brazil have been and are being advected northward along the inner part of the continental platform to about 22 degrees S. Water parcels containing this biota may, in a sporadic fashion, enter into the tropical Sepetiba Bay. The passage of meteorological fronts through the region is considered to be an important if not the principal mechanism for the sporadic entry of the cool water into the Southern Coastal Entrance of the State of Rio de Janeiro. (C) 1998 Elsevier B.V.s Ltd. All rights reserved.

Effects of Cold Water Immersion and Active Recovery on Post-Exercise Heart Rate Variability

The aim of the present study was to investigate the potential benefits of cold water immersion (CWI) and active recovery (AR) on blood lactate concentration ([Lac]) and heart rate variability (HRV) indices following high-intensity exercise. 20 male subjects were recruited. on the first visit, an incremental test was performed to determine maximal oxygen consumption and the associated speed (MAS). The remaining 3 visits for the performance of constant velocity exhaustive tests at MAS and different recovery methods (6 min) were separated by 7-day intervals [randomized: CWI, AR or passive recovery (PR)]. The CWI and AR lowered [Lac] (p < 0.05) at 11, 13 and 15 min after exercise cessation in comparison to PR. There was a 'time' and 'recovery mode' interaction for 2 HRV indices: standard deviation of normal R-R intervals (SDNN) (partial eta squared = 0.114) and natural log of low-frequency power density (lnLF) (partial eta squared = 0.090). CWI presented significantly higher SDNN compared to PR at 15 min of recovery (p < 0.05). In addition, greater SDNN values were found in CWI vs. AR during the application of recovery interventions, and at 30 and 75 min post-exercise (p < 0.05 for all differences). The lnLF during the recovery interventions and at 75 min post-exercise was greater using CWI compared with AR (p < 0.05). For square root of the mean of the sum of the squares of differences between adjacent R-R intervals (RMSSD) and natural log of high-frequency power density (lnHF), a moderate effect size was found between CWI and PR during the recovery interventions and at 15 min post-exercise. Our findings show that AR and CWI offer benefits regarding the removal of [Lac] following high-intensity exercise. While limited, CWI results in some improvement in post-exercise cardiac autonomic regulation compared to AR and PR. Further, AR is not recommended if the aim is to accelerate the parasympathetic reactivation.

Alternative procedure for the cold test for soybean seeds

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dimensionamento e sobreposição de nichos dos portunídeos (Decapoda, Brachyura), na Enseada da Fortaleza, Ubatuba, São Paulo, Brasil

The niche breadth of the Portunidae and their overlap on the subtidal sediments of Fortaleza bay, Ubatuba (São Paulo) was analyzed. Samples were made monthly from November/1988 to October/1989, inseven areas of the bay using a shrimp fishery boat equipped with two otter-trawls. Each area was characterized based on environmental factors such as depth, temperature, salinity, dissolved oxygen, organic matter and granulometric composition of the sediment. The number of individuais of each species was registered to each area (resource). Levins's standardized measure (BA) and niche percentage were calculated. Five species of swimming crabs were recorded in this study: Callinectes ornatus Ordway, 1863, Arenaeus cribrarius (Lamarck, 1818), Portunus spinimanus Latreille, 1819, Callinectes danae Smith, 1869 and Portunus spinicarpus (Stimpson, 1871). The widest ecological niche occurred to C. ornatus, present in all sampled areas (generalist species). Such fact can be related to high sediment tolerance when it is compared to P. spinimanus (especialist species) which was limited to the areas with coarse granulometric fractions. Highest niche overlap was verified between C. danae and A. cribrarius may be due to greater salinity tolerance of these species. The low occurrence of P. spinicarpus and its reduced niche size in Fortaleza Bay are due to association of this species to cold water currents (ACAS) more evidente in smaler depths during summer months. One future evaluation of the portunid diet can be useful to complement informations about this important aspect of the marine ecology.

Métodos para quebra de dormência de unidades de dispersão de Zizyphus joazeiro Mart. (Rhamnaceae)

O Z. joazeiro é uma espécie florestal de grande importância socioeconômica para a Região Nordeste do Brasil e apresenta dificuldades na germinação das unidades de dispersão, causada pela impermeabilidade à água. Este estudo avaliou tratamentos pré-germinativos de superação de dormência de unidades de dispersão de Z. joazeiro. O experimento foi conduzido em casa de vegetação, no Centro de Ciências Agrárias da Universidade Federal da Paraíba, em Areia, PB, Brasil. Os tratamentos consistiram em: testemunha (unidades de dispersão intactas), escarificação mecânica com lixa d'água, imersão em água, à temperatura ambiente, por 24, 48, 72, 96 e 120 h, imersão em água à temperatura de 70 ºC, por 3 min, e imersão em ácido sulfúrico concentrado por 30, 60, 90, 120 e 150 min. As variáveis avaliadas foram porcentagem de emergência, primeira contagem e velocidade de emergência, comprimento e massa seca de plantas. Os tratamentos que propiciaram máxima emergência de plântulas de Z. joazeiro foram imersão de unidades de dispersão em água fria por 48 h, imersão em água a 70 ºC por 3 min e escarificação manual com lixa, por superar a dureza tegumentar das unidades de dispersão dessa espécie.

Temperaturas para a germinação de sementes de capixingui (Croton floribundus - Spreng - Euphorbiaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fuel cell cogeneration system: a case of technoeconomic analysis

Fuel Cell is the emerging technology of cogeneration, and has been applied successfully in Japan, U.S.A. and some OECD countries. This system produces electric power by an electrolytic process, in which chemical substances (the most utilized substances are solid oxide, phosphoric acid and molten carbonate) absorb the components H-2 and O-2 of the combustion fuel. This technology allows the recovery of residual heat, available from 200 degrees C up to 1000 degrees C (depending on the electrochemical substance utilized), which can be used for the production of steam, hot or cold water, or hot or cold air, depending on the recuperation equipment used. This article presents some configurations of fuel cell cogeneration cycles and a study of the technical and economic feasibility for the installation of the cogeneration systems utilizing fuel cell, connected to an absorption refrigeration system for st building of the tertiary sector, subject to conditions in Brazil. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Spatial-temporal variation of Paralonchurus brasiliensis (Actinopterygii: Sciaenidae) density in relation to some environmental factors on the inner shelf of south-eastern Brazilian coast

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síndrome da cauda flácida em cão da raça labrador retriever: primeiro relato no Brasil

A síndrome da cauda flácida é uma enfermidade que acomete cães de caça, principalmente Labradores Retriever e do grupo Pointer. Embora sua etiologia não esteja totalmente definida, sabe-se que sua ocorrência é precedida de esforço físico extenuante, exposição ao frio ou água fria e confinamento em caixas de transporte. O presente trabalho descreve o caso de um cão da raça Labrador Retriever, macho não castrado, de quatro anos de idade que apresentou súbita dor e flacidez da cauda após banho frio. Fratura vertebral, síndrome da cauda eqüina, outras enfermidades da medula espinhal ou de glândulas adanais e afecções prostáticas foram descartadas após exames auxiliares. A divulgação deste relato é relevante uma vez que esta síndrome ainda não foi descrita no Brasil.

Study of fuel cell co-generation systems applied to a dairy industry

This paper presents a methodology for the study of a molten carbonate fuel cell co-generation system. This system is applied to a dairy industry of medium size that typically demands 2100 kW of electricity, 8500 kg/h of saturated steam (P = 1.08 MPa) and 2725 kW of cold water production. Depending on the associated recuperation equipment, the co-generation system permits the recovery of waste heat, which can be used for the production of steam, hot and cold water, hot and cold air. In this study, a comparison is made between two configurations of fuel cell co-generation systems (FCCS). The plant performance has been evaluated on the basis of fuel utilisation efficiency and each system component evaluated on the basis of second law efficiency. The energy analysis presented shows a fuel utilisation efficiency of about 87% and exergy analysis shows that the irreversibilities in the combustion chamber of the plant are significant. Further, the payback period estimated for the fuel cell investment between US$ 1000 and US$ 1500/k-W is about 3 and 6 years, respectively. (C) 2002 Elsevier B.V. B.V. All rights reserved.

A new Pennsylvanian Oriocrassatellinae from Brazil and the distribution of the genus Oriocrassatella in space and time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of the heat treatment in the electrochemical corrosion of Al-Zn-Mg alloys

The localized corrosion of Al-(5.03%)Zn-(1.67%)Mg-(0.23%)Cu alloys and high purity Al has been studied using electrochemical techniques, optical microscopy, SEM and EDX. The samples were previously submitted to different heat treatments in which coherent and incoherent MgZn 2 precipitates with different distribution and aggregation degree were produced. The influence of NaCl and Na 2SO 4, dissolved oxygen, immersion time and convection were studied. In NaCl solutions, pitting potentials for the alloys were more negative than for aluminium, indicating an increase in their susceptibility to localized corrosion. Moreover, annealed and cold-rolled alloys presented more negative pitting and repassivation potentials than those submitted to age hardening with direct or interrupted quenching. In annealed and cold-rolled samples, pit nucleation and propagation takes place in the zones where MgZn 2 is accumulated. In the case of the age-hardened alloys, a double pitting behaviour is observed, the first one in the magnesium and zinc enriched regions and the second in the matrix. While the cold water quenched alloy is susceptible to stress corrosion craking, the alloy submitted to the interrupted quenching process is less susceptible to intergranular attack. The sulphate ion shifts the pitting potential of aluminium and the alloys by chloride towards more positive values because it impedes local accumulations of the latter. © 1992 Chapman & Hall.