Modelado matemático y simulación numérica de una planta desaladora - MSF

La complejidad del problema del acceso al agua potable apunta a la necesidad de estudios y evaluaciones que faciliten el uso de fuentes alternativas de agua potable, las cuales puedan satisfacer las necesidades humanas básicas y también permitan el desarrollo de actividades económicas en estas regiones. En estos términos, motivados por la discusión de un tema tan relevante, el objetivo de este trabajo fue realizar el modelado matemático y la simulación numérica de una planta de desalinización utilizando el método de Destilación Flash de Etapa Múltiple (MSF), como un método de desalinización para cumplir las demandas existentes. Para la ejecución de este estudio, se utilizó el software de modelado EES®, en el que se evaluó la influencia de los parámetros operativos en el rendimiento de la planta desaladora. El modelo resultante pudo reproducir los datos operativos reales y las condiciones operativas previstas. Las herramientas de modelado matemático y simulación numérica son importantes para el desarrollo de propuestas de proyectos y tecnologías eficientes tecnologías eficientes, viables para la desalinización del agua con capacidad de ayudar en el suministro de la misma. En teoría, su uso puede reducir significativamente el tiempo de ingeniería, creando la capacidad de probar diferentes opciones variables, operativas y otros parámetros, en un programa de computadora y no en modelos de prueba física. Esta capacidad fue teóricamente el costo del proyecto / instalación, y el costo final para la población que puede aprovechar estas instalaciones (si se construyen, instalan y ponen en funcionamiento), eliminando la necesidad de hacer y probar múltiples prototipos físicos. Los resultados del estudio muestran que el número de etapas es la variable que más afecta el rendimiento de la planta, ya que el flujo de vapor de calefacción disminuye dramáticamente con el aumento en el número de etapas, esto hace que la planta sea más eficiente y económica desde el punto de vista energético. También se verifica que las variables relacionadas con el agua de mar no proporcionan variaciones significativas en el rendimiento de la planta. Finalmente, la elevación de la temperatura máxima de salmuera causa una reducción en el área total de transferencia de calor, sin embargo, con respecto al rendimiento de la planta, la temperatura máxima de la salmuera no afecta significativamente este parámetro en el proceso.The complexity of the access to drinking water problem points to the need for studies and evaluations that facilitate the use of alternative sources of drinking water able meet basic human needs and also enable the development of economic activities in these regions. In these terms, motivated by the discussion of such a relevant subject, the objective of this work was to perform the mathematical modeling and the numerical simulation of a desalination plant using the Multiple Stage Flash Distillation (MSF) method, as a desalination method to meet the existing demands. For the execution of this study, the EES® modeling software was used, in which the influence of operational parameters on the performance of the desalination plant was evaluated. The resulting model was able to reproduce the actual operationa data and forecast operating conditions. The tools of mathematical modeling and numerical simulation are important for the development of proposals of projects and efficient and viable technologies for water desalination, able to assist in water supply. In theory, its use can significantly reduce engineering time, creating the ability to test different variableand operational options and other parameters, in a computer program, and not in physical test models. This capabilitycan theoretically affect the cost of the project/installation, and the final cost to the population that can take advantageof these facilities (if constructed, installed and put into operation), eliminating the need for multiple physical prototypesto be made and tested. The results of the study show that the number of stages is the variable that most affects theperformance of the plant, since the flow of heating steam decreases dramatically with the increase in the number ofstages, this makes the plant more efficient and economical from an energetic point of view. It is also verified that thevariables related to sea water do not provide significant variations in plant performance. And finally, the elevation ofthe maximum brine temperature causes a reduction in the total area of heat transfer, however, with respect to plantperformance, the maximum brine temperature does not significantly affect this parameter in the process.A complexidade do problema de acesso à água potável aponta para a necessidade de estudos e avaliações que viabilizem a utilização de fontes alternativas de água potável, capazes suprir as necessidades básicas humanas, e também possibilitar o desenvolvimento de atividades econômicas nessas regiões. Nestes termos, motivado pela discussão de um assunto tão relevante, o objetivo deste trabalho foi realizar a modelagem matemática e a simulação numérica de uma planta de dessalinização pelo método de Destilação Flash de Múltiplos Estágios (MSF), como método de dessalinização para atender as demandas existentes. Para a execução deste estudo foi utilizado o software de modelagem EES®, em que se avaliou a influência dos parâmetros operacionais sobre o desempenho da planta de dessalinização. O modelo resultante foi capaz de reproduzir os dados operacionais reais e prever as condições de operação. As ferramentas de modelagem matemática e simulação numérica são importantes para o desenvolvimento de proposições de projetos e tecnologias eficientes e viáveis de dessalinização da água, capazes de auxiliar no suprimento de água. Em teoria, a sua utilização pode reduzir significativamente o tempo de engenharia, criando a capacidade de se testar diferentes opções variáveis e operacionais e demais parâmetros, em um programa de computador, e não em modelos de teste físico. Essa capacidade pode afetar teoricamente o custo do projeto/instalação, bem como o custo final para a população que poderá usufruir destas instalações (se construídas, instaladas e colocadas em operação), eliminando a necessidade de vários protótipos físicos a serem feitos e testados. Os resultados do estudo mostram que o número de estágios é a variável que mais afeta o desempenho da planta, uma vez que a vazão de vapor de aquecimento diminui drasticamente com o aumento do número de estágios, isso torna a planta mais eficiente e econômica no ponto de vista energético. Verifica-se ainda que as variáveis relacionadas à água do mar não fornecem variações significativas no desempenho da planta. E, finalmente que a elevação da temperatura máxima da salmoura ocasiona a redução na área total de troca térmica, no entanto, com relação ao desempenho da planta, a temperatura máxima da salmoura não afeta significativamente esse parâmetro no processo

Exergoeconomic analysis in a food industry boiler: a case study

This study aims to apply the SPECO method in a firetube steam generating unit located in a food industry to measure the cost and to suggest actions that will increase its efficiency. In the current global scenario, researches for alternatives of the cost reduction and increased sustainability are more and more on the agenda in companies. Therefore, the present work develops a study to make possible the energy losses minimization in biomass boilers located in Saudali food industry, Ponte Nova (Minas Gerais, Brazil). The used methodology was developed from the exergoeconomic analysis using the Specific Exergy Costing (SPECO) method. To possibilitate this procedure it was necessary to map all the exergetic flows and to find its thermodynamic values. Regarding the fuel calorific potential, it was necessary the measurement of its average humidity, measured in (25 ± 1%), approximately, in order to obtain a Lower Calorific Power of 15960 kJ.kg-1. The massic and exergy flow rates values were defined using measurement equipments, thermodynamic tables and company’s information. The obtained results for exergetic efficiency, steam cost and fuel cost were, respectively, 51.74%, 0.0446 R$.(kWh)-1 and 0.01490 R$.(kWh)-1. These results evidenced a cost ratio between product and fuel of 1.99, which represents a product cost two times superior to the fuel cost, approximately. It is concluded that SPECO method application in Saudali industry evidenced important and often disregarded points, as the moisture interference in biomass available exergy and great variance between steam and fuel costs

Análise da eficiência energética de uma caldeira industrial movida a madeira

El objetivo de este trabajo fue caracterizar el rendimiento térmico de un generador de vapor con la intención de reducir el desperdicio de combustible y los costos involucrados. El potencial económico y social de un país tiene gran relación con su reserva energética y la manera como es explotada. El desarrollo provoca impactos ambientales significativos, siendo que la mayoría se debe a la generación y al uso de energía, cuya demanda se ha tornado cada vez mayor. La metodología empleada fue el análisis de una caldera industrial del tipo pirotubular modelo ATA 14 H 3N, de la marca ATA, con capacidad de 33,3 kg/s de vapor y una presión de hasta 1034 kPa, alimentada por combustible sólido (leña de eucalipto en troncos). Los datos necesarios para el análisis fueron obtenidos por medio de mediciones en campo y de informes de análisis químicos elaborados por empresas especializadas. El resultado de la eficiencia térmica de la caldera fue obtenido, por el método indirecto, en torno al 74%. Se concluye que para mejorar la eficiencia de la caldera será necesario optimizar el exceso de aire, así como el aislamiento de más tramos de la línea de vapor y la instalación de purgadores de condensado en los puntos distantes del centro de generación de vapor.The objective of this work was to characterize the thermal performance of a steam generator with the intention of reducing the waste of fuel and the costs involved. The economic and social potential of a country is closely related to its energy reserve and the way it is exploited. Development causes significant environmental impacts, the majority being due to the generation and use of energy, of which the demand has become increasingly large. The methodology used was the analysis of an industrial boiler of the ATA 14 H 3N pyrotubular type, of the ATA brand, with a capacity of 33.3 kg / s of steam and a pressure of up to 1034 kPa, fueled by solid fuel (eucalyptus firewood trunks). Data needed for the analysis were obtained through field measurements and chemical analysis reports prepared by specialized companies. The result of the thermal efficiency of the boiler was obtained, by the indirect method, around 74%. It has been concluded that in order to improve the efficiency of the boiler it will be necessary to optimize the excess air, as well as the isolation of more stretches of the steam line and the installation of condensate traps in distant points from the steam generation center.O objetivo deste trabalho foi caracterizar o desempenho térmico de um gerador de vapor com a intenção de reduzir o desperdício de combustível e os custos envolvidos. O potencial econômico e social de um país está intimamente relacionado à sua reserva de energia e à maneira como é explorada. O desenvolvimento causa impactos ambientais significativos, a maioria devido à geração e uso de energia, cuja demanda se torna cada vez maior. A metodologia utilizada foi a análise de uma caldeira industrial do tipo pirotubular ATA 14 H 3N, da marca ATA, com capacidade de 33,3 kg / s de vapor e pressão de até 1034 kPa, alimentada a combustível sólido (lenha eucalipto em troncos). Os dados necessários para a análise foram obtidos através de medições de campo e relatórios de análises químicas elaborados por empresas especializadas. O resultado da eficiência térmica da caldeira foi obtido, pelo método indireto, em torno de 74%. Conclui-se que, para melhorar a eficiência da caldeira, será necessário otimizar o excesso de ar, o isolamento de mais trechos da linha de vapor e a instalação de purgadores de condensado nos pontos distantes do centro de geração de vapor

Análisis de la Eficiencia Energética de una Caldera Industrial Alimentada por Leña

The objective of this work was to characterize the thermal performance of a steam generator with the intention of reducing the waste of fuel and the costs involved. The economic and social potential of a country is closely related to its energy reserve and the way it is exploited. Development causes significant environmental impacts, the majority being due to the generation and use of energy, of which the demand has become increasingly large. The methodology used was the analysis of an industrial boiler of the ATA 14 H 3N pyrotubular type, of the ATA brand, with a capacity of 33.3 kg / s of steam and a pressure of up to 1034 kPa, fueled by solid fuel (eucalyptus firewood trunks). Data needed for the analysis were obtained through field measurements and chemical analysis reports prepared by specialized companies. The result of the thermal efficiency of the boiler was obtained, by the indirect method, around 74%. It has been concluded that in order to improve the efficiency of the boiler it will be necessary to optimize the excess air, as well as the isolation of more stretches of the steam line and the installation of condensate traps in distant points from the steam generation center.O objetivo deste trabalho foi caracterizar o desempenho térmico de um gerador de vapor com a intenção de reduzir o desperdício de combustível e os custos envolvidos. O potencial econômico e social de um país está intimamente relacionado à sua reserva de energia e à maneira como é explorada. O desenvolvimento causa impactos ambientais significativos, a maioria devido à geração e uso de energia, cuja demanda se torna cada vez maior. A metodologia utilizada foi a análise de uma caldeira industrial do tipo pirotubular ATA 14 H 3N, da marca ATA, com capacidade de 33,3 kg / s de vapor e pressão de até 1034 kPa, alimentada a combustível sólido (lenha eucalipto em troncos). Os dados necessários para a análise foram obtidos através de medições de campo e relatórios de análises químicas elaborados por empresas especializadas. O resultado da eficiência térmica da caldeira foi obtido, pelo método indireto, em torno de 74%. Conclui-se que, para melhorar a eficiência da caldeira, será necessário otimizar o excesso de ar, o isolamento de mais trechos da linha de vapor e a instalação de purgadores de condensado nos pontos distantes do centro de geração de vapor.El objetivo de este trabajo fue caracterizar el rendimiento térmico de un generador de vapor con la intención de reducir el desperdicio de combustible y los costos involucrados. El potencial económico y social de un país tiene gran relación con su reserva energética y la manera como es explotada. El desarrollo provoca impactos ambientales significativos, siendo que la mayoría se debe a la generación y al uso de energía, cuya demanda se ha tornado cada vez mayor. La metodología empleada fue el análisis de una caldera industrial del tipo pirotubular modelo ATA 14 H 3N, de la marca ATA, con capacidad de 33,3 kg/s de vapor y una presión de hasta 1034 kPa, alimentada por combustible sólido (leña de eucalipto en troncos). Los datos necesarios para el análisis fueron obtenidos por medio de mediciones en campo y de informes de análisis químicos elaborados por empresas especializadas. El resultado de la eficiencia térmica de la caldera fue obtenido, por el método indirecto, en torno al 74%. Se concluye que para mejorar la eficiencia de la caldera será necesario optimizar el exceso de aire, así como el aislamiento de más tramos de la línea de vapor y la instalación de purgadores de condensado en los puntos distantes del centro de generación de vapor

Impact of a High-Intensity Training on Ventricular Function in Rats After Acute Myocardial Infarction

<div><p>Abstract Background: Physical exercise should be part of the treatment of post-acute myocardial infarction (AMI) patients. Objective: To evaluate the effects of two training prescription models (continuous x interval) and its impact on ventricular function in rats after AMI with normal ventricular function. Methods: Forty Wistar rats were evaluated by echocardiography 21 days after the AMI. Those with LVEF = 50% (n = 29) were included in the study and randomized to control group (CG n = 10), continuous training group (CTG n = 9) or interval training group (ITG, n = 10). Then, a swimming test with control of lactate production was performed. Based on its result, the lactate threshold (LT) was established to define the training intensities. After six weeks, the animals were reassessed by echocardiography and lactate production. Outcome measures were end-diastolic diameter (EDD), end-systolic diameter (ESD), left ventricular ejection fraction (LVEF, %) lactate at rest, lactate without overload, and lactate with 12g and 13.5g of additional load. Group comparisons of quantitative variables of the study were performed by one-factor analysis of variance (ANOVA). The Newman-Keuls test was used for multiple comparisons of the groups. Within-group comparisons of dependent variables between the two training protocols were performed by Student's t-test. Normality of the variables was tested by the Shapiro-Wilks test. Values of p < 0.05 indicated statistical significance. Results: EDD, ESD, and LVEF before and after the training period were similar in within-group comparisons. However, EDD was significantly different (p=0.008) in the CG. Significant differences were found for L12g (p=0.002) and L13.5g (p = 0.032) in the ITG, and for L12g (p = 0.014) in the CG. No differences were found in the echocardiographic parameters between the groups. Significant differences were found in lactate without overload (p = 0.016) and L12 (p = 0.031) in the second assessment compared with the first, and between the groups - ITG vs. CG (p = 0.019) and CTG vs. CG (p = 0.035). Conclusion: Both methods produced a training effect without altering ventricular function.</p></div

Effects of edge dislocations and intentional Si doping on the electron mobility of n-type GaN films

The effects of dislocations and Si doping on the electrical properties of n-type GaN grown by metal organic chemical vapor deposition (MOCVD) are investigated. It is found that both electron mobility and carrier concentration are strongly influenced by edge dislocations. A moderate Si doping during the GaN growth improves the electron mobility, but the best doping effect depends on the dislocation density of the sample. High quality about 4-mu m-thick MOCVD-grown GaN film with a room temperature electron mobility as high as 1005 cm(2)/V s is obtained by optimizing growth conditions. (c) 2006 American Institute of Physics

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data