34 research outputs found

    A marine turbocharger retrofitting platform

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    A turbocharger retrofitting platform utilizing 1D models for calculating turbomachinery components maps and a fully coupled process for integration with the turbomachinery components and the diesel engine, is presented. The platform has been developed with two modes of operation, allowing the retrofitting process to become fully automatic. In the first mode, available turbo-components are examined, in order to select the one that best matches the entire engine system, aiming to retain or improve the diesel engine efficiency. In the second mode, an optimization procedure is employed, in order to redesign the compressor to match the entire system in an optimum way. Dimensionless parameters are used as optimization variables, for a given compressor mass flow and power. A retrofitting case study is presented, where three retrofitting options are analyzed (compressor retrofit, turbocharger retrofit and compressor redesign). In the first and second option, turbocharger retrofitting is carried out, using available turbo-components. It is shown that initial performance cannot be reconstituted using off-the-self solutions. In the third option, compressor designing is performed, using the optimization mode, in order to provide an improved retrofitting solution, aiming to at least reconstituting the original diesel engine performance. Finally, a CFD analysis is carried out, in order to validate the compressor optimization tool capability to capture the performance trends, based on geometry variatio

    A marine turbocharger retrofitting platform

    Get PDF
    A turbocharger retrofitting platform utilizing 1D models for calculating turbomachinery components maps and a fully coupled process for integration with the turbomachinery components and the diesel engine, is presented. The platform has been developed with two modes of operation, allowing the retrofitting process to become fully automatic. In the first mode, available turbo-components are examined, in order to select the one that best matches the entire engine system, aiming to retain or improve the diesel engine efficiency. In the second mode, an optimization procedure is employed, in order to redesign the compressor to match the entire system in an optimum way. Dimensionless parameters are used as optimization variables, for a given compressor mass flow and power. A retrofitting case study is presented, where three retrofitting options are analyzed (compressor retrofit, turbocharger retrofit and compressor redesign). In the first and second option, turbocharger retrofitting is carried out, using available turbo-components. It is shown that initial performance cannot be reconstituted using off-the-self solutions. In the third option, compressor designing is performed, using the optimization mode, in order to provide an improved retrofitting solution, aiming to at least reconstituting the original diesel engine performance. Finally, a CFD analysis is carried out, in order to validate the compressor optimization tool capability to capture the performance trends, based on geometry variation

    Non-chemical treatments for preventing the postharvest fungal rotting of citrus caused by Penicillium digitatum (green mold) and Penicillium italicum (blue mold)

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    Background: Citrus is one of the most economically important horticultural crops in the world. Citrus are vulnerable to the postharvest decay caused by Penicillium digitatum and P. italicum, which are both wound pathogens. To date, several non-chemical postharvest treatments have been investigated for the control of both pathogens, trying to provide an alternative solution to the synthetic fungicides (imazalil, thiabendazole, pyrimethanil, and fludioxonil), which are mainly employed and may have harmful effects on human health and environment. Scope and approach: The current study emphasizes the non-chemical postharvest treatments, such as irradiations, biocontrol agents, natural compounds, hot water treatment (HWT), and salts, on the prevention of decay caused by P. digitatum and P. italicum, also known as green and blue molds, respectively. The mode of action of each technique is presented and comprehensively discussed. Key findings and conclusions: In vivo and in vitro experiments in a laboratory scale have shown that the control of green and blue molds can be accomplished by the application of non-chemical treatments. The mechanisms of action of the non-chemical techniques have not been clearly elucidated. Several studies have mentioned that the application of non-chemical treatments results in the synthesis of secondary metabolites with antifungal activities (i.e. polyphenols, phytoalexins) in fruit surface. Moreover, non-chemical treatments may exert direct effects on fungal growth, such as disruption of cell walls, inhibition of metabolic respiration, and disruption of energy production related enzymes.Centro de Investigación y Desarrollo en Criotecnología de Alimento

    Burden of non-communicable diseases among adolescents aged 10–24 years in the EU, 1990–2019: a systematic analysis of the Global Burden of Diseases Study 2019

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    Background Disability and mortality burden of non-communicable diseases (NCDs) have risen worldwide; however, the NCD burden among adolescents remains poorly described in the EU. Methods Estimates were retrieved from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. Causes of NCDs were analysed at three different levels of the GBD 2019 hierarchy, for which mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) were extracted. Estimates, with the 95% uncertainty intervals (UI), were retrieved for EU Member States from 1990 to 2019, three age subgroups (10–14 years, 15–19 years, and 20–24 years), and by sex. Spearman's correlation was conducted between DALY rates for NCDs and the Socio-demographic Index (SDI) of each EU Member State. Findings In 2019, NCDs accounted for 86·4% (95% uncertainty interval 83·5–88·8) of all YLDs and 38·8% (37·4–39·8) of total deaths in adolescents aged 10–24 years. For NCDs in this age group, neoplasms were the leading causes of both mortality (4·01 [95% uncertainty interval 3·62–4·25] per 100 000 population) and YLLs (281·78 [254·25–298·92] per 100 000 population), whereas mental disorders were the leading cause for YLDs (2039·36 [1432·56–2773·47] per 100 000 population) and DALYs (2040·59 [1433·96–2774·62] per 100 000 population) in all EU Member States, and in all studied age groups. In 2019, among adolescents aged 10–24 years, males had a higher mortality rate per 100 000 population due to NCDs than females (11·66 [11·04–12·28] vs 7·89 [7·53–8·23]), whereas females presented a higher DALY rate per 100 000 population due to NCDs (8003·25 [5812·78–10 701·59] vs 6083·91 [4576·63–7857·92]). From 1990 to 2019, mortality rate due to NCDs in adolescents aged 10–24 years substantially decreased (–40·41% [–43·00 to –37·61), and also the YLL rate considerably decreased (–40·56% [–43·16 to –37·74]), except for mental disorders (which increased by 32·18% [1·67 to 66·49]), whereas the YLD rate increased slightly (1·44% [0·09 to 2·79]). Positive correlations were observed between DALY rates and SDIs for substance use disorders (rs=0·58, p=0·0012) and skin and subcutaneous diseases (rs=0·45, p=0·017), whereas negative correlations were found between DALY rates and SDIs for cardiovascular diseases (rs=–0·46, p=0·015), neoplasms (rs=–0·57, p=0·0015), and sense organ diseases (rs=–0·61, p=0·0005)

    Solar Hybrid Micro Gas Turbine Based on Turbocharger

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    The performance of solar hybrid Brayton cycle materialized by a micro-gas turbine based on a turbocharger is studied. The use of a turbocharger is aimed at investment cost reduction and construction simplification. Two configurations are investigated, namely hybrid and solar-only. Design aspects are discussed, in view of the requirement for minimizing the cost of electricity produced. A key parameter is the turbine inlet temperature and its effect on performance is investigated. The effect of heliostat field size is also investigated. Augmentation of the maximum temperature leads to better performance, as a result of higher cycle efficiency. Solar-only configuration features are compared with hybrid ones and the contribution of different cost components to the final electricity cost is discussed

    Novel Aero-Engine Multi-Disciplinary Preliminary Design Optimization Framework Accounting for Dynamic System Operation and Aircraft Mission Performance

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    This paper presents a modular, flexible, extendable and fast-computational framework that implements a multidisciplinary, varying fidelity, multi-system approach for the conceptual and preliminary design of novel aero-engines. In its current status, the framework includes modules for multi-point steady-state engine design, aerodynamic design, engine geometry and weight, aircraft mission analysis, Nitrogen Oxide (NOx) emissions, control system design and integrated controller-engine transient-performance analysis. All the modules have been developed in the same software environment, ensuring consistent and transparent modeling while facilitating code maintainability, extendibility and integration at modeling and simulation levels. Any simulation workflow can be defined by appropriately combining the relevant modules. Different types of analysis can be specified such as sensitivity, design of experiment and optimization. Any combination of engine parameters can be selected as design variables, and multi-disciplinary requirements and constraints at different operating points in the flight envelope can be specified. The framework implementation is exemplified through the optimization of an ultra-high bypass ratio geared turbofan engine with a variable area fan nozzle, for which specific aircraft requirements and technology limits apply. Although the optimum design resulted in double-digit fuel-burn benefits compared to current technology engines, it did not meet engine-response requirements, highlighting the need to include transient-performance assessments as early as possible in the preliminary engine design phase

    Axial Compressor Mean-Line Analysis: Choking Modelling and Fully-Coupled Integration in Engine Performance Simulations

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    A mean-line compressor performance calculation method is presented that covers the entire operating range, including the choked region of the map. It can be directly integrated into overall engine performance models, as it is developed in the same simulation environment. The code materializing the model can inherit the same interfaces, fluid models, and solvers, as the engine cycle model, allowing consistent, transparent, and robust simulations. In order to deal with convergence problems when the compressor operates close to or within the choked operation region, an approach to model choking conditions at blade row and overall compressor level is proposed. The choked portion of the compressor characteristics map is thus numerically established, allowing full knowledge and handling of inter-stage flow conditions. Such choking modelling capabilities are illustrated, for the first time in the open literature, for the case of multi-stage compressors. Integration capabilities of the 1D code within an overall engine model are demonstrated through steady state and transient simulations of a contemporary turbofan layout. Advantages offered by this approach are discussed, while comparison of using alternative approaches for representing compressor performance in overall engine models is discussed

    Non-chemical treatments for preventing the postharvest fungal rotting of citrus caused by Penicillium digitatum (green mold) and Penicillium italicum (blue mold)

    No full text
    Citrus is one of the most economically important horticultural crops in the world. Citrus are vulnerable to the postharvest decay caused by Penicillium digitatum and P. italicum, which are both wound pathogens. To date, several non-chemical postharvest treatments have been investigated for the control of both pathogens, trying to provide an alternative solution to the synthetic fungicides (imazalil, thiabendazole, pyrimethanil, and fludioxonil), which are mainly employed and may have harmful effects on human health and environment.Scope and approachThe current study emphasizes the non-chemical postharvest treatments, such as irradiations, biocontrol agents, natural compounds, hot water treatment (HWT), and salts, on the prevention of decay caused by P. digitatum and P. italicum, also known as green and blue molds, respectively. The mode of action of each technique is presented and comprehensively discussed.Key findings and conclusionsIn vivo and in vitro experiments in a laboratory scale have shown that the control of green and blue molds can be accomplished by the application of non-chemical treatments. The mechanisms of action of the non-chemical techniques have not been clearly elucidated. Several studies have mentioned that the application of non-chemical treatments results in the synthesis of secondary metabolites with antifungal activities (i.e. polyphenols, phytoalexins) in fruit surface. Moreover, non-chemical treatments may exert direct effects on fungal growth, such as disruption of cell walls, inhibition of metabolic respiration, and disruption of energy production related enzymes.Fil: Papoutsis, Konstantinos. Universidad de Dublin; IrlandaFil: Mathioudakis, Matthaios M.. Institute of Olive Tree Subtropical Crops and Viticulture; GreciaFil: Hasperué, Héctor Joaquín. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Ziogas, Vasileios. Institute of Olive Tree Subtropical Crops and Viticulture; Greci
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