812 research outputs found
Review of "Milton's Italy: Anglo-Italian Literature, Travel, and Religion in Seventeenth-Century England" by Catherine Gimelli Martin
No full textCatherine Gimelli Martin. Milton's Italy: Anglo-Italian Literature, Travel, and Religion in Seventeenth-Century England. New York: Routledge, 2017. xv + 318 pp. $138.10. Review by John Mulryan, St. Bonaventure University
A micro gas turbine one-dimensional model: approach description, calibration with a vector optimization methodology and validation
No full textBased on recent studies, it is mandatory to match energy supply with user demand with the aim of achieving a
significant primary energy saving. In order to ensure an efficient matching, the power plant must be capable to
follow the energy demand fluctuation of specific users. The paper deals with the one-dimensional modeling,
calibration and validation of a micro gas turbine plant which performs a regenerative Brayton cycle. Compressor
and turbine have been outlined with performance maps, the combustor behavior is simulated by a 0D block and
the recuperator is defined by a steady-state block; seven pipes have been modeled as 1D unsteady flow, and they
connect the main components of the power plant. Although a micro gas turbine is substantially a steady plant,
the application of a one-dimensional approach allows the accurate investigation of transient and stable part-load
working conditions. The model has been calibrated using a multi-variable multi-objective methodology in which
a genetic algorithm was coupled with the model and was capable to find out the optimal model settings. The
model has been validated through the comparison between calculated and experimental data at part-load
working conditions. The novelty of the paper is the modeling approach and its validation methodology
Performance assessment of a 15 kW Micro-CHCP plant through the 0D/1D thermo-fluid dynamic characterization of a double water circuit waste heat recovery system
No full textThe exploitation of renewable energy sources and the use of primary energy saving techniques have been
recognized as key solutions to face climate changes. The consequent energy policies are pushing the
transition from a centralized power generation system to a distributed polygeneration system able to
meet simultaneous heating, cooling and electricity demand. However, small scale polygeneration plants
do not ensure any primary energy and cost saving without a proper sizing and operation of the plant.
Furthermore, a flexible configuration of the waste heat recovery system (WHRS) adopted for polygeneration
purposes can be equally important. Therefore, starting from the experimental data concerning
a 15 kW micro-CHP plant previously designed and prototyped, the paper addresses the
performance assessment of a CHCP plant configuration based on the same basic engine-electric generator
system through the 1D thermo-fluid dynamic characterization of an alternative double water circuit
WHRS. This configuration, delivering thermal power at different temperature level, could be useful to
meet thermal and cooling demand from different user or when seasonal energy demand occurs. This
paper also provides an effective approach for the design of WHRS which are capable to ensure a
reasonable matching between the temperature level required by the user and that provided by the plant.
In this way, being the energy saving dependent on the thermal power recovered and actually exploited,
and so on the temperature level which characterizes the user's heat demand, primary energy savings are
more easily achievable even when small scale polygeneration applications are considered. Results shows
the possibility of supplying an absorption chiller and obtaining a coolling capacity of about 10.5 kW from
the resulting CHCP plant configuration
Thermodynamic and experimental analysis of a biomass steam power plant: critical issues and their possible solutions with CCGT systems
No full textThis paper shows the experimental and numerical analysis of a biomass steam power plant from maximum power of 2.3 MW with a maximum pressure of 48 bar and a turbine inlet temperature of about 430 °C at the design point. The analysis has been conducted using experimental data, collected directly on the power plant, at the design point, and they have been afterwards used to validate a thermodynamic model. The analysis of the biomass power plant pointed out some critical issues that can be summarized in three points: low plant efficiency due to the small size, biomass supply range and continuous variation of the operating point. In order to solve this problem, different plant configurations were numerically evaluated. The first solution to these problems consists of a 100 kWe micro gas turbine (MGT) fueled by natural gas, whose exhaust gas were sent to the steam generator of the biomass power plant in order to evaluate the benefits on the power fluctuations and on global electric efficiency. A thermodynamic model of the MGT has been developed and validated with experimental data from technical literature, creating a CCGT (Combined Cycle Gas Turbine) system. The analysis of the results of this system showed improvement in terms of efficiency and operational stability. The second option was to fuel the previously validated method of MGT with four different alternative fuels and to evaluate the integration with the biomass plant for all of them. Furthermore, to emphasize the benefits of this integration, the power of the micro turbine has been increased assuming the use of more MGT at the same time. These analyses show an increase of the system efficiency, it could been also used the biomass, not suitable for direct combustion (high humidity), to produce biogas that fuels the MGT, reducing the range of biomass supply
The role of cardiovascular imaging for myocardial injury in hospitalized COVID-19 patients
No full textThis is a pre-copyedited, author-produced version of an article accepted for publication in European Heart Journal - Cardiovascular Imaging, following peer review. The version of record: Bernard Cosyns, Stijn Lochy, Maria Luiza Luchian, Alessia Gimelli, Gianluca Pontone, Sabine D Allard, Johan de Mey, Peter Rosseel, Marc Dweck, Steffen E Petersen, Thor Edvardsen, on behalf of the European Association of Cardiovascular Imaging (EACVI), The role of cardiovascular imaging for myocardial injury in hospitalized COVID-19 patients, European Heart Journal - Cardiovascular Imaging, Volume 21, Issue 7, July 2020, Pages 709–714, https://doi.org/10.1093/ehjci/jeaa136
is available online at: https://doi.org/10.1093/ehjci/jeaa13
The Key Role of the Vector Optimization Algorithm and Robust Design Approach for the Design of Polygeneration Systems
No full textIn recent decades, growing concerns about global warming and climate change effects have led to specific directives, especially in Europe, promoting the use of primary energy-saving techniques and renewable energy systems. The increasingly stringent requirements for carbon dioxide reduction have led to a more widespread adoption of distributed energy systems. In particular, besides renewable energy systems for power generation, one of the most effective techniques used to face the energy-saving challenges has been the adoption of polygeneration plants for combined heating, cooling, and electricity generation. This technique offers the possibility to achieve a considerable enhancement in energy and cost savings as well as a simultaneous reduction of greenhouse gas emissions. However, the use of small-scale polygeneration systems does not ensure the achievement of mandatory, but sometimes conflicting, aims without the proper sizing and operation of the plant. This paper is focused on a methodology based on vector optimization algorithms and developed by the authors for the identification of optimal polygeneration plant solutions. To this aim, a specific calculation algorithm for the study of cogeneration systems has also been developed. This paper provides, after a detailed description of the proposed methodology, some specific applications to the study of combined heat and power (CHP) and organic Rankine cycle (ORC) plants, thus highlighting the potential of the proposed techniques and the main results achieved
Development of a 1 kW Micro-Polygeneration System Fueled by Natural Gas for Single-Family Users
No full textThe use of primary energy saving techniques and renewable energy systems has become mandatory to tackle the effects of global temperature rise. As a result, a transition is taking place from centralized energy generation to distributed energy generation. Starting from the experience concerning a 15 kW micro-CHP plant previously designed at DII, this paper addresses the development of a 1 kW micro-CHP system fueled by natural gas for single-family users. Specifically, the paper presents a wide experimental investigation aimed at optimizing performance and emissions of a small scale two-stroke spark ignition gasoline engine properly modified to be fueled with natural gas to make the engine more suitable for cogeneration purposes. The described activity was carried out at the DII of the University of Naples Federico II. Rigorous laboratory tests were conducted with the engine in order to characterize both gasoline and CNG operation in terms of brake mechanical power, overall efficiency and exhaust gas emissions in different operating regimes. Furthermore, several physical quantities associated with the engine operation were measured through several sensors in order to optimize performance and emissions achieved when the engine is fueled with CNG. In particular, dynamic pressure variations inside the cylinder were measured and analyzed to evaluate the effect of the adopted fuel on the optimum ignition-timing angle and cyclic dispersion
A multi-variable multi-objective methodology for experimental data and thermodynamic analysis validation: An application to micro gas turbines
No full textA methodology aimed at defining thermodynamic model parameters and validating experimental data has been proposed. The methodology consists of a thermodynamic model of a micro gas turbine coupled with a multi-variable multi-objective genetic optimization algorithm, in which decision variables and objectives are set depending on available experimental data. To validate both the thermodynamic model and the collected experimental data, the methodology has been applied to two micro gas turbine plants: the Capstone C30 and the Turbec T100. Validations of the thermodynamic model and the collected experimental data for the two plants have been performed by evaluating the match between input and output physical parameters. The optimal results of the optimization algorithm have plausible thermodynamic parameters and constitute the Pareto front; between these results, the one with the minimum difference between experimental data and calculated values is chosen as preferred. The two studied cases highlight the effect of measurement chain errors on experimental data reliability: the greater is the overall variance of the objectives, the lower is the accuracy of the experimental data. The effectiveness of proposed methodology has been verified for the Capstone C30 through the congruence of the design operating conditions on both the compressor and turbine maps.
In this study, a methodology aimed at performing a validation of micro gas turbine experimental data congruence and the related thermodynamic analysis was investigated through two studied cases. This methodology was based on setting up of a thermodynamic analysis and verifying experimental data reliability through a genetic algorithm that optimizes the input thermodynamic parameters.
The following conclusions can be made:
• The methodology verifies the experimental data congruence and highlights the less reliable parameters. For example, the combustion chamber pressure for the Turbec T100 has a variance that is one order of magnitude greater than that of other parameters. The Capstone C30 has the overall efficiency as the least reliable parameter, but the other ones have similar variances.
• The methodology can define an optimal set of thermodynamic input data, using the Euclidean norm to evaluate the preferred solution: this useful mathematical tool ranks the obtained designs by the minimum variance of the overall objectives, determining the preferred design. Consequently, the preferred solution for each case has congruent thermodynamic input parameters and the related results are very close to the objectives set.
• As stated above, the methodology, when coupled with experimental tests, could decrease the needed measurement campaigns.
• Because of its generic nature, the methodology applied here on two typical gas turbine plants could also be used on other plants, for treatment of both steady flow (e.g., a steam plant or an organic Rankine cycle plant) and unsteady flow (e.g., an internal combustion engine).
The methodology effectiveness was proved by plotting the preferred experimental design onto turbomachinery performance maps, examining the congruent matching of the design operating conditions
A t(7;12) balanced translocation with breakpoints overlapping those of the Williams-Beuren and 12q14 microdeltion syndromes.
No full textDynamic ultrafast CZT imaging: Time for a paradigm change in myocardial perfusion imaging
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