1,721,025 research outputs found
Caratterizzazione del Flusso in un Modello di Diffusore di Scarico di Turbina a Gas
No full textCaratterizzazione sperimentale di un modello di diffusore palettato di turbina a gas con sonde di misura della velocità e della direzione del flusso
Flow and turbulence Survey for a Model of Gas Turbine Exhaust Diffuser
Full text linkThis paper presents the results of an extensive set of measurements on a 35%-scale model of an exhaust diffuser for gas turbines. The diffuser is of the straight-wall annular-axial type, typically employed in small-to-medium size gas turbines. It features six high-solidity struts, which support, in the real machine, one of the shaft bearings and have piping for oil supply inside. The instrumentation, the movement of the measurement point, and data acquisition system have been designed for automatic running of the tests. For four test sections, contour plots are produced of average velocity components, flow angle and turbulence quantities as three components of the Reynolds stress tensor
Thermoeconomic evaluation of the SCGT Cycle
No full textThe analysis of the SCGT (Semi-Closed Gas Turbine cycle) is extended to the treatment of acid condensation (sulphur compounds) at the exit of the separator (SEP), with reference to different possible configurations already studied from the thermodynamic and environmental points of view. This detailed analysis was considered necessary because the natural gas fuel can contain a small amount of H2S which, reacting with air, can form SO2 and finally sulphuric acid. This can represent a problem (mainly from the economic point of view) because of the possibility of sulphuric acid condensation at the exit of the separator, where the temperature can reach values below the acid dew point of the mixture.
The data obtained from ENI publications were used for the natural gas composition, and a 0.005% H2S molar fraction was additionally hypothesized. With these assumptions, about 0.1% SO2 can be found in the exhaust gases at the separator inlet.
Aspen Plus was used in order to evaluate the chemical effects of the acidity of the condensate produced in the separator. An evaluation about costs of the devices to be used for condensation of the recirculated flue gas humidity has been performed, considering use of the special materials necessary for reducing the aggressive effects of acid water condensation.
A final evaluation of the overall conversion system plant is also produced, showing the economic balance in terms of resulting cost of the unit of electrical energy produced and of inlet power in terms of fuel.
The results are also evaluated in terms of CO2 emissions, considering the ratio between the global cost of the power generation plant and the global carbon dioxide emissions, compared to other types of energy conversion open cycle solutions
Life cycle assessment of geothermal power plants: A comparison with other energy conversion technologies
No full textGeothermal is a very promising renewable energy, which differently from variable renewable energies is independent of external/climate conditions and can cover both power and heat demands. Nonetheless, albeit these advantageous characteristics, traditional geothermal power plants may have not negligible environmental impacts: these range from emissions of pollutants or greenhouse gases to relevant use of chemicals, power, and other resources during plant development (wells), operation, and construction.It is therefore of paramount importance to provide a reliable methodology to assess the environmental performance of geothermal systems, which should also allow a comparison of the effects with other renewable energies and with traditional fossil fuels used in the power and heat sector.For this reason, Life Cycle Assessment (LCA) was selected as the proper tool to conduct the comparison. An updated analysis of several representative geothermal power plant reference cases of different types and sizes was performed using the Product Environmental Footprint EF 2.0 assessment method. This represents also an update concerning the current practice documented in the technical literature, which often applies different methods (e.g. RECIPE, ILCD, CML, or Eco-Indicator) which are being superseded.In this research, the final single score of each power plant was also calculated and compared among different plants, as well as with other renewables and national energy mixes. The single score results indicate that geothermal plants' environmental impacts are in line with other renewable technologies and that they are in general lower than the corresponding national energy mixes
Measurements of primary and secondary flows in an industrial forward-curved centrifugal fan
No full textAn industrial-type centrifugal-flow fan was instrumented and tested in order to obtain a fully-detailed relative flow pattern at impeller discharge. Testing entailed investigation of both primary flows (jet-wake pattern and presence of return flows) and secondary flows (due to streamwise vorticity either from meridional curvature or rotation effects). In addition to conventional probing, a crossed hot-wire probe was employed in the tests. Ensemble-averaging the hot-wire signals made it possible to obtain the three-dimensional phase-averaged relative flow pattern at discharge by means of double positioning of the probe. Results show secondary-flow effects of appreciable magnitude interacting with primary flows (e. g. , return flow in the hub region and variations in vortex structure and wake position with variations in flowrate
Environmental Wind Tunnel Study on a Municipal Waste Incinerator
No full textIn this paper results concerning a diffusion experiment on a small scale model of a waste incinerator, carried out in a boundary layer wind tunnel, will be presented. At the beginning a description of the measurement system that has recently been placed in the wind tunnel will be given together with a study of repeatability of the measurements results. A comprehensive study of the flow mean characteristics at different position in the tunnel working section will be reported and at the end some vertical and horizontal concentration profiles results will be described and discussed
Semi Closed Gas Turbine Cycle and Humid Air Turbine: Thermoeconomic Evaluation of Cycle Performance and of the Water Recovery Process
No full textSemi Closed Gas Turbine Cycle and Humid Air Turbine: Thermoeconomic Evaluation of Cycle Performance and of the Water Recovery Process
No full textA comparison between power plants built according to the HAT (Humid Air Turbine) and SCGT/CC (Semi-Closed Gas Turbine/Combined Cycle) concepts is presented, ranging from thermodynamic performance (efficiency and specific power output) to projected data for plant construction and operating costs. Both options appear to be of potential interest to electric utilities considering advanced gas turbine power plants, with significant differences form the point of view of plant size, water consumption, and adaptability to advanced developments for the limitation of environmental impact (CO2 emissions)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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