1,721,118 research outputs found
Ventilated pitched roof with forced ventilation and flow homogenizer device: Testing and performance assessment
Full text linkVentilated tile roofs are common objects in the construction sector of Italy. A preferred type is characterized by a ventilated air space between the upper tile layer and the roof structure below. The air enters through openings at the gutters level, flows up below sheathing in the air space along the pitch and is finally discharged through openings along the ridge. This setup, which leaves the room below the roof sealed and habitable, allows removing the heat brought by the absorbed solar radiation thanks to the flow that is established by natural ventilation in the air space. However, its actual performance is often weak and also unpredictable due to continuously changing buoyancy forces. Nonetheless, a permanent and adequate flow can be ensured even through a relatively thin air space and for whichever irradiance and wind conditions by forced ventilation: a properly designed fan can provide the desired flow rate by extracting the air after this is collected along the ridge by a manifold. A thorough design and manufacturing of the manifold is needed, however, to avoid a highly inhomogeneous flow, which would follow the easiest path and leave most of the pitch practically unventilated. As an alternative, a throttling shutter parallel to the ridge has been proposed to progressively choke the flow entering the manifold through parallel climbing ducts as the fan is approached, possibly allowing onsite adjustment after installation. In this work the solution, developed by means of a small scale test bed, is illustrated in details and some methods to assess the performance are presented
Industry 4.0: national and regional comparative advantages in key enabling technologies
No full textIndustry 4.0 is a name used to indicate a ‘fourth industrial revolution’, characterised by the emergence of smart factories in which cyber-physical systems monitor physical processes and communicate with each other and human beings in real time. European Member States and regions are committed to adapt their innovation systems to the trends of Industry 4.0 and Europe as a whole is facing the challenge of finding a balance between promoting research and innovation excellence and putting less advanced regions in the position to benefit from the ongoing industrial revolution. However, relatively little is known about the magnitude of this economic phenomenon, the comparative advantages of countries and regions and their technological specialisation. We use data from European regions’ participation in collaborative research projects promoted by the 7th Framework Programme for research and innovation to investigate relative and absolute advantages in the enabling technologies of Industry 4.0. Data are regionalised and categorised on the basis of an original taxonomy of technologies developed with the support of a team of European experts in each technological domain. The article also explores regional networks promoted by the Framework Programme and draws policy indications to support the competitiveness of European manufacturing
Potential of Thermal Engine Encapsulation on Automotive Diesel Engines
No full textThermal Engine Encapsulation (TEE) is a technique for reducing heat loss from an engine after it has been switched off, in order to get a warmer re-start. This practice yields benefits in terms of fuel economy, emissions and wear, especially for vehicles used for short journeys in cold weather and with engines warming up slowly. In this study, the encapsulation of a small automotive diesel engine is investigated by means of theoretical and experimental analyses. In particular, the influence of oil temperature on brake specific fuel consumption and emissions is calculated. Furthermore, the thermal behavior of the engine has been simulated by a lumped-capacitance model, in order to assess the correlation between encapsulation thickness and cool-down time. Finally, the 0-D thermal model and the 1-D engine model have been coupled in order to predict the influence of engine cranking temperature on fuel consumption and pollutant emissions, considering a B-class vehicle running a short journey (15 minutes) at medium speed and load and very low external temperature (0emDC)
Numerical Modeling and Simulation of a Small-Scale Locomotive Powered by Solid Oxide Fuel Cells
Full text linkThe adverse environmental effects of fossil fuels resulted in a sharp rise in demand for renewable energy sources such as solar, wind, and hydrogen. Environmental pollution might be drastically reduced by using renewable energy sources. Various examples of solid oxide fuel cells being employed in locomotives exist in the literature. This work used numerical techniques to simulate and model a vehicle with eight wheels, considered as a small-scale locomotive powered by solid oxide fuel cells. The feasibility of solid oxide fuel cell-based locomotive was investigated through numerical modeling and simulation. The Matlab-Simulink platform, which includes an electrical system, an energy management system, and vehicle dynamics, was used to run the simulations. Four different locomotive configurations were created, (1) The mass of the locomotive (m) = 65000 kg, operating temperature (T) = 750°C, (2) m = 65000 kg, T = 1000°C, (3) m = 80000 kg, T = 750°C, and (4) m = 80000 kg and T = 1000°C. The performance parameters of the vehicle were recorded after the simulations. These factors are crucial for optimizing the locomotives' design and operation since they provide light on their performance. Future locomotive design and operation may be influenced by the findings of this study, resulting in more environmentally friendly and sustainable transportation networks
An experimental protocol using N. commune as pioneer organism to induce bio-deterioration of surfaces: comparison between new and soiled surfaces
No full textBiological growth on building surfaces can be responsible for degradation of their aesthetical and functional properties. This is damaging for solar reflective materials (SRM), which are characterised by the ability to reflect solar radiation in the whole wavelength spectrum. SRM represent one of the most efficient countermeasures to the urban heat Island effect. The present study compares different experimental setups to expose SRM samples to laboratory bio-ageing and define which setup is the most repeatable in terms of biodegradation on surfaces
Indirect evaporative cooling by sub-roof forced ventilation to counter extreme heat events
No full textIn a pitched ventilated roof, an air stream enters a cavity below the roof surface through openings at the level of the gutters, then it flows up along the roof and is finally discharged through openings along the ridge. The heat brought by the absorbed solar radiation is removed thanks to the flow established by natural ventilation, but only in part because the flow is relatively weak and unstable. As shown in previous work, a stronger and more regular air flow can be ensured by forced ventilation, extracting the air by means of a fan after it has been collected along the ridge by a properly designed manifold. This setup can be further enhanced by humidifying and saturating the air as it enters the cavity, thus significantly lowering the downstream air temperature. An indirect evaporative cooling system is thus obtained, by which an inhabited space under the roof can be cooled through the ceiling while remaining sealed and unaffected by the evaporative process. In this work, the setup is analyzed by a mathematical model and the concept tested by means of a small scale test bed, showing that it can be used to counter extremely hot ambient conditions with a relatively low consumption of liquid water and almost negligible energy need
Conventional Building Energy Performance and Actual Energy Costs: A Critical Reflection
Full text linkEnergy Performance Certificates (EPCs) provide information about the energy consumption of the building under conventional climate and use conditions. The calculation method compares the envelope efficiency, energy consumption and carbon emissions of the building with those of a “reference building”, of the same location, size, geometry, use and boundary but with thermo-physical characteristics corresponding to the minimum energy requirements in force. Due to its intrinsic definition, the reference building might actually be highly energy-consuming and costly, allowing the actual building to reach a higher energy class thanks e.g., to the use of renewable energies or more performing windows or walls. This study proposes an in-depth analysis of the actual energetic and economic sustainability of buildings on top of the conventional energy classification concept. By exploring variables such as glass surfaces, imported energy consumption and architectural design, the study aims to develop a novel approach to EPCs, based on a novel concept of reference building. The work aims to contribute to the evolution of the EPC definition, providing a more complete overview of the energy and economic performance of buildings. New qualitative indicators are proposed to be included in the EPCs, depicting a more informative picture of the building energy performance. Results show that for the selected case studies, according to the actual EPC methodology, the quality of the envelope would be medium-high, while the novel indicators would present a rather worse envelope performance. The divergence is particularly evident in the case of highly glazed buildings
Performance produttive di conigli di razza “Nuova Zelanda” svezzati 24 e a 31 giorni di età. Accrescimenti, consumi alimentari e qualità delle carcasse
No full textReplacing batteries with water by an innovative evaporative cooling process for vehicle air conditioning
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