INESCC-DL - Artigos em Revistas Internacionais
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Percorrer INESCC-DL - Artigos em Revistas Internacionais por Domínios Científicos e Tecnológicos (FOS) "Engenharia e Tecnologia::Engenharia do Ambiente"
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- The Effect of a Naturally Ventilated Roof on the Thermal Behaviour of a Building under Mediterranean Summer ConditionsPublication . Ramos, João; Aires, LuisWith the increasing cost associated with energy consumption, climate change and the greater awareness of the population to issues related to energy and environmental efficiency, energy conservation in buildings has been encouraged, along with the development of several solutions based on a more sustainable construction. Building cooling is the most challenging issue in the Mediterranean climate. The roof is one of the main elements of the building’s opaque envelope, where the choice of materials and the implementation of appropriate passive technologies determine the thermal performance of a building. The present work aims to assess the impact of natural ventilation of a roof cavity on the thermal environment of a dwelling house under Mediterranean summer conditions. An experimental study was developed in a small-scale prototype of a typical dwelling house, comprising a ceramic tile roof with vented eaves and insulated sub-tile panels according to the construction solution of the Humbelino Monteiro SA company. The thermal performance of this roof solution was assessed under real climatic conditions based on continuous measurements of the air velocity inside the air gap, the temperature of the air and the surface temperature of all roof layers. Weather conditions were also monitored continuously. Connected with the heat transfer mechanisms, the obtained temperature and air velocity profiles data were analysed and discussed.
- Efficiency in an Intensive Energy Industrial ConsumerPublication . Galvão, J.; Nabais, A.; Galvão, M.; Candeias, J.; Pereira, Thiago; Ramos, J.Energy efficiency actions were made in a glass production industry such as reduction in the energy consumption that will reduce greenhouse gas emissions. All measures were applied regarding European Union-EU guidelines and legislation.
- Rotating speed stability and mechanical vibration analysis of one-stage inertia flexible rotor driven by variable speed drivesPublication . Oliveira, Filipe Tadeu; Donsión, M.P.; Peláez, G.This paper poses some questions as to the adequacy of the widespread use of variable speed drives. It presents a comparison of different variable speed drives, by studying their output wave forms and applying them to a mechanical one stage inertia flexible rotor specially designed for this purpose. The comparison of the output of the variable speed drives used reveals significant differences between them, which affect the way the load is driven and the overall behaviour of the mechanical system. A comparison against a sine wave reference shows that even the best of the variable speed drives used is outperformed, since the “perfect” sine wave ensures constant rotating speed, thus minimizing vibrations along the mechanical shaft.