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CFD parametric studies for global performance improvement of open refrigerated ...
Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, R. A.A detailed CFD modelling of an open refrigerated display cabinet has been formulated in a previous study. Some modifications are introduced in order to perform parametric studies dealing with low-cost geometrical and functional characteristics for improvement of the global performance and energy efficiency. The parametric studies are devoted to the analysis of the thermal response and behaviour inside the food ...
Criteria Assessment of Energy Carrier Systems Sustainability
Gaspar, Pedro Dinis; Mendes, Rui Pedro; Gonçalves, Luís Carlos CarrilhoThe sustainability assessment of an energy conversion process into electrical energy is carried out in technological, economical, environmental and social dimensions. A solid basis for a state-of-the-art interdisciplinary assessment using data obtained from the literature supports the sustainability comparison. Thus, indicators that best describe the technologies and that are related to each of the abovemention...
Detailed CFD modelling of open refrigerated display cabinets
Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, R. A.A comprehensive and detailed computational fluid dynamics (CFDs) modelling of air flow and heat transfer in an open refrigerated display cabinet (ORDC) is performed in this study. The physical-mathematical model considers the flow through the internal ducts, across fans and evaporator, and includes the thermal response of food products. The air humidity effect and thermal radiation heat transfer between surface...
Comparação da sustentabilidade das tecnologias de conversão de energia a partir...
Mendes, Rui Pedro; Gaspar, Pedro Dinis; Gonçalves, Luís Carlos CarrilhoA sustentabilidade de vários processos de conversão de energia em energia eléctrica, especialmente, os alternativos aos combustíveis fosseis, são analisados e comparados neste trabalho. As tecnologias analisadas são baseadas em fontes de energia renovável: eólica, solar, oceanos (ondas e marés), hídrica, geotérmica, nuclear e hidrogénio. Os dados relativos ao processo tecnológico de conversão de energia são fun...
Contribution for a better understanding of the technological sustainability in ...
Mendes, R. P.; Gonçalves, Luís Carlos Carrilho; Gaspar, Pedro DinisThe conversion of solar energy into electricity reveals a huge importance in the production of “clean” energy, mainly when applied to decentralized production systems (micro-generation). However, there is the need to develop and optimize these processes in order to turn it more sustainable in economic and technological scoops. The main purpose of this work is to study the solar energy conversion into electricit...
Experimental results analysis of the energy conversion efficiency of thermoelec...
Richner, Patrizia; Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Almeida, DavidThermoelectric generators can be used for conversion of heat to electricity wherever a temperature difference exists. Such differences of temperatures are available in many applications, often without being used. In the case of photovoltaic panels the temperature difference is in the order of 50 ºC. This study experimentally examines the performance of two commercial thermoelectric generators. The resistance, o...
Sustainability quantification of renewable energy conversion systems for electr...
Mendes, Rui Pedro; Gaspar, Pedro Dinis; Gonçalves, Luís Carlos CarrilhoThe sustainability of renewable energy conversion systems for electricity supply is quantified and compared. The energy conversion systems considered are: wind, photovoltaic, geothermal, hydro, hydrogen, ocean (wave and tidal power) and nuclear. The sustainability analysis is performed covering technological, economic, environmental and social aspects. The indicators selected to characterize and quantify the su...
Energia, Entropia, Exergia
Gonçalves, Luís Carlos Carrilho; Gaspar, Pedro DinisOs conceitos de energia, entropia e exergia estão de um modo geral introduzidos no quotidiano das pessoas e assimilados por elas, sendo hoje em dia fontes de informação. Este trabalho pretende tornar mais acessíveis estes conceitos e obter expressões simplificadas de eficiência. A ligação dos conceitos a processos termodinâmicos é expressa pelos princípios de base e pelas equações propostas. A eficiência da con...
Experimental analysis of the thermal entrainment factor of air curtains in vert...
Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, R. A.The vertical open refrigerated display cabinets suffer alterations of their thermal performance and energy efficiency due to variations of ambient air conditions. The air curtain provides an aerothermodynamics insulation effect that can be evaluated by the thermal entrainment factor calculation as an engineering approximation or by the calculus of all sensible and latent thermal loads. This study presents the v...
Análise experimental da estabilidade de cortinas de ar de equipamentos de refri...
Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, Rui A.Os equipamentos de refrigeração abertos ao ar ambiente apresentam alterações do seu desempenho térmico e da eficiência energética devido a variações da temperatura, humidade e velocidade do ar ambiente externo. Estes equipamentos utilizam cortinas de ar para promover a separação térmica e mássica entre os dois espaços contíguos com comportamentos diferenciados ar, a zona de conservação de alimentos e ar ambient...