Browsing by Author "Caetano, Fernando J. P."
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- 2008 Ano Internacional do Planeta Terra: oceano, Terra e vidaPublication . Amador, Filomena; Caetano, Fernando J. P.; Caixeiro, Vanda; Antunes, Ana PaulaA formação de calcários e a génese do calcário de Ançã. A evolução da vida na Terra e nos oceanos, privilegiando aspetos relativos à sustentabilidade dos sistemas de vida. Visita à Pedreira do Boiça-Ançã e ao Museu da Pedra em Cantanhede, com os Professores Fernando Caetano, docente da Universidade Aberta e Maria Helena Henriques, geóloga da Universidade de Coimbra. Participação da Dra. Maria Carlos Pêgo, Diretora do Museu da Pedra de Cantanhede.
- Adipates as new phase change material: seeking for a low temperature energy storage systemPublication . Sequeira, Maria Carolina; Nogueira, Bernardo A.; Caetano, Fernando J. P.; Diogo, Herminio; Fareleira, João M. N. A.; Fausto, RuiThe recent and endless increasing need for energy is requiring imperative and efficient solutions. Renewable energies are an effective solution, but they are also intermittent, which often leads to a gap between the availability of energy and its demand. Therefore, energy storage becomes crucial for improving the efficiency by reducing the mismatch between demand and supply thus offering better management capabilities. The use of phase change materials (PCMs) became an attractive technology, especially for active cooling systems. In particular, eutectic systems can be designed for each application, allowing significant energy savings, which is very relevant in what concerns economic and environmental sustainability [1]. Equilibrium studies and their phase diagrams are crucial to characterize the behavior of these systems, particularly for new PCMs [2]. This work aims the characterization of a selected type of binary system composed by di-n-alkyl adipates that can be used for energy storage at low temperatures, starting by the construction of solid-liquid phase diagram based on Differential Scanning Calorimetry (DSC) and Raman Spectroscopy results. The studied system is a binary mixture of diethyl and dibutyl adipates and reveals to behave as a eutectic system at low temperatures, possessing also polymorphism, therefore presenting a relatively complex phase diagram. The eutectic point was found around -33ºC and the polymorphism transition, being characteristic of the dibutyl adipate, occurs at around -36ºC for the overall phase diagram. Raman spectroscopy was fundamental concerning the construction of the phase diagram, enabling to identify the different solid and liquid phases of the system. This work provides new phase equilibrium data, which, to the knowledge of the authors, are the first in the literature, concerning these compounds. The studied binary system has promising characteristics for low temperature energy storage. It is also demonstrated how solid-liquid-phase equilibrium studies are the key to select the most appropriate phase change material for a specific thermal energy storage (TES) application.
- An industrial reference fluid for moderately high viscosityPublication . Oliveira, Carla Padrel de; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Fröba, Andreas P.; Harris, Kenneth R.; Leipertz, Alfred; Trusler, J. P. Martin; Wakeham, William A.In industrial practice, there is a demand for a reference standard for viscosity that is established for a readily available fluid to simplify the calibration of industrial viscometers for moderately high viscosities [(50 to 125) mPa · s]. Diisodecyl phthalate (DIDP) has been suggested as that reference fluid, and a number of studies of its properties have been carried out in several laboratories throughout the world, within the auspices of a project coordinated by the International Association for Transport Properties. That project has now progressed to the point where it is possible to collate the results of studies of the viscosity of the fluid by a number of different techniques, so as to lead to a proposed standard reference value which will be included in the paper. To support this recommended value, the various measurements conducted have been critically reviewed, and the sample purity and other factors affecting the viscosity have been studied. Density and surface tension measurements have also been performed. This paper does not describe the individual viscosity determinations carried out in independent laboratories because these are the subject of individual publications, but it does describe the ancillary studies conducted and their relevance to the viscosity standard. In addition, the paper contains recommended values for the viscosity of liquid DIDP. The samples of DIDP to which the recommended values refer are isomeric mixtures available commercially from certain suppliers, with a minimum purity by gas chromatography of 99.8 %. The recommended values result from a critical examination of all the measurements conducted to date and are supported by careful arguments dealing with the likely effects of the isomeric content of the sample as well as of other impurities. The proposed reference standard is intended particularly to serve an industrial need for a readily available calibration material with a viscosity close to that required in practical situations. To that end, the recommended value has an overall relative uncertainty of approximately 1 %. It is therefore not intended to supersede for the reference value for the viscosity of water at 20 °C, which is known much more accurately, but rather to complement it.
- Ano Internacional da Química 2011: o que é a química?Publication . Caetano, Fernando J. P.; Oliveira, Carla Padrel de; Oliveira, PauloBreve explicação sobre o que é a Química. Participação do Professor Jorge Calado, do Departamento de Engenharia Química do Instituto Superior Técnico e Presidente da Comissão Nacional para o AIQ Ano Internacional da Química 2011.
- Ano Internacional da Química 2011: os mitos da químicaPublication . Caetano, Fernando J. P.; Oliveira, Carla Padrel de; Oliveira, PauloDesmistificação de alguns mitos da Química. O que é a Química? Participação do Professor Jorge Calado, do Departamento de Engenharia Química do Instituto Superior Técnico e Presidente da Comissão Nacional para o AIQ-Ano Internacional da Química, 2011.
- Ano Internacional da Química 2011: porquê 2011?Publication . Caetano, Fernando J. P.; Oliveira, Carla Padrel de; Oliveira, PauloPor que motivo 2011 foi escolhido para comemorar o Ano Internacional da Química (AIQ). Participação do Professor Jorge Calado, do Departamento de Engenharia Química do Instituto Superior Técnico e Presidente da Comissão Nacional para o AIQ-Ano Internacional da Química 2011.
- Aprendizagem ao Longo da Vida (ALV): desafios e inovaçãoPublication . Caetano, Fernando J. P.
- Aprendizagem ao Longo da Vida na UAb: desenvolvimento pessoal, capacitação e uma sociedade mais qualificadaPublication . Caetano, Fernando J. P.
- Capillary viscometry for routine measurements of newtonian liquidsPublication . Sequeira, Maria Carolina; Caetano, Fernando J. P.; Fareleira, João M. N. A.Viscosity is a thermophysical property of paramount importance, being essential for many scientific and industrial applications. The most common instruments for its measurement are glass capillary viscometers. Therefore, the use of capillary viscometers is widespread both in industry and in research. The range of viscosities of interest range from lower than that of water to several orders of magnitude higher values, the measurement of which requires different capillary viscometers. Most of the practical applications concern routine instruments, mainly for quality control. One main issue for the utilization of capillary viscometers relates to the need for their calibration, assuring its traceability to the water primary viscosity standard, to certify its worldwide validity. The present paper focuses on capillary instruments dedicated to perform viscosity measurements on Newtonian organic liquids at atmospheric pressure, as it is assumed that is the most widespread type of application for these viscometers. Capillary viscometry has a completely well-defined working equation, namely, the Hagen–Poiseuille equation. However, the practical performance of the measuring instruments deviates from that working equation. Most of those deviations are currently considered by many users. However, some of those deviations have not reached that status yet, like those concerning the effects due to the surface tension of the sample on the measurements. All these aspects are summarized and analyzed in the present article, together with a brief general description of the most common types of capillary viscometers, namely, the Ostwald and the constant-level or Ubbelohde instruments.
- Compreender o efeito das emissões de carbono sobre a biodiversidade em meio aquáticoPublication . Caetano, Fernando J. P.