Ciências e Tecnologia | Artigos em revistas internacionais / Papers in international journals
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Browsing Ciências e Tecnologia | Artigos em revistas internacionais / Papers in international journals by Sustainable Development Goals (SDG) "07:Energias Renováveis e Acessíveis"
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- Challenges ahead for sustainable cities: an urban form and transport system reviewPublication . Medina Monteiro, João Pedro; Sousa, Nuno; Coutinho-Rodrigues, João; Natividade-Jesus, EduardoThis article reviews the critical issues surrounding the development of sustainable urban environments, focusing on the impact of transport and urban form on energy consumption and greenhouse gas emissions. The aim is to provide an overview of the state-of-the-art on the subject and to unravel what directions the literature suggests for sustainable urban planning. Current research and practices are synthesized, highlighting the interdependence of urban design and transportation systems in achieving sustainability goals. Important dimensions and practices of city planning and transport policies are explored, including urban form, urban sprawl, mixed land use, densification and infill, and urban public spaces, and how these directly influence transport dynamics, including modal choices and energy consumption. Innovative approaches in urban planning, such as transit-oriented development, and technological advancements, such as electric mobility, are also examined and their potential roles in sustainable urban transport. The conclusion underscores the urgency of adopting holistic and adaptable strategies to foster sustainable urban environments, calling for concerted efforts from policymakers, urban planners, and communities. Awareness of the conclusions can help municipal decision-makers in planning their cities for a sustainable future. Finally, the authors analyze important directions for future research and practical applications towards developing cities that are environmentally sound, socially equitable, and economically viable.
- Correction: Di-Alkyl Adipates as new phase change material for low temperature energy storagePublication . Nogueira, Bernardo A.; Diogo, Hermínio P.; Fausto, Rui; Caetano, Fernando J. P.; Fareleira, João; Sequeira, Maria CarolinaThe following is a correction to the supplementary information of the paper titled “Di-Alkyl Adipates as new phase change material for low temperature energy storage” by Maria C.M. Sequeira, Bernardo A. Nogueira, Fernando J.P. Caetano, Hermínio P. Diogo, João M.N.A. Fareleira, Rui Fausto that appeared in International Journal of Thermophysics 44:165 (2023). https://doi.org/10.1007/s10765-023-03274-3
- Di-Alkyl adipates as new phase change material for low temperature energy storagePublication . Sequeira, Maria Carolina; Nogueira, Bernardo A.; Caetano, Fernando J. P.; Diogo, Herminio; Fareleira, João M. N. A.; Fausto, RuiThis work is a contribution to the thermal characterization of a selected binary system of two di-n-alkyl adipates that can be used as phase change material for thermal energy storage at low temperatures. The construction of the solid–liquid phase diagram using differential scanning calorimetry (DSC), complemented with Raman Spectroscopy studies for the system composed by diethyl and dibutyl adipates is presented. The solidus and liquidus equilibrium temperatures were determined by DSC for the pure components and 30 binary mixtures at selected molar compositions were used to construct the corresponding solid–liquid phase diagram. The binary system of diethyl and dibutyl adipates presents eutectic behaviour at low temperatures. The eutectic temperature was found at 240.46 K, and the eutectic composition was determined to occur at the molar fraction xdibutyl = 0.46. Additionally, the system shows a polymorphic transition, characteristic of dibutyl adipate, occurring at ca. 238 K, confirmed by optical microscopy. To the best of our knowledge, no reference to the phase diagram of the present system could be found in the literature. Raman spectroscopy was essential to complement the construction of the phase equilibrium diagram, enabling the identification of the solid and liquid phases of the system. Finally, the liquidus curve of the phase diagram was also successfully predicted using a suitable fitting equation, being the root mean square deviation of the data from the correlation equal to 0.54 K. In addition, this fitting operation enabled a correct prediction of the eutectic composition of the system.
- A multicriteria methodology for estimating consumer acceptance of alternative powertrain technologiesPublication . Sousa, Nuno; Almeida, Arminda; Rodrigues, João CoutinhoA multicriteria methodology for estimating consumer acceptance of vehicles with alternative powertrain technologies is presented. The approach is based on the non-compensatory ELECTRE TRI method and compares hybrid, plug-in hybrid, and electric vehicles to conventional models. Criteria considered are ownership costs and restrictions to vehicle use, which apply mainly to electric vehicles. The methodology is applied to a case study of 94 vehicles of different market segments and alternative powertrains. The analysis is carried out per segment and considers two driver profiles, city and all-purpose, and a baseline scenario for all cases. Output is tested for statistical significance, with powertrain technology as disaggregating factor, and a sensitivity analysis on the base scenario is also carried out, as well as a comparison with results derived by a compensatory multicriteria method (TOPSIS). Results show that conventional vehicles are the top choice for the small vehicles segment, due to lower purchase prices and higher use flexibility. For medium sized vehicles, all powertrain technologies are competitive for city drivers, whereas for all-purpose drivers, use restrictions for electric vehicles make these less attractive. The baseline scenario and sensitivity analysis highlight that opting for an electric vehicle depends strongly on the driver's use flexibility needs. As such, an electric vehicle can be either very attractive or outright unusable, regardless of financial considerations. It is also seen that plug-in hybrids do not present any significant advantage, as compared to other, non-electric choices, due to their higher purchase prices.
- Solid–liquid phase equilibrium of the n-Nonane + n-Undecane system for low-temperature thermal energy storagePublication . Nikitin, Timur; Sequeira, Maria Carolina; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Fausto , Rui; Diogo, HerminioThe current article presents an exploration of the solid–liquid phase diagram for a binary system comprising n-alkanes with an odd number of carbon atoms, specifically n-nonane (n-C9) and n-undecane (n-C11). This binary system exhibits promising characteristics for application as a phase change material (PCM) in low-temperature thermal energy storage (TES), due to the fusion temperatures of the individual components, thereby motivating an in-depth investigation of the solid–liquid phase diagram of their mixtures. The n-nonane (n-C9) + n-undecane (n-C11) solid–liquid phase equilibrium study herein reported includes the construction of the phase diagram using Differential Scanning Calorimetry (DSC) data, complemented with Hot–Stage Microscopy (HSM) and low-temperature Raman Spectroscopy results. From the DSC analysis, both the temperature and the enthalpy of solid–solid and solid–liquid transitions were obtained. The binary system n-C9 + n-C11 has evidenced a congruent melting solid solution at low temperatures. In particular, the blend with a molar composition xundecane = 0.10 shows to be a congruent melting solid solution with a melting point at 215.84 K and an enthalpy of fusion of 13.6 kJ·mol–1. For this reason, this system has confirmed the initial signs to be a candidate with good potential to be applied as a PCM in low-temperature TES applications. This work aims not only to contribute to gather information on the solid–liquid phase equilibrium on the system n-C9 + n-C11, which presently are not available in the literature, but especially to obtain essential and practical information on the possibility to use this system as PCM at low temperatures. The solid–liquid phase diagram of the system n-C9 + n-C11 is being published for the first time, as far as the authors are aware.
- Solid–liquid phase equilibrium: alkane systems for low-temperature energy storagePublication . Diogo, Hermínio P.; Fausto , Rui; Sequeira, Maria Carolina; Fernando J. P. Caetano; Fareleira, João M. N. A.; Nogueira, Bernardo A.The thermal characterization of two binary systems of n-alkanes that can be used as Phase Change Materials (PCMs) for thermal energy storage at low temperatures is reported in this work. The construction of the solid–liquid binary phase diagrams was achieved using differential scanning calorimetry (DSC) and Raman spectroscopy. The solidus and liquidus equilibrium temperatures were determined using DSC for thirty-nine different samples, three for the pure n-alkanes and the remaining for binary mixtures at selected molar compositions and used to acquire the corresponding solid–liquid phase diagrams. The two binary systems of n-octane/n-decane (C8/C10) and n-decane/n-dodecane (C10/C12) are characterized by a eutectic behavior at low temperatures. The eutectic temperature for the system C8/C10 was found at 211.95 K and the eutectic composition appeared at the molar fraction xoctane = 0.87. For the system C10/C12, the eutectic temperature was found at 237.85 K, and the eutectic composition appeared for the molar fraction xdecane = 0.78. This work aims to fulfill the lack of available data in the existing literature, considering the potential application of these systems for low-temperature thermal energy storage. Raman spectroscopy was used to complement the DSC data for the construction of the solid–liquid phase equilibrium diagrams, enabling the identification of the solid and liquid phases of the system. Additionally, the liquidus curve of the phase diagram was successfully described using a modified freezing point depression curve as fitting equation, the absolute root mean square deviation for the data correlation of the C8/C10 and C10/C12 systems being 2.56 K and 1.22 K, respectively. Ultimately, the fitting procedure also enabled a good prediction of the eutectic point for both studied systems.
- Viscosity and density measurements of Poly(ethyleneglycol) 200 and Poly(ethyleneglycol) 600 at high pressuresPublication . Sequeira, Maria Carolina; Avelino, Helena Maria da Nóbrega Teixeira; Caetano, Fernando J. P.; Fareleira, João M. N. A.New measurements for the viscosity and density of poly(ethyleneglycol) 200 [PEG 200] and of poly(ethyleneglycol) 600 [PEG 600], at pressures up to 50 MPa, are presented. The temperature range of the measurements performed for PEG 200 was from 293 to 348 K and for PEG 600 was from 303 to 348 K. A vibrating wire viscometer operated in the steady-state mode was used to carry out the measurements with an estimated overall uncertainty less than U(η) = 0.02·η, for viscosities up to 68 mPa s, and less than U(η) = 0.026·η, for higher viscosities with a confidence level of 0.95 (k = 2). Complementary density measurements for both PEGs were performed in the same ranges of temperature and pressure as for the viscosity measurements, using an Anton Paar HP vibrating tube densimeter, with an estimated overall uncertainty of about U(ρ) = 0.002·ρ with a confidence level of 0.95 (k = 2). Moreover, pressure–viscosity coefficients were obtained for both PEGs. A method based on a dense hard-sphere fluid theory was used to correlate the viscosity data with the density, for both PEGs, with a deviation of the experimental results less than 1%. A modified Tait equation was used to correlate the density results with temperature and pressure.