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- Water-Energy Nexus: Review of Literature in Management of Integrated Systems, Challenges and Opportunities. Case Study in Urban ContextPublication . Silva, Ana Rita Carriço; Santos, Fernando Charrua; Espírito Santo, António; Páscoa, J. C.; Fael, Cristina Maria SenaIn a society where Energy and Water walk side by side in practically all sectors of activity, it becomes necessary to analyze them from a productive, economic and sustainable point of view. From the extraction of mines and wells, to its treatment and transportation, and to the cooling systems of energy production, and despite being independently developed, managed and regulated, it is known that water needs energy and energy needs water. All these concerns, decision-making and the relationship between water and energy by itself create an opportunity to improve management in both sectors. There is an urgent need to consider all the assumptions and alternatives to improve the system and reduce energy consumption, which includes technological modifications and optimized resources management, leading to a more sustainable future. The increasing demand for energy and its exponential trend will have repercussions at all levels and will consequently increase the strain on freshwater resources with the most affected agricultural and industrial sectors. By improving the efficiency of water and energy use, there are positive repercussions that allow for substantial savings, especially where there is a lack of such resources. This article aims to address all these crucial issues related to energy and water in order to increase knowledge on the subject and to help promote alternatives for managing and developing integrated management systems and, consequently, for a rational use of both resources and a more sustainable future.
- Development of the Concept vs Prototyping: Implementation of a real scale Water-Energy Integrated SystemPublication . Silva, Ana Rita; Santos, Fernando Charrua; Espírito Santo, António; Páscoa, J. C.; Fael, Cristina Maria SenaCurrently, the concept of smart cities and renewable energy are more consolidated and developed. With each passing day, new technological advances are emerging within both themes. At the same time, the water sector has becoming increasingly demanding in terms of quality and compliance with all existing legislation. That said, it is understandable that both sectors and their management entities come together in search of more sustainable operations that go against the reduction of greenhouse gas emissions, decentralization of energy production and the improvement of efficiency, quality and use of resources. It is important to understand the synergies between water and energy to contradict what has been said so far about the increasing demand for energy, its exponential trend and the negative repercussions on freshwater resources. As such, this article aims to address the interconnection between both sectors to promote alternative scientific and technological improvements to the management and development of Integrated Water-Energy systems, while studying the dynamics between the theoretical development of the problem and the challenges of prototyping of such complex systems in real and urban context.
- Numerical simulation of the polymer electrolyte membrane fuel cells with intermediate blocked interdigitated flow fieldsPublication . Bagherighajari, Fatemeh; Ramiar, Abbas; Abdollahzadehsangroudi, Mohammadmahdi; Pascoa, José; Oliveira, Paulo J.The main purpose of this paper is to study fuel cell performance using an interdigitated flow field with intermediate channel blocks on the cathode side. Application of an intermediate block in the middle of the interdigitated flow channel is a very new idea aimed at increasing the performance of polymer membrane fuel cells, which in practice result in novel arrangements of interdigitated flow channels. A middle block is desirable because the change in flow channel is minimal, the cost of fabricating bipolar plates does not increase, and it leads to an increase in the transfer rate of reactants into the gas diffusion layer due to enhanced over-rib flow pattern and direction. In this work, a three-dimensional, isothermal, and two-phase model is used to simulate the performance of such fuel cells. The polarization curves, the distribution of reactants on the cathode side, the distribution of liquid water, and the induced transverse flow were analyzed for three type of interdigitated flow fields along with parallel flow fields at reference conditions. The results showed that interdigitated flow fields with middle blocks lead to an increase in reactant transfer to the catalyst layer, an increase in reaction rate, and better removal of the resulting liquid water within the fuel cell. In the reference condition, in terms of maximum power density, the type I interdigitated flow field (without intermediate block) increased the net power by 8.2% compared to the parallel flow field, and the type II and III interdigitated flow fields also increased the power by 12.58% and 9.03%, respectively. At high current density, the type II interdigital flow field had the best performance in terms of enhancing the transfer of reactants to the catalyst layer and the expulsion of liquid water from that layer.
- Study of a Water-Energy Integrated System: Challenges of PrototypingPublication . Silva, Ana Rita; Santos, Fernando Charrua; Espírito Santo, António; Páscoa, J. C.; Fael, Cristina Maria SenaIn a society where Energy and Water walk side by side in practically all sectors of activity, it becomes necessary to analyze them from a productive, economic and sustainable point of view. Although independently developed and regulated, it is known that water needs energy and energy needs water. The increasing demand for energy and its exponential trend will have repercussions at all levels in the short term. and consequently, will increase the strain on freshwater resources. All these concerns and associated decision-making policies create an opportunity to improve the management of both sectors. There is an urgent need to improve the water-energy system and reduce energy consumption, using advanced technological changes and an optimized management strategy, leading to a more sustainable future. By improving the efficiency of water and energy use through integrated smart strategies, there are very positive repercussions on savings and impact on the local economy, especially in decentralized cases. The present paper aims to address the theme of the nexus of water-energy in the scope of promoting alternatives of management and development of integrated systems and study the dynamics of the development of the theoretical concept vs. prototyping in case of urban context and real environment.
- Development of a Background-Oriented Schlieren (BOS) System for Thermal Characterization of Flow Induced by Plasma ActuatorsPublication . Moreira, Miguel; Rodrigues, Frederico; Cândido, Sílvio; Santos, Guilherme; Pascoa, JoséCold climate regions have great potential for wind power generation. The available wind energy in these regions is about 10% higher than in other regions due to higher wind speeds and increased air density. However, these regions usually have favorable icing conditions that lead to ice accumulation on the wind turbine blades, which in turn increases the weight of the blades and disrupts local airflow, resulting in a reduction in wind turbine performance. Considering this problem, plasma actuators have been proposed as devices for simultaneous flow control and deicing. These devices transfer momentum to the local airflow, improving the aerodynamic performances of the turbine blades while producing significant thermal effects that can be used to prevent ice formation. Considering the potential application of plasma actuators for simultaneous flow control and deicing, it is very important to investigate the thermal effects induced by these devices. However, due to the significant electromagnetic interference generated by the operation of these devices, there is a lack of experimental techniques that can be used to analyze them. In the current work, a background-oriented Schlieren system was developed and is presented as a new experimental technique for the thermal characterization of the plasma-induced flow. For the first time, the induced flow temperatures are characterized for plasma actuators with different dielectric materials and different dielectric thicknesses. The results demonstrate that, due to the plasma discharge, the temperature of the plasma-induced flow increases with the increase of the applied voltage and may achieve temperatures five times higher than the room temperature, which proves the potential of plasma actuators for deicing applications. The results are presented and discussed with respect to the potential application of plasma actuators for simultaneous flow control and deicing of wind turbine blades.
- Dielectric barrier discharge plasma actuators based on thermosetting composites for flow control in wind turbines bladesPublication . Nunes-Pereira, João; Rodrigues, Frederico; Abdollahzadehsangroudi, Mohammadmahdi; Pina dos Santos, Paulo Sérgio; Silva, Marco; Pereira Silva, A; Pascoa, Jose; Lanceros-Mendez, SenentxuThe massive use of fibre reinforced plastics (FRP) in several industrial sectors such as aeronautics, aerospace, or wind turbines, raises serious environmental concerns with respect to the end-of-life of these structures, based on their poor recyclability. The low density of FRP gives it outstanding specific properties, such as strength and stiffness, when compared to materials with high recyclability rates, such as metals1. FRP find several applications in structures in which the aerodynamic performance is of extreme importance to guarantee a proper operation. In this sense, to endow these structures with the ability to control or modulate the flow around their surface could be an extraordinary feature to improve the performance of the structure, thus saving considerable amounts of energy and increasing its useful life cycle, contributing in this sense also to reduce the environmental impact of the materials. This work is focused on the development of dielectric barrier discharge (DBD) plasma actuators supported on fibre reinforced thermosetting composites, which can be used in manufacturing of wind turbine blades: epoxy resin and glass, aramid (Fig. 1) and natural flax fibres. DBD plasma actuators are electrohydrodynamic devices capable of generating induced flows of a few m/s through nonthermal plasma, that can be successfully leveraged for flow control applications2, 3. The characterization of the system was carried out in terms of mechanical (flexural strength, strain and stiffness), electrical (power consumption, capacitance, charge-discharge cycles) and electromechanical (induced flow velocity, electromechanical power and efficiency) properties. The results showed the multifunctionality of the composites, demonstrating their suitability for the application, in particular, the epoxy/glass composite with a bending stress of ≈600 MPa, which obtained an induced flow velocity of ≈2.1 m/s with a power consumption of ≈15.1 W, when powered by an AC signal of 11 kVpp and 24 kHz.
- Multifunctional Ceramics for Aeronautical and Aerospace ApplicationsPublication . Shvydyuk, Kateryna; Nunes-Pereira, João; Rodrigues, Frederico; Pascoa, Jose; Lanceros-Mendez, Senentxu; Pereira Silva, AIn the areas of aeronautics and aerospace, ceramic composites play an essential and increasing role due to their superior performance and tailorable properties, exhibiting highly specialized mechanical, thermal, and electric features1. Their main applications include thermal protection systems (TPS), thermal barrier coatings (TBC), and dielectric barrier discharge (DBD) plasma actuators, both for instrumentation and control purposes2. This work reports the manufacture and characterization of three ceramic composites capable of fulfilling the multifunctional ceramic condition according to the aforementioned applications. Accordingly, MgO-Al2O3 (MA), MgOCaZrO3 (MCZ), and Y2O3 stabilized ZrO2 (YSZ) are introduced for TPS, TBC, and DBD dielectric elements. To this aim, MA, MCZ, and YSZ ceramic composites were fabricated via a sequential process, encompassing the selection of raw powders and milling, die pressing, and sintering. Further, the samples were polished for surface optimization. Overall, the results obtained, including mechanical (Young’s and shear moduli, flexural strength, hardness, and fracture toughness), thermal (thermal conductivity and thermal expansion (CTE)), and electrical (dielectric constant) properties, report evidence that the developed ceramics show suitable multifunctional characteristics and therefore fulfil the aeronautical and aerospace demands for increased materials performances. The combined analysis of the Young’s and shear moduli (Fig.1a) with the CTE – the latter over a wide range of temperatures (Fig. 1b) – allows concluding that the cost-effective and widely used alumina appears suitable for bulk monolithic (TPS) and joint applications (TPS, TBC, and DBD).
- Plasma Actuators Based on Alumina Ceramics for Active Flow Control ApplicationsPublication . Rodrigues, Frederico; Shvydyuk, Kateryna; Nunes-Pereira, João; Pascoa, Jose; Silva, AbilioPlasma actuators have demonstrated great potential for active flow control applications, including boundary layer control, flow separation delay, turbulence control, and aircraft noise reduction. In particular, the material used as a dielectric barrier is crucial for the proper operation of the device. Currently, the variety of dielectrics reported in the literature is still quite restricted to polymers including Kapton, Teflon, poly(methyl methacrylate) (PMMA), Cirlex, polyisobutylene (PIB) rubber, or polystyrene. Nevertheless, several studies have highlighted the fragilities of polymeric dielectric layers when actuators operate at significantly high-voltage and -frequency levels or for long periods. In the current study, we propose the use of alumina-based ceramic composites as alternative materials for plasma actuator dielectric layers. The alumina composite samples were fabricated and characterized in terms of microstructure, electrical parameters, and plasma-induced flow velocity and compared with a conventional Kapton-based actuator. It was concluded that alumina-based dielectrics are suitable materials for plasma actuator applications, being able to generate plasma-induced flow velocities of approximately 4.5 m/s. In addition, it was verified that alumina-based ceramic actuators can provide similar fluid mechanical efficiencies to Kapton actuators. Furthermore, the ceramic dielectrics present additional characteristics, such as high-temperature resistance, which are not encompassed by conventional Kapton actuators, which makes them suitable for high-temperature applications such as turbine blade film cooling enhancement and plasma-assisted combustion. The high porosity of the ceramic results in lower plasma-induced flow velocity and lower fluid mechanical efficiency, but by minimizing the porosity, the fluid mechanical efficiency is increased.
- Long-lasting ceramic composites for surface dielectric barrier discharge plasma actuatorsPublication . Shvydyuk, Kateryna; Rodrigues, F.F.; Nunes-Pereira, João; Pascoa, José; Lanceros-Mendez, Senentxu; Silva, A PereiraThe developed research presents a novel experimental study of the cost-effective MgO-Al2O3, MgO-CaZrO3 perovskite, and thermally stable YSZ ceramic composites for DBD plasma actuators in aerospace applications. This study focuses on the implementation of ceramic DBD plasma actuators for aerodynamic flow control and ice creation mitigation. For this purpose, electrical power consumption analysis, induced flow velocities assessment, and mechanical and thermal characterization were performed. MgO-Al2O3 presented higher induced velocities than its zirconia-based counterparts of up to 3.3 m/s, and lower heat dissipation, achieving a ceiling temperature of 46 ºC, being thereby the best-suited candidate for active flow control mechanisms. In contrast, YSZ had very high-power consumption translated into a maximum surface temperature of 155.4 ºC, establishing itself for ice mitigation. This extensive research evinces that the strategic combination of the developed ceramics’ thermomechanical, thermoelectric, and electromechanical properties allows them to be a promising breakthrough material for DBD plasma actuators.
- Improved performance of polyimide Cirlex‐based dielectric barrier discharge plasma actuators for flow controlPublication . Nunes-Pereira, João; Rodrigues, Frederico Miguel Freire; Abdollahzadehsangroudi, Mohammadmahdi; Pascoa, José; Lanceros-Mendez, SenentxuDielectric barrier discharge (DBD) plasma actuators are simple electrohydrodynamic devices, which are able to provide effective aerodynamic control. One of the main components of these devices is the thin dielectric layer, which allows to separate and prevent the arc between the high-voltage electrodes. Different materials can be used as dielectric layer to reduce the power consumption or boost the flow controlling effect of the actuators. In this context, this report presents a comparative study of two commercial polyimides, Kapton and Cirlex, used as dielectric layer of surface DBD plasma actuators. The electrical, dielectric, mechanical, electromechanical, and thermal properties were obtained to evaluate overall performance. It was verified that Cirlex (8.3 W) consumes less power than Kapton (21.3 W) to generate higher induced flow velocity of ≈3.4 m/s for an input voltage of 11 kVpp and 24 kHz. During one AC cycle at 11 kVpp the charge transferred for Cirlex (70 nC) is lower than for Kapton (100 nC), as well as the dielectric breakdown voltage to ignite the plasma discharge, 1.5 and 2.2 kVpp, respectively. The Cirlex DBD presents a higher voltage operation limit (at least 14 kVpp) and a more regular plasma discharge, which results in a more homogenous thermal profile and temperature distribution during its operation. The Cirlex actuator delivered higher mechanical power (6.2 mW) and achieved higher electromechanical efficiency (0.004%). The polyimide Cirlex proved to be a suitable alternative for Kapton to fabricate DBD plasma actuators for flow control with improved performance.