ES - Comunicações em actas de encontros científicos internacionais
Permanent URI for this collection
Browse
Recent Submissions
- EU-SOLARIS: The European Research Infrastructure Consortium for CSP TechnologiesPublication . Martinez, Diego; Blanco Galvez, Julian; Zarza, Eduardo; Sánchez-Moreno, Ricardo; Bataille, Francoise; Flamant, Gilles; Georgiou, Marios; Richter, Christoph; Blanco, Manuel; Cardoso, João P.; Horta, Pedro; Canavarro, DiogoABSTRACT: After many years of fruitful collaboration in the field of research infrastructures (RIs) for concentrated solar power/solar thermal energy applications, several European countries decided to apply to the European Commission to go a step forward and create a European Research Infrastructure Consortium (ERIC), a new legal form of association which poses a number of advantages in the endeavour for a further development of this technology in Europe at all levels. This new consortium, EU-SOLARIS ERIC, is likely to be legally implemented in October 2022, after a long negotiation and evaluation process, where the support of the respective Governmental research agencies of the countries involved has been crucial. EU-SOLARIS ERIC will be a legal entity and its main goal will be the improvement of the interoperability, accessibility and quality of services provided by the existing European research infrastructures to the CSP/STE research communities and industrial stakeholders. Although the current Members of the EU-SOLARIS consortium are Germany, France, Cyprus and Spain (Statutory Seat at Plataforma Solar de Almeria, Spain), plus Portugal as an Observer, it is open to any other country willing to participate as Member or Observer.
- Solar Irradiance (Global, Direct and Diffuse) Quality Control Methodologies. Review: Application to Time Series Measured At LES/LNEG, Lisboa, PortugalPublication . Marques, Filipe; Páscoa, Soraia; Carvalho, Maria João; Cardoso, João P.ABSTRACT: Solar irradiance spatial and temporal quantification is essential to the development, implementation, and operation of solar systems, being used throughout a solar project lifecycle. It is crucial to have good quality data measured in meteorological and radiometric ground stations in order to enable the calibration and validation of irradiance models and data series. The Solar Energy laboratory at LNEG operates a meteorological station gathering relevant parameters to characterize the solar irradiation profile for the city of Lisbon in Portugal. This work presents and compares the application of different methodologies used for quality control of solar irradiance measurements. Three methods - the CIE (1994) / Muneer and Fairooz (2002), the QCRad and the IEC - were tested against two synthetic data sets: a clear-sky year and a typical meteorological year randomly and uniformly infused with errors. IEC showed to have limitation regarding the extreme value criteria for beam normal irradiance and CIE for the diffuse horizontal irradiance. The QCRad presented the best performance, with total sensitivity above 80% and maximum specificity. This method was applied to the measured data of LES-LNEG between 2014 and 2018. Most of the detected errors were detected during the coherence test stage, having a higher prevalence between 2015 and mid-2016, highlighting the need to modify the diffuse horizontal irradiance measuring system.
- Aging of elastomeric components of a solar thermal collector under solar radiationPublication . Ferreira, Cristina; Ritto, G.; Cidade, M. T.; Carvalho, Maria João; Cunha Diamantino, TeresaABSTRACT: Elastomeric components play important functions in solar thermal collectors (STC’s) as sealings, fittings or absorbers, being important that they maintain their performance along STC lifetime. However, stress factors such as high temperatures and high levels of solar radiation, as exist in southern Europe countries, can affect the properties of those components. A testing programme for the assessment of elastomeric materials of such components is detailed in international standards (ISO 9808 and ISO 9553), which already considers the effect of heating.
- Accelerated aging tests for solar absorber coatingsPublication . Cunha Diamantino, Teresa; Gonçalves, Rita; Páscoa, Soraia; Alves, Isabel Nascimento; Chambino, Teresa; Ferreira, Cristina; Carvalho, Maria JoãoABSTRACT: The need of a higher role of solar energy within the energy mix in the coming decades obliges the systems to increase their performance and reliability. It is demanded that the solar absorbers, as the key component of solar thermal systems, should be low cost with high efficiency for extended lifetimes under different kinds of environments. Commercially, there are two different types of solutions as selective solar absorbers coatings: coatings obtained by physical vapor deposition (PVD) and by paint coatings (PC). These coatings present different physical and chemical characteristics. Therefore, it is important to know how these coatings degrade over time in different environments. Results obtained with two different PVD coatings and three PC, under different accelerated aging tests, are presented. The aging tests performed included different environmental stress corrosion conditions: temperature, humidity, chlorides, sulphur dioxide and nitrogen oxides. Cyclic variation of corrosion promoting gases (sulfur dioxide and nitrogen dioxide), higher humidity, salt spraying and drying seem to be an aging test that reflects the different environments where the solar thermal collectors are exposed. In addition to the contaminants, drying / wetting cycles also play an important role in degradation mechanisms of absorber coatings.
- Assessment of durability of solar absorbers : performance criterionPublication . Páscoa, Soraia; Carvalho, Maria João; Cunha Diamantino, TeresaABSTRACT: Solar fraction, Fs, defined as the ratio between the delivered energy from a solar domestic hot water (DHW) system and the load (thermal energy necessary to satisfy domestic water heating needs), is widely accepted as performance indicator for this type of systems. Considering solar absorptance αs and thermal emittance εt as the most relevant characteristics of solar absorbers, the relation between the depreciation of these optical properties and depreciation of Fs was used by Hollands et al (1992) to define a performance criterion (PC) for assessment of long-term behavior and service life of selective solar absorbers. The PC was established mainly for solar DHW systems working with solar fractions lower than 50%. In this work, systems working with solar fractions higher than 50%, in climates of south of Europe, are considered and the suitability of solar fraction as performance indicator to develop an adequate PC is studied. As a first step simulations of thermal performance of systems using an in-house software were performed for a reduction of 5% and 10% of Fs. In ISO 22975-3, solar fraction Fs degradation must be lower than 5% to guarantee 25 years of service life for DHW system. The results showed that the parameters obtained to define the PC were incoherent considering solar fractions higher than 50%. In a second step, supplied energy was considered as performance indicator and using similar methodology as Hollands et al (1992), but using as performance indicator energy supplied by the solar system, the PC for systems working with solar fractions higher than 50%, in climates of south of Europe, was establish. The results showed that this is not significantly different from the PC considered in ISO 22975-3.
- Optical properties of solar absorbers : results on Round Robin and guidelinesPublication . Carvalho, Maria João; Páscoa, Soraia; Sallaberry, Fabienne; Wilson, Helen Rose; Fischer, S.; Loren, Anders; Bohren, Andreas; Nielsen, Jan ErikABSTRACT: The scope of the standard ISO 22975-3:2014 is the determination of the long term behavior and service life of selective solar absorbers for use in vented flat plate collectors used in typical solar domestic hot water systems or combisystems. With this scope, this standard can be the basis for the certification of solar absorbers in the framework of Solar Keymark European Certification Scheme. Measurements of optical properties are fundamental to support this certification. Six test laboratories participated in a Round Robin test for the measurement of solar absorptance and thermal emittance of different absorber coatings. The samples used were one PVD coating and two selective paint coatings all on aluminum substrates. The results were submitted anonymously and were analyzed according to standard ISO 13528:2015. The results obtained showed good agreement among the measurements made by the participants and allowed the preparation of guidelines to guarantee quality of the measurements of optical properties of solar absorbers. A proposal to include absorber coatings in the Solar Keymark certification scheme was prepared.
- Smart battery management systems: towards an efficient integration of electrical energy storage in smart regionsPublication . Gano, António; Silva, Hugo M.; Correia, João Bernardino; Martins, Maria JoãoElectrical energy storage systems for electric vehicles or stationary applications will be important actors in Smart Region's energy scenarios, strongly contributing to increase the efficient and sustainable use of available resources. However, massive integration of such systems stillposes many problems, requiring enhancements in batteries's life time, autonomy, reliability and cost. The development of new smart and accurate battery management systems able to communicate with a broad range of smart devices and energy management systems, to account with users' needs and smart management directives, are essential to operate such battery based energy storage systems, improving their overall performance. The paper discusses some of the technological developments needed in this domain and the requirements of smart battery management systems to comply with, presenting a modular hardward platform, developed at LNEG, as an example of required structure and functionalities, relevant both in electrical mobility and decentralized smart-grid energy storage systems.
- Cork wastes as energy sourcesPublication . Gil, Luís; Marques, Isabel PaulaThis work shows the possibility of using cork wastes form cork processing for energy production. In cork processing operations an important waste is produced, cork powder, the main waste of the cork industry, which is estimated to reach over 30000 tons/year. There are various types of cork powders with higher calorific values ranging from 4,000-7,000 Kcal/kg. This powder is commonly burned to produce steam or heat used in the factories themselves, given the high energy content of this material. As an example, a cork company of a large industrial group that produces cork products for construction meets 60% of its energy needs using waste cork. Cork boiling wastewater (CBW) is an aqueous and complex effluent of the cork industry which is produced during the boiling of the cork planks. CBW contains organic materials such as phenolic. This boiling wastewater has no utility, being a serious environmental hazard. Anaerobic digestion is a promising technology for the treatment of organic effluents and for the simultaneous recovery of its energetic potential through methane production. Its application to cork effluents was studied. An anaerobic assay was conducted. The resultant methane potentials were 0.126 - 0.142 m3 CH4 kg-1 COD. The calculated total volume of CBW produced yearly in Portugal is 30 374 m3. As 1 m3 of CBW (6,5 COD kg m-3) in cogeneration can produce in average 1,72 kWh of electric energy and 3,73 kWh of thermal energy, the total CBW volume produced in Portugal in one year corresponds to a total energy value of 165 400 kWh.
- Phenolic compouds with antiradical activity from the cork boiling wastewater anaerobic digestionPublication . Gil, Luís; La Cara, F.; Marques, Isabel PaulaThis work aims to develop a procedure that explores the different types of valorization that can be obtained by integrating a biological process, such as the anaerobic digestion, to promote the bioconversion of the industrial cork effluents (cork boiling wastewater, CBW).
- Cork wastes treatment and biogas productionPublication . Gil, Luís; Marques, Isabel PaulaCork industry is an important economic and social sector in the western Mediterranean region. Portugal is the producer and processing leader of this sector. The cork processing industry gives rise to several effluents that must be treated and valorised. This work is a part of a study that aims to develop an integrated process in order to maximize the valorization of the different wastes/effluents of the cork processing sector taking in count the biorefinery concept. The main objective of the present work is to conduct a survey of all operations involve in the cork processing and identify the possible effluents which may be treated and valorise by anaerobic digestion for energy production.