The Portland cement concrete material is the most consumed after the water worldwide due to their versatility molding, strength and durability as a structural material. The curing is the procedure that aims to keep the concrete saturated with water in their early ages and it is essential to ensure the reactions of cement hydration, promoting its consolidation as artificial rock. Curing accomplished through controlled procedures is essential to promote or measure the performance potential of concrete, both resistance and durability. The curing of concrete is therefore an important variable to be controlled in the works, in assays for quality control of the material in manufacturing processes of prefabricateds or also in research. Moreover, the normal period and ideal curing concrete that lasts 28 days is in excess in all cases cited, so it is usual the prediction of the strength by early ages or shorter periods by accelerated curing of the concrete. In this work, the main objective was to design and test a hybrid solar reactor to promote accelerated curing of concrete in warm water, a modified method of the Type A ASTM C 684:1999, seeking a future evolution to a Brazilian test method that can be used in quality control of concrete. The major design challenges were address control and distribution of the temperature inside the reactor and to test the time reduction of curing Portland cement pastes from 28 days in water at 23°C to 7 days in water at warm 35°C. The reactor was assembled in the laboratory and consists of a solar water heater attached to a sealed tank, and that alone should keep the warm water at the temperature indicated. Should make maximum use of solar energy, ie, with greater use of renewable and clean energy. Account is also supported by an electric heater and a generator to supply power on cloudy days or in a possible power outage by the local distributor or maintenance of the electrical system. The water/cement ratio of the cement pastes studied ranged between 0.25 and 0.35 kg/kg and the development of hydration was monitored both by thermogravimetric analysis and by tests of compression strength. The sample tests pastes cured in the reactor at 35°C, initially followed the curing range of ASTM Method A (0 to 24h) and they also were tested in the other three options for adapting the accelerated test (24 to 48 h, 24 h to 72h and 24 h to 168 h), because the period 0-24 h is only feasible in a laboratory situation. The sample test pastes underwent cure (23°C) were tested at 7 and 28 days. It was concluded that there were changes in hydration during the three tested accelerated periods, but even within 24 h to 168 h accelerated curing the pastes not achieved the strength of normal curing after 28 days. / O concreto de cimento Portland é o material mais consumido no mundo depois da água, devido à sua versatilidade de moldagem, resistência e durabilidade como material estrutural. A cura é o procedimento que visa manter o concreto saturado de água nas suas primeiras idades e é essencial para garantir as reações de hidratação do cimento, promovendo a sua consolidação como rocha artificial. A cura realizada através de procedimentos controlados é fundamental para se promover ou medir o desempenho potencial do concreto, tanto de resistência como de durabilidade. A cura do concreto é, portanto, uma variável importante de ser controlada nas obras, nos ensaios de controle de qualidade do material, em processos de pré-fabricação ou ainda em pesquisas. Por outro lado, o prazo normal e ideal de cura do concreto, que dura 28 dias, é excessivo em todas as situações citadas, sendo usual a predição da resistência por prazos menores ou por cura acelerada do concreto. Neste trabalho, o objetivo principal foi projetar e testar um reator solar híbrido para promover a cura acelerada do concreto em água morna, por método modificado do Tipo A ASTM C 684:1999, visando uma futura evolução para um método de ensaio brasileiro, que possa ser utilizado em controle de qualidade do concreto. Os desafios principais do projeto foram solucionar o controle e a distribuição da temperatura no interior do reator para testar a redução do tempo de cura de concreto e de pastas de cimento Portland, de 28 dias, em água a 23oC, para até 7 dias em água à temperatura morna de 35oC.O reator foi montado em laboratório e consiste de um aquecedor solar acoplado a um tanque lacrado, isolado e que deve manter a água morna na temperatura indicada. eve utilizar ao máximo a energia solar, ou seja, com maior aproveitamento das energias renováveis e limpas. Contou-se, também, com o apoio de um aquecedor elétrico e um gerador para suprir energia em dias nublados, ou em uma eventual falta de energia por parte da distribuidora local ou manutenção do sistema elétrico. A pasta de cimento estudada teve a proporção água/cimento variando entre 0,25 e 0,35, e a evolução da hidratação foi monitorada tanto por análise termogravimétrica, quanto por ensaios de resistência à compressão. Os corpos-de-prova curados no reator a 35°C, inicialmente obedeceram ao intervalo de cura do método A da ASTM (0 a 24h) e, nas mesmas pastas, foram testadas três alternativas de adaptação do ensaio acelerado (24h a 48h; 24 h a 72h e 24 h a 168 h), pois o prazo de 0 a 24 h é uma situação apenas viável em laboratório. Os corpos-de-prova submetidos à cura normal (23°C) foram ensaiados a 7 e 28 dias. Concluiu-se que houve evolução da hidratação nos três períodos de cura acelerada testados, mas, até o prazo 24 h a 168 h de cura acelerada foi insuficiente para as pastas alcançarem a resistência de cura normal, a 28 dias.

This Master thesis, in collaboration with Morgonsol Väst AB, was completed as a part of the Solar Energy engineering program at Dalarna University. It analyses the electrical and thermal performance of a prototype PVT collector developed by Morgonsol Väst AB. By following the standards EN 12975 and EN ISO 9806 as guides, the thermal tests of the collector were completed at the facility in Borlänge. The electrical performance of the PVT collector was evaluated by comparing it to a reference PV panel fitted next to it. The result from the tests shows an improved electrical performance of the PVT collector caused by the cooling and a thermal performance described by the linear efficiency curve ηth=0.53-21.6(Tm-Ta/G). The experimental work in this thesis is an initial study of the prototype PVT collector that will supply Morgonsol Väst with important data for future development and research of the product.

Οι ανανεώσιμες πηγές ενέργειας (ΑΠΕ), όπως η ηλιακή ενέργεια, μπορούν να προσφέρουν εναλλακτικούς τρόπους παραγωγής ενέργειας. Κάθε μορφή ΑΠΕ έχει τις δικές της ιδιομορφίες και μπορούν να εφαρμοστούν είτε σε μεγάλες εγκαταστάσεις παραγωγής ηλεκτρικής και θερμικής ενέργειας είτε σε μικρότερες μονάδες όπως στα κτίρια. Ενδιαφέρον παρουσιάζει η συνδυασμένη αξιοποίηση των παραπάνω ενεργειακών πηγών, ιδίως για την κάλυψη των ηλεκτρικών και θερμικών αναγκών των κτιρίων.Αντικείμενο αυτής της διπλωματικής εργασίας είναι η μελέτη συγκεντρωτικών συστημάτων χαμηλής συγκέντρωσης και των παραγόντων που επηρεάζουν την λειτουργία τους, με την χρήση τριών γεωμετρικών συγκεντρωτικών μέσων, τα οποία είναι: το σύστημα V-Trough, το σύστημα Fresnel γραμμικής εστίας και το κυλινδροπαραβολικό σύστημα γραμμικής εστίας, με χρήση συμβατικών φωτοβολταϊκών για την παραγωγή ηλεκτρικής ισχύος. Όμως, από το την προσπίπτουσα ηλιακή ακτινοβολία που συγκεντρώνεται στον απορροφητή, ένα μέρος μετατρέπεται σε ηλεκτρική ενέργεια, ενώ το υπόλοιπο μεταδίδεται στο περιβάλλον με την μορφή θερμότητας. Έτσι, περαιτέρω μελέτη έγινε με βάση την δημιουργία υβριδικού συγκεντρωτικού φωτοβολταϊκού/θερμικού συστήματος, ταυτόχρονης παραγωγής ηλεκτρικής και θερμικής ενέργειας χρησιμοποιώντας την βέλτιστη γεωμετρία, το οποίο θα μπορούσε να δώσει ικανοποιητικά ποσά θερμικής ενέργειας, χωρίς να ζημιώνεται η ηλεκτρική και το αντίστροφο, κάτι που θα καθιστούσε τα συστήματα αυτά ενεργειακώς και οικονομικώς πιο ανταγωνιστικά.Τα πειραματικά αποτελέσματα περιλαμβάνουν διαγράμματα ηλεκτρικών αποδοτικοτήτων των πειραματικών συστημάτων καθώς και των μεγεθών Pmax, Vpmax, Voc, Ιpmax, Ιsc, συναρτήσει της θερμοκρασίας λειτουργίας Tpv, κάτω από σταθερή ακτινοβολία G, θερμικών αποδόσεων, προφίλ κατανομών συγκεντρωτικής ακτινοβολίας καθώς και χαρακτηριστικές καμπύλες I-V για καθένα απ αυτά. / The renewable energy sources (RES) like solar energy, can offer an alternative solution to power production. Each form of RES, has its own specifications and they can be applied in big installations of electric and thermal energy production or in smaller units as the buildings. This thesis investigates the performance of three different types of solar concentrating systems, which are: the V-Trough system, the linear Fresnel system and the Parabolic Trough system, with usage of common photovoltaics, instead of concentrating photovoltaics, for the electricity production.However, only a small part of the incoming solar radiation it is changed by an absorber into electric energy, while the rest is transmitted to the environment with the form of heat. Thus, further study has been done with base of the creation of a hybrid concentrating photovoltaic/thermal system, with simultaneous production of electric and thermal energy using the most optimal geometry. This could give satisfactory sums of thermal energy, without affecting the production of electric energy and vice versa, something that would render this systems economically more competitively.The experimental results include diagrams with the electric performance of the experimental systems as well as values of Pmax, Vpmax, Voc, Ipmax, Isc, associated with the operating temperature Tpv, under constant radiation G, thermal output, distribution profiles of the concentrating radiation as well as characteristic curves I-V for each one of them.