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- New test methodologies to analyse direct expansion solar assisted heat pumps for domestic hot waterPublication . Facão, Jorge; Carvalho, Maria JoãoSince there are not specific standards for testing direct expansion solar assisted heat pumps for domestic hot water, new testing methodologies are proposed supported by laboratory experiments. Two methodologies were developed for performance measurement: modified BIN method and long term performance prediction with a TRNSYS model validated with specific experimental conditions. The long term performance prediction is a methodology similar to the already obtained for solar thermal systems. A system was tested in Lisbon during one year, covering almost all possible local weather conditions. The hot water tapping test cycle used was in agreement with recent standards EN16147:2011 or EN15316-3-1:2007. The influence of average daily air temperature, dew point temperature and solar irradiation was analysed. The seasonal performance factor was calculated for two cities in Portugal (Lisbon and Porto) and for additional four cities in Europe (Davos, Athens, Helsinki and Strasburg). The establishment of a procedure to calculate the seasonal performance of this kind of systems is very important according to the directive 2009/28/EC of the European Parliament and of the Council.
- Optimization of flow distribution in flat plate solar thermal collectors with riser and header arrangementsPublication . Facão, JorgeThe thermal performance of flat-plate solar collectors with riser and header arrangements is strongly influenced by the flow distribution through the absorber tubes. A more uniform flow distribution leads to a homogenous temperature distribution which gives higher collector efficiency. The Z distribution usually has better performance when compared to P distribution. The design of the manifold influences the observed flow distribution. To optimize the manifold design, a correlation model was developed, based on correlations for minor pressure losses. Furthermore, the flow in this optimized geometry was simulated in 3D using the computational fluid dynamics (CFD) software code in order to confirm the results of the correlation based model. A new experimental low-intrusive technique was used to measure the flow distribution in an existing solar collector, validating the simulation results. The flow inside the absorber tubes is laminar; the major pressure loss inside riser tubes was measured using a high accuracy differential pressure transmitter, which then permits the indirect estimation of the mean velocity inside the tubes. It was the first time that this experimental methodology has been applied to analyse the flow distribution in solar collectors. The influence of the total water flow rate was analysed. For a good flow distribution it was concluded that the outlet header manifold should have a higher diameter compared to the inlet header diameter. Usually commercialised solar collectors have the headers with same diameter.
- Estimativa de potenciais técnicos de energia renovável em Portugal: eólico, solar fotovoltaico, solar concentrado, biomassa e oceanosPublication . Simoes, Sofia; Simões, Teresa; Barbosa, Juliana; Rodrigues, Carlos; Azevedo, Pedro; Cardoso, João P.; Facão, Jorge; Costa, Paula Silva; Justino, Paulo Alexandre; Gírio, Francisco; Reis, Alberto; Passarinho, Paula; Duarte, Luís C.; Moura, Patrícia; Abreu, Mariana; Estanqueiro, Ana; Couto, António; Oliveira, Paula; Quental, Lídia; Patinha, Pedro; Catarino, Justina; Picado, AnaExecutive Summary: There is a clear need to accelerate the energy transition, including the implementation of renewable electricity production plants, as well as the increase in consumption of other renewable energy carriers in buildings, industry, transport and other sectors. This work provides key information to make this transition possible, that is, the technical renewable energy potentials for Portugal. The aim is thus to contribute to policy support, as well as to decision-making by various Portuguese stakeholders (public and private) in the domains of energy, energy transition and greenhouse gases emissions mitigation. The work presents the technical renewable energy potentials for Portugal to: (i) decentralized solar photovoltaic (PV) plants in artificialized (or built-up) areas; (ii) centralized solar PV plants in non-artificialized (or natural) areas; (iii) concentrated solar power; (iv) onshore wind; (v) offshore wind (floating and fixed); (vi) bioenergy, and (vii) solar thermal. The wave energy primary energy resource potential is also presented (not the technical potential). The technical potential values of renewable energy sources (RES) presented are dynamic values, given the substantial uncertainty associated with their estimation. The study identifies technical RES potentials i.e., the technically viable energy generation achievable from a specific technology, considering the primary energy resource available and the geographic, environmental and land use limitations. RES economic potentials represent the fraction of RES technical potential that is economically viable, but they are not presented in this work. Likewise, this report does not address market potential, that translate the capacity and energy generation that the market effectively manages to implement. The presented RES technical potentials include the total capacity currently installed in the country. The technical potentials are estimated mostly for mainland Portugal, in most cases with a spatial disaggregation of at least NUT2 and sometimes for NUT5 and/or type of building. Despite adopting an approach based on a territorial analysis in which some areas of the country are excluded, this potential does not correspond to the work done in mapping less-sensitive areas towards future definition of RES “Go-To Areas”. The decentralized solar PV potential in artificialized areas is divided into 6 area types: industrial areas; commercial buildings; residential and mixed-use buildings; villas; health, education, cultural, tourist and military buildings, and other land uses (including parking lots and patios, ports, waste and wastewater treatment infrastructure, sports facilities, among others). It is estimated a technical potential of 23.33 GW that could generate up to 36.84 TWh/year. This potential is distributed throughout the entire territory of mainland Portugal but is higher in the North and Center regions. The RES technical potential for centralized solar PV was estimated as a range of values that translate the uncertainty associated with using different levels of concern in excluding certain areas in which solar PV can be deployed (for example to safeguard ecosystems, water resources, agriculture or archaeological heritage). The centralized solar PV potential varies between 168.82 GW and 45.63 GW. The maximum threshold of installed capacity could generate 278.11 TWh/year of electricity. The value is high and reflects on the one hand, the excellence of the solar resource throughout the country, and on the other, the large size of the considered areas. The CSP potential is 62.6 GW with a corresponding electrical production potential of 183.61 TWh/year. It is mainly located in the Alentejo region, although other areas have also been identified in other regions of the country. The wind onshore technical potential is 15.7 GW, that could generate 37.13 TWh/year, taking into account the safeguarding of various areas for the protection of ecosystems and also social acceptability issues. In the case of offshore wind and considering a capacity density of 4 MW/km2 for floating offshore and 5.5 MW/km2 for fixed offshore, a total of 36 GW and 2 GW are obtained, respectively. This capacity could generate up to 126.14 TWh/year (floating offshore) or 6.31 TWh/year (fixed offshore). The solar thermal energy potential focused residential and service buildings (such as nursing homes, barracks, etc., tourism, hospitals, indoor swimming pools and other sports facilities). The potential is of 0.95 GWt and 0.95 TWh/year for service buildings, 7.26 GWt and 5.84 TWh/year for residential buildings. For industry there is a potential of 1.06 GWt, which could generate up to 1.15 TWh/year for applications up to 160 ºC. The total technical potential of solar thermal is 9.25 GWt and 7.93 TWh/year of thermal energy generated, with a substantial weight of residential buildings in the total value. Potential values are disaggregated by NUTS III and type of building. In terms of biomass and bioenergy potential, annual values of forest biomass, agricultural biomass, agro-industrial waste, urban waste and wastewater treatment are estimated, totaling around 58 TWh/year. Regarding the production of biofuels (HVO and FAME) it is estimated that the annual production of domestic used oils and other similar residues is 1.4 TWh/year. The use of oils from food crops such as soybean, sunflower and rapeseed is limited by European (and national) policy guidelines and is 2.1 TWh/year. Regarding wave energy, the resource potential is estimated between 1.4 GW for 80 m bathymetry and 4.8 for 20 m bathymetry. There are substantial uncertainties associated with the presented values, inherent to the methodological approach considered. Nevertheless, these estimates are a valuable starting point to be refined and improved in subsequent updates.
- Conversão de edifícios existentes em nzeb através da integração de energias renováveis, de micro-redes e de soluções de eficiência energéticaPublication . Estanqueiro, Ana; Joyce, A; Aelenei, Laura Elena; Facão, Jorge; Rodrigues, Carlos; Loureiro, David; Teixeira, J.; Correia, J.B.; Ramalho, Álvaro; Camelo, Susana; Silva, Carlos; Neto, Rui C.RESUMO: O Projeto IMPROVEMENT “Integration of combined cooling, heating and power microgrids in zero-energy public buildings under high power quality and continuity of service requirements” é um projeto financiado pelo Programa INTERREG SUDOE, de cariz marcadamente multidisciplinar e que reúne competências da área de integração e modelação de sistemas energéticos, da gestão de energia em edifícios, de energias renováveis, micro-redes inteligentes e sistemas de monitorização e gestão de consumo. Tem ainda como objetivo geral renovar edifícios públicos existentes, convertendo-os em edifícios com necessidades de energia quase nulas (NZEB), e para tal integra micro-redes com fontes renováveis e geração combinada de calor, frio, eletricidade, equipadas com sistemas de armazenamento.
- The COOLSUN triple-technology approach to reach high solar fractions for space heating, space cooling and domestic hot waterPublication . Facão, Jorge; Lobato, António; Baldo, CatherineWithin the framework of the COOLSUN project a triple-technology approach to reach high solar fractions for space heating, space cooling and domestic hot water preparation is being developed. The three core components are a thermo fluid with a low environmental impact and a boiling point above 200 °C, a high efficient adsorption chiller, and an advanced controller. System simulations modelling the transient behaviour of the entire application, i.e. building, hot water preparation and space heating/cooling, show that for Mediterranean locations the solar fraction reaches values up to 100 %; and even in Central Europe remarkable energy savings can be reached. The first prototype of the system is installed since spring 2013 in a building and monitored under real operation conditions.
- Factory Made Solar Thermal Systems - Dynamic System Testing and development of parameter identification tool and LTPP validationPublication . Neves, Ana; Mexa, Nuno; Facão, Jorge; Gomes, José Dias; Carvalho, Maria JoãoThis paper presents first results of a project that aims at the development of new mathematical models for characterization of Solar Thermal Systems (Factory Made Systems as defined in EN 12976) that can be used in association with dynamic system testing (non intrusive test method defined in the document ISO 9459-5) and which, based on the characteristic parameters defined in the adopted models, allow determination of those parameters by fitting between real test sequences and test sequences produced by the developed models, using fitting techniques independent of the models chosen for system characterization. Another important goal of the project is the validation of results for Long Term (thermal) Performance (LTP) of the solar systems, based on the models developed, by comparison with long term measurement sequences obtained by the monitoring of different system types. Installation of the testing facility for this purpose is also described in the present paper.
- The COOLSUN triple-technology approach to reach high solar fractions for space heating, space cooling and domestic hot waterPublication . Facão, Jorge; Lobato, António; Baldo, CatherineWithin the framework of the COOLSUN project a triple-technology approach to reach high solar fractions for space heating, space cooling and domestic hot water preparation is being developed. The three core components are a thermo fluid with a low environmental impact and a boiling point above 200 °C, a high efficient adsorption chiller, and an advanced controller. System simulations modelling the transient behaviour of the entire application, i.e. building, hot water preparation and space heating/cooling, show that for Mediterranean locations the solar fraction reaches values up to 100 %; and even in Central Europe remarkable energy savings can be reached. The first prototype of the system is installed since spring 2013 in a building and monitored under real operation conditions.
- UNISOL: solar combistore evaluation and optimizationPublication . Amorim, Ricardo; Facão, Jorge; Rodrigues, João Carlos Teixeira; Carvalho, Maria JoãoIn the frame of UNISOL project, a test bench was installed to perform tests of a combistore which includes a two-way heat exchanger already submitted to a national patent application. The present work describes the main characteristics of the test bench installed and the tests performed with the objective of optimization of the configuration of the inner storage tank of the combistore (two way heat exchanger), used for DHW pre-heating or as back-up of the space heating. Tests according to EN 12977-3:2012 were performed in order to evaluate distinct configurations of the inner storage tank. Tests according to EN 12977-4:2012 were also performed for characterization of the complete combistore. Long-term performances of solar thermal systems using these combistore are presented.
- The use of key enabling technologies in the nearly zero energy buildings monitoring, control and intelligent managementPublication . Lourenço, José Marco; Aelenei, Laura Elena; Facão, Jorge; Goncalves, Helder; Aelenei, Daniel; Pina, João MurtaABSTRACT: The 2018 revision of the European Performance Building Directive (EPBD) requires that from the year 2020 onwards, all new buildings will have to be "nearly zero energy buildings". It also further promotes smart building technologies, raising awareness amongst building owners and occupants of the value behind building automation. The European Commission also identified, in 2011, Key Enabling Technologies (KETs), which provide the basis for innovation in the EU. In the frame of the SUDOKET project, the Solar XXI building was used as a pilot case, as innovative integrated solutions and technologies are monitored and controlled. The objective of this paper is to validate a simulation of the laboratorial test room in EnergyPlus with data obtained experimentally and determine the impact of the control systems on energy needs and on thermal comfort. Two systems, in particular, were studied: the Building-Integrated Photovoltaic (BIPV) and the earth tubes. Once validated, the simulation of the test room without the systems was created, allowing their impact to be determined. The results show that, for the analysed periods, BIPVs reduced the heating consumption by 22% while also increasing thermal comfort, and the earth tube system would reduce the cooling needs by 97%.
- UNISOL: solar combistore evaluation and optimizationPublication . Amorim, Ricardo; Facão, Jorge; Rodrigues, João Carlos Teixeira; Carvalho, Maria JoãoIn the frame of UNISOL project, a test bench was installed to perform tests of a combistore which includes a two-way heat exchanger already submitted to a national patent application. The present work describes the main characteristics of the test bench installed and the tests performed with the objective of optimization of the configuration of the inner storage tank of the combistore (two way heat exchanger), used for DHW pre-heating or as back-up of the space heating. Tests according to EN 12977-3:2012 were performed in order to evaluate distinct configurations of the inner storage tank. Tests according to EN 12977-4:2012 were also performed for characterization of the complete combistore. Long-term performances of solar thermal systems using these combistore are presented. Long-term performance prediction based on testing results according to EN 12977-3:2012, showed how an increased active volume of the heat exchanger enhances the energy available for space heating, although it may decrease solar collector thermal performance and increase the energy losses of the combistore. Long-term performance prediction based on testing results according to EN 12977-4:2012, considering a lower heat loss coefficient since a better insulation of the combistore is expected in future prototypes, showed fsav values for Davos and Wurzburg of 39.3% and 25.3%, respectively.