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Encontrado(s) 2019106 resultado(s)
Encontrada(s) 201911 página(s)

Phenomenological modelling of solid/liquid phase transitions in non-ideal PCM

  • Barz, Tilman
  • Emhofer, Johann
  • Marx, Klemens
  • Zsembinszki, Gabriel
  • Cabeza, Luisa F.
Thermal energy storage technologies through solid/liquid phase change materials (PCMs) use the thermodynamic principles of melting and solidification to absorb and release thermal energy. In the ideal case, this technology allows to charge and discharge relatively high amounts of thermal energy at a constant, unique temperature. However, for most commercially available technicalgrade solid/liquid PCMs melting and solidification cannot be assigned to a single, unique temperature. Instead, the phase transition takes place over a temperature range in which solid and liquid phases coexist. Moreover, supercooling sometimes causes hysteresis in the phase transitions depending on the applied heating and cooling rates. These phenomena cause non-ideal phase transition behaviour and generally reduce the applicability of the PCMs. PCM models which can reproduce this non-ideal behaviour are crucial for the numerical analysis of the charging and discharging operation of latent heat storages. This contribution presents a generic workflow for the identification of phase transition models for industrial-grade solid/liquid PCMs. Adopting a purely phenomenological approach models are directly identified from PCM heat capacity measurement data. Thus, if the data contains information on temperature ranges with coexisting phases and hysteresis in the temperature induced phase transitions these phenomena are directly accounted for. The identified transition models predict liquid mass phase fractions using PCM temperature as a model input. These models are then used to describe apparent (effective) PCM properties in the phase transition temperature range, i.e. specific heat, density and thermal conductivity. Applications of the workflow are presented for different commercial PCMs from Climator Sweden AB. The effects of non-ideal phase transition behaviour on absorption and release of heat in a latent thermal energy storage are discussed by simulation studies., This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 768824 (HYBUILD). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). This work is partially supported by ICREA under the ICREA Academia programme.

Proyecto: //768824

Corrosion inhibitors for TES material at high temperature for CSP plants

  • Fernández, Ángel G.
  • Cabeza, Luisa F.
Molten salt technology using nitrate salts as thermal energy storage material is the current state-of-the-art of concentrated solar power technology and power tower central receivers are currently limited by the maximum operating temperature of their working fluid. The limit of solar salt (60wt.%NaNO3 + 40wt.%KNO3) thermal stability is around 565°C with ambient air as the cover gas. In order to obtain higher efficiency goals using molten salt technologies working at higher temperatures (e.g., 650°C to 750°C), a different salt chemistry is required for new generation of CSP plants and chlorides molten salts could be a feasible option. Corrosion mitigation could solve the current issues related with the use of chloride salt at high temperature. In this work, the proposal of different corrosion mitigation strategies has been evaluated, as well as the identification of the most corrosive impurities present in the ternary chloride salt composed by MgCl2/KCl/NaCl (60/20/20 mol%). For this purpose, electrochemical impedance spectroscopy tests were carried out at 700°C on austenitic stainless steel (AISI 304) and a Ni base alloy (Inconel 702) during 100 hours. In this case, MgOHCl was identified as the main important corrosive impurity, present in the chloride salt, to control in the storage system. Regarding the materials tested, Ni base alloy (Inconel 702) showed the most promising results for their use as container material., The research leading to these results has received funding from Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia. Angel G. Fernández wants to acknowledge the financial support from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant No 712949 (TECNIOspring PLUS) and from the Agency for Business Competitiveness of the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.

Proyecto: //712949

Innovative concentrated solar micro organic Rankine cycle plant system for residential buildings

  • Maldonado, José Miguel
  • Gracia Cuesta, Alvaro de
  • Mahkamov, Khamid
  • Costa, Carolina
  • Kenisarin, Murat
  • Pili, Piero
  • Manca, Roberto
  • Leroux, Arthur
  • Mintsa, André Charles
  • Bartolini, Carlo M.
  • Pirro, Matteo
  • Lynn, Kevin
  • Mullen, David
  • Halimic, Elvedin
  • Cioccolanti, Luca
  • Arteconi, Alessia
  • Gimbernat, Toni
  • Botargues, Teresa
  • Cabeza, Luisa F.
Reducing the energy consumption in the building sector, as well as its associated CO2 emissions, is one of the main environmental concerns at worldwide level. In developed countries, the building sector means 41% of the total energy consumption and 40% of the total greenhouse gases emissions. To improve the energy efficiency of residential buildings, several energy strategies were carried out in European countries to encourage the development of active energy saving systems; such as the solar thermal energy. The presented study is in the frame of the Innova MicroSolar European project, which is sponsored by the European Union’s Horizon 2020 research and innovation programme. The main goal of this project is to develop an innovative concentrated solar heat and power system for residential buildings, which supplies 2-kWelec and 18-kWth. This technology includes a concentrated solar system, a high performance micro organic Rankine cycle (ORC) turbine, and an enhanced latent heat thermal energy storage (LHTES). The solar system is based on linear Fresnel mirrors which are considerably easier and cheaper to manufacture than their parabolic equals. Also, the mirrors are led by a sun tracking mechanism so they are always focusing the absorber tubes, heating up to 295ºC the heat transfer fluid (HTF) flow. The total area of the real scale prototype solar field is 140 square metres, which could provide from 80 to 15 kWth. The micro ORC technology is equipped with a high speed permanent magnet AC alternator able to supply 2.3 kWel. The ORC block has to be fed with 22 kWth. Finally, the TES tank consists of two main blocks, the PCM tank and the enhanced heat sink. Both blocks are connected between them by reversible heat pipes as heat carrier. The storage is designed to supply 25 kWth during four working hours. The whole system will supply 60% of the total building energy demand, reducing the energy cost up to 20%, as well as the greenhouse gases emissions when comparing against the best renewable energy technologies available on the market. This study shows the first experiments of the whole systems. The HTF (Therminol 62) is heated up to 270ºC with the solar field, then the HTF is lead to the ORC evaporator and the organic fluid (cyclopenthane) evaporates and runs the turbine. The TES tank is charged when the solar field reaches maximum power levels. Once the solar production cannot run the ORC, the solar field is bypassed and the TES tank successfully becomes the main energy supplier., The research leading to these results has received funding from the European Union´s Horizon 2020 Research & Innovation Programme under Grant Agreement 723596 with reference name Innova MicroSolar. This work was partially funded by Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). José Miguel Maldonado would like to thank the Spanish Government for his research fellowship (BES-2016-076554). Alvaro de Gracia has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 712949 (TECNIOspring PLUS) and from the Agency for Business Competitiveness of the Government of Catalonia. The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia.


Prácticas no laborales de los estudiantes universitarios y titulados recientes versus relación laboral: la adecuada tutorización como factor clave: A propósito de la STSJ del País Vasco de 14 de mayo de 2019, Internships of graduate students and recent graduates versus labor relationship: the right to tutor as a key factor. Comments on the decision of the Superior Court of Justice the País Vasco, May 14, 2019.

  • Moreno Gené, Josep
Siendo el carácter no laboral la característica esencial de estas prácticas no laborales de los estudiantes universitarios y de los titulados recientes, la primera cuestión que se plantea debe ser necesariamente la delimitación entre la prestación de servicios que se desarrolla en el marco de estas prácticas no laborales y la prestación de servicios propia de la relación laboral. A esta ingente tarea de delimitación entre las prácticas no laborales de los estudiantes universitarios y titulados recientes y la relación laboral contribuye de un modo decisivo la STSJ del País Vasco de 14 de mayo de 2019 objeto de este comentario, al conocer de la demanda presentada por la Tesorería General de la Seguridad Social contra una empresa en la que desarrollaban prácticas no laborales diferentes estudiantes universitarios y titulados recientes al amparo del Real Decreto 592/2014 y del Real Decreto 1543/2011., Being the non-work character the essential characteristic of these non-work practices of university students and recent graduates, the first question that arises must necessarily be the demarcation between the provision of services that is carried out within the framework of these non-work practices and the provision of services related to the employment relationship. This enormous task of delimitation between the non-work practices of recent university students and graduates and the employment relationship contributes decisively to the STSJ of the País Vasco of May 14, 2019, object of this comment, knowing the demand presented by the General Treasury of the Social Security against a company in which non-work practices were developed by university students and recent graduates under the terms of Royal Decree 592/2014 and Royal Decree 1543/2011., Este trabajo se ha elaborado en el marco del proyecto de investigación RTI2018-097947-B-I00, concedido por el Ministerio de Ciencia, Innovación y Universidades que lleva por título “Nuevas tecnologías, cambios organizativos y trabajo: una visión multidisciplinar”.

Proyecto: //

La Nulidad del despido de trabajadora con cáncer uterino: discriminación por discapacidad y ¿tal vez, también por razón de sexo? Comentario a la sentencia del Tribunal Superior Justicia de Cantabria de 18 de enero de 2019, The nullity of the dismissal of workers with uterine cancer: discrimination due to disability and, maybe, also for the reason of sex? Comment on the Judgment of the High Court of Cantabria of 18 January 2019

  • Moreno Gené, Josep
La STSJ de Cantabria de 18 de enero de 2019 ha venido a declarar la nulidad del despido de una trabajadora enferma por considerar que en el mismo concurre un doble factor de discriminación. Por una parte, mantiene que el mismo comporta una discriminación de la trabajadora por motivo de discapacidad, al considerar que la enfermedad sufrida por la misma constituye una enfermedad de larga duración asimilable a la discapacidad y, por otra parte, aunque con menor vehemencia y fundamentación, parece afirmar que dicho despido también puede constituir una discriminación por razón de sexo, al considerar que nos encontramos ante una patología netamente femenina, que obliga a enjuiciar la cuestión desde una perspectiva de género. En este trabajo se analizan los argumentos esgrimidos por dicha resolución judicial para alcanzar ambas conclusiones., The Judgment of the High Court of Cantabria of 18 January 2019 has come to declare the nullity of the dismissal of a sick worker because it considers that there is a double factor of discrimination. On the one hand, maintains that it involves discrimination of the worker due to disability, considering that the disease suffered by it is a long-term disease comparable to disability and, on the other hand, although with less vehemence and substantiation, it seems to affirm that said dismissal can also constitute discrimination based on sex, considering that we are dealing with a distinctly female pathology, which forces us to judge the issue from a gender perspective. This paper analyzes the arguments used by the judicial resolution to reach both conclusions.

Proyecto: //

Benchmarking of energy demand of domestic and small business buildings

  • Coma Arpón, Julià
  • Maldonado, José Miguel
  • Gracia Cuesta, Alvaro de
  • Gimbernat, Toni
  • Botargues, Teresa
  • Cabeza, Luisa F.
In Europe the building sector represents 41% of the final energy consumption and the 40% of the total GHG emissions of end-use sectors (Directive 2010/31/EU) [1]. Solar energy is one of the forms of renewable energy that has great potential to enable EU the ambition of 12% of heating coming from renewable sources by 2020 [2]. Within this context, the overall objective of the project Innovative Micro Solar Heat and Power System (Innova MicroSolar) is to develop a high performance and cost effective solar heat and power system, which consist in a novel flat Fresnel mirror solar concentrating collector and micro organic Rankine cycle plant combined with advanced phase change materials as thermal storage, all system managed by smart control units. This technology will be initially implemented in individual dwellings and small business residential buildings for on-site electricity and heat generation using solar thermal energy., This study has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement Nº723596 (Innova MicroSolar) and Nº 657466 (INPATHTES), from the European Commission Seventh Framework Programme (FP/2007-2013) under grant agreement Nº PIRSES-GA-2013-610692 (INNOSTORAGE). The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER) and ENE2015- 64117-C5-3-R (MINECO/FEDER)). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). Alvaro de Gracia would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-19940.


Numerical Investigation of the Pipelines modeling in a Small-Scale Concentrated Solar Combined Heating and Power Plant

  • Tascioni, Roberto
  • Arteconi, Alessia
  • Del Zotto, Luca
  • Habib, Emanuele
  • Bocci, Enrico
  • Moradi, Ramin
  • Mahkamov, Khamid
  • Costa, Carolina
  • Cabeza, Luisa F.
  • Gracia Cuesta, Alvaro de
  • Pili, Piero
  • Mintsa, André Charles
  • Pirro, Matteo
  • Gimbernat, Toni
  • Botargues, Teresa
  • Halimic, Elvedin
  • Cioccolanti, Luca
Ha generat l'article: Energies, 2020, 13(2), 429; https://doi.org/10.3390/en13020429, In this paper four different detailed models of pipelines have been proposed, they are supposed to be used in a quasi steady-state model of a micro solar Combined Heat and Power plant developed under the EU funded project Innova MicroSolar. The integrated plant consists of a Linear Fresnel Reflectors solar field, 3.8 tons of Latent Heat Thermal Energy Storage system equipped with reversible heat pipes and an Organic Rankine Cycle unit designed for a power production of 2 kWe/18 kWth. Previous numerical analyses carried out by some of the authors have revealed a high incidence of pipelines on the plant performance due to thermal losses and their dynamic behavior. Hence, in this paper four different levels of models detail of such pipelines have been developed and tested based on the micro CHP operating conditions in order to find out which approach provides the most accurate dynamic behavior in small scale CHP systems simulations., This study is a part of the Innova MicroSolar Project, funded in the framework of the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement No 723596)

Proyecto: //723596

Toponimia occitana problematica. Sus era representacion grafica de quauqui nòms de lòc dera Gasconha pirenenca

  • Carrera Baiget, Aitor
Aguest trabalh qu’estúdie mès d’un vintenat de toponims des Pirenèus gascons, qu’apertien as departaments francesi des Nauti Pirenèus, de Nauta Garona e d’Arièja. Aqueri toponims non son pas estats causits ar azard. Coma toti es nòms de viles e de vilatges der Estat francés situats en un domeni lingüistic que non ei pas eth dethquite francés, es sòns nòms oficiaus que son deformacions des toponims originaus occitans. En moment que s’asajat de recuperar-ne era forma occitana, d’un aute costat, que i a agut trabalhs qu’an proposat representacions grafiques qu’ath nòste vejaire non son pas bones, perque –per exemple– non son bric d’acòrd damb era etimologia o era prononciacion d’aqueri madeishi toponims, o perque non s’i aplique pas coma cau es convencions grafiques dera lengua occitana. En aguest trabalhòt, donques, que hèm a veir es representacions vertadèraments corrèctes d’aqueri nòms de viles e de vilatges en lengua occitana, en tot aportar arguments lingüistics solids.

Proyecto: //

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