A considerable amount of energy is used in the building sector for air conditioning purposes. Additionally, the building sector contributes to the urban heat island (UHI) phenomenon which causes temperature rise in urban areas. Cool roof is an emerging passive cooling technology that can contribute to reduce the cooling energy use in buildings and to mitigate the UHI effects in the urban area. Cool roofs and reflective coatings, despite of being effective in terms of reducing the cooling thermal loads in buildings and decrease the UHI, can suffer from extreme thermal stress which negatively influences their lifespan and performance. Thermal energy storage (TES) is a promising technology which can be applied together with cool roof technology to decrease the extreme thermal stress due to solar radiation as well as providing thermal inertia to the building. In this study, simulation-based optimization will be used to optimize the PCM melting temperature when integrated into a polyurethane-based cool roof membrane to reduce the thermal stress of the cool roof and also to improve the annual energy performance of the building. The optimization results showed that the application of PCM and cool roof technologies together can reduce the severe thermal stress of the cool roof membrane when the optimization objective is the annual thermal stress of the cool roof. On the other hand, when PCM melting temperature is optimized to reduce the annual energy needs, higher annual energy savings could be achieved with acceptable reductions in the cool roof membrane thermal stress. ; The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER) and ENE2015-64117-C5-3-R (MINECO/FEDER)). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREA (2014 SGR 123). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This project has received funding from the European Commission Seventh Framework Program (FP/2007-2013) under Grant agreement Nº PIRSES-GA-2013-610692 (INNOSTORAGE). Alvaro de Gracia would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-19940. A.L. Pisello's acknowledgments are due to the UNESCO Chair "Water Resources Management and Culture", for supporting her research.
Thermal energy storage (TES) is a technology with a high potential for different thermal applications. It is well known that TES could be the most appropriate way and method to correct the gap between the demand and supply of energy and therefore it has become a very attractive technology. In this paper, a review of TES for cold storage applications using solid–liquid phase change materials has been carried out. The scope of the work was focussed on different aspects: phase change materials (PCMs), encapsulation, heat transfer enhancement, and the effect of storage on food quality. Materials used by researchers as potential PCM at low temperatures (less than 20 C) are summarized and some of their thermophysical properties are reported. Over 88 materials that can be used as PCM, and about 40 commercially available PCM have been listed. Problems in long term stability of the materials, such as corrosion, phase segregation, stability under extended cycling or subcooling are discussed. Heat transfer is considered both from theoretical and experimental point of view and the different methods of PCM encapsulation are reviewed. Many applications of PCM at low temperature can be found, such as, ice storage, conservation and transport of temperature sensitive materials and in air conditioning, cold stores, and refrigerated trucks. ; The work partially funded by the Spanish Government (ENE2008-06687-C02-01/CON and ENE2011-22722) and the European Union (COST Action COST TU0802 and project EFFIBUILDINGS – FP7-PEOPLE-2009-IIF-/-253914). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2009 SGR 534). Eduard Oró would like to thank the University of Lleida for his research fellowship.
The high intermittency of solar energy is still a challenge yet to be overcome. The use of thermal storage has proven to be a good option, with phase change materials (PCM) as very promising candidates. Nevertheless, PCM compounds have typically poor thermal conductivity, reducing their attractiveness for commercial uses. This paper demonstrates the viability of increasing the PCM effective thermal conductivity to industrial required values (around 4 W/m·K) by using metal wool infiltrated into the resin under vacuum conditions. To achieve this result, the authors used an inert resin, decoupling the specific PCM material selection from the enhancement effect of the metal wools. To ensure proper behavior of the metal wool under standard industrial environments at a broad range of temperatures, a set of analyses were performed at high temperatures and an inert atmosphere, presenting a thorough analysis of the obtained results. ; The research leading to these results has received funding from CDTI in the project Innterconecta Thesto (ITC-20111050). The work partially funded by the by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31-MCIU/AEI/FEDER, UE) and by the Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación (AEI) (RED2018-102431-T). Dr. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group GREiA (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.
An evaluation of the environmental impact of construction systems that are composed of facades based on alveolar bricks and macroencapsulated phase change materials done using Life Cycle Assessment (LCA) is presented. Their energy consumption rates for both heating and cooling have been measured and registered in two experimental cubicles located in Puigverd de Lleida (Spain). This work examines if the reduction of the environmental impact that is reached due to the energy savings achieved during the operational phase of these cubicles compensates the increase of the environmental impact that is induced during the manufacturing phase. Theoretical case studies, such as assuming different climatization and weather conditions, are proposed and studied to determine the most suitable climatic conditions for using the alveolar bricks and PCM technologies. Within the context of the LCA study, it is concluded that the overall benefit of PCM is the highest when summer weather conditions throughout the whole year is theoretically assumed, where for different assumed lifetime periods of the cubicles the reduction of the overall global impact of the cubicle containing PCM ranges from 12% to 14% in comparison to the other cubicle without PCM. ; The work was partially funded by the Spanish government (Projects ENE2008-06687-C02-01/CON and DPI2008-04099) and the European Union (COST Action COST TU0802), in collaboration with the company Hyspalit and City hall of Puigverd de Lleida. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2009 SGR 534). Lídia Rincón would like to thank the University of Lleida for her research fellowship.
The use of thermal energy storage by phase change materials (PCM) is increasing in interest for building applications. For the deployment of the technology, appropriate characterization of PCM and hybrid PCM is essential, but it is not always possible to carry it out with conventional equipment, mainly due to the sample size. This paper shows equipment developed in different research centers and universities to analyze thermophysical properties, such as specific heat, latent heat and melting temperature, and thermal conductivity and diffusivity of PCM and hybrid PCM materials. ; The work is partially funded by the European Union (COST Action COST TU0802), the Spanish government (ENE2011-28269-C03-01, ENE2011-28269-C03-02 and ENE2011- 22722), TUBITAK (project 110M032), and by Qatar National Foundation through the NPRP No.: 4-465-2-173. The authors would like to thank the Catalan Government for the quality accreditation given to the research group GREA (2009 SGR 534) and their research group DIOPMA (2009 SGR 645), both in Spain. Laia Miró would like to thank the Spanish Government for her research fellowship (BES-2012-051861).
Phase change materials are capable of storing and releasing energy in the form of heat in determined temperature ranges, so to increase a building"s thermal inertia, stabilize its indoor temperatures and reduce its energetic demand. Therefore, if we used these materials we could have more energetically efficient buildings. Nevertheless, are these materials most appropriate to be used in buildings? Could the incorporation of phase change materials in buildings with concrete structures be generalized? This article aims to carry out a review of these phase change materials from construction professionals" points of view, study their applications for buildings with reinforced concrete structures and the key points for these applications, draw conclusions and provide recommendations useful for all professionals within the sector who are considering the application of these materials. ; Revisión crítica del uso de materiales de cambio de fase en edificios con estructuras de hormigón armado. Los materiales de cambio de fase son capaces de almacenar y liberar energía en forma de calor en un determinando rango de temperaturas, y así aumentar la inercia térmica de un edificio, estabilizar las temperaturas en el interior y reducir la demanda energética. En consecuencia, si utilizáramos estos materiales podríamos tener un parque de edificios más eficientes energéticamente. No obstante, ¿estos materiales son apropiados para usarse en edificios? ¿Se podría generalizar la incorporación de materiales de cambio de fase en edificios con estructuras de hormigón? Este artículo tiene como objetivos hacer una revisión del estado del arte de estos materiales de cambio de fase desde el punto de vista de los profesionales de la construcción, estudiar las aplicaciones en edificios con estructuras de hormigón armado y los puntos clave para estas aplicaciones, extraer conclusiones y recomendaciones útiles para los profesionales del sector que se planteen la utilización de estos materiales. ; This research was partially funded by the Spanish government (ENE2011-28269-C03-02). The authors would like to acknowledge the support received from the Concrete Technology Research Group of Barcelona Tech (UPC). The authors would also like to thank the Catalan Government for the quality accreditation given to the research group GREA (2009 SGR 534) and the research group DIOPMA (2009 SGR 645).
L'edificació, la indústria i el transport són els tres principals sectors consumidors d'energia, representant el 96 % de l'energia final consumida a la Unió Europea, i essent responsable de gairebé la totalitat de les emissions de CO2. El programa Horizon 2020 de la Comissió Europea expressa la necessitat de reduir el consum d'energia i les emissions d'efecte hivernacle en un 20 % per l'any 2020. L'emmagatzematge d'energia és un dels principals camps considerats i desenvolupats per reduir les emissions, doncs permet emparellar la demanda i el subministrament d'energia amb sistemes simples i eficients. Els sistemes d'emmagatzematge d'energia tèrmica (TES) permeten emmagatzemar densitats d'energia elevades per poder variar la demanda d'energia i facilitat l'ús d'energia renovables. Aquesta tesi està principalment enfocada en l'emmagatzematge de calor latent, una tecnologia què, tot i que ha estat àmpliament estudiada, encara necessita millores i presenta buits importants. ; La edificación, la industria i el transporte son los tres principales sectores consumidores de energía, representando el 96 % de la energía total consumida en la Unión Europea, y siendo responsables de casi la totalidad de las emisiones de CO2. El programa Horizon 2020 de la Comisión Europea expresa la necesidad de reducir el consuma de energía i las emisiones de efecto invernadero en un 20 % para el año 2020. El almacenaje de energía es uno de los principales campos considerados y desarrollados para reducir las emisiones, pues permite emparejar la demanda y el subministro de energía con sistemas simples y eficientes.Los sistemas de almacenaje de energía térmica (TES) permiten almacenar densidades de energía elevadas para poder variar la demanda de energía y facilitar el uso de energías renovables. Esta tesis está principalmente enfocada en el almacenaje de calor latente, una tecnología que, aunque ha sido ampliamente estudiada, aún necesita mejoras y presenta vacíos importantes. ; Buildings, industry and transport are the three main energy consuming sectors, representing the 96 % of the final energy consumption in the European Union, and being responsible of almost the totality of the CO2 emissions. The horizon 2020 program of the European Commission expresses the need to reduce by 20 % the energy consumption and greenhouse emissions by the year 2020Energy storage is one of the main fields considered and developed to reduce emissions, allowing to match energy demand and supply with simple and efficient systems.Thermal energy storage (TES) systems allow the storage of high energy densities in order to shift the energy demand and ease the use of renewable energies. This thesis is mainly focused in latent energy storage, a technology that despite having been widely studied, still requires improvements and presents important gaps.
Concentrated solar power (CSP) is today recognized as a unique renewable energy for electricity generation due to its capability to provide dispatchable electricity incorporating thermal energy storage (TES). Molten salts TES is the most widespread technology in commercial CSP but the industry is looking for cheaper and more efficient TES systems and phase change materials (PCM) have been highlighted as potential low cost and high energy TES systems. This paper presents a completely new concept of PCM energy storage systems to be used in solar thermal electricity plants with its technical assessment. A cascade type PCM storage system is evaluated, using four buckets with the PCM organized based on melting temperature and the latent energy of the materials. Daily, monthly, and annual transient simulations of the plant performance are carried out. The main conclusion is the similarity between this new concept and the commercial two-tank indirect molten salt system. The cumulative power production over the year is similar and the net production of both systems is well matched. ; The work was partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). Dr. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia.
Actualment, la demanda d'energia per satisfer el confort tèrmic en edificació és un dels majors reptes per a les administracions. Per tant, l'eficiència dels diferents sistemes d'emmagatzematge d'energia s està investigant intensament per la comunitat científica. Una alternativa viable és l'ús de materials de canvi de fase (PCM). Les parafines han estat molt utilitzades com PCM per la seva alta capacitat d'emmagatzematge de calor (al voltant de 100-130 kJ·kg-1) i la seva baixa temperatura de fusió la qual és molt estable. A més, el consum d'energia i les oscil·lacions de la temperatura internes d'edificis es poden reduir quan un PCM s'incorpora en evolvents. L'objectiu principal d'aquesta tesi és el desenvolupament de nous materials que continguin PCM basant-se en l'estudi del procés per obtenir la correcta introducció del PCM dins el material. A més, les propietats termofísiques d'aquests nous materials s'han de conèixer i per tant caracteritzar a nivell de laboratori. Aquesta tesi doctoral se centra en els treballs publicats en revistes científiques amb alt factor d'impacte indexats al camp de l Energia els quals reflecteixen treball realitzat. D'altra banda, aquesta tesi conté una revisió de l'estat de l'art destacant els requisits per a un PCM i llista tots els tipus de PCM disponibles al mercat i utilitzats en investigació. D'altra banda, un nou concepte de material compost que incorpora PCM ha estat desenvolupat en aquesta tesi. Aquest compost té la matriu polimèrica, i inclou un residu del procés de reciclatge de l acer. D'aquesta manera s'obtenen làmines denses que es poden modelar. La fabricació d'aquest material podria considerar-se un mètode per a la reutilització d'aquest residu. D'altra banda, aquest tipus de residus conté òxids de metalls pesants que augmenten les propietats d'aïllant acústic de la làmina aconseguint millorar el resultat final de la solució constructiva. A més, el comportament termofísico dels materials compostos utilitzats en edificis és difícil de caracteritzar i l'anàlisi tèrmica dels PCM és un pas necessari per al disseny dels mateixos. Les dues primeres caracteritzacions termofísiques estudiades en aquesta tesi es van realitzar mitjançant corbes calorimètriques que és una de les tècniques més potents disponibles actualment. tres estudis més van ser van realitzar amb dispositius desenvolupats per diferents grups d'investigació a Espanya per tal de mesurar les propietats termofísiques dels materials compostos o materials multicapa que incorporen PCM. ; Hoy en día, la demanda de energía para satisfacer el confort térmico en edificación es uno de los mayores desafíos para las administraciones. Por lo tanto, la eficiencia de los diferentes sistemas de almacenamiento de energía está siendo intensamente investigado por la comunidad científica. Una alternativa viable es el uso de materiales de cambio de fase (PCM). La parafina ha sido muy usada como PCM debido a su alta capacidad de almacenamiento de calor (alrededor de 100-130 kJ·kg-1) y a su baja temperatura de fusión la cual es muy estable. Además, el consumo de energía y las oscilaciones de la temperatura internas se pueden reducir cuando un PCM se incorpora en envolventes de edificios. El objetivo principal de esta tesis es el desarrollo de nuevos materiales que contengan PCM basándose en el estudio del proceso para obtener la correcta introducción del PCM. Además, las propiedades termofísicas de estos nuevos materiales se debe conocer y por tanto caracterizar a nivel de laboratorio. Esta tesis doctoral se centra en los trabajos publicados en revistas científicas con alto factor de impacto indexados en el campo de Energía los cuales reflejan el trabajo realizado. Por otra parte, esta tesis contiene una revisión del estado del arte destacando los requisitos para un PCM y lista todos los tipos de PCM comercializados y utilizados en investigación. Por otra parte, un nuevo concepto de material compuesto que incorpora PCM ha sido desarrollado en esta tesis. Este compuesto tiene la matriz polimérica, e incluye un residuo del proceso de reciclaje de acero. De este modo se obtienen láminas densas moldeables. La fabricación de este material podría considerarse un método para la reutilización de este residuo. Por otra parte, este tipo de residuos contiene óxidos de metales pesados que aumentan las propiedades de aislante acústico de la lámina consiguiendo mejorar el resultado final de la solución constructiva. Además, el comportamiento termofísico de los materiales compuestos utilizados en edificios es difícil de caracterizar y el análisis térmico de los PCM es un paso necesario para el diseño de los mismos. Las dos primeras caracterizaciones termofísicas estudiadas en esta tesis se realizaron mediante calorimetría diferencial de barrido que es una de las técnicas más potentes disponibles actualmente. tres estudios más fueron realizaron con dispositivos desarrollados por diferentes grupos de investigación en España con el fin de medir las propiedades termofísicas de los materiales compuestos o materiales multicapa que incorporan PCM. ; Nowadays, energy demand to satisfy thermal comfort in buildings is one of the major challenges for governments and administrations. Therefore, energy storage system efficiency is being studied by the international scientific community. A feasible alternative is the use of phase change materials (PCM). Paraffin waxes have been used as PCM because of their high heat storage capacity (around 100-130 kJ·kg"1) and their low and stable melting temperature. Furthermore, the energy consumption and indoor oscillations temperature may be reduced when PCM is incorporated in building envelopes and the thermal inertia increment when PCM is combined with thermal insulation was widely studied. The main objective of this thesis is the development of new materials containing PCM based on the study of process to get the correct PCM introduction. In addition, thermophysical properties of these new materials must be characterized. In order to perform the characterization, it was used several developed devices. This PhD thesis is based on papers published in scientific journals with high impact factor in the Energy field and one patent that reflect the work performed. This thesis contains a review of the state of the art highlighting the requirements order to a certain PCM and lists and sorts all PCM available in the market and used in research. On the other hand, a new concept of composite material incorporating PCM is developed in this thesis. This composite has polymeric matrix and includes one waste from the steel recycling process obtaining mouldable dense sheets. The manufacture of this material is considered a way to reuse the waste. Furthermore, this waste contains heavy metals oxides which add acoustic insulation properties to the final constructive system. One patent and two papers are the main result. Moreover, thermophysical behaviour of composite materials used in buildings envelopes is difficult to characterize. In addition, PCM thermal analysis is a necessary step of building design as well as it will be a key point in the final thermal results of the envelope. The first two thermophysical characterizations studied in this thesis were performed using differential scanning calorimetry which is one of the most powerful techniques. Three more studies were performed using devices developed by different research groups in Spain in order to measure thermophysical properties of composite materials or multilayered materials incorporating PCM.
From the literature review it was observed that there is no established methodology, neither a common pattern, when selecting a phase change material for a thermal energy storage application. Melting temperature and enthalpy have traditionally been the considered thermal properties for the material selection. Therefore, the authors of this paper propose a new method of investigation on the suitability of a PCM that takes into account not only thermal properties but also health hazard and both cycling and thermal stability. Health hazard is related with the handling of the material, and both cycling and thermal stabilities with durability. This methodology is applied to five different PCM in the 150–200 °C range: salicylic acid, benzanilide, d-mannitol, hydroquinone, and potassium thiocyanate. Results show that for an application in the 150–200 °C range the suitable PCM are benzanilide and d-mannitol. Moreover, hydroquinone is also suitable but only in closed systems. ; The research leading to these results has received funding from the European Commission Seventh Framework Programme (FP/2007-2013) under Grant agreement N° PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union's Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). The work is partially funded by the Spanish government (ENE2011-22722). The authors would also like to thank the Catalan Government for the quality accreditation given to their research group GREA (2014 SGR 123). Aran Solé would like to thank the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for her research fellowship. Laia Miró would like to thank the Spanish Government for her research fellowship (BES-2012-051861).
Phase change materials (PCM) is one of the most interesting solutions to be used in thermal energy storage (TES) systems for direct steam generation (DSG) thermosolar facilities. Properties such as high energy density and energy storing/delivery at constant temperature bring PCM based systems in excellent candidates for DSG facility storage units. Accordingly, LiOH-KOH peritectic mixture, with a melting point of 315 °C and an enthalpy change of 535 kJ/kg, has been reported as attractive solution for the saturated storage module in DSG plants. A steam-PCM heat exchanger is the critical component to carry out the thermal transference between both substances. Although materials selection to be applied for steam applications is well known, lack of knowledge is detected in the field of high temperature hydroxides corrosion. Therefore, three metallic materials, A516 Gr70 carbon steel, A316L stainless steel and Inconel 625 Ni-base alloy, have been evaluated to determine their corrosion performance after hydroxides exposure. While A516 Gr70 was discarded for this application due to high corrosion rates, A316L and Inconel 625 displayed good corrosion resistance after 2640 h. Finally, A316L stainless steel was selected as potential candidate for the construction of the steam-PCM heat exchanger considering cost and thermal efficiency optimization. ; The research leading to these results has received funding from CDTI in the project Innterconecta Thesto (ITC-20111050). The work is partially funded by the Spanish Government (ENE2011-28269-C03-02, ENE2011-22722, ENE2015-64117-C5-1-R, and ENE2015-64117-C5-2-R). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREA (2014 SGR 123) and research group DIOPMA (2014 SGR 1543).
Unidad de excelencia María de Maeztu MdM-2015-0552 ; Altres ajuts: the Catalan Government, La Generalitat de Catalunya, for awarding a research scholarship (FI-AGUAR 2015) to Pere Llorach Massana ; INIA RTA2012-00039-C02-01 ; Root zone heating systems offer increasing crops quality and productivity. However, these systems are based on the use of nonrenewable fuels. This paper reports on a study of different design solutions for a root zone heating system, based on thermal energy storage with PCM. The objective of the study was to define, through multiple experiments, the most efficient PCM melting/freezing temperature and location with respect to the substrate (i.e., under the substrate) for the application under study; as well as, to determine the system's environmental and economic feasibility, with life cycle assessment and life cycle cost methodologies. Results show that the best melting temperature for the application under study is 15 °C. To increase the efficiency of the system, PCMs may be macro encapsulated and wrap the entire perlite bag. Moreover, it seems that PCMs are far to substitute conventional root zone heating systems because it does not provided enough heat during nights. Nevertheless, PCMs can help to reduce the operation time of conventional systems. Based on one night results it seem that PCM could provide annual saving of between 22 and 30 kg of eq. CO2/ha·day. However, it does not seem to be feasible if PCM prices (8€/kg) do not decrease significantly.
Building envelope systems that integrate Phase Change Materials (PCMs) are solutions aimed at increasing the thermal energy storage potential of the building envelope while keeping its mass reasonably low. Building envelope components with PCMs can be either opaque or transparent and can be based on different types of PCMs and integration methods. In opposition to conventional building components, these elements present thermal and optical properties that are highly non-linear and depend to a great extent on the boundary conditions. Such a characteristic requires the system development and optimisation process during the design phase to be carried out with particular care in order to achieve the desired performance. In this paper, a review of the existing modelling capa-bilities of different building energy simulation (BES) tools for PCM-based envelope components is reported, and the main challenges associated with the modelling and simulation of these systems through the most popular BES tools (among them, EnergyPlus, IDA-ICE, TRNSYS, IES-VE, and ESP-r) are highlighted. The aim of this paper is to summarise the evidence found in the literature of the latest development in the successful use of BES to replicate the thermal and optical behaviour of opaque and transparent components inte-grating PCMs, in order to provide the community of professionals with an overview of the tools available and their limitations. ; The authors would like to thank EU Cost Action TU1403 'Adaptive Facades Network' for providing excellent research networking. The authors Albert Castell and Marc Medrano would like to thank the Catalan Government for the project grant (2017 SGR 659) given to their research group. The author Francesco Goia would like to thank the Research Council of Norway and several partners through The Research Centre on Zero Emission Buildings (ZEB) (2009 – 2017, grant 193830) at the Norwegian University of Sci-ence and Technology.
