Suchergebnisse

Solar thermal energy systems combined with heat pumps are becoming popular solutions for covering space heating and domestic hot water demand in European Union households. There is a great potential for developing high performing systems by combining components in systems in new ways. This study focuses on the performance of a system consisting of heat pump, photovoltaic-thermal solar collector and two storage tanks. This system is proposed to potentially have better performance compared to air-to-liquid heat pump system while being less costly compared to a liquid-to-liquid heat pump system with ground sourced heat exchanger. The system was set up at the Technical University of Denmark in 2017, for providing domestic hot water. A simulation model of the system was created in the transient simulation software TRNSYS and the data from the experiment were used for its validation. The modulating heat pump was modelled via a function applied to the scale factor and the thermal mass of the heat pump was taken into account by including additional pipes around the heat pump. The performance of the system was assessed using selected key performance indicators. A parametric analysis was performed identifying component sizes that improved the system's performance. The improved system produced 55% more electricity, had 23% lower electric consumption and wasted 11% less heat by minimizing heat losses compared to the demonstration system. The improved system had a solar thermal fraction of 0.58, a solar electrical fraction of 1.51 and a renewable energy fraction of 0.75. The system was however oversized compared to the load applied to the system as it was built to cover only domestic hot water demand. For the system to be economically attractive it must cover a larger load.

An important prerequisite to select a reliable phase change material (PCM) for thermal energy storage applications is to test it under application conditions. In the case of solid-liquid PCM, a large amount of thermal energy can be stored and released in a small temperature range around the solid-liquid phase transition. Therefore, to test the long‐term stability of solid-liquid PCM, they are subjected to melting and solidification processes taking into account the conditions of the intended application. In this work, 18 experimental devices to investigate the long‐term stability of PCM are presented. The experiments can be divided into thermal cycling stability tests, tests on PCM with stable supercooling, and tests on the stability of phase change slurries (PCS). In addition to these experiments, appropriate methods to investigate a possible degradation of the PCM are introduced. Considering the diversity of the investigated devices and the wide range of experimental parameters, further work toward a standardization of PCM stability testing is recommended. ; This survey has been carried out within the framework of IEA ES Annex 33/SHC Task 58 "Material and Component Development for Compact Thermal Energy Storage", a joint working group of the "Energy Storage" (ES) and the "Solar Heating and Cooling" (SHC) Technology Collaboration Programmes of the International Energy Agency (IEA). The responsibility for the content of this publication is with the authors. The work of ZAE Bayern is part of the project properPCM and was supported by the German Federal Ministry of Economic Affairs and Energy under the project code 03ET1342A. The work of CIEMAT is part of two projects: ACES2030 (S2018/EM-4319) which is supported by Comunidad de Madrid and European Structural Funds through and SFERA III (GA No 823802) which is supported by European Union's Horizon H2020 Research and Innovation Programme. The work of DTU was supported by HM Heizkörper GmbH and the Danish Energy Agency through the EUDP program. The work of EHU is part of the project Sweet-TES (RTI2018-099557-B-C22), funded by the Spanish Ministry of Science, Innovation and Universities. The work of GREiA was partially funded 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). The authors would like to thank the Catalan Government for the quality accreditation given to their 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. The work of HSLU was partially funded by the Swiss Competence Centre for Energy Research on Heat and Electricity (SCCER HaE). The authors would like to thank the SCCER HaE as well as METTLER TOLEDO AG for the support given. The work of Fraunhofer ISE was part of the projects KOLAN (FKZ 03ESP357B) and KOKAP (FKZ 03ET1463A) which were administrated by the Projektträger Jülich (PtJ) and funded by the German Federal Ministry of Economic Affairs and Energy. The work of LAMTE was supported by Intel Corporation, along with the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation. The work of LGCgE is partly funded by the French National Research Agency (ANR) under the project "Hybrid storage and heat exchanger device with PCM—EUROPA". Noé Beaupere's PhD work was funded by the French Alternative Energies and Atomic Energy Commission (CEA) Grenoble. The work of LTTT is part of the project MALATrans and was funded by the German Federal Ministry for Economic Affairs and Energy (BMWi) under the project code 03ESP227B.

Proceedings of the 4th International Conference on Solar Heating and Cooling for Buildings and Industry (SHC 2015) ; Within the framework of IEA SHC Task 42 / ECES Annex 29, a simple tool for the economic evaluation of thermal energy storages has been developed and tested on various existing storages. On that account, the storage capacity costs (costs per installed storage capacity) of thermal energy storages have been evaluated via a Top-down and a Bottom-up approach. The Top-down approach follows the assumption that the costs of energy supplied by the storage should not exceed the costs of energy from the market. The maximum acceptable storage capacity costs depend on the interest rate assigned to the capital costs, the intended payback period of the user class (e.g. industry or building), the reference energy costs, and the annual number of storage cycles. The Bottom-up approach focuses on the realised storage capacity costs of existing storages. The economic evaluation via Top-down and Bottom-up approach is a valuable tool to make a rough estimate of the economic viability of an energy storage for a specific application. An important finding is that the annual number of storage cycles has the largest influence on the cost effectiveness. At present and with respect to the investigated storages, seasonal heat storage is only economical via large sensible hot water storages. Contrary, if the annual number of storage cycles is sufficiently high, all thermal energy storage technologies can become competitive. ; This study is part of IEA SHC Task 42 / ECES Annex 29 "Compact Thermal Energy Storage - Material Development and System Integration" (http://task42.iea-shc.org). The work of ZAE Bayern is part of the project PC-Cools_V and supported by the German Federal Ministry for Economic Affairs and Energy under the project code 03ESP138A. University of Zaragoza thanks the Spanish Government for the funding of their work under the projects ENE2008-06687-C02-02, ENE2011-28269-C03-01 and ENE2014-57262-R. University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). The research leading to these results has received funding from the European Union's Seventh Framework Program (FP7/2007-2013) under grant agreement n° PIRSES-GA-2013-610692 (INNOSTORAGE) and European Union's Horizon 2020 research and innovationprogramme under grant agreement No 657466 (INPATH-TES). Laia Miró would like to thank the Spanish Government for her research fellowship (BES-2012-051861). The University of the Basque Country acknowledges the financial support of the Spanish's Ministry of Economy and Competitiveness through the MicroTES (ENE2012- 38633) research project. The responsibility for the content of this publication is with the authors