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Item type:Publication, Access status: without files , Electric thermal energy storage based on packed bedAn energy storage concept based on high-temperature thermal energy storage in a packed bed of crushed rock is presented. The packed bed is charged with hot air from an electric heater. At discharge, the stored heat is transferred with a heat recovery steam generator to a conventional water-steam cycle for electricity generation. A fan is used to move the air in closed loop. The deployment of the storage concept in existing large-scale water-steam cycle power plants is feasible, as the low-cost storage material is resistant to high temperatures. Further applications are industrial process heat electrification, waste heat recovery or combined heat and power generation. The power-to-power efficiency is mainly limited by the water-steam cycle, the fan work at discharge and the heat losses. Thermal destratification inside the packed bed limits the usable storage capacity with respect to the nominal storage capacity and must be compensated by packed bed over-sizing. The first demonstration plant with a thermal storage capacity of 130 MWhth and a storage temperature up to 750 °C has been commissioned in July 2019 in Hamburg, Germany.Publicationtype: Book Part596 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Electric thermal energy storage based on packed beds for renewable energy integrationA novel energy storage technology for the integration of variable renewable energy is investigated in this work. The energy is stored as thermal energy at high-temperature in a packed bed of low-cost natural rock. Electrically heated air is used for charge and a heat recovery steam generator, which can supply steam to a turbine or other consumers, for discharge. The investigation includes dynamic system simulation of the air cycle as well as computational fluid dynamics on packed-bed and particle scale. The energy-based air cycle efficiency as well as the ratio of usable to nominal thermal storage capacity are derived for a selection of test cases.Publicationtype: Doctoral Thesis703 9767 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Particle-Resolved CFD-Simulations of Thermal Energy Storage in Rock Beds(2017-03); Publicationtype: Conference Paper132 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Using modelica to investigate the dynamic behaviour of the German national standard for high pressure natural gas flow meteringThis paper presents a computational model written in Modelica for the high pressure piston prover (HPPP) used as the national primary standard for high pressure natural gas flow metering in Germany. With a piston prover the gas flow rate is determined by measuring the time a piston needs to displace a certain volume of gas in a cylinder. Fluctuating piston velocity during measurement can be a significant source of uncertainty if not considered in an appropriate way. The model was built to investigate measures for the reduction of this uncertainty. Validation shows a good compliance of the piston velocity in the model with measured data for certain volume flow rates. Reduction of the piston weight, variation of the start valve switching time and integration of a flow straightener were found to reduce the piston velocity fluctuations in the model significantly. The fast and cost effective generation of those results shows the strength of the used modelling approach.Publicationtype: Journal ArticleScopus© Citations 1 265 362 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Verwendung von Modelica zur Untersuchung des dynamischen Verhaltens des deutschen Primärnormals für Hochdruck-GaszählerIn diesem Artikel wird ein dynamisches Modell für die Rohrprüfstrecke, welche als deutsches Primärnormal für Hochdruck-Gaszähler verwendet wird, vorgestellt. In einer Rohrprüfstrecke wird der Volumenstrom mit Hilfe der Zeit ermittelt, die ein Kolben in einem Messrohr benötigt, um eine bestimmte Strecke zurück zu legen. Schwankungen der Kolbengeschwindigkeit über der Messzeit können einen Einfluss auf die Messungenauigkeit haben, wenn diese nicht entsprechend berücksichtigt werden. Das Modell im Sprachstandard Modelica wurde entwickelt, um Wege zu finden, diese Messungenauigkeit zu verringern. Die Validierung des Modells zeigt eine hohe Übereinstimmung von Simulationsergebnissen und Messergebnissen in einem bestimmten Volumenstrombereich. Eine Reduktion des Kolbengewichtes, eine Variation der Schaltdauer des Startventils und die Integration eines Strömungsgleichrichters verringern die Schwankungen der Kolbengeschwindigkeit im Modell deutlich. Die schnelle und kostgengünstige Erstellung der Simulationsergebnisse zeigt die Vorzüge eines Modellierungsansatzes.Publicationtype: Journal Article62 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Modeling of the German National Standard for High Pressure Natural Gas Flow Metering in Modelica(2015-09); ; The German national metrological institute Physikalisch-Technische Bundesanstalt uses a High Pressure Piston Prover as the primary standard for high pressure natural gas flow meters. The High Pressure Piston Prover measures the gas flow rate using the time a piston needs to displace a defined enclosed volume of gas in a cylinder. Fluctuating piston velocity during measurement can be a significant source of uncertainty if not considered in an appropriate way (Mickan et al., 2010). A computational model written in Modelica was developed to investigate measures for the reduction of this uncertainty. Validation of the model shows good compliance of the piston velocity in the model with measured data for certain volume flow rates. Reduction of the piston weight, variation of the start valve switching time and integration of a flow straightener were found to reduce the piston velocity fluctuations in the model significantly.Publicationtype: Conference Paper200 227 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Measures to enable the performing of system simulations in a joint research project(Royal Institution of Naval Architects (RINA), 2015); ; Modelling and simulation of complex energy systems is a challenging task by nature. Various component models need to be combined which might have been developed using different software. Model interfaces have to be defined clearly in order to guarantee connectivity of components. Mother challenge is to ensure sufficient component model quality to be able to achieve reliable simulation results on system level. In addition, performing system simulations in a joint research project requires extensive cornmwucation among project partners to hamnoroze the modelling process and the objectives of investigation. To encounter all these challenges, several measures, as described in this paper, were realized in the European research project JOULES (Joint Operation for Ultra Low Emission Shipping, www.joules-pvoject.eu).Publicationtype: Conference Paper43 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Thermodynamic Model for Heat Pump Energy Storage(2014-09); ; A new thermodynamic model for Heat Pump Energy Storage (HPES) is derived. HPES is a large scale electric energy storage technology that stores energy as thermal energy. This model utilizes the partition of energy into exergy and anergy to account for the quality of energy conversion or transfer processes. The model is used to identify and categorize the exergy losses of HPES systems. The exergy losses lead to the degree of utilization. For demonstration the model is applied to the HPES system described in [1] which works with a gaseous working fluid and stores the thermal energy in two regenerators.Publicationtype: Conference Paper230