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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 Thesis706 9780 - 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: 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