@misc{BergKleisslHimmelbergetal., author = {Berg, Heinz Peter and Kleissl, Marko and Himmelberg, Axel and Lehmann, Mario and Prechavut, Nontavut and Vorpahl, Michael}, title = {Heat balancing of direct reforming fuel cells in MGT-SOFC hybrid systems}, series = {9th Thai Society of Mechanical Engineers, International Conference on Mechanical Engineering (TSME-ICoME 2018) 11-14 December 2018, Phuket, Thailand}, journal = {9th Thai Society of Mechanical Engineers, International Conference on Mechanical Engineering (TSME-ICoME 2018) 11-14 December 2018, Phuket, Thailand}, editor = {Prukvilailert, Monchai}, edition = {1. Auflage}, publisher = {IOP Publishing/IOP Science}, address = {Bristol}, issn = {1757-899X}, doi = {10.1088/1757-899X/501/1/012007}, pages = {50 -- 60}, abstract = {Solid oxide fuel cells convert chemical energy in electrical energy and are highly suitable for the conversion of hydrocarbon based fuels and products from PowerToGas conversions. Embedded in a micro gas turbine-cycle instead of the combustion chamber the heat energy of the injected fuel, released in the SOFC-Stack, can additionally converted into work and by a turbine-generator into electricity. In a compact system, SOFC stacks are designed to realize a direct steam-reforming process inside. In such direct-reforming fuel cell systems the SOFC operating temperature due to the heat demand for reforming, can be reduced to a value in the range of the outlet temperature of the downstream flow (650°C). If the cycle uses a recuperating system, the operating conditions of the SOFC can be realized without additional high-temperature heat exchanger systems. The system with an uncooled turbine, described in [1], just can reach the operating temperature with an additional high-temperature heat exchange. The system described in this publication does not require an additional high-temperature heat exchanger, because the X-value, as the ratio between the exchanged heat quantity and the required amount of heat to complete the MGT-cycle [2] due to the referring process, is nearly zero and can be realized via the inner container wall (of the MLC). The cycle is completed (between the SOFC and the turbine entry) by the heat input of an afterburner. Here the unreacted fuel of the SOFC fuel-stream is used to provide the necessary heat energy for the downstream turbo-generator-system.}, language = {en} } @misc{DueckershoffBergHimmelbergetal., author = {D{\"u}ckershoff, Roland and Berg, Heinz Peter and Himmelberg, Axel and Lehmann, Mario and Kleissl, Marko}, title = {Influence on the Electrical Efficiency of a Hybrid MGT-SOFC-System by μ-fogging in a-Two-Staged Compressor System}, series = {IOP Conference Series: Materials Science and Engineering}, journal = {IOP Conference Series: Materials Science and Engineering}, editor = {Ashton, Anete}, edition = {1. Auflage}, publisher = {IOP Science}, address = {Bristol}, issn = {1757-899X}, doi = {10.1088/1757-899X/886/1/012041}, pages = {1 -- 8}, abstract = {Hybrid combinations of solid oxide fuel cell and recuperated micro gas turbines can convert the chemical energy of hydrocarbon-based fuels in electrical energy with high electrical efficiency. With an integrated and improved cycle management, more than 70\% of the energy content of the fuel could be converted. Therefore, the systems are highly suitable for the Power-To-Gas conversion. In particular, a pressure charging of the SOFC fuel cell leads to an increase in stack performance. By a downstream turbo set, after residual fuels are intentionally oxidized with an afterburner, additional electrical energy can be gained from the expansion of the hot exhaust gas stream and the overall efficiency can be increased. In order to increase the electrical efficiency of the system, it is proposed, to ensure the required compression of the process air in particular by a-two-staged turbo compressor with an intermediate cooling system. By thus achievable reduction of the dissipation of the compressor and by targeted condensation of finest drops in front of the second compressor stage affected by intermediate cooling, an increase in efficiency of the system is possible. This is achieved by targeted cooling of the process air behind a low pressure compression, so that it is saturated over 100\% relative air humidity. As a result, a slightly supersaturated airflow is available for the second compressor stage, which enters the compressor after heat removal via an intermediate cooling having a small number of microdroplets. Therefore, the condensed water evaporates again by the heat of compression in the second stage and the compressed flow ultimately enters the recuperation at a lower temperature than during normal compression. Thus, more heat can be recovered within the recuperation system. Therefore, the electrical energy of the system can be produced having higher efficiency, because the heat dissipation of the overall system decreases. In this article it is presented, how such a process is thermodynamically modelled and how a technical realization can be built after optimization by simulations. Finally, in this study, the process-influencing factors are analyzed to show the highest possible electrical yield of such a system.}, language = {en} }