The problem of end effects influencing the ejection angles of fragments near the ends of cylindrical warheads is approached semi‐empirically. A correction term is added to the Taylor angle, based on the accepted concept that the reduced fragment velocities near the ends of a warhead are due to release waves in the detonation gas. Acceptable agreement between experiment and prediction is found for available experimental data. The results indicate that the accelerative drag due to the axially‐outward component of the release‐wave gas flow over the fragments dominates the divergence of the fragments for prefragmented casings, the axial pressure drop playing a minor part, while the reverse seems to be true for the divergence of fragments from solid casings.
Based on system tests, a model‐aided system analysis tool is developed to model different types of fuel cell systems. In the experimental modeling approach, a model system which is general and flexible is parameterized on the basis of data measured from a system. The aim of this model is to obtain information concerning the efficiency of the system and its individual system components, to reveal problems during operation and to analyze the potential for optimization. A first evaluation of the procedure is performed on a 2 kWel and 4 kWthermal Polymer Electrolyte Membrane fuel cell (PEMFC) Combined Heat and Power (CHP) prototype system, installed at the Institut für Werkstoffe der Elektrotechnik (IWE), Universität Karlsruhe (TH). The system, which was developed at the Zentrum für Sonnenenergie‐ und Wasserstoff‐Forschung ZSW, Ulm (FC stack) and the Fraunhofer‐Institut für Solare Energiesysteme ISE, Freiburg (natural gas reformer) is operated and tested in close cooperation with the Stadtwerke Karlsruhe. The CHP system including the measurement equipment, as well as the modeling and simulation approach based on system tests are presented.
Fuel cell combined heat and power (FC CHP) systems propose a high-efficient, low emission and decentralized power and heat supply for buildings. An exact comparison between the different fuel cell CHP systems as well as detailed conclusions about efficiencies and optimization potential is hardly possible. Therefore, based on system tests, a model- aided system analysis tool using Matlab/Simulink{trade mark, serif} was developed to model and simulate different types of fuel cell systems. In the experimental modeling and simulation approach the general and flexible system model structure was parameterized and validated on the basis of measured data of a natural gas operated PEMFC CHP system. The results of the simulation agree well with the measured values.
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