Ponencias (Ingeniería de la Construcción y Proyectos de Ingeniería)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11339

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    Acceso AbiertoPonencia
    Inverse mass matrix via the method of localized lagrange multipliers
    (National Technical University of Athens, 2017-06) González Pérez, José Ángel; Kolman, R.; Cho, Sang S.; Felippa, C.A.; Park, K.C.; Universidad de Sevilla. Departamento de Ingeniería de la Construcción y Proyectos de Ingeniería; Papadrakakis M., Fragiadakis M.; Universidad de Sevilla. TIC152: Diseño, Construcciones y Proyectos de Ingenieria
    An efficient method for generating the mass matrix inverse is presented, which can be tailored to improve the accuracy of target frequency ranges and/or wave contents. The present method bypasses the use of biorthogonal construction of a kernel inverse mass matrix that requires special procedures for boundary conditions and free edges or surfaces, and constructs the free-free inverse mass matrix employing the standard FEM procedure. The various boundary conditions are realized by the method of localized Lagrange multipliers. Numerical experiments with the proposed inverse mass matrix method are carried out to validate the effectiveness proposed technique when applied to vibration analysis of bars and beams. A perfect agreement is found between the exact inverse of the mass matrix and its direct inverse computed through biorthogonal basis functions.
  • Miniatura
    Acceso AbiertoPonencia
    Perfomance analysis of hybrid systems based on externally heayed closed-cycle engines
    (ENEA, 2011) Sánchez Martínez, David Tomás; Muñoz de Escalona, J.; Chacartegui, Ricardo; Sánchez Lencero, Tomás Manuel; Universidad de Sevilla. Departamento de Ingeniería Energética; Universidad de Sevilla. Departamento de Ingeniería de la Construcción y Proyectos de Ingeniería; Universidad de Sevilla.TEP137: Maquinas y Motores Termicos
    This work presents a comparative analysis of hybrid systems that make use of closed-cycle externally heated bottoming systems. Two options are considered: reciprocating (Stirling) engines and supercritical carbon dioxide turbines. These engines share the common feature of working on closed cycles with optimised fluids (H2 and CO2 respectively). However, they differ in their internal structure: Stirling engines make use of volumetric machinery whereas the SCO2 system is composed by turbomachinery. In both cases, the working fluid is subjected to very high pressure and temperature in the range of 50-200 bar and 40-650 ºC. A brief description of both bottoming systems is provided in the article along with the expected performance of each case in on-design and off-design (part load) conditions. The analysis is therefore split into two stages. First, a comparison is shown for on-design operation aiming to evaluate the maximum efficiency attainable by the proposed systems. Second, a preliminary analysis of off-design operation is presented. The paper concludes that hybrid systems based on atmospheric fuel cells and externally heated closed-cycle bottoming engines have the potential to outperform conventional pressurised fuel cells and gas turbines hybrids while preserving the topping system from the demanding operating conditions of the latter configuration