Thermo-fluid dynamic evaluation of components in adiabatic absorption systems

• Autores: Geydy Gutiérrez Urueta
• Directores de la Tesis: Pedro A. Rodríguez Aumente (dir. tes.)
• Lectura: En la Universidad Carlos III de Madrid ( España ) en 2009
• Idioma: inglés
• Tribunal Calificador de la Tesis: Antonio Lecuona Neumann (presid.), Jose Ignacio Nogueira Goriba (secret.), Felix Ziegler (voc.), José Miguel Corberán Salvador (voc.), Alberto Coronas Salcedo (voc.)
• Materias:
  • Ciencias tecnológicas
    • Procesos tecnológicos
      • Absorción
      • Transferencia de calor
• Enlaces
  • Tesis en acceso abierto en: e-Archivo
• Resumen

  • In this PhD thesis, a facility for experimental evaluation of innovative components forming part of a single effect H20-LiBr adiabatic absorption chiller is analyzed. The adopted methodology has been mainly experimental. Plate heat exchangers functioning as generator, solution heat exchanger, condenser and subcooler have been incorporated in the design. Two adiabatic absorber configurations, droplets and liquid sheets, were tested and evaluation parameters were experimentally determined. Overall test facility performance is analyzed in the first stage of the research. The preliminary analysis gives an idea about the operational features of the machine, which allow subsequent detailed components analysis. This analysis is oriented to the interpretation of experimental data including the particular features, in both design and operation, of the facility here presented: study of evaporators� efficiency, solution heat exchanger efficiency and thermal losses. Performance parameters, cooling capacity and COP, are expressed in terms of a diagnostic absorption model and compared with experimental results. The differences observed between ideal and experimental results help to validate the influence of components performances on the overall performance of the facility. An extension of the characteristic equation method, based on the characteristic temperature difference to adiabatic absorption chillers, has been developed and applied considering the facility features. Evaporator limitations have been included in the analysis. The agreement between experimental data and the extended characteristic equation is discussed, showing a good predictive capability, even at off-design operating conditions. The performances of two types of absorbers (liquid sheets and droplets as solution spreading mechanisms in the absorber) have been characterized in terms of heat and mass transfer. The liquid sheet configuration has shown better evaluation parameters than droplets configuration. Single and two phase heat transfer and pressure drop in a plate heat exchanger operating as generator, has been analyzed. For the cases of subcooler and solution heat exchanger, single phase heat transfer data has been obtained. The corresponding results are analysed for each case and correlations equations have been obtained and compared with those reported in literature.