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Calcul approximatif de l'efficacité du cycle frigorifique à compression de vapeur tout-ou-rien par des modèles pseudo-stationnaires.

Approximate calculation of on-off vapor refrigeration cycle efficiency through pseudo-stationary models.

Numéro : 2226

Auteurs : MATSUDA V. A., FALCETTI E. P., TIBIRIÇÁ C. B., CABEZAS-GÓMEZ L.

Résumé

The present work main objective is the development of a simulation mathematical model for vapor compression refrigeration cycles that can provide approximate average values for the system efficiency, as the coefficient of performance (COP) and the second law efficiency (ηII), during on-off operation. For this aim, two different pseudo-stationary models were developed. Each model calculates the cabinet internal air temperature in order to estimate the periods in which the compressor must be tuned on and off, in order to maintain the system in the desired operational regime. The first model considers that the refrigerant pressures in system components, the degrees of sub-cooling and super-heating, the system mass flow-rate and the compressor operational conditions assume constant values, which are equal to the pulldown steady-state simulated values. Otherwise the lumped temperatures of the condenser, evaporator and compressor components and of cabinet air are calculated for each simulated time step. The second model takes into consideration the changes of the compressor operational regime, and thus additionally considers variations in the system mass flow rates. In order to validate the two models, a comparison with available experimental data and various transient simulation data from a detailed transient model was performed. In general, it was observed that both the COP and ηII presented slightly higher values for the pseudo-stationary models due to consideration of compressor power consumption values calculated for the stationary regime. The COP and ηII also presented a similar behavior for the variation of the refrigerant charge and environmental temperature in relation to the values obtained with the more detailed simulation model. The developed models can be useful for a quick system analysis, or yet, for a first optimization analysis of the refrigeration system operation.

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Pages : 10 p.

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Détails

  • Titre original : Approximate calculation of on-off vapor refrigeration cycle efficiency through pseudo-stationary models.
  • Identifiant de la fiche : 30030614
  • Langues : Anglais
  • Sujet : Technologie
  • Source : 2022 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Date d'édition : 2022

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