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Une charte des propriétés thermodynamiques utilisée pour illustrer l'interférence entre la récupération lors de la détente et l'échange de chaleur interne.

A thermodynamic property chart as a visual aid to illustrate the interference between expansion work recovery and internal heat exchange.

Auteurs : ELBEL S., HRNJAK P.

Résumé

Expansion work recovering devices (EWRDs) such as the refrigerant ejector or expander can significantly improve the cycle efficiency of transcritical R-744 systems by approaching isentropic expansion. This paper uses a thermodynamic property chart to visualize the work recovery potentials of such devices. Two distinguished cases regarding the operational characteristics of an internal heat exchanger (IHX) are discussed and the possible interferences with the EWRD potentials are analyzed. The thermodynamic property chart reveals how the use of an IHX reduces the EWRD potential by competing for the same temperature difference. While the assessments of the effects on cooling capacity are readily available, it is generally more complex to predict the associated changes in COP. Thus, a numerical system model is used to address the issue of how efficient the EWRD has to be in order to reduce or eliminate the need for an IHX. For the system investigated it was found than an approximately 50% efficient ejector can replace a 60% effective IHX in order to achieve identical COPs at a given cooling capacity in a transcritical R-744 cycle.

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  • Prix public

    20 €

  • Prix membre*

    15 €

* meilleur tarif applicable selon le type d'adhésion (voir le détail des avantages des adhésions individuelles et collectives)

Détails

  • Titre original : A thermodynamic property chart as a visual aid to illustrate the interference between expansion work recovery and internal heat exchange.
  • Identifiant de la fiche : 2007-1901
  • Langues : Anglais
  • Source : 2006 Purdue Conferences. 18th International Compressor Engineering Conference at Purdue & 11th International Refrigeration and Air-Conditioning Conference at Purdue [CD-ROM].
  • Date d'édition : 17/07/2006

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