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Document IIF

Paramètres de mise à l’échelle entre l’ammoniac et l’eau.

Scaling parameters between ammonia and water.

Numéro : pap. n. 191

Auteurs : SPINDLER K.

Résumé

The thermodynamic critical values pcr and Tcr are used to obtain corresponding states for the thermophysical properties. The normalized pressure p/pcr has found to be the better scaling parameter. The thermophysical properties of ammonia are presented as function of normalized pressure. The density ratio ?´/?´´ and the density difference ?´-?´´ play an important role in thermosiphons and in two-phase flow heat transfer. Surface tension, viscosity and thermal conductivity influence the process of boiling and condensation. For depressurisation by opening a safety valve, the first derivatives of the enthalpy of vaporization and the density of the saturated liquid with respect to the pressure are relevant. The scaling factors between ammonia and water are given for the thermophysical properties and derivatives in a wide pressure range up to the critical point. The influence of the pressure depending thermophysical properties on boiling and condensation heat transfer of ammonia will be presented.

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Détails

Titre original : Scaling parameters between ammonia and water.
Identifiant de la fiche : 30025962
Langues : Anglais
Source : Proceedings of the 25^th IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019.
Date d'édition : 24/08/2019
DOI : http://dx.doi.org/10.18462/iir.icr.2019.0191

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Indexation

Thèmes : Mesures thermodynamiques;
Ammoniac;
Eau
Mots-clés : Frigorigène naturel; Coefficient de transfert de chaleur; R718; R717; Ammoniac; Propriété thermodynamique; Modélisation; Entartrage; Ébullition; Eau