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Coefficient de transfert de chaleur local de l'ébullition en écoulement du R245fa dans un échangeur de chaleur à plaques avec visualisation simultanée de l'écoulement.

Local heat transfer coefficient of R245fa flow boiling in plate heat exchanger with simultaneous flow visualization.

Numéro : 2398

Auteurs : FARRAJ A. R., HRNJAK P.

Résumé

This paper presents an experimental investigation of the thermal fields in a three-channel chevron-type plate heat exchanger with simultaneous flow visualization. Temperature, heat flux, and heat transfer coefficient maps of the three-phase evaporating low-pressure refrigerants R245fa are obtained from an inner heat flux meter plate placed on one side of the refrigerant channel. The other side of the refrigerant channel is a transparent resin-formed plate that serves as the endplate to allow direct visualization. The high-speed camera recorded the evaporating flow regimes assisted by the desired amount of light source. This method collects information without interrupting the heat exchanger's flow by preserving the geometry and operating conditions. The effects of heat flux, mass flow rate, and saturation pressure on the evaporated flow are studied. The results show that in the case of boiling R245fa, the local heat transfer coefficients increase with an increase in the vapor quality and mass flux and decrease with an increase in the heat flux. The visualization showed bubbles at the nucleation sites at the channel's inlet, like the liquid pool boiling. Also, nucleation is observed in the liquid retained close to the dry-out regions near the outlet.

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Pages : 10 p.

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Détails

  • Titre original : Local heat transfer coefficient of R245fa flow boiling in plate heat exchanger with simultaneous flow visualization.
  • Identifiant de la fiche : 30030712
  • 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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