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R502 and two near-azeotropic alternatives. 2. Two-phase flow patterns.

Author(s) : KATTAN N., THOME J. R., FAVRAT D.

Summary

Flow patterns for horizontal in-tube flow boiling have been studied for the new refrigerants R402A and R404A and the conventional refrigerant R502. The flow pattern observations were compared with several criteria utilized in horizontal flow boiling correlations for determining whether the entire circumference of a horizontal evaporator tube is all wet or partially wet. Use of only the liquid Froude number (utilized in numerous flow-boiling correlations) is shown to be completely unreliable. Stratified (partially wet wall) flow was found to occur at liquid Froude numbers up to 16 times those of the recommended threshold values utilized by the correlations. A semi-empirical method for predicting stratification proposed by Klimenko and Fyodorov is an improvement but still is not very successful in predicting the present data.

Details

  • Original title: R502 and two near-azeotropic alternatives. 2. Two-phase flow patterns.
  • Record ID : 1996-1476
  • Languages: English
  • Source: ASHRAE Transactions.
  • Publication date: 1995/01
  • Document available for consultation in the library of the IIR headquarters only.

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