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Horizontal Flow Boiling of Alternative Refrigerants Within a Fluid Heated Micro-Fin Tube.


pdf icon Horizontal Flow Boiling of Alternative Refrigerants Within a Fluid Heated Micro-Fin Tube. (678 K)
Kaul, M. P.; Kedzierski, M. A.; Didion, D. A.

Process, Enhanced, and Multiphase Heat Transfer. "A Symposium in Honor of Professor Arthur E. Bergles." Proceedings. Georgia Institute of Technology. November 16, 1996, Begell House, Inc., New York, NY, Manglik, R. M.; Kraus, A. D., Editor(s)(s), 167-173 pp, 1996.

Keywords:

refrigerants; enhanced heat transfer; fluid heating; microfin; refrigerant mixtures

Abstract:

This paper presents local, fluid-heated, flow boiling measurements for three refrigerant mixtures: [1] R410B (R32/125, 45/55 % mass), [2] R32R134a (28/72 % mass) and [3] R407C (R32/125/134a, 25/23/52 % mass). Flow boiling heat transfer coefficients for the mixtures pure components and R22 were also measured to establish a baseline for the heat transfer degradation calculations. The heat transfer degradation was shown to be a relatively strong function of heat flux and thermodynamic mass quality. The heat transfer degradation associated with the R32/125 mixture was believed to be mostly due to nonlinear property effects. The R410B appears to be a good alternative refrigerant for R22 having approximately a 20% larger heat transfer coefficient. The degradation of the R407C was shown to increase with heat flux for all qualities except for 0.6. The dependency of the R32/134a degradation was not consistent with heat flux. The influence of nonlinear property effects was apparently responsible for the inconsistency. Correlations of the two-phase Nusselt number were derived for each fluid.