ABSTRACT
This work compared an asymptotic model for flow boiling heat transfer with experimental data for R-113 in a small-diameter round tube (2.92 mm) from Wambsganss et al. [1993]. The asymptotic model was developed using data from alternative refrigerant studies for larger tubes (7–11 mm) [Wattelet, 1994]. The small-diameter, round-tube experimental data were shown to be dependent on heat flux alone and not mass flux, indicating flow boiling behavior dominated by nucleate boiling effects. The asymptotic model predicted the data fairly well, with a mean deviation of 14.4%. This mean deviation was lower than several other correlations from the literature based on the superposition model [Wambsganss et al., 1993]. Experimental data for Frl < 0.25 were also well correlated by the asymptotic model (mean deviation: 14.8%), showing that a Froude number dependent term can be used to account for diminished convective boiling effects for low mass fluxes. However, better prediction of the small-diameter round-tube experimental data was obtained using nucleate boiling correlations, such as those of Lazarek and Black [1982] and Cooper [1984], which had mean deviations of 12.7% and 11.4%, respectively, when compared with the experimental data.
