Extensive critical study of five popular microfin tube correlations for condensation heat transfer coefficients (HTCs) was carried out. The principal aim of this investigation was to develop an application-specific quantitative tool to assess the predictive accuracy and applicability of these correlations for halogenated refrigerants as well as CO2. This novel methodology was developed and validated against a dataset of 1163 experimental data points for CO2, R22, R134a, R410A, R407C, R125 and other halogenated refrigerants obtained from a large number of published works which included diverse microfin tube geometries and condensing conditions. The tool will enable the engineer or experimentalist to select the best (i.e., most accurate) condensation HTC correlation for a given microfin tube application, thereby significantly reducing tube testing costs, leading to lower turn-around times and more efficient designs. Based on the analysis carried out using the new methodology, it was found that overall, Cavallini et al. (2009) was the most widely applicable and accurate flow condensation correlation. Yu and Koyama (1998) was found to perform well for CO2, 7 mm and smaller tubes and low helix angles (5° to 10°). Interestingly, Cavallini et al. (2009), Yu and Koyama (1998) and Chamra et al. (2005) were found to predict the HTC satisfactorily for zeotropic refrigerants such as R407C, although their development was based on pure and near-azeotropic refrigerants only. The Han and Lee (2005) correlation was found to be inaccurate over most of the data set and therefore has a very low probability of being recommended for any application.

This content is only available via PDF.
You do not currently have access to this content.