The applicability of an existing fluted tube condenser model when used with refrigerant R-407C

• Fluted tube-in-tube condensers are key components in energy efficient water heating heat pumps.
• The applicability of the Rousseau et al. (2003) model for R-407C condensation inside fluted tube annuli was evaluated.
• New enhancement factors were derived and implemented in the model.
• The average difference between the simulated and measured pressure drops was 9.5% and 3.3% for the LMTD.

Fluted tube-in-tube condensers are key components in energy efficient water heating heat pumps. Rousseau et al. (2003) developed a model that incorporates all the essential features of these heat exchangers. A feature of the model was that it allowed for the extension to simulate heat exchangers for cycles employing zeotropic refrigerant mixtures. This paper investigates the applicability of the model for R-407C condensation inside fluted tube annuli. To evaluate the model experimental data was gathered using a test facility. Comparisons between the experimental results and the model showed an average model accuracy of 48% when predicting the pressure drop and 56% for the log mean temperature difference (LMTD) for the tubes sizes used. Based on these accuracies new enhancement factors were derived and implemented in the model. This resulted in an average difference between the simulated and measured pressure drops of 9.5% and an average difference for the LMTD of 3.3%.