Condensation of Halogenated Refrigerants Inside Smooth Tubes

The paper presents a new predicting model to compute the heat transfer coefficient and pressure drop during condensation inside smooth tubes when operating with pure or blended halogenated refrigerants, including the new high-pressure HFC fluids, for which the existing predicting methods are inadequate. The suggested model is based on a predictive study of the flow patterns occurring during the condensation process. Predictions from this new procedure are compared both with the authors' experimental data and with a wide experimental data bank from independent authors; excellent agreement is demonstrated in almost all cases. Heat transfer coefficients were obtained during condensation of refrigerants R-22, R-134a, R-125, R-32, R-236ea, R-407C, and R-410A in an 8 mm inside diameter plain tube, carried out at a saturation temperature ranging between 30 and 50°C, and mass velocities varying from 100 to 750 kg/(m2·s), over the entire vapor quality range. For zeotropic blended refrigerants, such as R-407C, the Silver (1947) and Bell and Ghaly (1973) correction has been implemented in the prediction.