4507 -- In-Tube Condensation of Halogenated Refrigerants PDF

This 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 show as quite 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 to present authors' experimental data and to a wide experimental data bank from independent authors; an excellent agreement in almost all cases is demonstrated. Heat transfer coefficients from present authors 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 inner diameter plain tube, carried out at a saturation temperature ranging between 30ºC and 50°C and mass velocities varying from 100 to 750 kg m -2 s -1 over the entire vapor quality range. For zeotro-pic blended refrigerants, such as R-407C, the Silver (1947) and Bell and Ghaly (1973) corrections have been implemented in the prediction.

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