CT-7 Resistance Proration Methods for Downflow Condensation of Mixed Vapors with Noncondensing Gases inside Vertical Tubes
The performance of the resistance proration method from literature (Silver-Bell-Ward) was compared against a data bank for condensation of vapors from a mixture with noncondensing gas inside vertical tubes. The databank consists of 85 data points and was compiled using published data from four different sources. The resistance proration method from literature was found to overpredict the heat transfer coefficient under certain conditions. The empirically corrected resistance proration method (refer to Report CT-6) was found to predict the majority of the data within ± 25 percent. A theoretical correction was suggested to the resistance proration method from literature and a theoretical correction factor qs was introduced. The resistance proration method form literature and the empirically corrected resistance proration method (refer to Report CT-6) showed a distinct trend of overpredicting the heat transfer coefficient at low values of qs. The introduction of qs in the resistance proration method eliminated this trend.
An HTRI resistance proration method was recommended. The method includes the theoretical correction factor qs and an empirical correction for the effect of flow regimes. The method predicts the data within ± 20 percent.