CT-6 Downflow Condensation of Mixed Vapors with Noncondensable Gases inside Vertical Tubes
The Silver-Ward-Bell method for condensation of mixtures with noncondensable gases was evaluated and compared to a total of 300 published data points for vertical downflow condensation. These data were obtained on a representative size tube (40 mm ID by 5 m long) using h-hexane, benzene, and toluene mixtures with nitrogen as a noncondensable gas. All of the data are in the gravity-controlled flow regime. The Silver-Ward-Bell method gave a reasonably consistent prediction, although it was somewhat on the unsafe side.
The HTRI Resistance Proration method was reevaluated and modified for vertical downflow for use as the HTRI recommended procedure. The resulting correlation gives very good prediction of the available data. The recommended calculation procedure for vertical tubes is, therefore, the same as for horizontal tubes for the vapor-phase heat transfer coefficient as given in HTRI Report CT-3, except that the correlation constants are different. The liquid-phase heat transfer coefficient is calculated as described in HTRI Report CT-5.