FORCED-CONVECTIVE CONDENSATION OF PURE STEAM AND AMMONIA-STEAM VAPOR MIXTURES IN A SHELL-TUBE CONDENSER

摘要

In this paper, we present our experimentalfindings for the forced-convective condensation of pure steamand ammoniasleam vapor mixture in a horizontal annulus in acountercurrent shell-tube condenser. Experiments withammonia-steam mixtures were conducted for 90 percentammonia concentration (by wt.) for vapor inlet mass fluxesranging from 2 to 5 kg/m~2s. The local heat transfercoefficient varied considerably along the condenser and thisvariation was strongly linked to the condensate flow patterns inthe annulus. Based on a condensate drainage model, the flow inthe annulus was mapped on to flow maps for horizontal in-tubecondensing flows. The delineated flow regimes were utilized toexplain augmentation or deterioration of local heat transfer inthe condenser. The average heat transfer coefficients arepresented as a function of the condensate and vapor Reynoldsnumber for both steam and ammonia-steam mixture. Theresults for pure steam are higher than those predicted byannular flow correlation developed in the past. For ammonia-steam mixtures, the average heat transfer coefficients are about16 percent of those for pure steam due to the vapor layerresistance at the interface.