Transport phenomena in two-phase flows during condensation of special fluids and non-azeotropic fluid mixtures

This thesis presents first-ever experimental data for laminar condensation heat transfer on vertical plates, horizontal and vertical cylinders and bank of tubes for fluids with Stefan number greater than unity. The condensation experiments were carried out in saturated vapor of FC5311® with ¼&inches; (6.35mm) and ½&inches; (12.7mm) diameter copper cylinders for length-to-diameter aspect ratios (L/ D) ranging from 1 to 32. In our first set of experiments, lumped capacity method was used to determine the heat transfer coefficients. Benchmarking experiments for spheres matched with those reported in literature. Our results for horizontal cylinder indicate that for large aspect ratios (>16) condensation heat transfer coefficients were close to those predicted by Nusselt correlation for horizontal circular cylinders. With decrease in aspect ratio, the heat transfer rate increased due to contribution from cross flow and the sides. A correlation incorporating the effect of aspect ratio is presented.; Experimental data for steady state film condensation of Fluorinert fluid FC5311® on a vertical bank of smooth horizontal tubes of various diameters ranging from ⅜&inches;(9.5mm) to ⅞&inches;(22.2mm), with different spacings, is presented. The heat transfer results for single tubes compare very favorably with the transient heat transfer results for L/D > 16. Multiple tube results with spacing-to-diameter ratios (s/D) ranging from 2 to 12, explain the effect of momentum gain and condensation between tubes in the laminar film condensation of high Stefan number fluids.; To understand the condensation phenomena in vapor mixtures, forced-convective condensation experiments were carried with pure steam and ammonia-steam vapor mixture in a horizontal annulus in a counter-current shell-tube condenser. The average heat transfer coefficients are presented as a function of the condensate and vapor Reynolds number for both steam and ammonia-steam mixture. The presence of an ammonia-rich interfacial vapor layer provided a barrier to condensation heat transfer in the condenser. Based on a condensate drainage model, the flow in the annulus was mapped on to flow maps for horizontal in-tube condensing flows. The delineated flow regimes were utilized to explain augmentation or deterioration of local heat transfer in the condenser. (Abstract shortened by UMI.)...