Film condensation vertical flat plate

Consider a vertical flat plate exposed to a condensable vapor. If the temperature of the plate is below the saturation temperature of the vapor, condensate will form on the surface and under the action of gravity will flow down the plate. If the liquid wets the surface, a smooth film is formed, and the process is called film condensation. If the liquid does not wet the surface, droplets are formed which fall down the surface in some random fashion. This process is called dropwise condensation. In the film-condensation process the surface is blanketed by the film, which grows in thickness as it moves down the plate. A temperature gradient exists in the film, and the film represents a thermal resistance to heat transfer. In dropwise condensation a large portion of the area... 

The Reynolds number Re = wm 6/z/L for the condensation on a vertical tube can, due to the mass balance M = wm dn 8 gL and with r/L = i/LgL, also be written as Re = M/(d,TT i]L ). As the tube diameter d, on which the calculations from Fig. 4.12 are based, is much larger than the assumed thickness of the film, the curvature of the condensate film has no effect on the heat transfer. The results also hold for condensation on a vertical flat plate, with the Reynolds number defined in (4.38). 

O. A. Plumb, D. B. Burnett, and A. Shekarriz, Film Condensation on a Vertical Flat Plate in a Packed Bed, ASMEJ. Heat Transfer, (112) 235-239,1990. 

Shang and Adamek [15] recently studied laminar film condensation of saturated steam on a vertical flat plate using variable thermophysical properties and found that the Nusselt theory with the Drew [14] reference temperature cited above produces a heat transfer coefficient that is as much as 5.1 percent lower than their more correct model predicts (i.e., the Nusselt theory is conservative). 

D. Y. Shang and T. Adamek, Study on Laminar Film Condensation of Saturated Steam on a Vertical Flat Plate for Consideration of Various Physical Factors Including Variable Thermophysical Properties, Wdrme-und Stoffiibertragung, 30, pp. 89-100,1994. 

Vertical Flat Plates. Following the earlier work by Bromley [190] on cylinders (see below), Hsu and Westwater [191] derived an expression for laminar film boiling on a vertical plate that is analogous to that for laminar film condensation. The average value of hc over a plate of height L is given by... 

At a distance x down a vertical, isothermal flat plate on which a saturated vapor is condensing in a continuous film, the thickness of the liquid condensate layer is 8. The heal transfer coefficient at this location on the plate is given by (a) kJS (b) Shf (c) Sh ... 

When a saturated vapor condenses on a vertical, i.sothermal flat plate in a continuous film, the rale of heat transfer is proportional to... 

Film thidcness S is typically two or three orders of magnitude smaller than the tube diameter it can therefore be found, for flow either inside or outside a tube, from the equation for a flat plate, Eq. (5.77). Since there is a temperature gradient in the film, the properties of the liquid are evaluated at the average film temperature 7., given by Eq. (13.11). For condensation on a vertical surface, for which cos) = 1, Eq. (5.77) becomes... 

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