Abstract
The quantification of the condensate heat resistance is studied for dropwise condensation from flowing air-steam mixtures. Flows are essentially laminar and stable with gas Reynolds numbers around 900 and 2000. The condensate shaping up as hemispheres on a plastic plane wall and the presence of inert gases make it possible that thermocapillary convection occurs making the resistance less than the mean condensate thickness (ca. 0.185 mm) divided by the heat conduction coefficient. The analysis of experiments shows that the effective mean condensate resistance might indeed be less, by a factor of 0.8±0.2. The analysis takes account of the sensible heat transfer which may be as large as 35% of the total heat transfer if inlet vapor concentration,c in, is low (ca. 0.07). A method is presented to determine the gas-condensate interface temperature,t i , that is needed in the analysis of the heat resistance. The highest temperature differences(t i –t w ),t w being the mean temperature of the condenser plate at the gas side, have been found to occur for relatively high values ofc in (ca. 0.3).
| Original language | English |
|---|---|
| Pages (from-to) | 435-445 |
| Number of pages | 11 |
| Journal | Heat and Mass Transfer |
| Volume | 30 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1995 |