final report on the multiport dryer - Argonne National Laboratory

18∆qh(z) =s(z)∆A s [ T s(z) − T w(z)] = ∆q (z) + ∆q (z)c env∆A sT s(z) − T w(z)[ ] , (7)where ∆ A sis the heat transfer surface area of a particular test segment, and T s(z) and T w(z) arethe steam and wall temperatures, respectively. It should be noted that the heat transfer surfacearea used to define the condensing heat transfer coefficient was set to one-half of the entirechannel surface area because it represents the physical process of bottom-surface condensation,including a fin effect of the side walls of the channel. The local condensing heat transfercoefficients are evaluated at axial locations that correspond to the measurements of the walltemperature. The steam temperatures where wall temperatures are measured are calculated byusing the pressure and temperature correspondence of saturating steam, which can be expressedasT s (z) = f [p s (z)] , (8)where p s(z) is the local steam pressure. Because the pressure drop across the condensingchannel was small in all of our tests (