Heat transfer and pressure drop characteristics of fin-and-tube heat exchangers having spiral fins under wet conditions

摘要

In this study, wet surface j and / factors were obtained for spiral fin-and-tube heat exchangers. Nine samples having different fin pitches (2.12, 2.54 and 3.18 mm) and different tube rows (1, 2 and 3 row) were tested. Data are compared with those of the dry surface. For the wet surface, the effect of fin pitch on j factor is not significant. However, / factor decreases as the number of tube row increases. The j factor increases as the number of tube row increases. Different from the j factor, / factor decreases as the number of tube row increases. At one row configuration, the dry surface j factor is larger than that of the wet surface one. As the number of tube row increases, the trend is gradually reversed. Possible reasoning is provided considering the condensate behavior under wet condition. A new j and / factor correlation is developed, which predicts j and / factors within ± 20% and ± 30%, respectively.