Hautkondensation an feingewellten Oberflächen bei Berücksichtigung der Oberflächenspannungen

Summary

Following a synopsis on film- and drop-condensation, one deals with condensation on an uneven surface. The surface tensions give rise to very great pressure gradients because of the different curvatures of the surface of the condensate. The action of the latter can amount to a multiple (up to a few powers with basis ten) of the value corresponding to the gravitation. Large gradients of pressure produce thin films of condensate, and according to the theory ofNusselt they lead to large coefficients of heat transmission. Heat transfer coefficients are given determined with calculus of finite differences for a condenser with vertical tubes, grooves parallel to the tube axis and given geometrical form. The latter are confirmed by tests. Adimensional numbers determinate theNusselt number.