Rør med ribber, som på dets inderside danner et flergænget gevind, samt dampgenerator til dets anvendelse

摘要

Inner-finned tubes are used in steam generators in order to avoid film boiling or at least to shift it into the regions of the steam generator tubes in which the steam component is already present in percentages by weight of far more than 50%. According to the invention, tubes provided for this purpose are improved by having the pitch h of the thread forming the inner finning in the tubes equal to at most 0.9 times the root of the mean inside tube diameter d. By constructing the fins with a radial height of at least 0.04 times the mean inside tube diameter, effective coupling is necessarily produced between the shape of the inner tube wall and the flowing cooling agent. Consequently, a computational centrifugal acceleration at the level of 21/2 times the acceleration due to gravity is produced even given a comparatively low axial velocity of 1 m/s in the cooling agent, so that it is possible to use the inner-finned tubes according to the invention even in the case of comparatively low axial flow velocities. It is therefore possible for arbitrarily heated steam generators to be fitted with the inner-finned tubes according to the invention.