G8 Shell-Side Heat Transfer in Baffled Shell-and-Tube Heat Exchangers

The method described in this chapter for calculating the mean heat transfer coefficient on the shell-side of a baffled shell-and-tube heat exchanger is based on the corresponding method for calculating the mean heat transfer coefficient in a tube bundle with a cross flow. However, the flow configuration on the shell-side of a baffled shell-and-tube heat exchanger leads to a number of deviations from the case of a flow across a tube bundle. The geometry of the baffles in the heat exchanger shell – as shown in Fig. 1 – generates a main stream through the heat exchanger tube bundle, which is partly across and partly parallel to the tubes. Unavoidable clearances between the outer surface of the tubes and the holes in the heat exchanger baffles, as well as between the baffles and the inside shell surface lead to leakage streams, which participate in heat transfer, but not to the same extent as the main stream. Since the tubes in the tube bundle cannot be brought uniformly and very close to the shell, bypass streams occur in the gaps between the outer tubes of the bundle and the inside surface of the heat exchanger shell; such bypass streams do not participate effectively in heat transfer. These geometrical factors dictated by the design of a shell-and-tube heat exchanger lead to deviations between the heat transfer in a tube bundle and that on the shell-side of a baffled heat exchanger; they can be taken into account by means of correction factors. The correction factors described hereafter are based on data given by Bell [1]. The presented method of calculation was checked by Gnielinski and Gaddis [2] through a large number of experimental measurements available in the open literature.