Natural Convection in Inclined Pipes - A New Correlation for Heat Transfer Estimations

Heat intake minimization is one of the main challenges during the design process of cryogenic storage tanks. It is widely known that connection pipes significantly contribute to this residual heat transfer from ambient temperature conditions to the cold inner vessel. A certain pipe inclination can cause a convective flow field within the fluid. This effect usually increases the total heat transfer much more dramatically than anticipated. In several previous papers we discussed the impact of pipe geometry as well as boundary conditions intensively. However, there is no suitable correlation in literature available which could be used to estimate the total heat transfer properly. The large number of experimental data we gained during our investigations allows us to propose a new correlation in order to predict the total heat transfer through an inclined pipe in function of the inclination angle. In this paper we derivate this new correlation and show its application for heat transfer estimations. Several comparisons are carried out against our own measurements as well as literature data.