AbstractUsing a Lyon (3) type of analysis, theoretical Nusselt numbers have been calculated for liquid metals flowing in concentric annuli, under conditions of constant heat flux and fully-established turbulent flow. These have been expressed in the form of semiempirical equations for the case of heat transfer from the inner wall only and for the case of heat transfer from the outer wall only. Predictions on the basis of these equations are compared with those by other relationships and with experimental results. The proposed equations are consistent with those for turbulent flow of liquid metals inside circular tubes and between parallel plates; the former being the limit for an annulus asr2/r1approaches infinity, and the latter being the limit asr2/r1approaches unity.