CFD-based correlation for forced convection heat transfer in circular ducts of internally heated molten salts

Heat transfer phenomena involving internally heated fluid flows are of particular interest in several industrial applications, in chemical plants as in the nuclear field. This topic is relevant for the development of the Molten Salt Reactors (MSRs) since it involves the safety characteristics of the liquid molten salt fuel. In the literature, there is a lack of systematic studies on the heat transfer mechanism and correlations for flows in ducts featuring an internal heat source, apart from some analytical studies performed in Fiorina et al., ”Thermal-hydraulics of internally heated molten salts and application to the MSFR”, Journal of physics, Conference series 501 (2014). In this work, the Nusselt number is computed multiplying the traditional Nu for internal flows times a corrective factor to account for the internal heat source. As a main outcome of this work, it is possible to obtain a CFD-based improved estimate of the corrective factor correlation for turbulent flow regime with respect to the work by Fiorina. The numerical CFD analysis is performed with the open source code OpenFOAM. Despite its simplicity, the method is general and applicable for any geometrical and thermal situations.