Multi-design Innovative Cooling Research & Optimization (MICRO): a novel set of optimized solutions for enhanced heat transfer in DEMO

Several novel design solutions for high performance cooling systems have been developed and realized by Consorzio RFX, permitting to experimentally simulate the challenging heat transfer conditions foreseen in the future fusion devices. The project, called Multi-design Innovative Cooling Research & Optimization (MICRO), has the triple objective to verify the present solution applied inside the MITICA experiment, to perform improvements with an acceptable pressure drop and reliable manufacturing process and to develop further optimized solutions with a detailed exploration of the Design Space investigating the interrelated effects of input geometric parameters. The main advantages rely on the possibility to extend the fatigue life-cycle of different high thermal stress components and to investigate the possibility to employ alternative dielectric fluids instead of water. Design solutions characterized by a large enhancement of the heat transfer process would in fact allow the exploitation of less performing fluids in terms of cooling capability. If the unavoidable deterioration of the cooling parameters would not prevent satisfying the thermostructural requirements set for such kind of components, these dielectric fluids would represent a significantly advantageous option with respect to the existing technologies. This is particularly relevant in view of DEMO and future power plants characterized by higher efficiency and reliability. The numerical investigation has been carried out on a set of different scale components, focusing the CFD optimization stage on a suitable portion of the domain (exploiting the spatial repetition of the applied heat loads), while the numerical assessment from the mechanical point of view has been performed on a full-scale model in order to take into account the global effect of thermal strain and stress. This paper gives a detailed description of the analyses performed with ModeFRONTIER, the optimization multi-objective software, together with the samples manufacturing and of the experimental tests that have been carried out so far. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the EURATOM research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.