A 150 kWth second generation chemical looping combustion reactor system has been designed. It is a double loop circulating fluidized bed meant to achieve high solids circulation and be flexible in operation. Attention was also focused on the usage of industrial solutions and compactness, to go towards commercialization and pressurization as a further step. Both its hydrodynamic behaviour and design solutions were investigated by means of a full scale cold flow model. First the design of the nozzles and the share of kinetic losses were verified, together with the solids flow/flux measurements reliability. The air reactor and fuel reactor were then tested separately monitoring their entrainment capabilities and pressure/particles distribution, with main focus on finding the best way of operating the loop-seals and cooling panel configuration. The overall reactor system (combining air and fuel reactor) was tested achieving results close to the design values. Finally, some solutions to further improve its performance are proposed.