Interstage cooling system of a multi-compressor turbocharger, engine and turbocharger comprising such a cooling system, and method of operating the turbocharger

An interstage cooling system (10) for the turbocharger of an internal combustion engine is disclosed. Diffuser vanes (38), turning vanes 48 and/or deswirling vanes (40) are used as the heat exchangers in the interstage duct (12). A coolant fluid is supplied to the heat exchangers and flows between the heat exchangers, in series, through internal coolant links or through internal cavities as defined by the turbocharger housing.