Direct Cooling Systems for Turboalternator Rotors in View of the Maximum Rating of Hydrogen Cooling

The paper describes the solutions developed for direct cooling of turboalternator rotors. On the basis of calculations relating to the rotor of a 800-MW alternator, the different constructional solutions are compared from the aspect of cooling efficiency. On the basis of the results of the calculations, it is established that in addition to the water-cooling solutions the most efficient one is the gas-cooling layout based on the gap-pickup principle, where the cooling gas streams in transverse channels of small cross section. It is demonstrated that only water-cooling solutions provided with many parallel branches can compete with this gas- cooling system.