Research on gas-liquid-solid insulation system in stator slot
In evaporative cooling turbogenerator, all structures are immersing in evaporative cooling medium. Evaporative cooling turbogenerator which is transformed from inner water-cooling turbogenerator has been developed successfully. However, it has not taken full advantage of evaporative cooling medium's superiority in insulation. Besides, the amount of cooling medium is relatively large. This paper redesigns and analyzes gas-liquid-solid insulation system in stator slot from the perspective of the evaporative cooling technology. Furthermore, this paper provides the most appropriate materials and optimum thickness for solid insulation layer and fixed insulation layer in new insulation system. At last, this paper discusses wrapping width and interval of fixed insulation layer by three-dimensional model of new-designed insulation system.
Study of the gas-flow and heat-transfer in the wedge-shaped air gap of evaporation cooling turbo generator
Turbo generator with evaporative cooling stator and water cooling rotor possesses many excellent qualities for mid unit. The stator bars and core are immerged in evaporative coolant, which could be cooled fully. The rotor bars are cooled by water inner cooling mode. This paper presents the study of gas-flow and heat-transfer with different features in the turbo generator, and analyzing it by CFD. At last, the study provides foundation for the calculation of gas-flow and heat-transfer.
Cooling techniques for high-power thyristors
Along with the growth of the electric-power system capacity, the power densities of the components are steadily increasing. The power consumption of thyristors increases, so that more effective cooling techniques ought to be used. This paper described the principles, characteristics and status quo of the development of various cooling techniques for high-power thyristors. The immersion evaporative cooling technique was considered to have superiority over other cooling techniques and quite good prospects. In the immersion evaporative cooling system, an obturator is adopted, so that the internal pressure varies between vacuum and 3 atm.As pressure vessels, large high-pressure cooling equipment must abide by the safety regulations of the state, which exerts a negative influence on the development of the equipment. A new type of cooling system, the constant-pressure evaporative cooling system, was therefore proposed, and its principle and characteristics were discussed briefly.