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.
Boiling incipience in microchannels
Abstract The available data dealing with boiling incipience of water in microtubes (tubes with diameters in the 0.1–1 mm range) are analyzed. Macroscale models and correlations appear to under predict the heat fluxes that lead to the boiling incipience in microtubes. It is suggested that boiling incipience in microchannels may be controlled by the thermocapillary force that tends to suppress the microbubbles that form on wall cavities. Accordingly, a semi-empirical method is proposed for predicting the boiling incipience in microtubes. The effect of the turbulence characteristics of the microtube on the proposed method is also examined.