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A newly developed mechanistic model of bubble dynamics in single microchannel is presented in this paper. The comparison between high-speed visualization and simulation results shows that this model is capable of capturing the transient flow regime and slug velocity inside of single microchannel and predicting flow reversal. The model quantitatively demonstrates the mechanism of flow reversal. Within one periodic cycle, the evolvement of flow regime, pressure distribution along channel length and mass flux at tube inlet are well correlated with each other. The local pressure peak caused by the build-up of downstream flow resistance can cause negative pressure gradient, which induces flow reversal. [ABSTRACT FROM AUTHOR]

Thermal aging of insulation paper has obvious effects on its moisture absorption property. The presented studies aim to investigating the effects of aging on moisture diffusion in oil-immersed insulation paper. Based on the experimental designs and preparation of experimental materials, the transient moisture contents of insulation paper with different aging status were obtained at different conditions. Then, the experimental results were discussed. Furthermore, the diffusion factors and equilibrium time constants were extracted based on the model of moisture diffusion in oil-immersed insulation paper, which are applicable to our studies. Finally, the effects of thermal aging on the diffusion factor and equilibrium time constant were analyzed. The results show that: 1) With the aging of insulation paper, the rate of moisture absorption increases, and the equilibrium moisture content of insulation paper decreases at the same temperature. Besides, the equilibrium time constant decreases with aging at the same temperature. 2) Considering the effects of aging, thickness of insulation paper and temperature, the empirical expression of diffusion factor was obtained and verified. [ABSTRACT FROM AUTHOR]