Growth rate of a gas bubble during electrolysis in supersaturated liquid

The growth of a spherical gas bubble on a horizontal plane has been studied both experimentally and theoretically. Experiments with a miniature electrode have been carried out in a uniformly (super)-saturated solution of oxygen in water, with and without electrolysis. All experiments have been done at a temperature of 291 K and at (sub)atmospheric pressure(s). An analytical expression has been derived for bubble growth in a uniformly supersaturated (or superheated) liquid, which holds for all Jakob numbers. For the more complicated case of simultaneous electrolysis a power series expansion has been found suitable. The experimental results were reproducible and in all cases the agreement with theoretical models was excellent

Calculation of the remaining lifetime of power transformers paper insulation

Abstract-This paper presents the remaining lifetime calculation of power transformers paper insulation and consequently of power transformers. The calculations are performed based on two models, which are related to the thermal degradation of the cellulose winding paper insulation: the common IEC loading guide and a paper degradation model. The paper insulation model’s prediction can be improved by involving data from furfural analysis. The remaining lifetime is extracted from the fault probability (reliability) of the paper insulation. The two models are brought together, to aid the asset manager in the decision making process. A probabilistic approach is used, which can be coupled to analysis in terms of risks, benefits, costs, and availability by the asset manager