Modeling of degradation and regeneration of porous materials based on polytetrafluoroethylene in transformer oil filtration
DOI:
https://doi.org/10.31359/2311.441X.2026.28.131Keywords:
polytetrafluoroethylene ( PTFE), porous materials, transformer oil, microfiltration, mathematical modeling, degradation, regeneration, fouling, hydraulic resistance, dirt-holding capacity, filtration processesAbstract
Abstract. The paper addresses the problem of degradation and regeneration of porous filtering materials based on polytetrafluoroethylene (PTFE) used for purification of transformer oils during the operation of power electrical equipment. The relevance of the study is обусловлена the need to ensure stable dielectric and эксплуатационные properties of transformer oils, which deteriorate over time due to the accumulation of mechanical impurities, oxidation products, and moisture.
The aim of the work is to develop a mathematical model of multi-cycle operation of a PTFE filter, taking into account contaminant accumulation, increase in hydraulic resistance, structural degradation of the material, and reduction in regeneration efficiency. The object of the study is sintered PTFE obtained by leaching a NaCl pore-forming agent, which results in a bimodal cavity-channel pore structure.
The proposed model is based on Darcy’s law for describing fluid flow in porous media and introduces a dimensionless pore filling factor that relates the mass of accumulated contaminants to the dirt-holding capacity of the material. The nonlinear dependence of hydraulic resistance on the degree of clogging accounts for different mechanisms of filling of large cavities and narrow inter-pore channels. Particular attention is paid to modeling the degradation of regeneration efficiency under multi-cycle operation, as well as to the accumulation of irreversible residues that reduce the available dirt-holding capacity and increase the initial hydraulic resistance of the filter.
Numerical simulation of 10 filtration–regeneration cycles was carried out under specified operating parameters. It was established that the filter lifetime decreases by more than three times (from 8.64 to 2.80 hours), while the initial hydraulic resistance increases by a factor of 2.44. It is shown that the total volume of filtered oil in multi-cycle operation is 6.3 times higher than that of single-use operation, confirming the feasibility of regeneration despite its gradual degradation.
Sensitivity analysis revealed the dominant influence of two key factors: the initial dirt-holding capacity and the regeneration efficiency. It is shown that increasing the dirt-holding capacity through optimization of the pore-former granulometry significantly enhances the filter lifetime, while improving regeneration efficiency (e.g., by ultrasonic treatment combined with heated solvents) increases the number of operating cycles and the total volume of purified oil.
References
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