Abstract:

To improve the emergency handling ability of high expansion foam to mitigate the leakage and diffusion of cryogenic liquids such as liquefied natural gas (LNG) and pool fire combustion, three environmental-friendly nanoparticles with natural sources, degradability and stable structure were selected. The effects of different particle mass fractions on foaming ability and stability were experimentally tested, and the suppression effect of nanoparticles on cryogenic liquid evaporation was also analyzed. The results show that the foaming ability gradually decreases with the increasing particle concentrations, and the liquid drainage rate first increases and then decreases. The foam half-life reaches the maximum value at the lignin particle mass fraction of 0.1% and then decreases with the increasing mass fraction, while the foam stability increases with the increasing of nanofiber and nanowhisker concentrations. The foam size with the addition of lignin increases rapidly, while under the addition of nanofibers and whiskers, the increase of the foam size is relatively small as the time goes on. There are three stages of rapid evaporation, stage evaporation and decay evaporation during the foam suppression process, and the maintenance time of cryogenic liquids was extended with the presence of nanoparticles, which is beneficial for suppressing the liquid evaporation process.

Key words: nanoparticles, foam stability, suppression, foaming ability, foam half-life, evaporation rate