Экспериментальные исследования проливов криогенных жидкостей (топлив)

Abstract

Experimental studies were carried out, the analysis of the processes of spillage, spreading and evaporation of the cryogenic liquids (fuels) on a solid surface were carried out. It is shown that the intensity of evaporation of the cryogenic liquids during spills is influenced by many factors: the type of surface on which the spill occurred (concrete, steel, soil, sand, etc.), its penetrating ability, temperature, thickness of the receiving layer, humidity, atmospheric mobility, and, etc. The evaporation rate is determined by the total heat flow coming to the liquid from the external sources. In this case, the heat flow coming from the underlying surface is dominant. Studies of the evaporation of cryogenic liquids during spills on various surfaces showed that the evaporation process has a non-stationary character. This is especially evident at the initial stage of evaporation when its intensity decreases 5֪–6 times in the first 1.5 minutes. After 6–8 minutes, the process goes into a quasi-stationary mode, and the evaporation rate decreases slowly. In case of spills on the solid surfaces, the evaporation process is satisfactorily described (depending on the nature of the surface) by the calculated ratios obtained. Seepage of liquid deep into the sand increases the intensity of evaporation by 2–3 times. Presence of moisture in the ground, on the one hand, reduces the seepage of liquid due to its freezing, and on the other hand, additional heat is released during freezing to vaporize the liquid. Presence of moisture in the ground can increase the evaporation rate by up to 50 % at a non-stationary evaporation site. Based on two scenarios of cryogenic liquids spilling (instantaneous or prolonged expiration) onto a limited or unlimited surface, physicomathematical models of their spreading during leakage were developed. These models, in turn, are implemented as methods for assessing the hazardous factors of fires under various scenarios of their occurrence and explosions on the territory of the facility and in the residential area near the facility.