Heat Transfer Analysis Of The Cryogenic Liquid Drained Directly Into Water And Experimental Investigation Of The Draining Under Near-atmospheric Pressure

With the development of science and technology, all kinds of cryogenic liquids are used more and more widely. If the container of the cryogenic liquid is damaged, it may explode. Then the cryogenic liquid must be drained promptly. In some special conditions, the cryogenic liquid only can be drained underwater. Therefore, the problem of how to drain the cryogenic liquid into water effectively is worth researching.The necessity of draining the liquid directly when the cryogenic liquid is drained underwater is analyzed. The surviving distance of the cryogenic liquid column is defined. A simplified method is put forward independently to estimate the surviving distance of the cryogenic liquid column. The process and characteristics of heat transfer between cryogenic liquid and water are different under different environment pressure (water pressure). For different water pressure, four heat transfer models are established: the near-atmospheric pressure model, the common pressure model, the near-critical pressure model, and the high pressure model. The mathematical models of the near-atmospheric pressure model and the high pressure model are established. Some calculations based on the two mathematical models are done and the results of calculations are analyzed.The experiment of draining the liquid nitrogen directly into near-atmospheric pressure water is done for the first time. Some motive and still pictures of the flow patterns, the draining process and the experimental phenomena are gotten and analyzed. The flow patterns, the draining process, and the phenomena of icing and self-deicing are described. The temperature measurement data are qualitatively analyzed. The estimate value and the observed value of the surviving distance of the liquid nitrogen column are compared. The estimate value accords basically with the observed value. The icing problem is discussed emphatically. Some factors of the draining vent conditions that influence the icing state are analyzed. Multifold techniques and methods of anti-icing and deicing are summarized. Some ideas of anti-icing and deicing of the cryogenic liquid underwater draining vent are presented.The research validates the feasibility of draining the cryogenic liquid directly into water and offers the basis of designing the draining device. The heat transfer models established in the paper have important reference value to establishing the complex models that consider comprehensively heat transfer, mass transfer and flow.