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With the aim of clarifying conditions for dangerous discharge of cryogenic fuels into water in a test unit heat exchange in the area of the discharge pipe, evaporation and heating of vapors during their movement in water are studied. It is established that with continuous outflow of liquid nitrogen into water through fittings made of different materials in regimes that are possible in a real system the continuous shearing of ice due to the hydrodynamic thrust of the flow provides independence of the average flow rate on parameters of the emerging product, but it depends to a considerable degree on orientation of the flow. Calculated results are provided for emergence of liquid hydrogen during which with discharge from an industrial system into sea water there may be formation of an incendiary cloud.In creating cryogenic fuel systems, operating under sea water conditions, it is necessary to resolve some scientific and technical problems, one of which is dangerous discharge of cryogenic fuels into water. As studies have shown [1], depending on the thermodynamic properties of the liquid, the level of delivery, the permissible pressure at the instant of opening the drainage protection channel into the water, there is a possible outflow of liquid, vapor, a two-phase stream, or substance with critical parameters. With a reduction in the amount of liquid in a vessel and heating of it, the parameters of the discharged product also change. It is also necessary to consider that gas discharge may have a marked effect on heat and mass transfer in the zone of the end of the discharge pipe (nozzle). A particular problem is total or partial closing of a section of the pipe as a result of freezing over with ice that may lead to an impermissible increase in pressure in the vessel, particularly with unsealing of the heat insulation area.In view of this, in order to clarify conditions for dangerous discharge of cryogenic fuel into water an experimental study has been made of heat and mass transfer in the zone of the discharge pipe, evaporation and heating of vapors with movement in water. Heating is not connected with processes in the vessel and the discharge pipe, but it is necessary to know parameters of the evaporating cryogenic fuel in water in order to evaluate their effect on structural elements of a component, and also in order to evaluate the explosion danger of the situation in the atmosphere.In order to select a pipe construction and conditions for safe discharge of cryogenic fuel, experiments were carried out in a test unit (Fig. 1) created on the basis of a cryogenic reservoir 8 with a volume V = 0.112 m 3 and an operating pressure p w = 3.7 MPa. The working body used was liquid nitrogen 7, it was discharged into a vessel with water 1 (V = 6 m 3 ) fitted with five port-lights 2 for visual monitoring. The measurement system made it possible to record the temperature field in the cryogenic reservoir and the vessel with water, pressure and the level of delivery into the cryogenic reservoir, the liquid nitrogen flow rate (c...

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