DISTINCTIVE FEATURES OF CONSTRUCTION OF LARGE CRYOGENIC SYSTEMS

摘要

The distinctive features of construction of cryogenic systems depend on such specific properties of cryogenic fluids as low temperature, narrow range of occurrence in a fluid state, possibility of phase transition, etc. In this regard, processes in cryogenic systems encompass an extraordinarily wide range of phenomena and are associated with variation in the properties of the working medium, when, subject to temperature conditions, there occur a single-phase liquid, a single-phase liquid with vapor pockets in stagnant areas, a two-phase vapor-liquid stream, and a solid-liquid phase (slush ice); a special case is single- and two-phase superfluid helium (He Ⅱ) as a unique quantum fluid. Generation and maintenance of preset temperatures in various units of the cryogenic systems indeed determine the major features of their construction. By now, a lot of experience has been gained in constructing large cryogenic systems that have considerable lengths (from hundreds of meters to several scores of kilometers) and large volumes, and that consume a large amount of cryogenic product. Stringent demands are imposed on the operating conditions (temperature, pressure, flow rate, presence of vapor phase, etc.) of such systems. Often, during thermostatic control, complex external heat-loading conditions are assigned. Cryogenic systems are built for space rocket (SRT) and boosting technology. In SRT, successful use is being made of the Energiya-Buran (Energy-Blizzard) system (Fig. 1) and of ocean-based launching systems (Fig. 2) where the cryogen storage is constantly rocked by ocean waves. Depending on the purpose, large cryogenic systems may be divided into storing and filling systems and cryostatting systems.