Effects of Presence of Foreign Nuclei on Mass Flux at Cooling Walls in Cryogenic Freezer

概要

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A cryogenic freezer system is one of the most useful systems in connection with the hydrogen isotope recovery, which is expected to be used in a fuel cycle of a D-T fusion reactor, particularly in a fuel gas refining system. As an example of the cryogenic freezer system, it is designed to freeze water vapor containing tritium at a temperature of 160 K from all condensable impurities eluted from a molecular sieve bed(1)(2). It is very important to investigate the influence of the variables on a mass flux at cooling walls of the freezer. The effects of frost formation on cooling walls and mist formation in a gas stream on an average mass flux in a cooling pipe were experimentally and theoretically studied and were presented in a separate paper(3). It is considered that there are cases where foreign nuclei of impurities are present in the cryogenic freezer, because the gas eluted from the molecular sieve bed is generally composed of multi-component condensable mixtures. In this note the basic experiments and the numerical calculations were carried out for the investigation of the effects of the presence of foreign nuclei in a gas stream on the mass flux. The NaCI nuclei which are generated by the evaporation and the fast cooling-down of a NaCl solid in an electric furnace(4) were used in this experiment as the foreign nuclei.