Scientific and Technical Aspects of Thermal Control Two-Phase Systems Applications on Spacecraft

The article gives a survey of results on the application of the ammonia two-phase Centralized Heat Rejection System (CHRS) in the Russian Segment (RS) of the International Space Station (ISS). The work has been performed by the following organizations: RSC “Energiya”, Kharkov Aviation Institute, ZNII Mash, Bauman MSTU and the Keldysh Research Center. In this cooperation the Keldysh Research Center was responsible for the development of the two-phase system elements and the ammonia system as a whole. This stage of the work was concluded by the flight experiment with a model analogue of the ammonia two-phase CHRS of the RS for the ISS in the transport spacecraft “Progress-242” as a part of the space station “Mir”. The article describes scientific and technical problems, which should be solved to promote this work. These are the development of calculation procedures, test methods for two-phase system elements, development and engineering of a special experimental base for ammonia operation, designing of special units for preparation and filling loops with ammonia, performance of various testing experiments including a full-scale loop model testing. The primary attention in this article is given to the works of the Keldysh Research Center, their results as a whole being presented. It is shown that the data obtained from the flight experiment confirm the validity of scientific and technical developments being realized in the two-phase system of the CHRS of the RS for the ISS as well as the effectiveness of procedures and methods of ground-based experiments used for the two-phase loops designing.