Development of control principles for the desalination unit for closed life support systems for space purposes

The development of the Solar system by humans implies the creation of long-term habitable bases on a number of cosmic bodies: the Moon, Mars, etc. Maintaining an environment favorable for the crew on such bases is possible thanks to life support systems (LSS), in which a closed mass transfer of products and waste between the crew, the unit of higher plants and other links is implemented. Closure increases the reliability and autonomy of the system, and reduces the cost of its supply.Controlling such mass transfer appears to be a difficult technical task requiring many man-hours, which is a valuable resource in the implementation of manned space missions. In the general case, this problem is solved by means of automation, however, it is necessary to take into account the specifics of the processes that support mass transfer, since this will allow finding ways to simplify the hardware and logical components, increase their versatility and reliability. This article presents an analysis of the technological processes of the experimental unit for the separation of NaCl from solutions of mineralized human metabolites and proposes a simple control algorithm that can be used for all processes of the unit without fundamental changes. Without the development of a NaCl transformation cycle, it becomes almost impossible to create a long-term functioning biological and technical life support system - the optimal LSS option for alien bases.In such systems, mass transfer occurs between the crew and the link of higher plants and there is a danger of NaCl accumulation in irrigation solutions and subsequent poisoning of the plant link. Therefore, the problem of controlling the NaCl transformation cycle in mass transfer processes of a high degree of closure is relevant, and the universal principles of automated control can be used not only in space, but also in terrestrial applications: in closed agrotechnical cycles and scientific and educational stands.