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The paper deals with description and results of long-term operation of separation and heat-and-mass transfer hardware incorporated in Mir's water recovery systems. Static separators outfitted with hydrophilic capillary/ porous elements, a rotary separator, a through-flow condenser/static separator combination, a membrane evaporator as well as separation and distillation schematics are reviewed. Operational and life performance data are discussed and recommendations for hardware use on ISS are made.

The paper systematizes typical hydrodynamic and heat-and-mass transfer chemical engineering processes realized in water recovery systems. The impact of micro-gravity on the processes is analyzed and general principles of the process organization in gas/liquid fluids are described. As examples, some typical separation processes in a coccurred flow channel with liquid suction through a porous wall, liquid evaporation into a vapour/gas fluid and vapour condensation from the vapour/gas mixture are considered for water recovery systems. A versatile approach based on an extended analogy between friction, heat transfer and mass transfer and on limited relative laws of a boundary layer at the permeable surface is suggested for an analysis and calculation of the friction resistance of a two-phase flow, heat transfer and mass transfer on evaporation and condensation. Recommendations for an analysis of the influence of free convection are made.

The design of any complex system, especially eco-technical is very challenging due to the variety of processes, system composition, relation between different components and presence of the human. Process and technology selections affect the flow rate, composition, and phase of all resulting components. Therefore, evaluating alternative processes and/or technologies used often requires one to compare the relative environmental merits of distinctly different residual streams. Traditional thermodynamic analysis based on the first law of thermodynamics describes the conservation of energy. In this type of analysis all forms of energy are considered to be equivalent. The loss of quality of energy is not taken into account. It shows the energy flow to be continuous and energy balance is always closed. There can never be an energy loss, only energy transfer to the environment in which case it is useless.