Search Results

Space system design begins with mission objectives and constraints and then proceeds to the definition of a system, which will meet those objectives at the lowest possible cost. The complexity of design of any advanced system is driven by the lack of knowledge about future system parameters and uncertainty in mission objectives. It is important for the designer to be able to conduct preliminary analysis and evaluation of available alternative technologies and systems without finalized parameters. However it is very difficult for a designer to perform a valid evaluation using multiple criteria and selecting from multiple technologies. Present techniques for evaluation use a single criterion approach based on equivalent system mass metric. The conversion coefficients that represent power, volume, crew time, etc. in equivalent mass units are rather subjective and questionable.

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.

This paper describes the concept of Ecotechnical System (ETS) based on the analysis of mass, power and data flow exchange within a biocenosis and between a biocenosis and technical systems that support life and activity of any biological entity in isolated environment of space vehicle. A biocenosis is considered to be a gathering of live organisms (generally people, animals, plants and micro-organisms) in an artificial habitat of the isolated environment. An Ecotechnical System is defined and it is shown that the given concept brings together different life support systems based on physical-chemical and biological means of regeneration of crew metabolic products. The existing limitations to the ETS development are reviewed in the paper in respect to limited volumes of space vehicles based on the vehicle characteristics and particular space program tasks. Three step analysis approach proposed for ETS effectiveness evaluation.

This paper reviews the preliminary definition of integrated life support system configurations based on a single criterion decision-making task (SCDMT). Comparative analysis results are shown for currently used effectiveness models based on SCDMT. Possible areas of application for those models are determined. It is also proven that well-known effectiveness model, which uses an equivalent mass approach to determine system expenditures, can be used only in cases where useful effect from system operation is the same. The article proposes the use of a global thermodynamic effectiveness criterion based on the exergy method to account for ECLSS functional expenditures, i.e. functional costs. Exergy is a concept that fuses energy and material quality information in a measure that is both descriptive and physically significant. This method accounts for nonequivalence of different forms of energy and allows measuring technological flows in the system using same measuring units.

The research conducted at NIICHIMMASH for the past several years in the area of Integrated Life Support System (ILSS) strategy development for technology efficiency analysis and system structure synthesis is reviewed in this paper. This study proposes an generalized efficiency model for ILSS development, which includes global, thermodynamic and local quantitative and qualitative factors. The research resulted in a strategy for the synthesis of ILSS structure based on evolutionary and integral- hypothhetical approaches. This strategy allows development of new system configurations, evaluation of existing ILSS effectiveness and considers decision marker's (DM) preferences. Uncertainty in the initial information about properties of the system or technology has a big influence on DM making decisions about future system appearance. Fuzzy set theory is used to define the uncertainty in the initial information.

This paper considers one of the possible approaches to the synthesis of technologies for developing future Integrated Regenerative Life Support Systems (IRLSS) for space vehicle crews. The solution of technology synthesis task involves the following phases: (a) the efficiency model structuring for technical decision making process; (b) presentation of a discrete set of alternative technologies and their formal description; (c) the decision making task introduction. Modified efficiency model under consideration is based on use of local efficiency criteria set, reflecting designed system and its subsystems properties, space vehicle properties for which this system is intended. For the local criteria after verification of the independence terms quantitative and qualitative efficiency factors are applied. The qualitative efficiency factors were evaluated on the scale of order. The consideration of uncertainty in criteria values is based on a fuzzy set theory.