Abstract
During manned space missions, an environmental control and life-support system (ECLSS) is employed to meet the life-supporting requirements of astronauts. The ECLSS is a type of hierarchical system, with subsystem—component—single machines, forming a complex structure. Therefore, system-level conceptual designing and performance evaluation of the ECLSS must be conducted. This study reports the top-level scheme of ECLSS, including the subsystems of atmosphere revitalization, water management, and waste management. We propose two schemes based on the design criteria of improving closure and reducing power consumption. In this study, we use the structural entropy method (SEM) to calculate the system order degree to quantitatively evaluate the ECLSS complexity at the top level. The complexity of the system evaluated by directed SEM and undirected SEM presents different rules. The results show that the change in the system structure caused by the replacement of some single technologies will not have great impact on the overall system complexity. The top-level scheme design and complexity evaluation presented in this study may provide technical support for the development of ECLSS in future manned spaceflights.
Highlights
Environmental control and life-support systems (ECLSS) are utilized to meet the survival requirements of astronauts in a space environment
This study focuses on the scheme design and the complexity evaluation of ECLSSs
Two schemes are designed based on the principle of improving system closure and reducing power consumption
Summary
Environmental control and life-support systems (ECLSS) are utilized to meet the survival requirements of astronauts in a space environment. The quantitative evaluation of ECLSS top-level scheme can adopt many different evaluation indices, such as equivalent system mass [17], closure degree [31], complexity [31], robustness [32], life-cycle cost [33], etc. The SCM measures complexity by calculating the number of single machines or connections in the actual physical system structure, which is suitable for the initial screening of ECLSS technology [34]. Entropy is used to quantitatively describe the uncertainty and order degree of system structure, which can facilitate complexity evaluation [42,43,44,45]. Wang [46] built an evaluation model based on information entropy and investigated the order degree of the organizational structure of power regulatory agencies in terms of timeliness and quality of information flow. We focus on directionality and establish D-SEM to evaluate the complexity of the system structure
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